The bus environment comprises an one or more service integration buses, ESB servers, and their
resources, organized into logical administrative domains of cells and nodes.
If you create a Complete (default) installation for WebSphere ESB,
you get a stand-alone server on which you can deploy SCA modules without having
to do any configuration of the server.
However, administrators might still want to act on the bus environment,
so would benefit from some detail about the environment.
- The SCA runtime (exploited by mediation modules) uses queues on an SCA.SYSTEM service integration bus as a robust infrastructure
to support asynchronous interactions between components and modules. The queues
are hosted by the server as a member of the SCA.SYSTEM bus.
- The ESB server provides
the integration technologies, infrastructure services, configuration, and
runtime administration needed to run mediation modules and service applications
in WebSphere ESB.
As a bus member, the server has a messaging engine that provides the core
messaging functionality of the SCA.SYSTEM bus.
Both the server and SCA.SYSTEM are configured with default properties that
might be suitable for you to deploy and run your SCA modules.
Figure 1. A bus environment with one server assigned
to the SCA.SYSTEM service integration bus.
As a bus member, the server is assigned one messaging engine, which
has a data store for storing state data and messages. This figure also shows
a mediation module deployed into the bus environment and assigned to the bus
member.
For more advanced usage, you might want to change the configuration of
the bus environment for a stand-alone server, or create a bus environment
for a deployment manager cell. For example:
- You can configure a variety of quality of service from secure, assured
delivery (where messages are guaranteed not to get lost and are transported
securely) to best-effort (where messages might get lost in case of a system
failure).
- You might want to set up a deployment manager cell to provide several
servers to host mediation modules. This provides advantages of scalability,
the ability to handle more client connections, and greater message throughput.
You can also create server clusters, which enables you to manage a group of
servers together and enables those servers to participate in workload management.
- Your complete bus environment might be made up of several stand-alone
and deployment manager profiles, to provide separate administrative domains
for different departments or to separate test and production facilities. Each
profile has its own SCA.SYSTEMservice integration bus.
For more information about the different bus topologies, see Choosing a bus environment.
Besides the SCA.SYSTEM bus used for SCA modules, you can also create other service integration buses that you can
use to support the service integration logic provided by the modules. For
example, the SCA.APPLICATION.cell_name.Bus is provided
and used to define JMS queue destinations and other JMS resources for modules
deployed with JMS bindings.
You can create other buses for use as in WebSphere Application Server;
for example, for applications acting as service requesters and providers within WebSphere ESB,
or to link to WebSphere MQ. You can also use a WebSphere ESB deployment
manager to manage separate application servers for use with applications and
modules deployed onto WebSphere Application Server.