WebSphere Application Server Architecture

Applications:

WebSphere Application Server can run the following types of applications:

• Java EE Applications
• Portlet Applications
• Session Initiation Protocol Applications
• OSGI Applications
• Batch Applications
• Business-level Applications

Containers:

Containers provide runtime support for applications. They are specialized code in the application server that runs specific types of applications. Containers can interact with other containers by sharing session management, security, and other attributes. 

Web Container:

 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, JSPs, and HTML files that you can manage as a unit. The Web container processes servlets, JSP files, and other types of server-side includes. Each application server runtime has one logical web container, which can be modified, but not created or removed. Each web container provides the following.

• Web container transport chains
• Servlet processing
• HTML and other static content processing
• Session Management
• SIP Application and their container
• Portlet applications and their container

EJB Container:

EJB container provides all of the runtime services needed to deploy and manage enterprise beans. It is a server process that handles requests for both session and entity beans.

EJBs are Java components that typically implement the business logic of Java EE applications, as well as accessing data. The enterprise beans, packaged in EJB modules, installed in an application server do not communicate directly with the server. Instead, the EJB container is an interface between EJB components and the application server. 

The container provides many low-level services, including threading and transaction support. From an administrative perspective, the container handles data access for the contained beans. A single container can host more than one EJB Java archive file.

Batch container: 

The Batch container is where the job scheduler runs jobs that are written in XML job control language(xJCL)

The batch container provides and execution environment for the execution of batch applications that are based on Java EE.

Batch applications are deployed as EAR files and follow either the transactional batch or compute-intensive programming models.

Application Server:

The application server is the platform where Java EE applications can run. It provides services that can be used by business applications, such as database connectivity, threading, and workload management. 

Client Applications and other types of clients:

In a client-server environment, clients communicate with applications running on the server. 

1) Client applications and their containers: The client container is installed separately from the application server, on the client machine. It enables the client to run applications in an EJB-compatible Java EE environment. 

2) Web clients or web browser clients: The web client makes a request to the web container of the application server. A web client or web browser client runs in a web browser, and typically is a web application.

3) Web services client: Web services clients are another kind of client that might exist in your application servicing environment.

4) Administrative clients: A scripting client or the administrative console.

Web Services engine:

Web services are self-contained, modular applications that can be described, published, located, and invoked over a network. They implement a service-oriented architecture (SOA), which supports the connecting or sharing of resources and data in a flexible and standardized manner.

Service Component Architecture (SCA):

SCA composites consists of components that implement business functions in the form of services.

Data access, messaging, and Java EE resources:

Data access resources:

Connection management for accessing to Enterprise information systems (EIS) in the application server is based on the Java EE connector Architecture. JCA services helps an application to access a database in which the application retrieves and persists data.

The connection between 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 specifications. 

JDBC resources: JDBC resources are a type of Java EE resources used by applications to access data. 

JCA resource adapters: JCA resource adapters are another type of Java EE resources used by applications. The JCA defines the standard architecture for connecting Java EE platform to EIS.

Messaging resources and messaging engines:

JMS support enables applications to exchange messages asynchronously with other JMS clients by using JMS destination (Queues or Topics). Applications can use message-driven beans to automatically retrieve messages from JMS destinations and JCA endpoints with out explicit polling for messages

The messaging engine supports the following types of message providers:

Default messaging provider (service integration bus): 

The default messaging provider uses the service integration bus for transport. The default message provider provider print-to-point functions, as well as publish and subscribe functions. With this provider you define JMS connection factories and destinations that correspond to service integration bus destination. 

WebSphere MQ provider:

WebSphere MQ provider can be used as the external JMS provider. The application server provides the JMS client classes and administration interface, while WebSphere MQ provides the queue-based messaging system.

Generic JMS provider:

You can use another messaging provider as long as it implements the ASF components of the JMS 1.0.2 specifications. JMS resources for this provider can't be configured using the admin console.

Security:

The product provides security infrastructure and mechanisms to protect sensitive Java EE 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.

Security infrastructure and mechanisms protect Java Platform, Enterprise Edition (Java EE) resources and administrative resources, addressing your enterprise security requirements. In turn, the security infrastructure of this product works with the existing security infrastructure of your multiple-tier enterprise computing framework. Based on open architecture, the product provides many plug-in points to integrate with enterprise software components to provide end-to-end security.

The security infrastructure involves both a programming model and elements of the product architecture that are independent of the application type.

Additional Services for use by applications:

• Naming and directory service (JNDI)
• Object Request Broker (ORB)
• Transactions

WebSphere extensions:

WebSphere programming model extensions are the programming model benefits you gain by purchasing the product. 

• Application profiling
• Dynamic query
• Dynamic cache
• Activity Sessions
• Web services
• Asynchronous beans
• Startup beans
• Object pools
• Internationalization
• Scheduler
• Work areas