All processing within Cocoon is handled within a pipeline. i.e. input, zero or more processing stages, and ultimately some output.

Processing steps are modelled as different types of Components, the simplest pipeline is:

• Input: Generator
• Processing: Transformer
• Output: Serializer
  

Therefore a pipeline consists of a generator, zero or more transformers and a serializer. A pipeline may also define its own ErrorHandling.

Requests to Cocoon are mapped to pipeline by a Matcher or a Selector. These are configured in the Sitemap.

Aggregator allow pipeline to be configured into a hierarchy, producing a compound document.

Definition

The map:pipeline element can contain:

• map:match – Selects pipeline processing depending on Matcher
• map:select, map:when, map:otherwise – Selector pipeline processing depending on Selector
• map:mount – Mounts a sub Sitemap
• map:redirect-to – Redirects to another pipeline
• map:parameter – Defines additional parameters for the sitemap components
• map:act – Peform Action processing
• map:generate – Defines the Generator step
• map:aggregate, map:part – Defines an alternate generation step by merging pipelines
• map:transform – Defines zero or more Transformer steps
• map:serialize – Defines the final Serializer step
• map:handle-errors – ErrorHandling
  
  

Types of Pipeline

• Normal pipelines
• Internal pipelines – can't be accessed externally, can only be addressed from within a sitemap. Specified by internal-only="true" attribute on map:pipeline
• Resource pipelines – basically normal pipelines that act as reusable definitions that can be called by others. See Resources
• Error pipelines – defined within handle-errors section. Fixed error Generator which is provided automatically by Cocoon, subsequent processing under user definition. See ErrorHandling