[jboss-as7-dev] Default Configuration Namespace

[Darran Lofthouse]

Working on this issue (AS7-1923) so far the biggest task I see is 
ensuring namespace handling in StandaloneXml.java, DomainXml.java, 
HostXml.java and CommonXml.java

Firstly I think consistency across the files I listed is essential so 
whichever approach we choose I will ensure is implemented across these 
files.

Generally I see these options for handling multiple versions: -

* 1 - Switch statement on version and duplicate parsing. *

Here I would see each readElement type method with a switch on the 
schema version, the attribute and element parsing would then be version 
specific so no further version specific checks would be needed for that 
version.

The biggest disadvantage of this would be duplication of code where 
complex type definitions have only minor changes, where they are 
identical the same code could handle mutliple versions.

The main advantages would be ease for commiters to verify old schema 
parsing not inadvertently updated by a change and easier to map code 1:1 
to exact schema version.

* 2 - Leave entire implementation based on V1.0 with specific checks for 
updates *

Here everything remains written in terms of version 1.0 but as changes 
are made for subsequent versions we just add version checks at the 
points where updates are made to the schemas e.g. for new elements / 
types or removed types.

This keeps us with the least duplication as the version checks are at 
exactly the points where they are required.

The down side I see here is for longer term maintenance, if you are 
going to work on a bug in existing parsing code you will need to review 
every schema we support to ensure the one block of code is compatible 
with them all.  If in the future we wanted to deprecate or remove old 
versions I think this approach could lead to having to re-write all the 
classes I listed to re-base on a new base version and take into account 
the subsequent versions or risk a build up of dead code.

* 3 Duplicate the *Xml.java classes *

When the version of the xsd is switched all parsing will be in terms of 
the new schema so we don't need to support the version switching 
mid-parse (although we should still detect to ensure it doesn't happen) 
- if we created version specific classes each version will be completely 
isolated.

At this stage unless bugs are reported there should be no further 
updates to 1.0 parsing as we move to 1.1 parsing.


Any other thoughts?  Personally for longer term maintenance I would 
think options 1 or 3 even with the code duplication.

Regards,
Darran Lofthouse.


On 09/23/2011 03:30 PM, Darran Lofthouse wrote:
> Anyone mind if I make these changes?  My next changes are dependent on
> being on the next version of the schema.
>
> Regards,
> Darran Lofthouse.
>
>
> On 09/23/2011 03:03 PM, Brian Stansberry wrote:
>> We should shift the 1.1 as the default and the marshallers should write
>> the latest.
>>
>> On 9/23/11 8:57 AM, Darran Lofthouse wrote:
>>> Also one more question.
>>>
>>> Which version should the server now be writing when the configuration is
>>> persisted?
>>>
>>> Do we have a policy for everything to write using the latest schema
>>> version or are we going to be trying to use the version specified until
>>> new elements/attributes are encountered?
>>>
>>> Regards,
>>> Darran Lofthouse.
>>>
>>>
>>> On 09/23/2011 02:33 PM, Darran Lofthouse wrote:
>>>> Now that 7.0.2 is out and the only subsequent planned releases are for
>>>> 7.1 can we switch the namespace for all default configuration to
>>>> 'urn:jboss:domain:1.1'?
>>>>
>>>> Regards,
>>>> Darran Lofthouse.
>>>>
>>>>
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