ease of use proposal - adding 'from' attribute to step to define connection

-- 

Todays WG meeting discussed the vagaries of explicitly defining port connections.

A number of proposals was floated to try and make life easier for the author. I thought I would
send through some informal emails to give an initial airing of each of the ideas percolating.

One syntax proposal which struck a chord with the WG, was an idea proposed by Henry S. Thompson,
to make it much easier (in the general use case) to define connection flow. 

The idea is a new 'from' attribte would be defined on a step. 

<p:pipeline>
  <p:identity name="mystep"/>
  <p:wrap-sequence .../>
  <p:count from="mystep"/>
</p:pipeline>

In this example, the 'from' attribute defines a connection from 'mystep' default readable port (eg. primary
output port of the p:identity 'mystep') to the p:count primary input port.

Which is semantically equivalent to the following pipeline.

<p:pipeline>
  <p:identity name="mystep"/>
  <p:wrap-sequence .../>
  <p:count>
    <p:input port="source">
      <p:pipe step="mystep" port="result"/>
    </p:input>
</p:pipeline>

While this simplification does not provide a broad range of new behaviour its a concise start towards making the
general use case easier and leverages existing port machinery already in place.

Obviously, there are still details to work out for the concrete proposal.

I am sure there are lots of room for variation and we want to hear your comments; though I am personally keen
to avoid ratholing on syntax, that is simplicity of use and alignment with current vnext will trump over complexity
or breadth of new behavior.

thx, Jim Fuller

ps- big thanks to Romain Deltour, his original email[1] which helped motivate action on this

[1] http://lists.w3.org/Archives/Public/public-xml-processing-model-comments/2014Feb/0001.html

Received on Wednesday, 26 November 2014 17:01:41 UTC