Patterns: Implementing Self-Service in an SOA Environment

76 Patterns: Implementing Self-Service in an SOA Environment

򐂰 The Caching Proxy intercepts data requests from a client, retrieves the

requested information from the application servers, and delivers that content

back to the client. It stores cacheable content in a local cache before

delivering it to the client. Subsequent requests for the same content are

served from the local cache, which is much faster and reduces the network

and application server load.

򐂰 The Load Balancer provides horizontal scalability by dispatching HTTP

requests among several, identically configured Web server or application

server nodes.

5.2.2 Service integration

The service integration functionality within WebSphere Application Server V6

provides the infrastructure to support both message-oriented and

service-oriented applications. This new functionality is based on the concept of

the service integration bus, or simply, the bus.

The bus provides advanced support for application integration. It combines

support for applications connecting through native JMS, WebSphere MQ JMS,

WebSphere MQ, and Web services. It supports the message-oriented

middleware and request-response interaction models. As a part of this, the

service integration bus supports multiple message distribution models, reliability

options, and transactional messaging.

Figure 5-3 on page 77 gives you a high-level view of the bus functionality.

Chapter 5. Product mappings and product overview 77

Figure 5-3 Service integration bus

򐂰 Bus

A service integration bus, or bus, provides a conceptual connection point for

destinations and services. The application integration capabilities of the

service integration bus are provided by a number of connected messaging

engines.

򐂰 Messaging engine

While the conceptual entity clients connect to is the bus, the physical

connection is to a messaging engine. A

messaging engine manages bus

resources and provides the connection point for applications. Each

messaging engine is associated with a server or cluster that is a member of

the bus.

A messaging engine manages messages by routing them to the appropriate

endpoint, through additional messaging engines if required. These messages

can be persisted to a database and managed within a transactional scope.

Bus

Application

Server 3

Messaging

Engine

Cell

WebSphere MQ

Queue Manager

C

h

a

n

n

e

l

Node

Deployment Manager

WebSphere Application Server V6 Cell

Bus

Application

Server 1

Messaging

Engine

Publication Point

Queue

Destination

Topi c Space

Destination

Application

Server 2

Messaging

Engine

Queue Point

Foreign Bus

Link

Foreign Bus

Link

Mediation Point

78 Patterns: Implementing Self-Service in an SOA Environment

Clients can connect into any messaging engine in the bus and send

messages to it. If the destination is assigned to a different messaging engine,

the messaging engine will route it to the correct messaging engine.

򐂰 Destination

A

destination is an addressing point within a bus. A destination is assigned to

one bus member and, therefore, one or more messaging engines. Clients

send messages to a destination and the bus ensures that it is routed to the

correct localization on the bus. The following destination types are supported

by the service integration bus:

– Web service destinations

Web service destinations are a representation of an outbound Web service

in the bus. They are used as a placeholder for a port selection mediation.

– Port destinations

Port destinations are a representation of an outbound Web service port.

Sending a Web service request to a port destination will result in the target

Web service being invoked.

– Queue destinations

Queue destinations are destinations that are configured for point-to-point

messaging.

– Topic space destinations

Topic space destinations are destinations that are configured for

publish/subscribe messaging.

– Alias destinations

Alias destinations are destinations that are configured to refer to another

destination. They provide an extra level of indirection for messaging

applications. An alias destination can also be used to override some of the

values specified on the target destination, such as default reliability and

maximum reliability. An alias destination can also refer to a destination on

a foreign bus. Foreign buses are discussed in “Foreign bus link” on

page 79.

– Foreign destinations

Foreign destinations are not actual destinations within a service

integration bus, but they can be used override the default reliability and

maximum reliability properties of a destination that exists on a foreign bus.

Foreign buses are discussed in “Foreign bus link” on page 79.

Destinations can be mediated to provide advanced message formatting and

routing function.