[jbpm-dev] [jBPM Development] - Re: parser for each jpdl release

kukeltje do-not-reply at jboss.com
Mon Oct 5 19:01:34 EDT 2009


"tom.baeyens at jboss.com" wrote : "kukeltje" wrote : Ok, the 'parking' of older parsers makes sense. I do have som questions though
  |   | - A version is not only the parser but also accompanying activity implementations. These are instantiated once a process is started (from what I understand). Does this have implications?
  |   | 
  | 
  | very true !  that's the tricky thing i ran into yesterday.
  | 
  | so now i think we should aim for the following approach:
  | 
  | * make sure that we can know the version of each process when we parse it.  this can be a bit tricky, because 1) we do not enforce people to specify namespace, so when deploying a process, the current library version somehow has to be added in to the db.  
  | 

I disagree. We should just enforce the namespace(declaration) That is what it is for.


"tom.baeyens at jboss.com" wrote : and another issue is this:  if we use the namespace for knowing the version, then this is also used to activate or not activate the xml validation.  so we could end up with the situation that an invalid process deploys because originally the namespace was not present.
  | 
  | if we then add the namespace before we save it in the deployment, then when loading it from the db it contains the namespace and that will activate validation.  and hence the process can not be used. given that we use a cache after deployment, this kind of problem might not show up in test environments.
  | 

Then don't add it, but (unfortunately) assume that every deployed process without a namespace declaration is 4.0 or 4.1. 

"tom.baeyens at jboss.com" wrote : 
  | 
  | * introduce a couple of if-then-else statements in the parser that depend on the version
  | 
  | * the hard part is testing.  i'm still trying to find how to we test this?  how can we make sure that old deployed processes will still work correctly in newer versions of jBPM.
  | 
  | i've been thinking about making sure that we run the test suite with a version parameter.  then all the processes in the testsuite which don't have an explicit namespace, will use the configured parser version.
  | 
  | but i'm not yet sure if this tests what we actually need.  and to what extend it protects us from making backwards incompatible changes.
  | 
  | if we get this wrong, the risk is that we break existing installations after they upgrade.
  | 
  | 

Yes, this is *the* challenge. But I'd use a namespace declaration for this. If none is there, assume 4.1. For the testing itself, maybe there is an option to use the tagged 
svn) testcases for a specific version and run them against the latest jbpm release. This would prevent an explosion of the number of testcases that we need (to duplicate?) in the source.

"tom.baeyens at jboss.com" wrote : 
  | 
  | "kukeltje" wrote : - Currently the schema is not fully 'any:any' aware. (I still think it should be 'other:any' for the extensibility. Fully supporting this is needed if you automatically want to add a namespace since people can remove the ns now if they want to add custom attributes. 
  |   | 
  | 
  | if you declare extensibility with any:any, then users can *still* define all their extensions in their own namespace.  they are just not forced to do it if they want to.
  | 
  | Again I strongly disagree. What if they extend some things and we start using the same tags? I *hate* the any:any. It was probably introduced (read forced upon us) in some weird way by a company that already developed something for it's customers. Just like with BPMN2 ;-)

"tom.baeyens at jboss.com" wrote : 
  | why do think users *need* to define their extensions in a separate namespace.  i agree that it would be good practice from a user perspective.  but i don't see a reason why we should enforce our users to it like that.
  | 
  | to prevent future element/tag clashes, to be explicit (I love explicit things, no.... I hate implicit things. Probably because it is one of the (few) negative aspects of females. Saying one thing but implying another.... "tom.baeyens at jboss.com" wrote : 
  | 
  | "kukeltje" wrote : - Does this mean that people have to redeploy their old processes if they want to take advantage of certain bugfixes in e.g. activity implementations?
  | 
  | that's the kind of questions that we have to ask ourselves when composing a solution.
  | 

What about an activities file per jpdl version? If we know we are breaking backwards compatibility (testcases of previous version failing against the latest source) , we create a new activities class which extends the previous one and we e.g. introduce a version number in the packagename and put that in the new activities file? (I was dreaming when I wrote this, forgive me if it goes astray

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