WebSphere applications: Overview and new features

Product subsystems	WebSphere applications	WebSphere applications
Servers Application servers More server types Core groups Workload balancing Environment Virtual hosts Variable settings Shared libraries Replication domains System administration Administrative clients Configuration files Domains (cells, nodes) Performance Monitoring Tuning performance Troubleshooting Diagnostic tools Support and self-help	Services Security Naming ORB Transactions J2EE applications Web applications EJB applications Clients Client applications Web clients Web services clients Administrative clients Web services Web services and Service Oriented Architecture (SOA)	J2EE resources Data access resources Messaging resources Mail, URLs, and more WebSphere extensions ActivitySessions Application profiling Asynchronous beans Dynamic caching Dynamic and EJB query Internationalization Object pools Scheduler Startup beans Work areas

The product subsystems are discussed in the Product architecture. For the most part, they do not depend on the type of applications being deployed

J2EE application components

Web applications

The Web container is the part of the application server in which Web application components run. Web applications are comprised of one or more related servlets, JSP, and HTML files that one can manage as a unit. Combined, they perform a business logic function.

Servlets can support dynamic Web page content, provide database access, serve multiple clients at one time, and filter data.

JSP files enable the separation of the HTML code from the business logic in Web pages. IBM extensions to the JSP specification make it easy for HTML authors to add the power of Java technology to Web pages, without being experts in Java programming.

An HTTP session is a series of requests to a servlet, originating from the same user at the same browser. Sessions allow applications running in a Web container to keep track of individual users. For example, many Web applications allow users to dynamically collect data as they move through the site, based on a series of selections on pages they visit. Where the user goes next, or what the site displays next, might depend on what the user has chosen previously from the site. To maintain this data, the application stores it in a "session."

EJB (Enterprise JavaBeans) applications

The EJB container provides all of the runtime services needed to administer enterprise beans. The container is an interface between EJB components and the application server. It provides many low-level services, including threading and transaction support. From an administrative perspective, the container handles data access for the contained beans.

Enterprise beans are Java components that typically implement the business logic of J2EE applications, as well as accessing data.

Client applications and other types of clients

In a client-server environment, clients communicate with applications running on the server. Client applications or application clients generally refers to clients implemented according to a particular set of Java specifications, and which run in the client container of a J2EE-compliant application server. Other clients in the WAS environment include clients implemented as Web applications (Web clients), clients of Web services programs (Web services clients), and clients of the product systems administration (administrative clients).

Client applications: Java clients run in the client container, which is installed separately on the client machine. It enables the client to run applications in an EJB-compatible J2EE environment. Depending on the source of technical information, client applications might be called application clients. This documentation tends to use the two terms synonymously
Web clients: Web browser clients make requests to the Web container of the application server, by route of the HTTP server. A Web client or Web browser client runs in a Web browser, and is comprised of Web application components. See the Web applications section for Web client information.
Web services clients: Web services clients are yet another kind of client that might exist in your application serving environment. See the Web services section for details about this kind of client.
Administrative clients: The administrative interface (Admin UI) and scripting clients access parts of the systems administration infrastructure. the current discussion focuses on the technologies in the programming model,

Web services

Web services: The Web services engine is part of the Web services support in the application server runtime. Web services are self-contained, modular applications that can be described, published, located, and invoked over a network. They implement a services oriented architecture (SOA), which supports the connecting or sharing of resources and data in a very flexible and standardized manner. Services are described and organized to support their dynamic, automated discovery and reuse.

Data access, messaging, and J2EE resources

Data access resources

Applications use the JCA container to access application databases. Connection management for access to enterprise information systems (EIS) in the application server is based on the J2EE Connector Architecture (JCA) specification. The connection between the enterprise application and the EIS is done through the use of EIS-provided resource adapters, which are plugged into the application server. The architecture specifies the connection management, transaction management, and security contracts between the application server and EIS.

The Connection Manager in the application server pools and manages connections. It is capable of managing connections obtained through both resource adapters defined by the JCA specification and data sources defined by the JDBC 2.0 Extensions specification.

JDBC resources (JDBC providers and data sources) are a type of J2EE resource used by applications to access data. Although data access is a broader subject than that of JDBC resources, this documentation often groups data access under the heading of J2EE resources for simplicity.

Messaging resources

JMS support enables applications to exchange messages asynchronously with other JMS clients by using JMS destinations (queues or topics). Applications can use message-driven beans to automatically to automatically retrieve messages from JMS destinations and JCA endpoints without explicitly polling for messages.

For inbound non-JMS requests, message-driven beans use a Java Connector Architecture (JCA 1.5 resource adapter written for that purpose.

For JMS messaging, message-driven beans can use a JCA-based messaging provider such as the default messaging provider that is part of WebSphere Application Server. For compatibility with WAS v5, one can configure JMS message-driven beans against a listener port.

Mail, URLs, and other J2EE resources

J2EE resources are used by applications deployed on a J2EE-compliant application server. They include:

JDBC resources and other technology for data access (previously discussed)
JMS resources and other messaging system support (previously discussed)
JavaMail support, for applications to send Internet mail
URLs, for describing logical locations
Resource environment entries, for mapping logical names to physical names

Security

Security: The security server provides security infrastructure and mechanisms to protect sensitive J2EE resources and administrative resources and to address enterprise end-to-end security requirements on authentication, resource access control, data integrity, confidentiality, privacy, and secure interoperability.

Additional services for use by applications

Naming and directory

The name server provides a Java Naming and Directory Interface (JNDI) name space. The naming service registers resources hosted on the application server. It is built on top of a Common Object Request Broker Architecture (CORBA) naming service (CosNaming).

JNDI provides the client-side access to naming and presents the programming model used by application developers. CosNaming provides the server-side implementation and is where its name space is actually stored. JNDI essentially provides a client-side wrapper of the name space stored in CosNaming, and interacts with the CosNaming server on behalf of the client.

Clients of the application server use the naming architecture to obtain references to objects related to those applications. The objects are bound into a mostly hierarchical structure called the name space. It consists of a set of name bindings, each one of which is a name relative to a specific context and the object bound with that name. The name space can be accessed and manipulated through a name server.

With this product, you receive the following features:

Distributed name space, for additional scalability
Transient and persistent partitions, for binding at various scopes
Federated name space structure across multiple servers
Configured bindings for defining bindings bound by the system at server startup
Support for CORBA Interoperable Naming Service (INS) object URLs

Object Request Broker (ORB)

The product uses an ORB to manage communication between client applications and server applications, as well as among product components.

An ORB manages the interaction between clients and servers, using IIOP. It enables clients to make requests and receive requests from servers in a network distributed environment.

The ORB provides a framework for clients to locate objects in the network and call operations on those objects as though the remote objects were located in the same running process as the client, providing location transparency.

Transactions

Part of the application server is the transaction service. The product provides advanced transactional capabilities to help application developers avoid custom coding. It provides support for the many challenges related to integrating existing software assets with a J2EE environment. These measures include ActivitySessions (described below).

Applications running on the server can use transactions to coordinate multiple updates to resources as one unit of work such that all or none of the updates are made permanent. Transactions are started and ended by applications or the container in which the applications are deployed.

The application server is a transaction manager that supports coordination of resource managers and participates in distributed global transactions with other compliant transaction managers.

The server can be configured to interact with databases, JMS queues, and JCA connectors through their local transaction support when distributed transaction support is not required.

WebSphere extensions

WebSphere extensions are the programming model benefits you gain by purchasing WAS products. They represent leading edge technology to enhance application capability and performance, and make programming and deployment faster and more productive. WebSphere extensions (and the corresponding application services that support them in the application server runtime) can be considered in three groups: Business Object Model extensions, Business Process Model extensions, and extensions for producing Next Generation Applications.

Extensions pertaining to the Business Object Model

Business object model extensions operate with business objects, such as enterprise bean (EJB) applications.

Application profiling

Application profiling is a WebSphere extension for defining strategies to dynamically control concurrency, prefetch, and read-ahead.

Application profiling and access intent provide a flexible method to fine-tune application performance for enterprise beans without impacting source code. Different enterprise beans, and even different methods in one enterprise bean, can have their own intent to access resources. Profiling the components based on their access intent increases performance in the application server runtime.

Dynamic query

Dynamic query is a WebSphere programming extension for unprecedented application flexibility. It lets you dynamically build and submit queries that select, sort, join, and perform calculations on application data at runtime. Dynamic Query service provides the ability to pass in and process EJB query language queries at runtime, eliminating the need to hard-code required queries into deployment descriptors during application development.

Dynamic query improves enterprise beans by enabling the client to run custom queries on EJB components during runtime. Until now, EJB lookups and field mappings were implemented at development time and required further development or reassembly in order to be changed.

Dynamic cache

The dynamic cache service improves performance by caching the output of servlets, commands, and JSP files. This service within the application server intercepts calls to cacheable objects and either stores the output of the object or serves the content of the object from the dynamic cache.

Because J2EE applications have high read-write ratios and can tolerate small degrees of latency in the currency of their data, the dynamic cache can create opportunity for significant gains in server response time, throughput, and scalability.

Features include cache replication among clusters, cache disk offload, Edge side include caching, and external caching - the ability to control caches outside of the application server, such as that of your Web server.

Extensions pertaining to the Business Process Model

Business process model extensions provide process, workflow functionality, and services for the application server. Use them in conjunction with business integration capabilities.

ActivitySessions: ActivitySessions are a WebSphere extension for reducing the complexity of dealing with commitment rules and limitations associated with one-phase commit resources.
ActivitySessions provide the ability to extend the scope of multiple local transactions, and to group them. This enables them to be committed based on deployment criteria or through explicit program logic.
Web services: Web services are self-contained, modular applications that can be described, published, located, and invoked over a network. They implement a services oriented architecture (SOA), which supports the connecting or sharing of resources and data in a very flexible and standardized manner. Services are described and organized to support their dynamic, automated discovery and reuse.

Extensions for creating next generation applications

Next generation applications can be used in applications that need the specific extensions. These enable next generation development by leveraging the latest innovations that build on today's J2EE standards. This provides greater control over application development, execution, and performance than was ever possible before.

Asynchronous beans: Asynchronous beans offer performance enhancements for resource-intensive tasks by enabling single tasks to run as multiple tasks. Asynchronous scheduling facilities can also be used to process parallel processing requests in "batch mode" at a designated time. The product provides full support for asynchronous execution and invocation of threads and components within the application server. The application server provides execution and security context for the components, making them an integral part of the application.
Startup beans: Startup beans allow the automatic execution of business logic when the application server starts or stops. For example, they might be used to pre-fill application-specific caches, initialize application-level connection pools, or perform other application-specific initialization and termination procedures.
Object pools: Object pools provide an effective means of improving application performance at runtime, by allowing multiple instances of objects to be reused. This reuse reduces the overhead associated with instantiating, initializing, and garbage-collecting the objects. Creating an object pool allows an application to obtain an instance of a Java object and return the instance to the pool when it has finished using it.
Internationalization: The internationalization service is a WebSphere extension for improving developer productivity. It allows you to automatically recognize the time zone and location information of the calling client, so that your application can act appropriately. The technology enables you to deliver each user, around the world, the right date and time information, the appropriate currencies and languages, and the correct date and decimal formats.
Scheduler: The scheduler service is a WebSphere programming extension responsible for starting actions at specific times or intervals. It helps minimize IT costs and increase application speed and responsiveness by maximizing utilization of existing computing resources. The scheduler service provides the ability to process workloads using parallel processing, set specific transactions as high priority, and schedule less time-sensitive tasks to process during low traffic off-hours.
Work areas: Work areas are a WebSphere extension for improving developer productivity. Work areas provide a capability much like that of "global variables." They provide a solution for passing and propagating contextual information between application components.
Work areas enable efficient sharing of information across a distributed application. For example, you might want to add profile information as each customer enters your application. By placing this information in a work area, it will be available throughout your application, eliminating the need to hand-code a solution or to read and write information to a database.