DISPLAY CHANNEL (MQTT)

Use the MQSC command DISPLAY CHANNEL (MQTT) to display an MQ Telemetry channel definition.

Use MQSC commands

For information on how we use MQSC commands, see Performing local administration tasks using MQSC commands.

Syntax diagram
Parameter descriptions for DISPLAY CHANNEL (MQTT)
Requested parameters

Synonym: DIS CHL

DISPLAY CHANNEL (MQTT)

Requested attrs

DISPLAY CHANNEL (MQTT) command is only valid for MQ Telemetry channels.

Parameter descriptions for DISPLAY CHANNEL (MQTT)

You must specify the name of the channel definition you want to display. This can be a specific channel name or a generic channel name. By using a generic channel name, we can display either:

All channel definitions
One or more channel definitions that match the specified name

(generic-channel-name)

The name of the channel definition to be displayed (see Rules for naming IBM MQ objects ). A trailing asterisk (*) matches all channel definitions with the specified stem followed by zero or more characters. An asterisk (*) on its own specifies all channel definitions.

CHLTYPE( type )

The value is always MQTT.

TYPE can be used as a synonym for this parameter.

WHERE

Specify a filter condition to display only those channels that satisfy the selection criterion of the filter condition. The filter condition is in three parts: filter-keyword, operator, and filter-value:

filter-keyword

Almost any parameter that can be used to display attributes for this DISPLAY command. However, we cannot use the CMDSCOPE, QSGDISP, or MCANAME parameters as filter keywords. We cannot use TYPE (or CHLTYPE) if it is also used to select channels. Channels of a type for which the filter keyword is not a valid attribute are not displayed.

operator

This is used to determine whether a channel satisfies the filter value on the given filter keyword. The operators are:

LT: Less than
GT: Greater than
EQ: Equal to
NE: Not equal to
LE: Less than or equal to
GE: Greater than or equal to
LK: Matches a generic string that you provide as a filter-value
NL: Does not match a generic string that you provide as a filter-value
CT: Contains a specified item. If the filter-keyword is a list, we can use this to display objects the attributes of which contain the specified item.
EX: Does not contain a specified item. If the filter-keyword is a list, we can use this to display objects the attributes of which do not contain the specified item.
CTG: Contains an item which matches a generic string that you provide as a filter-value. If the filter-keyword is a list, we can use this to display objects the attributes of which match the generic string.
EXG: Does not contain any item which matches a generic string that you provide as a filter-value. If the filter-keyword is a list, we can use this to display objects the attributes of which do not match the generic string.

filter-value

The value that the attribute value must be tested against using the operator. Depending on the filter-keyword, this can be:

An explicit value, that is a valid value for the attribute being tested.
We can use operators LT, GT, EQ, NE, LE, or GE only. However, if the attribute value is one from a possible set of values on a parameter (for example, the value SDR on the TYPE parameter), we can only use EQ or NE.
A generic value. This is a character string (such as the character string you supply for the DESCR parameter) with an asterisk at the end, for example ABC*. The characters must be valid for the attribute you are testing. If the operator is LK, all items where the attribute value begins with the string (ABC in the example) are listed. If the operator is NL, all items where the attribute value does not begin with the string are listed. Only a single trailing wildcard character (asterisk) is permitted.
We cannot use a generic filter-value for parameters with numeric values or with one of a set of values.
An item in a list of values. The value can be explicit or, if it is a character value, it can be explicit or generic. If it is explicit, use CT or EX as the operator. For example, if the value DEF is specified with the operator CT, all items where one of the attribute values is DEF are listed. If it is generic, use CTG or EXG as the operator. If ABC* is specified with the operator CTG, all items where one of the attribute values begins with ABC are listed.

ALL

Specify ALL to display the results of querying all the parameters. If ALL is specified, any request for a specific parameter is ignored. The result of querying with ALL is to return the results for all of the possible parameters.

This is the default, if we do not specify a generic name and do not request any specific parameters.

If no parameters are specified (and the ALL parameter is not specified or defaulted), the default is that the channel names only are displayed.

Requested parameters

Specify one or more DISPLAY CHANNEL parameters that define the data to be displayed. We can specify the parameters in any order, but do not specify the same parameter more than once.

Some parameters are relevant only for channels of a particular type or types. Attributes that are not relevant for a particular type of channel cause no output, nor is an error raised. The following table shows the parameters that are relevant for each type of channel. There is a description of each parameter after the table. Parameters are optional unless the description states that they are required.

BACKLOG: The number of outstanding connection requests that the telemetry channel can support at any one time. When the backlog limit is reached, any further clients trying to connect will be refused connection until the current backlog is processed. The value is in the range 0 - 999999999. The default value is 4096.
CHLTYPE: Channel type.; There is only one valid value for this parameter: MQTT.
JAASCFG: The name of a stanza in the JAAS configuration file.
LOCLADDR: The local communications address for the channel.
MCAUSER: The message channel agent user identifier.
PORT: The port number on which the telemetry (MQXR) service accepts client connections.
PROTOCOL: The communication protocol supported by the channel.
SSLCAUTH: Defines whether IBM MQ requires a certificate from the TLS client.
SSLCIPH: When SSLCIPH is used with a telemetry channel, it means TLS Cipher Suite.
SSLKEYP: The store for digital certificates and their associated private keys. If we do not specify a key file, TLS is not used.
SSLKEYR: The name of the TLS key repository. For full details, see the SSLKEYR parameter of the ALTER QMGR command.
TRPTYPE: The transmission protocol to be used. For a Telemetry channel, this is always TCP (that is, the TCP/IP protocol).
USECLTID: Indicates whether you want to use the MQTT client ID for the connection as the IBM MQ user ID for that connection.

For more details of these parameters, see DEFINE CHANNEL (MQTT).