Use cases

A survey of the use cases on my desktop boils down in the following
way:

Most pipelines are simple, linear sequences. For example:

  1. Parse XML
  2. Perform XInclude
  3. Validate with RELAX NG
  4. Validate with XSD
  5. Transform

Some pipelines begin with non-XML sources, so stage 1 reads
a non-XML source and produces XML:

  1. Read non-XML
  2. Transform

Some pipelines produce ultimately non-XML results:

  1. Read pim.rdf
  2. Transform
  3. Produce sched.txt

Some pipelines have several non-XML steps:

  1. Read diagram.n3
  2. Transform
  3. Produce diagram.dot
  4. Produce diagram.png

Some pipelines read several inputs:

  1. Parse 1.xml
  2. Parse 2.xml
  3. Transform 1.xml
  4. Transform 2.xml (also using the output of stage 3)

Some pipelines have sub-pipelines:

  1. Read 1.n3; transform it; produce 1.svg
  2. Read 2.n3; transform it; produce 2.svg
  3. Read doc.xml
  4. Transform doc.xml (incorporating 1.svg and 2.svg)

Some pipelines produce several outputs:

  1. Parse XML
  2. Transform (producing 1.xml, 2.xml, ..., n.xml)

Some pipelines need to process all the outputs from a preceding stage:

  1. Parse XML
  2. Transform (producing 1.xml, 2.xml, ..., n.xml)
  3. Transform 1.xml
     Transform 2.xml
     ...
     Transform 3.xml

Some stages have parameters (simple value parameters in addition to
XML input file(s)). I don't think I have any use cases where one stage
has to generate simple value parameters for a subsequent stage).

Although I can imagine wanting pipelines that handle conditionals and
errors, all of the examples I have at hand don't have conditional
processing and either succeed or fail.

                                        Be seeing you,
                                          norm

-- 
Norman.Walsh@Sun.COM / XML Standards Architect / Sun Microsystems, Inc.
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