Re: [jsr-314-open] [ajax] My AI on PartialResponseWriter.

Below, here's a description of the changes I'd like to make to the PartialResponseWriter - describing the problem, and the changes that I'd like to make in broad detail. This is one of the AIs I had from our Ajax breakout meeting. Please comment within a day or two, I'll write up a formal proposal with the exact proposed language to go in once I know I'm not spinning my wheels on a DOA idea. To save time, section 4 is the only part you may have a problem with - since it's the only part that changes current behavior... but we do have to address the issue somehow, so if you hate this idea, please propose another that also works... Jim ---------- Problem Description: PartialResponseWriter has very little JavaDoc or spec associated with it. Users are finding it difficult to use as a result. Additionally, the implicit call to startUpdate means that writing out other XML directives from a custom component is quite difficult. The JavaDoc preample says: PartialResponseWriter decorates an existing ResponseWriter to support the generation of a partial response suitable for Ajax operations. In addition to the markup generation methods inherited from javax.faces.context.ResponseWriter, this class provides methods for constructing the standard partial response elements. The individual method summaries say such things as: void startUpdate(String targetId) Write the start of an update operation. And void startEval() Write the start of an eval operation. And void startDocument() Write the start of a partial response. Currently, what to do if you were to call a startXXX method while already in a startXXX method is unspecified. The spec (section 13.4.4.1) simply says: Writing The Partial Response JavaServer Faces provides javax.faces.context.PartialResponseWriter to ensure the Ajax response that is written follows the standard format as specified in Section 1.3 “XML Schema Definition for Partial Responses”. Implementations must take care to properly handle nested CDATA sections when writing the response. PartialResponseWriter decorates an existing ResponseWriter implementation by extending javax.faces.context.ResponseWriterWrapper. Refer to the javax.faces.context.PartialResponseWriter JavaDocs, and the JavaScript documentation for the jsf.ajax.response function for more specifics. Proposal: We need to tighten up the spec in several ways: 1) Add comments to the JavaDoc that PartailResponseWriter will typically have startDocument and startUpdate called before the component can get ahold of it. Note that this is to allow interoperability with components that are not instrumented for Ajax. 2) Expand description in 13.4.4.1 to describe that an error will be thrown if: startDocument is called more than once on a response. any method is called after endDocument. any method is called before startDocument 3) Add a description to the spec of what methods will typically be called before the client receives the PartialResponseWriter in RenderResponse. Describe when this is not so (render = @none). 4) Allow for the calling of other methods besides startUpdate within a normal component’s Render Response. a) I propose that we treat all calls to the following methods as having their content placed on a queue, to be written out after the endUpdate is called: delete redirect startEval/endEval startUpdate/endUpdate startExtension/endExtension startInsertBefore/endInsert startInsertAfter/endInsert startError/endError updateAttributes b) nesting is only one deep - i.e., since the startUpdate is already called, if you call startEval, it will be an error to call anything other than endEval before calling any other method from this list... 5) Update JavaDoc to indicated paired methods - startEval/endEval startUpdate/endUpdate startExtension/endExtension startInsertBefore/endInsert startInsertAfter/endInsert startError/endError It will be an error, and an exception will be thrown, to call one method without the other. Concluding statement: While the description of this behavior (in particular the queuing) may be a little difficult, I believe that this behavior most closely matches what users are expecting when they currently use the API. If this approach is accepted by the EG, I’ll write up the formal changes.