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

...

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)

...

Rendering Pipeline Overview

The rendering pipeline uses a combination of XML Streaming APIs (StAX) and a custom Character Streaming API which mimics the StAX APIs but handles character and portal specific data. The rendering pipeline is comprised of small components each with a specific function. These components use a common input and output API allowing the runtime pipeline to be easily modified. Also all components are cache aware and can return a CacheKey that represents their current state for a request. This allows caching components to short-circuit the rendering pipeline when the output from a lower-level component is already in cache.