Need a way to use pre-compiled DFDL schemas

[mbeckerle]

Large DFDL schemas can take upwards of a minute to compile.

We must have a way to specify a pre-compiled DFDL schema rather than being required to compile the schema "on the fly" at startup every time you click to debug a test.

A parameter specifying a pre-compiled schema location is the minimum thing needed.

[scholarsmate]

@mbeckerle, pre-compiled schema meaning the output of the save-parser subcommand (ref: https://daffodil.apache.org/cli/#save-parser-subcommand) or something else?

[stevedlawrence]

Yeah, that's usually what we mean by a pre-compiled schema.

Note that a pre-compiled schema using that command is basically just a serialized DataProcessor. Maybe an alternatively is to have the extension cache DataProcessor it builds for reuse, and only rebuild it when the schema changes?

[mbeckerle]

Yeah, in the long run, having an IDE that eliminates all this schema compilation noise and just manages properly a cache of them would be great.

Of course just making compilation of schemas way faster would be better, but that's fairly hard to do, and runtime performance is more critical than schema compilation time, IF that is, one can avoid the schema compilation time as much as possible.

The TDML runner tries to cache compiled schemas for tests. Maybe that functionality should be exposed differently so that it can be reused from the IDE?

[lrbarber]

Does the precompiled schema have any information in it that would relate it to the .xsd file?
How can the source schema be displayed in the debugger if we don't have the original code that was compiled?
What if there is a link, but the .xsd file has been changed since the compiled version was saved?

[stevedlawrence]

The precompiled schema has all the same information in it that a normal DataProcessor has. As long as the pre-compiled parser was built using the same files that VS Code is looking at, I think it should work the same?

What if there is a link, but the .xsd file has been changed since the compiled version was saved?

Could you detect if the schema files are newer than the pre-compiled file and output a warning.