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Subject: Re: [wsrp] Portlet and Forms

After finishing shaking my head at the design decisions made in some of these technologies, I agree that the suggested updates to the various sections of the spec are appropriate. On the first, I would favor a new section calling out the issues with the html form tag.

On you optional suggestion of a requiresEnclosingForm flag. This sounds like it would be better addressed by the Consumer Resources feature that we have deferred to v3 and I would rather wait than have an idiosyncratic solution for html forms.

While you did not comment on it, would it be valuable to have form usage information in MarkupContext (i.e. containsForms)?


Michael Freedman <michael.freedman@oracle.com>

06/01/05 06:26 PM

wsrp <wsrp@lists.oasis-open.org>
[wsrp] Portlet and Forms

My action items from last week were to summarize the portlet/form issue/needs and enumerate the approaches we need to take.  As we identified a number of mechanism last week that these approaches could be expressed in, I was also asked to illustrate the approaches using each mechanism.  This message contains all this information except for the later.  While I continue to work on this information, a first step is to review the curernt guidance we give in wsrp 1.0 on dealing with forms and ask how we might recast this given our broader understanding of consumer environment.  To get things started I have included a discussion of this at the end of the message.

As we have been discussing, WSRP 1.0 allows/assumes portlets are free to generate markup that includes <form> tags.  Consumer view technologies including ASP.Net and JSF define/use a single all encompassing page form.  Unfortunately, html doesn't support nested forms.  WSRP portlets [that generate forms], therefore, can't be aggregated directly into such pages.  Current solutions [Microsoft WSRP Webpart] relies on parsing the portlet's generated markup and rewriting the content to conform with the aggregating page's requirements.  There are, however, a number of edge cases that such parsing finds difficult if not impossible to deal with.  These include:

1.        What do we do with Javascrlpt [form] event handlers registered in the form tag?
2.        What do we do if enctype isn't  "application/x-www-form-urlencoded" e.g. the portlet has a file upload form?
3.        What do we do if the portlet sets/uses the accept-charset tag?
4.        How do we recognize/deal with [unencoded -- i.e. no wsrp_rewrite token] field references in Javascript?
In addition there is the general performance question/concern in requiring the consumer to parse the portlet's markup whether of not the markup contains a form or not.  In addition, because of some of the edge cases above solutions may have to rely on multi-pass parsing.

As I said above, our first approach should be to review what wsrp 1.0 says about dealing with forms and consider recasting this to better fit with consumers that supply enclosing forms.  I suggest we add a new section to 10.5.1 [HTML markup Fragment Rules] -- or as a subsection of [Other tags].  The new section says something like this:

There are special considerations in using the <form> tag.  HTML disallows nested <form> tags.  The consumer is allowed to nest the portlet in a form.  Such consumers are responsible for transforming portlet markup to avoid this limitation.  However, depending on the complexity of the portlet's form, the consumer may not be able to provide a complete transformation.  To ensure the portlet works correctly across the widest variety of environments, the portlet SHOULD:

1.        always namespace prefix all form field names [hidden or otherwise].  See section 10.3 for namespace encoding techniques.
2.        avoid using form level Javascript.  Instead use field level Javascript.
3.        avoid using/setting the form tag's accept-charset attribute.
In addition, the portlet dmeveloper should be aware that consuers nesting portlets in a form may have a difficult time dealing with any form whose enctype attribute differs from the enclosing form.  

We also need to rewrite section 10.3 on Namespace encoding as this section discourages namespacing a field's name attribute. This section may also need to clarify what the portlet should expect when it uses wsrp_rewrite_ to namespace a token.  The section implies the consumer replaces this marker with a namespaceID and doesn't strip this ID when passing the submitted field onto the portlet in the subsequent request.  Is this correct?  If so, how does the portlet remove this prefix to identify its field?

Optionally, we can consider allowing portlets to rely on supplying the form tag.  In this option, a portlet would write its form fields according to the rules above but not enclose them in a form tag.  The portlet would return in the response a requiresEnclosingForm boolean indicating to the consumer it must wrap the markup in a form tag.  If we want to get general here, we could expand this to also indicate the encoding of the form so not just form parameters would be expressed.  The idea here is to solve this problem by not having the portlet code as if they are being inserted into an enclosing form.  That way its both easy for JSF/ASP.Net form-based consumers as well as other non-form based consumers to get the correct behavior.

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