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
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
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
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
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.
WebSphere Application Server V6 Cell
Topi c Space
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 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
– Topic space destinations
Topic space destinations are destinations that are configured for
– 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
– 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