Service integration buses

A service integration bus is a group of one or more application servers or server clusters in a WebSphere® Application Server cell that cooperate to provide asynchronous messaging services. 匯流排中的應用程式伺服器或伺服器叢集,稱為匯流排成員。 In the simplest case, a service integration bus consists of a single bus member, which is one application server.

Usually, a cell requires only one bus, but a cell can contain any number of buses. The server component that enables a bus to send and receive messages is a messaging engine.

A service integration bus provides the following capabilities:
  • Any application can exchange messages with any other application by using a destination to which one application sends, and from which the other application receives.
  • A message-producing application, that is, a producer, can produce messages for a destination regardless of which messaging engine the producer uses to connect to the bus.
  • A message-consuming application, that is, a consumer, can consume messages from a destination (whenever that destination is available) regardless of which messaging engine the consumer uses to connect to the bus.

必要的話,不同的服務整合匯流排可以連接起來。 如此一來,使用單一匯流排(本端匯流排)的應用程式就能夠將訊息傳給另一個匯流排(外部匯流排)中的目的地。 不過,請注意,應用程式無法接收來自外部匯流排之目的地的訊息。

An application can connect to more than one bus. For example, although an application cannot receive messages from destinations in a foreign bus, if the application connects to that bus, the bus becomes a local bus and then the application can receive messages.

For example, in the following diagram, the application can send messages to destination A and destination B, but it cannot receive messages from destination B.

Figure 1. An application that is connected to bus A
The application can send messages to destination A and destination B, but it cannot receive messages from destination B.

In the following diagram, the application can send messages to, and receive messages from, destination A and destination B.

Figure 2. An application that is connected to bus A and bus B
The application can send messages to, and receive messages from, destination A and destination B.

A service integration bus comprises a SIB Service, which is available on each application server in the WebSphere Application Server environment. By default, the SIB Service is disabled. This means that when a server starts it cannot undertake any messaging. The SIB Service is enabled automatically when you add a server to a service integration bus. You can choose to disable the service again by configuring the server.

[z/OS]When the SIB Service is enabled on z/OS®, a flag is set to start the control region adjunct process when the server starts up. If you delete a bus, or remove the last bus member from a server, you must disable the SIB Service to prevent an adjunct region process from starting because of this flag when the server starts up.

A service integration bus supports asynchronous messaging, that is, a program places a message on a message queue, then proceeds with its own processing without waiting for a reply to the message. Asynchronous messaging is possible regardless of whether the consuming application is running, or whether the destination is available. Also, point-to-point and publish/subscribe messaging are supported.

After an application connects to the bus, the bus behaves as a single logical entity and the connected application does not have to be aware of the bus topology. In many cases, connecting to the bus and defining bus resources is handled by an application programming interface (API) abstraction, for example the administered JMS connection factory and JMS destination objects.

The service integration bus is sometimes referred to as the messaging bus if it provides the messaging system for JMS applications that use the default messaging provider.

Many scenarios require a simple bus topology, for example, a single server. If you add multiple servers to a single bus, you increase the number of connection points for applications to use. If you add server clusters as members of a bus, you can increase scalability and achieve high availability. Servers, however, do not have to be bus members to connect to a bus. In more complex bus topologies, multiple buses are configured, and can be interconnected to form complex networks. An enterprise might deploy multiple interconnected buses for organizational reasons. For example, an enterprise with several independent departments might want separately administered buses in each location.


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時間戳記圖示 前次更新: July 9, 2016 11:10
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