Orchestrator 1.0.0-alpha expects message decl. as direct descendent of MessageType

[m8pple]

In the v4 structure initially proposed by UoS the MessageType element has a sub-element of type Message, and then the C-style decl is a text child within that. My vague memory was the rationale that we might want to put another element under MessageType in the future, which is difficult if the c-style decl is a direct text child.

So in the v4 structure as agreed, and in all the example v4 XML in PIP20 and the 2019 benchmarks, the element looks like:

<MessageType>
   <Message>
    float x;
    float y;
   </Message>
</MessageType>

However, the 1.0.0-alpha parser is expecting something of the form:

<MessageType>
    float x;
    float y;
</MessageType>

This is a breaking change for all existing v4 applications, parsers, and generators. It is less benign than

199, as it is putting an element at a different level.

If the Orchestrator really needs this change to the xml grammar then we should bump the Orchestrator version to v5, as it is a breaking-change at a quite a deep level.

[heliosfa]

We are happy to revert to the spec.

This will involve a change to the grammar and DS_XML. Plan is to "ignore" the extra level internally. Docs and examples update will likely take longer.

Suggestion is to add to the TODO list for "if EPIC"

[m8pple]

This is a blocking problem, as existing v4 XML can't be parsed without it. There is a proposed fix to make it comply with the spec in #264

[heliosfa]

resolved in #264