Rendering Pipeline Refactoring

Technologies

• StAX (XML Streaming APIs)

Pipeline Ordering Overview

1. User Layout Store
   • outputs XMLEventReader
2. Attribute Incorporation Filter (Structure)
   • outputs XMLEventReader
3. XSLT (Structure)
   • uses XSLT Parameter Provider to help setup the Transformer
   • outputs XMLEventReader
4. Portlet Rendering Initiator
   • Uses Portlet Renderer API to initiate async portlet rendering
   • outputs XMLEventReader
5. Attribute Incorporation Filter (Theme)
   • outputs XMLEventReader
6. XSLT (Theme)
   • uses XSLT Parameter Provider to help setup the Transformer
   • outputs XMLEventReader
7. Serializer
   • Uses XMLOutputFactory to convert from XMLEventReader to Character data
   • outputs CharacterEventReader
8. Portlet Incorporation Filter
   • Portlet Renderer API to retrieve portlet rendering results
   • outputs CharacterEventReader
9. Output Writer
   • Writes to response Writer

Pipeline Component API

interface PipelineComponent {
    CompositeCacheKey getCacheKey(HttpServletRequest, HttpServletResponse);
}

interface StAXPipelineComponent {
    XMLEventReader getEventReader(HttpServletRequest, HttpServletResponse);
}

interface CharacterPipelineComponent {
    CharacterEventReader getEventReader(HttpServletRequest, HttpServletResponse);
}

Pipeline Caching Flow

• Caching will be applied via additional filters in the chain, either a StAXCachingFilter or a CharacterCachingFilter.
• The filter will use the following steps when getEventReader is called
  1. key = parentComponent.getCacheKey(req, res)
  2. eventRender = cache.get(key)
  3. If eventReader is not null return it
  4. If eventReader is null call parentComponent.getEventReader(req, res)
• The caches that will be used will be chaining caches meaning they will be wired together in parallel to the rendering pipeline allowing parent expiration state checking.