[dfdl-wg] DFDL Telcon notes

[Westhead, Martin (Martin)]

Present


Mike Beckerle

Martin Westhead

Geoff Judd

Bob McGrath

 


Discussion


This was a very useful discussion. We started by formulating the outline
of the spec document and then reviewed some specific aspects of the new
format document. 

 

Spec document outline:

Introduction section

*         glossary

*         What is DFLD?

*         Model 

Language basics

*	syntax
*	scoping and context
*	guards and selectors on annotations
*	basic arrays
*	variables
*	layering (hidden layers and value calc/referencing)

Detailed semantics

*	properties and conversions

Arrays

Built-in specifications

Extensions

 

 

Extensibility - constructs like <dfdl:sequence> need to have their list
of allowed properties extensible

 

Format/defineFormat - is the dfdl:format tag correctly named. Martin
assumed a catch-all dfdl annotation tag. Mike assumed that dfdl:format
was *just* format and that other things (variable assignments,
conversion definitions etc.) would go in different tags. More examples
and investigation are required to see how this works in practice.

 

defineFormat is probably too specific right now, this is an important
reuse mechanism and it should be available to apply to all top level
dfdl tags. One solution would be to have a more generic "define" tag
that can contain "dfdl:format" tags along with others.

 

Properties and variables - we expect that properties and variables have
the same scoping, assignment and reference semantics. Properties are
only different in the sense that they represent parameters to
conversions.

 

Linked properties - we discussed the need for linked properties, it
seems like extra stuff that might not be required and it was useful to
see if there were different ways to achieve the same goal. From the
discussion it did not seem an unreasonable thing to include.

 

Applies default - we reviewed the issues around the "applies" default
(toScope or hereOnly) the current default is "hereOnly" different
examples suggest different defaults are more appropriate. We decided to
leave the decision where it was but a bigger selection of examples will
probably help inform this decision.

 


Actions


 

*	Assemble draft of spec document from the pieces that we have.
(Currently unassigned -  volunteers?)

 

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