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Joel Håkansson edited this page Apr 12, 2017 · 3 revisions

Identify, converting and enhancing are the types supported today, but there are additional types of activities that should be supported:

  • Identify ?>
  • Verify !>
  • Fix ~>
  • Tap ^>
  • Enhance +>
  • Convert ->

There might be additional types not listed above.

Identify

Assumption 1

The file extension is sufficient to identify a file type.

Caveats: Even under this assumption, there is still one case that needs solving. Many xml-formats have the same extension (xml), but it would be useful if one could provide an implementation for a specific xml-format in a separate bundle.

Assumption 2

The item to identify is always a single file.

Caveats: The item may be a fileset, with or without a known manifest or master file. The item might be a URL.

Convert

Properties of the convert type:

  • Inclusion of a converter in a path is determined by its usefulness in reaching the target format
  • Converters are included in the order required by input and target format
  • Converters can assume that the input is correctly identified and validated
  • Converters should return a valid result of the specified format

Enhance

Properties of the enhance type:

  • Inclusion of an enhancer in a path is always optional
  • An enhancer is qualified for inclusion by input format and specific keys and/or key-value combinations supplied by the user
  • Enhancements are included in an arbitrary order
  • Enhancements cannot be required by other parts
  • Enhancements cannot make any assumptions about the state of the input except for its identity and validity
  • An enhancer should be designed so that chaining the part any number of times directly after each other yields the same result as including the part only once.

Tap

Tap is a read-only task which produces a side effect, such as copying the intermediary result or uploading files to a server.

Properties of the tap type:

  • Inclusion of a tap in a path is always optional
  • A tap is qualified for inclusion by input format and specific keys and/or key-value combinations supplied by the user

Caveats: The location of the tap could be important (that is to say, before or after enhancements), but could perhaps be configurable (first/last).

For more information, see the common wiki

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