Glossary

This glossary provides terms and definitions for the IBM MQ software and products.

The following cross-references are used in this glossary:

See refers you from a nonpreferred term to the preferred term or from an abbreviation to the spelled-out form.
See also refers you to a related or contrasting term.

A B C D E F G H I J K L M N O P Q R S T U V W X Parent topic: About IBM MQ

A

abend reason code

A 4-byte hexadecimal code that uniquely identifies a problem with a program that runs on the z/OS operating system.

abstract class

In object-oriented programming, a class that represents a concept; classes derived from it represent implementations of the concept. An object cannot be constructed from an abstract class; that is, it cannot be instantiated. See also parent class.

Abstract Syntax Notation One (ASN.1)

The international standard for defining the syntax of information data. It defines a number of simple data types and specifies a notation for referencing these types and for specifying values of these types. The ASN.1 notations can be applied whenever it is necessary to define the abstract syntax of information without constraining in any way how the information is encoded for transmission.

access control

In computer security, the process of ensuring that users can access only those resources of a computer system for which they are authorized.

access control list (ACL)

In computer security, a list associated with an object that identifies all the subjects that can access the object and their access rights.

ACL

See access control list.

active log

A data set with a fixed size where recovery events are recorded as they occur. When the active log is full, the contents of the active log are copied to the archive log.

active queue manager instance

The instance of a running multi-instance queue manager that is processing requests. There is only one active instance of a multi-instance queue manager.

adapter

An intermediary software component that allows two other software components to communicate with one another.

address space

The range of addresses available to a computer program or process. Address space can refer to physical storage, virtual storage, or both. See also allied address space, buffer pool.

administration bag

In the IBM MQ Administration Interface (MQAI), a type of data bag that is created for administering IBM MQ by implying that it can change the order of data items, create lists, and check selectors within a message.

administrative topic object

An object that allows you to assign specific, non-default attributes to topics.

administrator command

A command used to manage IBM MQ objects, such as queues, processes, and namelists.

Advanced Message Queuing Protocol (AMQP)

An open-source wire protocol that is used to receive, queue, route, and deliver messages.

Advanced Program-to-Program Communication (APPC)

An implementation of the SNA LU 6.2 protocol that allows interconnected systems to communicate and share the processing of programs.

affinity

An association between objects that have some relationship or dependency upon each other.

alert

A message or other indication that signals an event or an impending event that meets a set of specified criteria.

alert monitor

In IBM MQ for z/OS, a component of the CICS adapter that handles unscheduled events occurring as a result of connection requests to IBM MQ for z/OS.

alias queue

An IBM MQ object, the name of which is an alias for a base queue or topic that is defined to the local queue manager. When an application or a queue manager uses an alias queue, the alias name is resolved and the requested operation is performed on the associated base object. For further information, see the topic Alias queues.

alias queue object

An IBM MQ object, the name of which is an alias for a base queue defined to the local queue manager. When an application or a queue manager uses an alias queue, the alias name is resolved and the requested operation is performed on the associated base queue.

allied address space

A z/OS address space that is connected to IBM MQ for z/OS.

ally

See allied address space.

alternate user authority

The ability of a user ID to supply a different user ID for security checks. When an application opens an IBM MQ object, it can supply a user ID on the MQOPEN, MQPUT1, or MQSUB call that the queue manager uses for authority checks instead of the one associated with the application. For further information, see the topic Alternate user authority.

alternate user security

On z/OS, the authority checks that are performed when an application requests alternate user authority when opening an IBM MQ object.

AMQP

See Advanced Message Queuing Protocol.

AMQP channel

A type of channel that provides a level of support for AMQP 1.0-compliant applications. MQ Light clients or other AMQP 1.0 compatible clients can be connected to an IBM MQ AMQP channel.

APAR

See authorized program analysis report.

APF

See authorized program facility.

API-crossing exit

A user written program that is similar in concept to an API exit. It is supported only for CICS applications on IBM MQ for z/OS.

API exit

A user-written program that monitors or modifies the function of an MQI call. For each MQI call issued by an application, the API exit is called before the queue manager starts to process the call and again after the queue manager has completed processing the call. The API exit can inspect and modify any of the parameters on the MQI call.

APPC

See Advanced Program-to-Program Communication.

application-defined format

Application data in a message for which the user application defines the meaning. See also built-in format.

application environment

The environment that includes the software and the server or network infrastructure that supports it.

application level security

The security services that are started when an application issues an MQI call.

application log

In Windows systems, a log that records significant application events.

application queue

A local queue that is used by applications for messaging, through the Message Queue Interface (MQI). Application queues are often set up as triggered queues.

archive log

A data set on a storage device to which IBM MQ copies the contents of each active log data set when the active log reaches its size limit. See also recovery log.

ARM

See automatic restart manager.

ASN.1

See Abstract Syntax Notation One.

asymmetric key cryptography

A system of cryptography that uses two keys: a public key known to everyone and a private key known only to the receiver or sender of the message. See also symmetric key cryptography. For further information, see the topic Cryptography.

asynchronous consumption

A process that uses a set of MQI calls that allow an application to consume messages from a set of queues. Messages are delivered to the application by using a unit of code identified by the application, passing either the message or a token representing the message.

asynchronous messaging

A method of communication between programs in which a program places a message on a message queue, then proceeds with its own processing without waiting for a reply to its message. See also synchronous messaging.

asynchronous put

A put of a message by an application, without waiting for a response from the queue manager.

attribute

A characteristic or trait of an entity that describes the entity; for example, the telephone number of an employee is one of the employee attributes. See also entity.
In object-oriented programming, a property of an object or class that can be distinguished distinctly from any other properties. Attributes often describe state information.

authentication

A security service that provides proof that a user of a computer system is genuinely who that person claims to be. Common mechanisms for implementing this service are passwords and digital signatures.

authentication information object

An object that provides the definitions needed to check certificate revocation lists (CRLs) using LDAP servers, in support for Secure Sockets Layer (SSL) security.

authority check

See authorization check.

authorization

The process of granting a user, system, or process either complete or restricted access to an object, resource, or function.

authorization check

A security check that is performed when a user or application attempts to access a system resource; for example, when an administrator attempts to issue a command to administer IBM MQ or when an application attempts to connect to a queue manager.

authorization file

A file that provides security definitions for an object, a class of objects, or all classes of objects.

authorization service

In IBM MQ on UNIX and Linux systems and IBM MQ for Windows, a service that provides authority checking of commands and MQI calls for the user identifier associated with the command or call.

authorized program analysis report (APAR)

A request for correction of a defect in a supported release of a program supplied by IBM.

authorized program facility (APF)

In a z/OS environment, a facility that permits the identification of programs that are authorized to use restricted functions.

automatic restart manager (ARM)

A z/OS recovery function that can automatically restart batch jobs and started tasks after they or the system on which they are running end unexpectedly.

B

backout: An operation that reverses all changes to resources made during the current unit of work. See also commit.
bag: See data bag.
bar: A z/OS memory limit, which in 64-bit systems is set at 2 GB. The bar separates storage below the 2-gigabyte address from storage above the 2 GB address. The area above the bar is intended for data; no programs run above the bar.
basic mapping support (BMS): An interface between CICS and application programs that formats input and output display data and routes multiple-page output messages without regard for control characters used by various terminals.
behavior: In object-oriented programming, the functionality embodied within a method.
BMS: See basic mapping support.
Booch methodology: An object-oriented methodology that helps users design systems using the object-oriented paradigm.
bootstrap data set (BSDS): A VSAM data set that contains an inventory of all active and archived log data sets known to IBM MQ for z/OS, and a wrap-around inventory of all recent IBM MQ for z/OS activity. The BSDS is required to restart the IBM MQ for z/OS subsystem.
browse: In message queuing, to copy a message without removing it from the queue. See also get, put.
browse cursor: In message queuing, an indicator used when browsing a queue to identify the message that is next in sequence.
BSDS: See bootstrap data set.
buffer pool: An area of memory into which data pages are read and in which they are modified and held during processing. See also address space.
built-in format: Application data in a message for which the queue manager defines the meaning. See also application-defined format.

C

CA

See certificate authority.

CAF

See client attachment feature.

callback

A message consumer or an event handler routine.

CCDT

See client channel definition table.

CCF

See channel control function.

CCSID

See coded character set identifier.

CDF

See channel definition file.

certificate authority (CA)

A trusted third-party organization or company that issues the digital certificates. The certificate authority typically verifies the identity of the individuals who are granted the unique certificate. See also Secure Sockets Layer. For further information, see the topic Certificate Authorities.

certificate chain

A hierarchy of certificates that are cryptographically related to one another, starting with the personal certificate and ending with root at the top of the chain.

certificate expiration

A digital certificate contains a date range when the certificate is valid. Outside the valid date range, the certificate is said to be "expired".

certificate request (CR)

Synonym for certificate signing request.

certificate revocation list (CRL)

A list of certificates that have been revoked before their scheduled expiration date. Certificate revocation lists are maintained by the certificate authority and used, during a Secure Sockets Layer (SSL) handshake to ensure that the certificates involved have not been revoked. For further information, see the topic Certificate management.

certificate signing request (CSR)

An electronic message that an organization sends to a certificate authority (CA) to obtain a certificate. The request includes a public key and is signed with a private key; the CA returns the certificate after signing with its own private key.

certificate store

The Windows name for a key repository. For further information, see the topic Personal certificate store.

CF

See coupling facility.

CFSTRUCT

An IBM MQ object used to describe the queue manager's use of a Coupling Facility list structure

channel

An IBM MQ object that defines a communication link between two queue managers (message channel) or between a client and a queue manager (MQI channel). See also message channel, MQI channel, queue manager.

channel callback

A mechanism that ensures that the channel connection is established to the correct machine. In a channel callback, a sender channel calls back the original requester channel using the sender's definition.

channel control function (CCF)

A program to move messages from a transmission queue to a communication link, and from a communication link to a local queue, together with an operator panel interface to allow the setup and control of channels.

channel definition file (CDF)

A file containing communication channel definitions that associate transmission queues with communication links.

channel event

An event reporting conditions detected during channel operations, such as when a channel instance is started or stopped. Channel events are generated on the queue managers at both ends of the channel.

channel exit program

A user-written program that is called from one of a defined number of places in the processing sequence of a message channel agent (MCA).

channel initiator

A component of IBM MQ distributed queuing that monitors the initiation queue and starts the sender channel when triggering criteria are met.

channel listener

A component of IBM MQ distributed queuing that monitors the network for a startup request and then starts the receiving channel.

checkpoint

A place in a program at which a check is made, or at which a recording of data is made to allow the program to be restarted in case of interruption.

CI

See control interval.

CipherSpec

The combination of encryption algorithm and hash function applied to an SSL message after authentication completes.

cipher suite

The combination of authentication, key exchange algorithm, and the Secure Sockets Layer (SSL) cipher specification used for the secure exchange of data.

ciphertext

Data that is encrypted. Ciphertext is unreadable until it is converted into plaintext (decrypted) with a key. See also cleartext.

circular logging

In IBM MQ on UNIX and Linux systems and IBM MQ for Windows, the process of keeping all restart data in a ring of log files. See also linear logging. For further information, see the topic Types of logging.

CL

See Command Language.

class

In object-oriented design or programming, a model or template that can be used to create objects with a common definition and common properties, operations, and behavior. An object is an instance of a class.

class hierarchy

The relationships between classes that share a single inheritance.

class library

In object-oriented programming, a collection of prewritten classes or coded templates, any of which can be specified and used by a programmer when developing an application.

cleartext

A string of characters sent over a network in readable form. It might be encoded for the purposes of compression, but it can easily be decoded. See also ciphertext.

client

A runtime component that provides access to queuing services on a server for local user applications. The queues used by the applications reside on the server. See also IBM MQ fully managed .NET client, IBM MQ Java client, IBM MQ MQI client.

client application

An application, running on a workstation and linked to a client, that gives the application access to queuing services on a server.

client attachment feature (CAF)

An option that supports the attachment of clients to z/OS.

client channel definition table (CCDT)

A file that contains one or more client-connection channel definitions. For further information, see the topic Client channel definition table.

client-connection channel type

The type of MQI channel definition associated with a IBM MQ client. See also server-connection channel type.

CLUSRCVR

See cluster-receiver channel.

CLUSSDR

See cluster-sender channel.

cluster

In IBM MQ, a group of two or more queue managers on one or more computers, providing automatic interconnection, and allowing queues and topics to be advertised among them for load balancing and redundancy.

cluster queue

A local queue that is hosted by a cluster queue manager, and defined as a target for messages being put from an application connected to any queue manager within the cluster. All applications retrieving messages must be locally connected.

cluster queue manager

A queue manager that is a member of a cluster. A queue manager can be a member of more than one cluster.

cluster-receiver channel (CLUSRCVR)

A channel on which a cluster queue manager can receive messages from other queue managers in the cluster, and cluster information from the repository queue managers.

cluster-sender channel (CLUSSDR)

A channel on which a cluster queue manager can send messages to other queue managers in the cluster, and cluster information to the repository queue managers.

cluster topic

An administrative topic that is defined on a cluster queue manager and made available to other queue managers in the cluster.

cluster transmission queue

A transmission queue that holds all messages from a queue manager destined for another queue manager that is in the same cluster. The queue is called SYSTEM.CLUSTER.TRANSMIT.QUEUE.

CMS key database

A CMS key database is the format of the Database supported by Windows systems, UNIX systems, Linux, and the clients of those platforms. Files ending with ".kdb" are CMS format. The ".kdb" files contain the certificates and the keys.

coded character set identifier (CCSID)

A 16-bit number that includes a specific set of encoding scheme identifiers, character set identifiers, code page identifiers, and other information that uniquely identifies the coded graphic-character representation.

coexistence

The ability of two or more different versions of IBM MQ to function on the same computer.

command

A statement used to initiate an action or start a service. A command consists of the command name abbreviation, and its parameters and flags if applicable.

command bag

In the MQAI, a type of bag that is created for administering IBM MQ objects, but cannot change the order of data items or create lists within a message.

command event

A notification that an MQSC or PCF command has run successfully.

Command Language (CL)

In IBM MQ for IBM i, a language that can be used to issue commands, either at the command line or by writing a CL program.

command prefix (CPF)

In IBM MQ for z/OS, a character string that identifies the queue manager to which IBM MQ for z/OS commands are directed, and from which IBM MQ for z/OS operator messages are received.
A 1-character to 8-character command identifier. The command prefix distinguishes the command as belonging to an application or subsystem rather than to z/OS.

command server

The IBM MQ component that reads commands from the system-command input queue, verifies them, and passes valid commands to the command processor.

commit

To apply all the changes made during the current unit of recovery (UR) or unit of work (UOW). After the operation is complete, a new UR or UOW can begin.

common name (CN)

The component in a Distinguished Name (DN) attribute of an X.509 certificate that represents the name normally associated with the owner of the certificate. For people, the CN is usually their actual name. For web servers, the CN is the fully qualified host and domain name of the server. For IBM MQ there are no specific requirements on this field, however many administrators use the name of the queue manager. See also "Distinguished Name"

completion code

A return code indicating how a message queue interface (MQI) call has ended.

confidentiality

The security service that protects sensitive information from unauthorized disclosure. Encryption is a common mechanism for implementing this service.

configuration event

Notifications about the attributes of an object. The notifications are generated when the object is created, changed, or deleted and also by explicit requests.

connection affinity

A channel attribute that specifies the client channel definition that client applications use to connect to the queue manager, if multiple connections are available.

connection factory

A set of configuration values that produces connections that enable a Java EE component to access a resource. Connection factories provide on-demand connections from an application to an enterprise information system (EIS) and allow an application server to enroll the EIS in a distributed transaction.

connection handle

The identifier or token by which a program accesses the queue manager to which it is connected.

constructor

In object-oriented programming, a special method used to initialize an object.

consume

To remove a message from a queue and return its contents to the calling application.

consumer

An application that receives and processes messages. See also message consumer.

context security

On z/OS, the authority checks that are performed when an application opens a queue and specifies that it will set the context in messages that it puts on the queue, or pass the context from messages that it has received to messages that it puts on the queue.

control command

In IBM MQ on UNIX and Linux systems and IBM MQ for Windows, a command that can be entered interactively from the operating system command line. Such a command requires only that the IBM MQ product be installed; it does not require a special utility or program to run it.

control interval (CI)

A fixed-length area of direct access storage in which VSAM stores records and creates distributed free space. The control interval is the unit of information that VSAM transmits to or from direct-access storage. A control interval always includes an integral number of physical records.

controlled shutdown

See quiesced shutdown.

correlation identifier

A field in a message that provides a means of identifying related messages. Correlation identifiers are used, for example, to match request messages with their corresponding reply message.

coupling facility (CF)

A special logical partition that provides high-speed caching, list processing, and locking functions in a sysplex.

CPF

See command prefix.

CRL

See certificate revocation list.

cross-system coupling facility (XCF)

A component of z/OS that provides functions to support cooperation between authorized programs running within a sysplex.

cryptography

A method for protecting information by transforming it (encrypting it) into an unreadable format, called ciphertext. Only users who possess a secret key can decipher (or decrypt) the message into plaintext.

D

DAE

See dump analysis and elimination.

daemon

A program that runs unattended to perform continuous or periodic functions, such as network control.

data bag

A container of object properties that the MQAI uses in administering queue managers. There are three types of data bag: user (for user data), administration (for administration with assumed options), and command (for administration with no options assumed).

data-conversion interface (DCI)

The IBM MQ interface to which customer-written or vendor-written programs that convert application data between different machine encodings and CCSIDs must conform.

data-conversion service

A service that converts application data to the character set and encoding that are required by applications on other platforms.

datagram

A form of asynchronous messaging in which an application sends a message, but does not require a response. See also request/reply.

data integrity

The security service that detects whether there has been unauthorized modification of data, or tampering. The service detects only whether data has been modified; it does not restore data to its original state if it has been modified.

data item

In the MQAI, an integer or character-string item that is contained within a data bag. A data item can be either a user item or a system item.

DCE

See Distributed Computing Environment.

DCE principal

A user ID that uses the distributed computing environment.

DCI

See data-conversion interface.

DCM

See Digital Certificate Manager.

dead-letter queue (DLQ)

A queue to which a queue manager or application sends messages that cannot be delivered to their correct destination.

dead-letter queue handler

A utility that monitors a dead-letter queue (DLQ) and processes messages on the queue in accordance with a user-written rules table. A sample dead letter queue handler is provided by IBM MQ.

decryption

The process of decoding data that has been encrypted into a secret format. Decryption requires a secret key or password.

default object

A definition of an object (for example, a queue) with all attributes defined. If a user defines an object but does not specify all possible attributes for that object, the queue manager uses default attributes in place of any that were not specified.

deferred connection

A pending event that is activated when a CICS subsystem tries to connect to IBM MQ for z/OS before it has started.

derivation

In object-oriented programming, the refinement or extension of one class from another.

destination

An end point to which messages are sent, such as a queue or topic.
In JMS, an object that specifies where and how messages should be sent and received.

Diffie-Hellman key exchange

A public, key-exchange algorithm that is used for securely establishing a shared secret over an insecure channel.

digital certificate

An electronic document used to identify an individual, a system, a server, a company, or some other entity, and to associate a public key with the entity. A digital certificate is issued by a certification authority and is digitally signed by that authority.

Digital Certificate Manager (DCM)

On IBM i systems, the method of managing digital certificates and using them in secure applications on the IBM i server. Digital Certificate Manager requests and processes digital certificates from certification authorities (CAs) or other third-parties.

digital signature

Information that is encrypted with a private key and is appended to a message or object to assure the recipient of the authenticity and integrity of the message or object. The digital signature proves that the message or object was signed by the entity that owns, or has access to, the private key or shared-secret symmetric key.

direct routing

An option for routing publications in a publish/subscribe cluster. With direct routing, every queue manager in the cluster sends publications from any publishing queue manager direct to any other queue manager in the cluster with a matching subscription.

disconnect

To break the connection between an application and a queue manager.

distinguished name (DN)

A set of name-value pairs (such as CN=person name and C=country or region) that uniquely identifies an entity in a digital certificate.

distributed application

In message queuing, a set of application programs that can each be connected to a different queue manager, but that collectively comprise a single application.

Distributed Computing Environment (DCE)

In network computing, a set of services and tools that supports the creation, use, and maintenance of distributed applications across heterogeneous operating systems and networks.

distributed publish/subscribe

Publish/subscribe messaging performed in a multiple queue manager environment.

distributed queue management

In message queuing, the setup and control of message channels between distributed queue managers.

distributed queuing

Send messages from one queue manager to another. The receiving queue manager could be on the same machine or on a remote one.

distribution list

A list of queues to which a message can be put with a single statement.

DLQ

See dead-letter queue.

DN

See distinguished name.

dual logging

A method of recording IBM MQ for z/OS activity, where each change is recorded on two data sets, so that if a restart is necessary and one data set is unreadable, the other can be used. See also single logging.

dual mode

See dual logging.

dump analysis and elimination (DAE)

A z/OS service that enables an installation to suppress SVC dumps and ABEND SYSUDUMP dumps that are not needed because they duplicate previously written dumps.

durable subscription

A subscription that is retained when the connection from a subscribing application to the queue manager is closed. When the subscribing application disconnects, the durable subscription remains in place and publications continue to be delivered. When the application reconnects, it can use the same subscription by specifying the unique subscription name. See also nondurable subscription.

dynamic queue

A local queue created when a program opens a model queue object.

E

eavesdropping: A breach of communication security in which the information remains intact, but its privacy is compromised. See also impersonation, tampering.
Eclipse: An open-source initiative that provides independent software vendors (ISVs) and other tool developers with a standard platform for developing plug-compatible application development tools.
encapsulation: In object-oriented programming, the technique that is used to hide the inherent details of an object, function, or class from client programs.
encryption: In computer security, the process of transforming data into an unintelligible form in such a way that the original data either cannot be obtained or can be obtained only by using a decryption process.
enqueue: To put a message or item in a queue.
entity: A user, group, or resource that is defined to a security service, such as RACF .
environment variable: A variable that specifies how an operating system or another program runs, or the devices that the operating system recognizes.
ESM: See external security manager.
ESTAE: See extended specify task abnormal exit.
event data: In an event message, the part of the message data that contains information about the event (such as the queue manager name, and the application that gave rise to the event). See also event header.
event header: In an event message, the part of the message data that identifies the event type of the reason code for the event. See also event data.
event message: A message that contains information (such as the category of event, the name of the application that caused the event, and queue manager statistics) relating to the origin of an instrumentation event in a network of IBM MQ systems.
event queue: The queue onto which the queue manager puts an event message after it detects an event. Each category of event (queue manager, performance, configuration, instrumentation, or channel event) has its own event queue.
Event Viewer: A tool provided by Windows systems to examine and manage log files.
exception listener: An instance of a class that can be registered by an application and for which the onException() method is called to pass a JMS exception to the application asynchronously.
exclusive method: In object-oriented programming, a method that is not intended to exhibit polymorphism; one with specific effect.
extended specify task abnormal exit (ESTAE): A z/OS macro that provides recovery capability and gives control to the user-specified exit routine for processing, diagnosing an abend, or specifying a retry address.
external security manager (ESM): A security product that performs security checking on users and resources. RACF is an example of an ESM.

F

failover

An automatic operation that switches to a redundant or standby system or node in the event of a software, hardware, or network interruption.

FAP

See Formats and Protocols.

Federal Information Processing Standard

A standard produced by the National Institute of Standards and Technology when national and international standards are nonexistent or inadequate to satisfy the U.S. government requirements.

FFDC

See first-failure data capture.

FFST

See First Failure Support Technology.

FFST file

See First Failure Support Technology file.

FIFO

See first-in first-out.

FIPS

See Federal Information Processing Standard.

first-failure data capture (FFDC)

The i5/OS implementation of the FFST architecture providing problem recognition, selective dump of diagnostic data, symptom string generation, and problem log entry.
A problem diagnosis aid that identifies errors, gathers and logs information about these errors, and returns control to the affected runtime software.

First Failure Support Technology (FFST)

An IBM architecture that defines a single approach to error detection through defensive programming techniques. These techniques provide proactive (passive until required) problem recognition and a description of diagnostic output required to debug a software problem.

First Failure Support Technology file (FFST file)

A file containing information for use in detecting and diagnosing software problems. In IBM MQ, FFST files have a file type of FDC.

first-in first-out (FIFO)

A queuing technique in which the next item to be retrieved is the item that has been in the queue for the longest time.

forced shutdown

A type of shutdown of the CICS adapter where the adapter immediately disconnects from IBM MQ for z/OS, regardless of the state of any currently active tasks. See also quiesced shutdown.

format

In message queuing, a term used to identify the nature of application data in a message.

Formats and Protocols (FAP)

In message queuing, a definition of how queue managers communicate with each other, and of how clients communicate with server queue managers.

Framework

In IBM MQ, a collection of programming interfaces that allow customers or vendors to write programs that extend or replace certain functions provided in IBM MQ products. The interfaces are the following: data conversion interface (DCI), message channel interface (MCI), name service interface (NSI), security enabling interface (SEI), trigger monitor interface (TMI).

friend class

A class in which all member functions are granted access to the private and protected members of another class. It is named in the declaration of another class and uses the keyword friend as a prefix to the class.

FRR

See functional recovery routine.

full repository

A complete set of information about every queue manager in a cluster. This set of information is called the repository or sometimes the full repository and is usually held by two of the queue managers in the cluster. See also partial repository.

function

A named group of statements that can be called and evaluated and can return a value to the calling statement.

functional recovery routine (FRR)

A z/OS recovery and termination manager that enables a recovery routine to gain control in the event of a program interrupt.

G

gateway queue manager: A cluster queue manager that is used to route messages from an application to other queue managers in the cluster.
generalized trace facility (GTF): A z/OS service program that records significant system events such as I/O interrupts, SVC interrupts, program interrupts, and external interrupts.
Generic Security Services API: See Generic Security Services application programming interface.
Generic Security Services application programming interface (Generic Security Services API, GSS API): A common application programming interface (API) for accessing security services.
get: In message queuing, to use the MQGET call to remove a message from a queue and return its contents to the calling application. See also browse, put.
globally defined object: On z/OS, an object whose definition is stored in the shared repository. The object is available to all queue managers in the queue sharing group. See also locally defined object.
global trace: An IBM MQ for z/OS trace option where the trace data comes from the entire IBM MQ for z/OS subsystem.
global transaction: A recoverable unit of work performed by one or more resource managers in a distributed transaction environment and coordinated by an external transaction manager.
GSS API: See Generic Security Services application programming interface.
GTF: See generalized trace facility.

H

handshake: The exchange of messages at the start of a Secure Sockets Layer session that allows the client to authenticate the server using public key techniques (and, optionally, for the server to authenticate the client) and then allows the client and server to cooperate in creating symmetric keys for encryption, decryption, and detection of tampering.
hardened message: A message that is written to auxiliary (disk) storage so that the message is not lost in the event of a system failure.
header: See message header.
heartbeat: A signal that one entity sends to another to convey that it is still active.
heartbeat flow: A pulse that is passed from a sending message channel agent (MCA) to a receiving MCA when there are no messages to send. The pulse unblocks the receiving MCA, which would otherwise remain in a wait state until a message arrived or the disconnect interval expired.
heartbeat interval: The time, in seconds, that is to elapse between heartbeat flows.
hierarchy: In publish/subscribe messaging topology, a local queue manager connected to a parent queue manager.
HTTP: See Hypertext Transfer Protocol.
Hypertext Transfer Protocol (HTTP): An Internet protocol that is used to transfer and display hypertext and XML documents on the web.

I

IBM MQ: A family of IBM licensed programs that provides message queuing services.
IBM MQ Administration Interface (MQAI): A programming interface that performs administration tasks on an IBM MQ queue manager through the use of data bags. Data bags allow the user to handle properties (or parameters) of IBM MQ objects.
IBM MQ classes for .NET: A set of classes that allow a program written in the .NET programming framework to connect to IBM MQ as an IBM MQ client or to connect directly to an IBM MQ server.
IBM MQ classes for C++: A set of classes that encapsulate the IBM MQ Message Queue Interface (MQI) in the C++ programming language.
IBM MQ classes for Java: A set of classes that encapsulate the IBM MQ Message Queue Interface (MQI) in the Java programming language.
IBM MQ fully managed .NET client: Part of an IBM MQ product that can be installed on a system without installing the full queue manager. The IBM MQ .NET client is used by fully-managed .NET applications and communicates with a queue manager on a server system. A .NET application that is not fully managed uses the IBM MQ MQI client. See also client, IBM MQ Java client, IBM MQ MQI client.
IBM MQ Java client: Part of an IBM MQ product that can be installed on a system without installing the full queue manager. The IBM MQ Java client is used by Java applications (both IBM MQ classes for Java and IBM MQ classes for JMS) and communicates with a queue manager on a server system. See also client, IBM MQ fully managed .NET client, IBM MQ MQI client.
IBM MQ MQI client: Part of an IBM MQ product that can be installed on a system without installing the full queue manager. The IBM MQ MQI client accepts MQI calls from applications and communicates with a queue manager on a server system. See also client, IBM MQ fully managed .NET client, IBM MQ Java client.
IBM MQ script commands (MQSC): Human readable commands, uniform across all platforms, that are used to manipulate IBM MQ objects. See also programmable command format.
IBM MQ server: A queue manager that provides queuing services to one or more clients. All the IBM MQ objects, for example queues, exist only on the queue manager system, that is, on the MQI server machine. A server can support normal local MQI applications as well.
IBM MQ Telemetry: Supports small client libraries that can be embedded into smart devices running on a number of different device platforms. Applications built with the clients use the MQ Telemetry Transport (MQTT) protocol and the IBM MQ telemetry service to publish and subscribe messages reliably with IBM MQ.
IBM MQ Telemetry daemon for devices: See MQTT daemon for devices.

identification: The security service that enables each user of a computer system to be identified uniquely. A common mechanism for implementing this service is to associate a user ID with each user.
identity context: Information that identifies the user of the application that first puts the message on a queue
IFCID: See instrumentation facility component identifier.
ILE: See Integrated Language Environment .
immediate shutdown: In IBM MQ, a shutdown of a queue manager that does not wait for applications to disconnect. Current message queue interface (MQI) calls are allowed to complete, but new MQI calls fail after an immediate shutdown has been requested. See also preemptive shutdown, quiesced shutdown.
impersonation: A breach of communication security in which the information is passed to a person posing as the intended receiver or information is sent by a person posing as someone else. See also eavesdropping, tampering.
inbound channel: A channel that receives messages from another queue manager.
in-built format: See built-in format.
index: In the IBM MQ Administration Interface (MQAI), a means of referencing data items.
indoubt unit of recovery: The status of a unit of recovery for which a sync point has been requested but not yet confirmed.
inflight: The state of a resource or unit of recovery that has not yet completed the prepare phase of the commit process.
inheritance: An object-oriented programming technique in which existing classes are used as a basis for creating other classes. Through inheritance, more specific elements incorporate the structure and behavior of more general elements.
initialization input data set: A data set that is used by IBM MQ for z/OS when it starts.
initiation queue: A local queue on which the queue manager puts trigger messages.
initiator: In distributed queuing, a program that requests network connections on another system. See also responder.
input parameter: A parameter of an MQI call in which information is supplied.
insertion order: In the IBM MQ Administration Interface (MQAI), the order that data items are placed into a data bag.
installable service: In IBM MQ on UNIX and Linux systems and IBM MQ for Windows, additional functionality provided as independent component. The installation of each component is optional: in-house or third-party components can be used instead.
instance: A specific occurrence of an object that belongs to a class. See also object.
instance data: In object-oriented programming, state information associated with an object.
intermediate certificate: A signer certificate that is not the root certificate. It is issued by the trusted root specifically to issue end-entity server certificates. The result is a certificate chain that begins at the trusted root CA, through a number of intermediates, and ends with the SSL certificate issued to the organization.
instrumentation event: A way of monitoring queue manager resource definitions, performance conditions, and channel conditions in a network of IBM MQ systems.
instrumentation facility component identifier (IFCID): In Db2 for z/OS, a value that names and identifies a trace record of an event. As a parameter on the START TRACE and MODIFY TRACE commands, it specifies that the corresponding event is to be traced.
Integrated Language Environment (ILE): A set of constructs and interfaces that provides a common runtime environment and runtime bindable application programming interfaces (APIs) for all ILE-conforming high-level languages.
Interactive Problem Control System (IPCS): A component of MVS and z/OS that permits online problem management, interactive problem diagnosis, online debugging for disk-resident abend dumps, problem tracking, and problem reporting.
Interactive System Productivity Facility (ISPF): An IBM licensed program that serves as a full-screen editor and dialog manager. Used for writing application programs, it provides a means of generating standard screen panels and interactive dialogs between the application programmer and the terminal user.
interface: In object-oriented programming, an abstract model of behavior; a collection of functions or methods.
Internet Protocol (IP): A protocol that routes data through a network or interconnected networks. This protocol acts as an intermediary between the higher protocol layers and the physical network. See also Transmission Control Protocol.
interprocess communication (IPC): The process by which programs send messages to each other. Sockets, semaphores, signals, and internal message queues are common methods of interprocess communication. See also client.
intersystem communication (ISC): A CICS facility that provides inbound and outbound support for communication from other computer systems.
IP: See Internet Protocol.
IPC: See interprocess communication.
IPCS: See Interactive Problem Control System.
ISC: See intersystem communication.
ISPF: See Interactive System Productivity Facility.

J

JAAS: See Java Authentication and Authorization Service.
Java Authentication and Authorization Service (JAAS): In Java EE technology, a standard API for performing security-based operations. Through JAAS, services can authenticate and authorize users while enabling the applications to remain independent from underlying technologies.
Java Message Service (JMS): An application programming interface that provides Java language functions for handling messages. See also Message Queue Interface.
Java runtime environment (JRE): A subset of a Java developer kit that contains the core executable programs and files that constitute the standard Java platform. The JRE includes the Java virtual machine (JVM), core classes, and supporting files.
JMS: See Java Message Service.
JMSAdmin: An administration tool that enables administrators to define the properties of JMS objects and to store them within a JNDI namespace
journal: A feature of OS/400 that IBM MQ for IBM i uses to control updates to local objects. Each queue manager library contains a journal for that queue manager.
JRE: See Java runtime environment.

K

keepalive: A TCP/IP mechanism where a small packet is sent across the network at predefined intervals to determine whether the socket is still working correctly.
Kerberos: A network authentication protocol that is based on symmetric key cryptography. Kerberos assigns a unique key, called a ticket, to each user who logs on to the network. The ticket is embedded in messages that are sent over the network. The receiver of a message uses the ticket to authenticate the sender.
key authentication: See authentication.
key repository: A store for digital certificates and their associated private keys.
key ring: In computer security, a file that contains public keys, private keys, trusted roots, and certificates.
keystore: In security, a file or a hardware cryptographic card where identities and private keys are stored, for authentication and encryption purposes. Some keystores also contain trusted or public keys. See also truststore.

L

last will and testament: An object that is registered with a monitor by a client, and used by the monitor if the client ends unexpectedly.
LDAP: See Lightweight Directory Access Protocol.
Lightweight Directory Access Protocol (LDAP): An open protocol that uses TCP/IP to provide access to directories that support an X.500 model and that does not incur the resource requirements of the more complex X.500 Directory Access Protocol (DAP). For example, LDAP can be used to locate people, organizations, and other resources in an Internet or intranet directory.
linear logging: In IBM MQ on UNIX and Linux systems, and IBM MQ for Windows, the process of keeping restart data in a sequence of files. New files are added to the sequence as necessary. The space in which the data is written is not reused. See also circular logging. For further information, see the topic Types of logging.
link level security: The security services that are started, directly or indirectly, by a message channel agent (MCA), the communications subsystem, or a combination of the two working together.
listener: A program that detects incoming requests and starts the associated channel.
local definition of a remote queue: An IBM MQ object belonging to a local queue manager that defines the attributes of a queue that is owned by another queue manager. In addition, it is used for queue manager aliasing and reply-to-queue aliasing.
locale: A setting that identifies language or geography and determines formatting conventions such as collation, case conversion, character classification, the language of messages, date and time representation, and numeric representation.
locally defined object: On z/OS, an object whose definition is stored on page set zero. The definition can be accessed only by the queue manager that defined it. See also globally defined object.
local queue: A queue that belongs to the local queue manager. A local queue can contain a list of messages waiting to be processed. See also remote queue.
local queue manager: The queue manager to which the program is connected and that provides message queuing services to the program. See also remote queue manager.
log: In IBM MQ, a file recording the work done by queue managers while they receive, transmit, and deliver messages, to enable them to recover in the event of failure.
log control file: In IBM MQ on UNIX and Linux systems, and IBM MQ for Windows, the file containing information needed to monitor the use of log files (for example, their size and location, and the name of the next available file).
log file: In IBM MQ on UNIX and Linux systems, and IBM MQ for Windows, a file in which all significant changes to the data controlled by a queue manager are recorded. If the primary log files become full, IBM MQ allocates secondary log files.
logical unit (LU): An access point through which a user or application program accesses the SNA network to communicate with another user or application program.
logical unit 6.2 (LU 6.2): An SNA logical unit that supports general communication between programs in a distributed processing environment.
logical unit of work identifier (LUWID): A name that uniquely identifies a thread within a network. This name consists of a fully qualified logical unit network name, a logical unit of work instance number, and a logical unit of work sequence number.
log record: A set of data that is treated as a single unit in a log file.
log record sequence number (LRSN): A unique identifier for a log record that is associated with a data sharing member. Db2 for z/OS uses the LRSN for recovery in the data sharing environment.
LRSN: See log record sequence number.
LU: See logical unit.
LU 6.2: See logical unit 6.2.
LU 6.2 conversation: In SNA, a logical connection between two transaction programs over an LU 6.2 session that enables them to communicate with each other.
LU 6.2 conversation level security: In SNA, a conversation level security protocol that enables a partner transaction program to authenticate the transaction program that initiated the conversation.
LU 6.2 session: In SNA, a session between two logical units (LUs) of type 6.2.
LU name: The name by which VTAM refers to a node in a network.
LUWID: See logical unit of work identifier.

M

managed destination

A queue that is provided by the queue manager, as the destination to which published messages are to be sent, for an application that elects to use a managed subscription. See also managed subscription.

managed handle

An identifier that is returned by the MQSUB call when a queue manager is specified to manage the storage of messages that are sent to the subscription.

managed subscription

A subscription for which the queue manager creates a subscriber queue to receive publications because the application does not require a specific queue to be used. See also managed destination.

marshalling

See serialization.

MCA

See message channel agent.

MCI

See message channel interface.

media image

In IBM MQ on UNIX and Linux systems and IBM MQ for Windows, the sequence of log records that contain an image of an object. The object can be re-created from this image.

message

In system programming, information intended for the terminal operator or system administrator.
A string of bytes that is passed from one application to another. Messages typically comprise a message header (used for message routing and identification) and a payload (containing the application data being sent). The data has a format that is compatible with both the sending and receiving application.

message affinity

The relationship between conversational messages that are exchanged between two applications, where the messages must be processed by a particular queue manager or in a particular sequence.

message channel

In distributed message queuing, a mechanism for moving messages from one queue manager to another. A message channel comprises two message channel agents (a sender at one end and a receiver at the other end) and a communication link. See also channel.

message channel agent (MCA)

A program that transmits prepared messages from a transmission queue to a communication link, or from a communication link to a destination queue. See also Message Queue Interface.

message channel interface (MCI)

The IBM MQ interface to which customer-written or vendor-written programs that transmit messages between a IBM MQ queue manager and another messaging system must conform. See also Message Queue Interface.

message consumer

In JMS, an object that is created within a session to receive messages from a destination.
A program, function, or organization that gets and processes messages. See also consumer.

message context

Information about the originator of a message that is held in fields in the message descriptor. There are two categories of context information: identity context and origin context.

message descriptor

Control information describing the message format and presentation that is carried as part of a IBM MQ message. The format of the message descriptor is defined by the MQMD structure.

message exit

A type of channel exit program that is used to modify the contents of a message. Message exits usually work in pairs, one at each end of a channel. At the sending end of a channel, a message exit is called after the message channel agent (MCA) has got a message from the transmission queue. At the receiving end of a channel, a message exit is called before the message channel agent (MCA) puts a message on its destination queue.

message flow control

A distributed queue management task that involves setting up and maintaining message routes between queue managers.

Message Format Service (MFS)

An IMS editing facility that allows application programs to deal with simple logical messages instead of device-dependent data, thus simplifying the application development process.

message group

A logical group of related messages. The relationship is defined by the application putting the messages, and ensures that the messages are retrieved in the sequence put if both the producer and consumer honor the grouping.

message handle

A reference to a message. The handle can be used to obtain access to the message properties of the message.

message header

The part of a message that contains control information such as a unique message ID, the sender and receiver of the message, the message priority, and the type of message.

message input descriptor (MID)

The Message Format Service (MFS) control block that describes the format of the data presented to the application program. See also message output descriptor.

message listener

An object that acts as an asynchronous message consumer.

message output descriptor (MOD)

The Message Format Service (MFS) control block that describes the format of the output data produced by the application program. See also message input descriptor.

message priority

In IBM MQ, an attribute of a message that can affect the order in which messages on a queue are retrieved, and whether a trigger event is generated.

message producer

In JMS, an object that is created by a session and that is used to send messages to a destination. See also producer.

message property

Data associated with a message, in name-value pair format. Message properties can be used as message selectors to filter publications or to selectively get messages from queues. Message properties can be used to include business data or state information about processing without having to alter the message body.

Message Queue Interface (MQI)

The programming interface provided by IBM MQ queue managers. The programming interface allows application programs to access message queuing services. See also Java Message Service, message channel agent, message channel interface.

message queue management (MQM)

In IBM MQ for HP NonStop Server, a facility that provides access to PCF command formats and control commands to manage queue managers, queues, and channels.

message queuing

A programming technique in which each program within an application communicates with the other programs by putting messages on queues.

message-retry

An option available to an MCA that is unable to put a message. The MCA can wait for a predefined amount of time and then try to put the message again.

message segment

One of a number of segments of a message that is too large either for the application or for the queue manager to handle.

message selector

In application programming, a variable-length string that is used by an application to register its interest in only those messages whose properties satisfy the Structured Query Language (SQL) query that the selection string represents. The syntax of a message selector is based on a subset of the SQL92 conditional expression syntax.

message sequence numbering

A programming technique in which messages are given unique numbers during transmission over a communication link. This number enables the receiving process to check whether all messages are received, to place them in a queue in the original order, and to discard duplicate messages.

message token

A unique identifier of a message within an active queue manager.

method

In object-oriented design or programming, the software that implements the behavior specified by an operation.

MFS

See Message Format Service.

MGAS

See mostly global address space.

Microsoft Cluster Server (MSCS)

A technology that provides high availability by grouping computers running Windows into MSCS clusters. If one of the computers in the cluster hits any one of a range of problems, MSCS shuts down the disrupted application in an orderly manner, transfers its state data to another computer in the cluster, and re-initiates the application there. For further information, see the topic Supporting the Microsoft Cluster Service (MSCS).

Microsoft Transaction Server (MTS)

A facility that helps Windows users run business logic applications in a middle tier server. MTS divides work up into activities, which are short independent chunks of business logic.

MID

See message input descriptor.

MOD

See message output descriptor.

model queue object

A set of queue attributes that act as a template when a program creates a dynamic queue.

mostly global address space (MGAS)

A flexible virtual address space model that preserves most of the address space for shared applications. This model can enhance performance for processes that share a lot of data. See also mostly private address space.

mostly private address space (MPAS)

A flexible virtual address space model that can allocate larger address space blocks to processes. This model can enhance performance for processes that require a lot of data space. See also mostly global address space.

MPAS

See mostly private address space.

MQAI

See IBM MQ Administration Interface.

MQI

See Message Queue Interface.

MQI channel

A connection between an IBM MQ client and a queue manager on a server system. An MQI channel transfers only MQI calls and responses in a bidirectional manner. See also channel.

MQM

See message queue management.

MQSC

See IBM MQ script commands.

MQSeries

A previous name for IBM MQ and IBM WebSphere MQ.

MQ Telemetry Transport (MQTT)

An open, lightweight publish/subscribe messaging protocol flowing over TCP/IP to connect large numbers of devices such as servos, actuators, smart phones, vehicles, homes, health, remote sensors, and control devices. MQTT is designed for constrained devices and low-bandwidth, high-latency or unreliable networks. The protocol minimises network bandwidth and device resource requirements, while ensuring some degree of reliability and assured delivery. It is used increasingly in the machine-to-machine (M2M) or Internet of Things world of connected devices, and for mobile applications where bandwidth and battery power are at a premium.

MQTT

See MQ Telemetry Transport.

MQTT client

An MQTT client application connects to MQTT capable servers such as IBM MQ Telemetry channels. We can write your own clients to use the published protocol, or download the free Paho clients. A typical client is responsible for collecting information from a telemetry device and publishing the information to the server. It can also subscribe to topics, receive messages, and use this information to control the telemetry device.

MQTT daemon for devices

The MQTT daemon for devices was an advanced MQTT V3 client. It was a very small footprint MQTT server designed for embedded systems. Its primary use was to store and forward messages from telemetry devices and other MQTT clients, including other MQTT daemons for devices.

MQTT server

A messaging server that supports the MQ Telemetry Transport protocol. It enables mobile apps and devices, supported by MQTT clients, to exchange messages. It typically allows many MQTT clients to connect to it at the same time, and provides a hub for messages distribution to the MQTT clients. MQTT servers are available from IBM and others. IBM MQ Telemetry is an MQTT server from IBM.

MQXR service

See telemetry service.

MSCS

See Microsoft Cluster Server. For further information, see the topic Supporting the Microsoft Cluster Service (MSCS).

MTS

See Microsoft Transaction Server.

multi-hop

To pass through one or more intermediate queue managers when there is no direct communication link between a source queue manager and the target queue manager.

multi-instance queue manager

A queue manager that is configured to share the use of queue manager data with other queue manager instances. One instance of a running multi-instance queue manager is active, other instances are on standby ready to take over from the active instance. See also queue manager, single instance queue manager.

N

namelist: An IBM MQ object that contains a list of object names, for example, queue names.
name service: In IBM MQ on UNIX and Linux systems and IBM MQ for Windows, the facility that determines which queue manager owns a specified queue.
name service interface (NSI): The IBM MQ interface to which customer-written or vendor-written programs that resolve queue-name ownership must conform.
name transformation: In IBM MQ on UNIX and Linux systems and IBM MQ for Windows, an internal process that changes a queue manager name so that it is unique and valid for the system being used. Externally, the queue manager name remains unchanged.
nested bag: In the IBM MQ Administration Interface (MQAI), a system bag that is inserted into another data bag
nesting: In the IBM MQ Administration Interface (MQAI), a means of grouping information returned from IBM MQ.
NetBIOS (Network Basic Input/Output System): A standard interface to networks and personal computers that is used on local area networks to provide message, print-server, and file-server functions. Application programs that use NetBIOS do not have to handle the details of LAN data link control (DLC) protocols.
Network Basic Input/Output System: See NetBIOS.
New Technology File System (NTFS): One of the native file systems in Windows operating environments.
node: In Microsoft Cluster Server (MSCS), each computer in the cluster.
nondurable subscription: A subscription that exists only while the connection from the subscribing application to the queue manager remains open. The subscription is removed when the subscribing application disconnects from the queue manager either deliberately or by loss of connection. See also durable subscription.
nonpersistent message: A message that does not survive a restart of the queue manager. See also persistent message.
NSI: See name service interface.
NTFS: See New Technology File System.
NUL: See null character.
null character (NUL): A control character with the value of X'00' that represents the absence of a displayed or printed character.

O

OAM

See object authority manager.

object

In IBM MQ, a queue manager, queue, process definition, channel, namelist, authentication information object, administrative topic object, listener, service object, or (on z/OS only) a CF structure object or storage class.
In object-oriented design or programming, a concrete realization (instance) of a class that consists of data and the operations associated with that data. An object contains the instance data that is defined by the class, but the class owns the operations that are associated with the data.

object authority manager (OAM)

In IBM MQ on UNIX and Linux systems, IBM MQ for IBM i, and IBM MQ for Windows, the default authorization service for command and object management. The OAM can be replaced by, or run in combination with, a customer-supplied security service.

object descriptor

A data structure that identifies a particular IBM MQ object. Included in the descriptor are the name of the object and the object type.

object handle

The identifier or token by which a program accesses the IBM MQ object with which it is working.

object-oriented programming

A programming approach based on the concepts of data abstraction and inheritance. Unlike procedural programming techniques, object-oriented programming concentrates not on how something is accomplished but instead on what data objects compose the problem and how they are manipulated.

OCSP

See Online Certificate Status Protocol.

offloading

In IBM MQ for z/OS, an automatic process whereby a queue manager's active log is transferred to its archive log.

Online Certificate Status Protocol

A method of checking if a certificate is revoked.

one way authentication

In this method of authentication, the queue manager presents the certificate to the client, but the authentication is not checked from the client to the queue manager.

open

To establish access to an object, such as a queue, topic, or hyperlink.

open systems interconnection (OSI)

The interconnection of open systems in accordance with standards of the International Organization for Standardization (ISO) for the exchange of information.

Open Transaction Manager Access (OTMA)

A component of IMS that implements a transaction-based, connectionless client/server protocol in an MVS sysplex environment. The domain of the protocol is restricted to the domain of the z/OS Cross-System Coupling Facility (XCF). OTMA connects clients to servers so that the client can support a large network (or a large number of sessions) while maintaining high performance.

OPM

See original program model.

original program model (OPM)

The set of functions for compiling source code and creating high-level language programs before the Integrated Language Environment (ILE) model was introduced.

OSGi Alliance

A consortium of more than 20 companies, including IBM, that creates specifications to outline open standards for the management of voice, data and multimedia wireless and wired networks.

OSI

See open systems interconnection.

OSI directory standard

The standard, known as X.500, that defines a comprehensive directory service, including an information model, a namespace, a functional model, and an authentication framework. X.500 also defines the Directory Access Protocol (DAP) used by clients to access the directory. The Lightweight Directory Access Protocol (LDAP) removes some of the burden of X.500 access from directory clients, making the directory available to a wider variety of machines and applications.

OTMA

See Open Transaction Manager Access.

outbound channel

A channel that takes messages from a transmission queue and sends them to another queue manager.

output log-buffer

In IBM MQ for z/OS, a buffer that holds recovery log records before they are written to the archive log.

output parameter

A parameter of an MQI call in which the queue manager returns information when the call completes or fails.

overloading

In object-oriented programming, the capability of an operator or method to have different meanings depending on the context. For example, in C++, a user can redefine functions and most standard operators when the functions and operators are used with class types. The method name or operator remains the same, but the method parameters differ in type, number, or both. This difference is collectively called the function's or the operator's signature and each signature requires a separate implementation.

P

page set: A VSAM data set used when IBM MQ for z/OS moves data (for example, queues and messages) from buffers in main storage to permanent backing storage (DASD).
parent class: A class from which another class inherits instance methods, attributes, and instance variables. See also abstract class.
partial repository: A partial set of information about queue managers in a cluster. A partial repository is maintained by all cluster queue managers that do not host a full repository. See also full repository.
partner queue manager: See remote queue manager.
PassTicket: In RACF secured sign-on, a dynamically generated, random, one-time-use, password substitute that a workstation or other client can use to sign on to the host rather than sending a RACF password across the network.
PCF: See programmable command format.
pending event: An unscheduled event that occurs as a result of a connect request from a CICS adapter.
percolation: In error recovery, the passing along a preestablished path of control from a recovery routine to a higher-level recovery routine.
performance event: A category of event indicating that a limit condition has occurred.
performance trace: An IBM MQ trace option where the trace data is to be used for performance analysis and tuning.
permanent dynamic queue: A dynamic queue that is deleted when it is closed only if deletion is explicitly requested. Permanent dynamic queues are recovered if the queue manager fails, so they can contain persistent messages. See also temporary dynamic queue.
persistent message: A message that survives a restart of the queue manager. See also nonpersistent message.
personal certificate: Certificate for which you own the corresponding private key. Associated with queue managers or applications.
PGM: See Pragmatic General Multicast.
PID: See process ID.
ping: The command that sends an Internet Control Message Protocol (ICMP) echo-request packet to a gateway, router, or host with the expectation of receiving a reply.
PKCS: Public Key Cryptography Standards. A set of standards for cryptography, of which:
7 is for messages
11 is for hardware security modules
12 is for the file format used in the key repository
PKI: See public key infrastructure.
plain text: See cleartext.
point of recovery: In IBM MQ for z/OS, a set of backup copies of IBM MQ for z/OS page sets and the corresponding log data sets required to recover these page sets. These backup copies provide a potential restart point in the event of page set loss (for example, page set I/O error).
poison message: In a queue, an incorrectly formatted message that the receiving application cannot process. The message can be repeatedly delivered to the input queue and repeatedly backed out by the application.
polymorphism: An object-oriented programming characteristic that allows a method to perform differently, depending on the class that implements it. Polymorphism allows a subclass to override an inherited method without affecting the method of the parent class. Polymorphism also enables a client to access two or more implementations of an object from a single interface.
Pragmatic General Multicast (PGM): A reliable multicast transport protocol that provides a reliable sequence of packets to multiple recipients simultaneously.
preemptive shutdown: In IBM MQ, a shutdown of a queue manager that does not wait for connected applications to disconnect, or for current MQI calls to complete. See also immediate shutdown, quiesced shutdown.
preferred computer: The primary computer used by an application running under Microsoft Cluster Server control. After a failover to another computer, MSCS monitors the preferred computer until it is repaired, and as soon as it is running correctly again, moves the application back to it.
principal: An entity that can communicate securely with another entity. A principal is identified by its associated security context, which defines its access rights.
privately defined object: See locally defined object.
private methods and instance data: In object-oriented programming, methods and instance data that are only accessible to the implementation of the same class.
process definition object: An IBM MQ object that contains the definition of an IBM MQ application. For example, a queue manager uses the definition when it works with trigger messages.
process ID (PID): The unique identifier that represents a process. A process ID is a positive integer and is not reused until the process lifetime ends.
producer: An application that creates and sends messages. See also message producer, publisher.
programmable command format (PCF): A type of IBM MQ message used by the following applications: user administration applications, to put PCF commands onto the system command input queue of a specified queue manager, user administration applications, to get the results of a PCF command from a specified queue manager, and a queue manager, as a notification that an event has occurred. See also IBM MQ script commands.
program temporary fix (PTF): For System i, System p, and IBM Z products, a package containing individual or multiple fixes that is made available to all licensed customers. A PTF resolves defects and might provide enhancements.
property: A characteristic of an object that describes the object. A property can be changed or modified. Properties can describe an object name, type, value, or behavior, among other things.
protected methods and instance data: In object-oriented programming, methods and instance data that are only accessible to the implementations of the same or derived classes, or from friend classes.
proxy subscription: A proxy subscription is a subscription made by one queue manager for topics published on another queue manager. A proxy subscription flows between queue managers for each individual topic string that is subscribed to by a subscription. You do not create proxy subscriptions explicitly, the queue manager does so on your behalf.
PTF: See program temporary fix.
public key cryptography: A cryptography system that uses two keys: a public key known to everyone and a private or secret key known only to the recipient of the message. The public and private keys are related in such a way that only the public key can be used to encrypt messages and only the corresponding private key can be used to decrypt them.
public key infrastructure (PKI): A system of digital certificates, certification authorities, and other registration authorities that verify and authenticate the validity of each party involved in a network transaction.
public methods and instance data: In object oriented programming, methods and instance data that are accessible to all classes.
public-private key cryptography: See public key cryptography.
publish: To make information about a specified topic available to a queue manager in a publish/subscribe system.
publisher: An application that makes information about a specified topic available to a broker in a publish/subscribe system. See also producer.
publish/subscribe: A type of messaging interaction in which information, provided by publishing applications, is delivered by an infrastructure to all subscribing applications that registered to receive that type of information.
publish/subscribe cluster: A set of queue managers that are fully interconnected and that form part of a multi queue manager network for publish/subscribe applications.
put: In message queuing, to use the MQPUT or MQPUT1 calls to place messages on a queue. See also browse, get.

Q

queue

An object that holds messages for message-queuing applications. A queue is owned and maintained by a queue manager.

queue index

In IBM MQ for z/OS, a list of message identifiers or a list of correlation identifiers that can be used to increase the speed of MQGET operations on the queue.

queue-manager

A component of a message queuing system that provides queuing services to applications. See also channel, multi-instance queue manager.

queue-manager-event

An event that indicates that an error condition has occurred in relation to the resources used by a queue manager (for example, a queue is unavailable), or a significant change has occurred in the queue manager (for example, a queue manager has stopped or started).

queue-manager-group

In a client channel definition table (CCDT), the group of queue managers a client tries to connect to when a connection is established to a server.

queue-manager-level-security

In IBM MQ for z/OS, the authorization checks that are performed using RACF profiles specific to a queue manager.

queue-manager-set

A grouping of queue managers in IBM MQ Explorer that allows a user to perform actions on all of the queue managers in the group.

queue sharing group

In IBM MQ for z/OS, a group of queue managers in the same sysplex that can access a single set of object definitions stored in the shared repository, and a single set of shared queues stored in the coupling facility. See also shared queue.

queue sharing group level security

In IBM MQ for z/OS, the authorization checks that are performed using RACF profiles that are shared by all queue managers in a queue sharing group.

quiesce

To end a process or shut down a system after allowing normal completion of active operations.

quiesced shutdown

In IBM MQ, a shutdown of a queue manager that allows all connected applications to disconnect. See also immediate shutdown, preemptive shutdown.
A type of shutdown of the CICS adapter where the adapter disconnects from IBM MQ, but only after all the currently active tasks have been completed. See also forced shutdown.

quiescing

In IBM MQ, the state of a queue manager before it stops. In this state, programs are allowed to finish processing, but no new programs are allowed to start.

quorum disk

The disk accessed exclusively by Microsoft Cluster Server to store the cluster recovery log, and to determine whether a server is up or down. Only one server can own the quorum disk at a time. Servers in the cluster can negotiate for the ownership.

R

RACF: See Resource Access Control Facility.
RAID: See Redundant Array of Independent Disks.
RBA: See relative byte address.
RC: See return code.
read ahead: An option that allows messages to be sent to a client before an application requests them.
reason code: A return code that describes the reason for the failure or partial success of a Message Queue Interface (MQI) call.
receive exit: A type of channel exit program that is called just after the message channel agent (MCA) has regained control following a communications receive and has received a unit of data from a communications connection. See also send exit.
receiver channel: In message queuing, a channel that responds to a sender channel, takes messages from a communication link, and puts them on a local queue.
recovery log: In IBM MQ for z/OS, data sets containing information needed to recover messages, queues, and the IBM MQ subsystem. See also archive log.
recovery termination manager (RTM): A program that handles all normal and abnormal termination of tasks by passing control to a recovery routine associated with the terminating function.
Redundant Array of Independent Disks (RAID): A collection of two or more physical disk drives that present to the host an image of one or more logical disk drives. In the event of a physical device failure, the data can be read or regenerated from the other disk drives in the array due to data redundancy.
reference message: A message that refers to a piece of data that is to be transmitted. The reference message is handled by message exit programs, which attach and detach the data from the message so allowing the data to be transmitted without having to be stored on any queues.
registry: A repository that contains access and configuration information for users, systems, and software.
Registry Editor: In Windows systems, the program that allows the user to edit the registry.
registry hive: In Windows systems, the structure of the data stored in the registry.
relative byte address (RBA): The offset of a data record or control interval from the beginning of the storage space that is allocated to the data set or file to which it belongs.
reliable multicast messaging (RMM): A high-throughput low-latency transport fabric designed for one-to-many data delivery or many-to-many data exchange, in a message-oriented middleware publish/subscribe fashion. RMM uses the IP multicast infrastructure to ensure scalable resource conservation and timely information distribution.
remote queue: A queue that belongs to a remote queue manager. Programs can put messages on remote queues, but they cannot get messages from remote queues. See also local queue.
remote queue manager: A queue manager to which a program is not connected, even if it is running on the same system as the program. See also local queue manager.
remote queue object: An IBM MQ object belonging to a local queue manager. This object defines the attributes of a queue that is owned by another queue manager. In addition, it is used for queue manager aliasing and reply-to-queue aliasing.
remote queuing: In message queuing, the provision of services to enable applications to put messages on queues belonging to other queue managers.
reply message: A type of message used for replies to request messages. See also report message, request message.
reply-to queue: The name of a queue to which the program that issued an MQPUT call wants a reply message or report message sent.
report message: A type of message that gives information about another message. A report message can indicate that a message has been delivered, has arrived at its destination, has expired, or could not be processed for some reason. See also reply message, request message.
repository: A collection of information about the queue managers that are members of a cluster. This information includes queue manager names, their locations, their channels, and what queues they host.
repository queue manager: A queue manager that hosts the full repository of information about a cluster.
requester channel: In message queuing, a channel that can be started locally to initiate operation of a server channel. See also server channel.
request message: A type of message used to request a reply from another program. See also reply message, report message.
request/reply: A type of messaging application in which a request message is used to request a reply from another application. See also datagram.
RESLEVEL: In IBM MQ for z/OS, an option that controls the number of user IDs checked for API-resource security.
resolution path: The set of queues that are opened when an application specifies an alias or a remote queue on input to an MQOPEN call.
resource: A facility of a computing system or operating system required by a job, task, or running program. Resources include main storage, input/output devices, the processing unit, data sets, files, libraries, folders, application servers, and control or processing programs.
Resource Access Control Facility (RACF): An IBM licensed program that provides access control by identifying users to the system; verifying users of the system; authorizing access to protected resources; logging unauthorized attempts to enter the system; and logging accesses to protected resources.
resource adapter: An implementation of the Java Enterprise Edition Connector Architecture that allows JMS applications and message driven beans, running in an application server, to access the resources of an IBM MQ queue manager.
resource manager: An application, program, or transaction that manages and controls access to shared resources such as memory buffers and data sets. IBM MQ, CICS, and IMS are resource managers.
Resource Recovery Services (RRS): A component of z/OS that uses a sync point manager to coordinate changes among participating resource managers.
responder: In distributed queuing, a program that replies to network connection requests from another system. See also initiator.
resynch: In IBM MQ, an option to direct a channel to start and resolve any in-doubt status messages, but without restarting message transfer.
return code (RC): A value returned by a program to indicate the result of its processing. Completion codes and reason codes are examples of return codes.
return-to-sender: An option available to an MCA that is unable to deliver a message. The MCA can send the message back to the originator.
Rivest-Shamir-Adleman algorithm (RSA): A public-key encryption technology developed by RSA Data Security, Inc, and used in the IBM implementation of SSL.
RMM: See reliable multicast messaging.
rollback: See backout.
root certificate: The top certificate in the chain. If this is a self-signed certificate, it is used only for signing other certificates. See also self-signed certificate.
RRS: See Resource Recovery Services.
RSA: See Rivest-Shamir-Adleman algorithm.
RTM: See recovery termination manager.
rules table: A control file containing one or more rules that the dead-letter queue handler applies to messages on the dead letter queue (DLQ).

S

SAF

See store and forward.

Scalable Parallel 2 (SP2)

IBM's parallel UNIX system: effectively parallel AIX systems on a high-speed network.

SDK

See software development kit.

SDWA

See system diagnostic work area.

SECMEC

See security mechanism.

Secure Sockets Layer (SSL)

A security protocol that provides communication privacy. With SSL, client/server applications can communicate in a way that is designed to prevent eavesdropping, tampering, and message forgery. See also certificate authority.

security enabling interface (SEI)

The IBM MQ interface to which customer-written or vendor-written programs that check authorization, supply a user identifier, or perform authentication must conform.

security exit

A channel exit program that is called immediately after the initial data negotiation has completed on channel startup. Security exits normally work in pairs and can be called on both message channels and MQI channels. The primary purpose of the security exit is to enable the message channel agent (MCA) at each end of a channel to authenticate its partner.

security identifier (SID)

On Windows systems, a supplement to the user ID that identifies the full user account details on the Windows security account manager database where the user is defined.

security mechanism (SECMEC)

A technical tool or technique that is used to implement a security service. A mechanism might operate by itself, or in conjunction with others, to provide a particular service. Examples of security mechanisms include access control lists, cryptography, and digital signatures.

security message

One of the messages, sent by security exits that are called at both ends of a channel, to communicate with each other. The format of a security message is not defined and is determined by the user.

security service

A service within a computer system that protect its resources. Access control is an example of a security service.

Security Support Provider Interface (SSI)

The means for networked applications to call one of several security support providers (SSPs) to establish authenticated connections and to exchange data securely over those connections. It is available for use on Windows systems.

segmentation

The division of a message that is too large for a queue manager, queue, or application, into a number of smaller physical messages, which are then reassembled by the receiving queue manager or application.

SEI

See security enabling interface.

selector

An identifier for a data item. In the IBM MQ Administration Interface (MQAI), there are two types of selector: a user selector and a system selector.

self-signed certificate

A certificate that is constructed like a digital certificate, but is signed by its subject. Unlike a digital certificate, a self-signed certificate cannot be used in a trustworthy manner to authenticate a public key to other parties.

semaphore

In UNIX and Linux systems, a general method of communication between two processes that extends the features of signals.

sender channel

In message queuing, a channel that initiates transfers, removes messages from a transmission queue, and moves them over a communication link to a receiver or requester channel.

send exit

A type of channel exit program that is called just before a message channel agent (MCA) issues a communications send to send a unit of data over a communications connection. See also receive exit.

Sequenced Packet Exchange protocol (SPX)

A session-oriented network protocol that provides connection-oriented services between two nodes on the network, and is used primarily by client/server applications. It relies on the Internet Packet Exchange (IPX) protocol, provides flow control and error recovery, and guarantees reliability of the physical network.

sequence number wrap value

In IBM MQ, a method of ensuring that both ends of a communication link reset their current message sequence numbers at the same time. Transmitting messages with a sequence number ensures that the receiving channel can reestablish the message sequence when storing the messages.

serialization

In object-oriented programming, the writing of data in sequential fashion to a communications medium from program memory.

server

A software program or a computer that provides services to other software programs or other computers. See also client.
A queue manager that provides queue services to client applications running on a remote workstation.

server channel

In message queuing, a channel that responds to a requester channel, removes messages from a transmission queue, and moves them over a communication link to the requester channel. See also requester channel.

server-connection channel type

The type of MQI channel definition associated with the server that runs a queue manager. See also client-connection channel type.

service interval

A time interval, against which the elapsed time between a put or a get and a subsequent get is compared by the queue manager in deciding whether the conditions for a service interval event have been met. The service interval for a queue is specified by a queue attribute.

service interval event

An event related to the service interval.

service object

An object that can start additional processes when the queue manager starts and can stop the processes when the queue manager stops.

session

A logical or virtual connection between two stations, software programs, or devices on a network that allows the two elements to communicate and exchange data for the duration of the session.

session ID

See session identifier.

session identifier (session ID)

In IBM MQ for z/OS, the identifier, unique to CICS, that defines the communication link to be used by a message channel agent when moving messages from a transmission queue to a link.

session-level authentication

In Systems Network Architecture (SNA), a session level security protocol that enables two logical units (LUs) to authenticate each other while they are activating a session. Session level authentication is also known as LU-LU verification.

session-level cryptography

In Systems Network Architecture (SNA), a method of encrypting and decrypting data that flows on a session between two logical units (LUs).

shared inbound channel

In IBM MQ for z/OS, a channel that was started by a listener using the group port. The channel definition of a shared channel can be stored either on page set zero (private) or in the shared repository (global).

shared outbound channel

In IBM MQ for z/OS, a channel that moves messages from a shared transmission queue. The channel definition of a shared channel can be stored either on page set zero (private) or in the shared repository (global).

shared queue

In IBM MQ for z/OS, a type of local queue. The messages on the queue are stored in the coupling facility and can be accessed by one or more queue managers in a queue sharing group. The definition of the queue is stored in the shared repository. See also queue sharing group.

shared repository

In IBM MQ for z/OS, a shared Db2 database that is used to hold object definitions that have been defined globally.

sharing conversations

The facility for more than one conversation to share a channel instance, or the conversations that share a channel instance.

shell

A software interface between users and an operating system. Shells generally fall into one of two categories: a command line shell, which provides a command line interface to the operating system; and a graphical shell, which provides a graphical user interface (GUI).

SID

See security identifier.

signal

A mechanism by which a process can be notified of, or affected by, an event occurring in the system. Examples of such events include hardware exceptions and specific actions by processes.

signaling

In IBM MQ for z/OS and IBM MQ, a feature that allows the operating system to notify a program when an expected message arrives on a queue.

signature

The collection of types associated with a method. The signature includes the type of the return value, if any, as well as the number, order, and type of each of the method's arguments.

signer certificate

The digital certificate that validates the issuer of a certificate. For a CA, the signer certificate is the root CA certificate. For a user who creates a self-signed certificate for testing purposes, the signer certificate is the user's personal certificate.

single instance queue manager

A queue manager that does not have multiple instances. See also multi-instance queue manager.

single logging

A method of recording IBM MQ for z/OS activity where each change is recorded on one data set only. See also dual logging.

single-phase backout

A method in which an action in progress must not be allowed to finish, and all changes that are part of that action must be undone.

single-phase commit

A method in which a program can commit updates to a commitment resource without coordinating those updates with updates the program has made to resources controlled by another resource manager.

SIT

See system initialization table.

SMF

See System Management Facilities.

SNA

See Systems Network Architecture.

software development kit (SDK)

A set of tools, APIs, and documentation to assist with the development of software in a specific computer language or for a particular operating environment.

source queue manager

See local queue manager.

SP2

See Scalable Parallel 2.

SPX

See Sequenced Packet Exchange protocol.

SSI

See Security Support Provider Interface.

SSL

See Secure Sockets Layer.

SSLPeer

The value in the issuer represents the distinguished name of the remote personal certificate.

SSL or TLS client

The initiating end of the connection. One outbound channel from a queue manager is also an SSL or TLS client.

standby queue manager instance

An instance of a running multi-instance queue manager ready to take over from the active instance. There are one or more standby instances of a multi-instance queue manager.

stanza

A group of lines in a file that together have a common function or define a part of the system. Stanzas are usually separated by blank lines or colons, and each stanza has a name.

star-connected communications network

A network in which all nodes are connected to a central node.

storage class

In IBM MQ for z/OS, the page set that is to hold the messages for a particular queue. The storage class is specified when the queue is defined.

store and forward (SAF)

The temporary storing of packets, messages, or frames in a data network before they are retransmitted toward their destination.

streaming

In object-oriented programming, the serialization of class information and object instance data.

subscribe

To request information about a topic.

subsystem

In z/OS, a service provider that performs one or many functions but does nothing until a request is made. For example, each IBM MQ for z/OS queue manager or instance of a Db2 for z/OS database management system is a z/OS subsystem.

supervisor call (SVC)

An instruction that interrupts the program being run and passes control to the supervisor so that it can perform the specific service indicated by the instruction.

SVC

See supervisor call.

switchover

The change from the active multi-instance queue manager instance to a standby instance. A switchover results from an operator intentionally stopping the active multi-instance queue manager instance.

switch profile

In IBM MQ for z/OS, a RACF profile used when IBM MQ starts up or when a refresh security command is issued. Each switch profile that IBM MQ detects turns off checking for the specified resource.

symmetric key cryptography

A system of cryptography in which the sender and receiver of a message share a single, common, secret key that is used to encrypt and decrypt the message. See also asymmetric key cryptography.

symptom string

Diagnostic information displayed in a structured format designed for searching the IBM software support database.

synchronous messaging

A method of communication between programs in which a program places a message on a message queue and then waits for a reply to its message before resuming its own processing. See also asynchronous messaging.

sync point

A point during the processing of a transaction at which protected resources are consistent.

sysplex

A set of z/OS systems that communicate with each other through certain multisystem hardware components and software services.

system bag

A type of data bag that is created by the MQAI.

system control commands

Commands used to manipulate platform-specific entities such as buffer pools, storage classes, and page sets.

system diagnostic work area (SDWA)

In a z/OS environment, the data that is recorded in a SYS1.LOGREC entry that describes a program or hardware error.

system initialization table (SIT)

A table containing parameters used by CICS at startup.

system item

A type of data item that is created by the MQAI.

System Management Facilities (SMF)

A component of z/OS that collects and records a variety of system and job-related information.

system selector

In the IBM MQ Administration Interface (MQAI), a system item identifier that is included in the data bag when it is created.

Systems Network Architecture (SNA)

The description of the logical structure, formats, protocols, and operational sequences for transmitting information through and controlling the configuration and operation of networks.

T

tampering: A breach of communication security in which information in transit is changed or replaced and then sent on to the recipient. See also eavesdropping, impersonation.
target library high-level qualifier (thlqual): A high-level qualifier for z/OS target data set names.
target queue manager: See remote queue manager.
task control block (TCB): A z/OS control block that is used to communicate information about tasks within an address space that is connected to a subsystem.
task switching: The overlapping of I/O operations and processing between several tasks.
TCB: See task control block.
TCP: See Transmission Control Protocol.
TCP/IP: See Transmission Control Protocol/Internet Protocol.
technote: A short document about a single topic.
telemetry channel: A communication link between a queue manager on IBM MQ, and MQTT clients. Each channel might have one or more telemetry devices connected to it.
telemetry service: The telemetry service is a IBM MQ service that handles the server side of the MQTT protocol (see MQTT Server). The telemetry service hosts telemetry channels. It is sometimes referred to as the MQXR (MQ extended reach) service.
temporary dynamic queue: A dynamic queue that is deleted when it is closed. Temporary dynamic queues are not recovered if the queue manager fails, so they can contain nonpersistent messages only. See also permanent dynamic queue.
teraspace: A one terabyte temporary storage area that provides storage that is private to a process.
termination notification: A pending event that is activated when a CICS subsystem successfully connects to IBM MQ for z/OS.
thlqual: See target library high-level qualifier.
thread: A stream of computer instructions that is in control of a process. In some operating systems, a thread is the smallest unit of operation in a process. Several threads can run concurrently, performing different jobs.
TID: See transaction identifier.
time-independent messaging: See asynchronous messaging.
TLS: See Transport Layer Security.
TMF: See Transaction Manager Facility.
TMI: See trigger monitor interface.
topic host routing: An option for routing publications in a publish/subscribe cluster. With topic host routing, only selected cluster queue managers host the topic definitions. Publications from non-hosting queue managers are routed through the hosting queue managers to any queue manager in the cluster with a matching subscription.
TP: See transaction program.
trace: A record of the processing of a computer program or transaction. The information collected from a trace can be used to assess problems and performance.
transaction ID: See transaction identifier.
transaction identifier (TID, transaction ID, XID): A unique name that is assigned to a transaction and is used to identify the actions associated with that transaction.
transaction manager: A software unit that coordinates the activities of resource managers by managing global transactions and coordinating the decision to commit them or roll them back.
Transaction Manager Facility (TMF): In IBM MQ for HP NonStop Server, a subsystem to protect business transactions and the integrity of databases.
transaction program (TP): A program that processes transactions in an SNA network.
Transmission Control Protocol (TCP): A communication protocol used in the Internet and in any network that follows the Internet Engineering Task Force (IETF) standards for internetwork protocol. TCP provides a reliable host-to-host protocol in packet-switched communication networks and in interconnected systems of such networks. See also Internet Protocol.
Transmission Control Protocol/Internet Protocol (TCP/IP): An industry-standard, nonproprietary set of communication protocols that provides reliable end-to-end connections between applications over interconnected networks of different types.
transmission program: See message channel agent.
transmission queue: A local queue on which prepared messages destined for a remote queue manager are temporarily stored.
Transport Layer Security: A set of encryption rules that uses verified certificates and encryption keys to secure communications over the Internet. TLS is an update to the SSL protocol.
triggered queue: A local queue, usually an application queue, that has triggering enabled so that a message is written when a trigger event occurs. The trigger message is often written to an initiation queue.
trigger event: An event, such as a message arriving on a queue, that causes a queue manager to create a trigger message on an initiation queue.
triggering: In IBM MQ, a facility that allows a queue manager to start an application automatically when predetermined conditions on a queue are satisfied.
trigger message: A message that contains information about the program that a trigger monitor is to start.
trigger monitor: A continuously running application that serves one or more initiation queues. When a trigger message arrives on an initiation queue, the trigger monitor retrieves the message. It uses the information in the trigger message to start a process that serves the queue on which a trigger event occurred.
trigger monitor interface (TMI): The IBM MQ interface to which customer-written or vendor-written trigger monitor programs must conform.
truststore: In security, a storage object, either a file or a hardware cryptographic card, where public keys are stored in the form of trusted certificates, for authentication purposes. In some applications, these trusted certificates are moved into the application keystore to be stored with the private keys.
two-phase commit: A two-step process by which recoverable resources and an external subsystem are committed. During the first step, the database manager subsystems are polled to ensure that they are ready to commit. If all subsystems respond positively, the database manager instructs them to commit.
two way authentication: In this method of authentication, the queue manager and the client, present the certificate to each other. Also known as mutual authentication.
type: A characteristic that specifies the internal format of data and determines how the data can be used.

U

UDP: See User Datagram Protocol.
unauthorized access: Gaining access to resources within a computer system without permission.
undelivered message queue: See dead-letter queue.
undo/redo record: A log record used in recovery. The redo part of the record describes a change to be made to an IBM MQ object. The undo part describes how to back out the change if the work is not committed.
unit of recovery: A recoverable sequence of operations within a single resource manager, such as an instance of Db2 for z/OS. See also unit of work.
unit of work (UOW): A recoverable sequence of operations performed by an application between two points of consistency. A unit of work begins when a transaction starts or at a user-requested sync point. It ends either at a user-requested sync point or at the end of a transaction.
UOW: See unit of work.
user bag: In the MQAI, a type of data bag that is created by the user.
User Datagram Protocol (UDP): An Internet protocol that provides unreliable, connectionless datagram service. It enables an application program on one machine or process to send a datagram to an application program on another machine or process.
user item: In the MQAI, a type of data item that is created by the user.
user selector: In the IBM MQ Administration Interface (MQAI), the identifier that is placed with a data item into a data bag to identify the data item. IBM MQ provides predefined user selectors for IBM MQ objects.
user token (UTOKEN): The RACF security token that encapsulates or represents the security characteristics of a user. RACF assigns a UTOKEN to each user in the system.
utility: In IBM MQ, a supplied set of programs that provide the system operator or system administrator with facilities in addition to those provided by the IBM MQ commands.
UTOKEN: See user token.

V

value: The content of a data item. The value can be an integer, a string, or the handle of another data bag.
virtual method: In object-oriented programming, a method that exhibits polymorphism.

W

IBM WebSphere MQ: A previous name for IBM MQ.

wiretapping: The act of gaining access to information that is flowing along a wire or any other type of conductor used in communications. The objective of wiretapping is to gain unauthorized access to information without being detected.

X

X509: International Telecommunications Union standard for PKI. Specifies the format of the public key certificate and the public key cryptography.
XCF: See cross-system coupling facility.
XID: See transaction identifier.
X/Open XA: The X/Open Distributed Transaction Processing XA interface. A proposed standard for distributed transaction communication. The standard specifies a bidirectional interface between resource managers that provide access to shared resources within transactions, and between a transaction service that monitors and resolves transactions.