Oracle Service Bus中的线程

jib以前在给客户讲产品的时候经常提到Oracle Service Bus服务总线适合于短连接，高频率的交易，而不适合那些大报文，然后花费很长的调用时间的应用，前一阵在给客户培训完企业服务总线后，又对OSB的限流机制有了一定了解，事实上，自己的理解也有很多偏差，下面就把在国外看到的一片讲Oracle Service Bus线程机制的文章和大家分享一下吧。

企业服务总线的典型场景

如果我们把pipeline中间的逻辑拉直的话，我们可以看到基本是这个图：

• Request Pipeline:在接收的pipeline中收到请求做处理
• RouteNode:通过路由节点调用业务服务
• Response Pipeline: 处理业务服务的回应，然后将结果返回.(这个图是个特例，具体是判断结果，修改请求，在去调用一个业务服务，然后回送回应)

基本模型

• 在请求pipeline中Oracle Service Bus会启用一个线程(Thread)
• 在调用业务服务的时候，线程释放，回到线程池，同时一个muxer等待回应
• 当回应收到，muxer把接收到的新的请求发送给一个新的线程，并执行response pipeline.

所以

我们可以为Proxy Service和Business Service定义不同的线程池，也就是Proxy Service WorkManager和Business Service WorkManager

没有包含路由节点

如果没有路由节点，OSB仍然会采用另外一个thread处理响应pipeline,但是采用的Default Work Manager

代理服务调用代理服务

同一线程调用Proxy Service的请求Pipeline,同一线程调用Response Pipeline

服务外调

Pipeline处理会block线程直到响应能够异步返回。在进行服务外调的时候，原来的线程不会释放，muxer使用Business Service Work Manager分配一个线程来处理请求，如果大家共享一个work manager,比较容易造成死锁。

总结

• Request Pipeline
  • Executes on Proxy Work Manager (WM) Thread so limited by setting of that WM.  If no WM specified then uses WLS default WM.
• Route Node
  • Request sent using Proxy WM Thread
  • Proxy WM Thread is released before getting response
  • Muxer is used to handle response
  • Muxer hands off response to Business Service (BS) WM
• Response Pipeline
  • Executes on Routed Business Service WM Thread so limited by setting of that WM.  If no WM specified then uses WLS default WM.
• No Route Node (Echo functionality)
  • Proxy WM thread released
  • New thread from the default WM used for response pipeline
• Service Callout
  • Request sent using proxy pipeline thread
  • Proxy thread is suspended (not released) until the response comes back
  • Notification of response handled by BS WM thread so limited by setting of that WM.  If no WM specified then uses WLS default WM.
    • Note this is a very short lived use of the thread
  • After notification by callout BS WM thread that thread is released and execution continues on the original pipeline thread.
• Route/Callout to Proxy Service
  • Request Pipeline of callee executes on requestor thread
  • Response Pipeline of caller executes on response thread of requested proxy
• Throttling
  • Request message may be queued if limit reached.
  • Requesting thread is released (route node) or suspended (callout)