Professional BizTalk® Server 2006

4.2. Pipeline Stages

As mentioned previously, pipelines are broken down into a number of stages. These stages are executed sequentially, although there are some complications, which I cover when I discuss the disassembler in more detail. Broadly speaking, pipeline stages are a logical grouping for similar types of processing. Each stage can have 0 or up to 255 pipeline components configured in it, with the exception of the assembler stage, which can have 0 components or 1 component in it. A pipeline with no components in any stages represents a pass-through pipeline, which, as the name implies, performs no processing on the message. Pass-through pipelines are often used for binary messages because they simply allow the message to flow through. Each stage is assigned an execution mode, which determines how the components within that stage are executed. There are three execution modes: all, first recognized, and all recognized.

• Most of the stages in both the send and receive pipelines are assigned the all execution mode with the exception of the Disassemble stage. The all execution mode does, of course, cause every pipeline component in that stage to be executed. They are executed in the order that they are specified in the stage. This means that, effectively, each stage is like a mini-pipeline in itself; the implications of this will be a little clearer when I discuss disassembly in more detail.

• Next is the first recognized mode. This execution mode is a little more interesting. ...