On Wed, Oct 15, 2008 at 11:38 PM, Paul Sandoz <Paul.Sandoz_at_sun.com> wrote:
>
> On Oct 15, 2008, at 5:50 PM, Matthieu Riou wrote:
>
> On Wed, Oct 15, 2008 at 8:26 AM, Paul Sandoz <Paul.Sandoz_at_sun.com> wrote:
>
>> Hi Matthieu,
>>
>> How will you determine from a business process what the URIs, HTTP methods
>> and representations for resources of that process are?
>>
>
> The URIs and methods for the processes are predefined so even if I don't
> know about the process yet, I know what the URL and methods are going to be
> like once I see the process (basically from its name and starting activity).
> Depending on the process implementation, new resources can then be created
> at runtime and their URIs, methods, ..., are defined by the process itself,
> depending on the process constructs used.
>
>
>
> OK.
>
>
>
>> One way this can be done is for the business processes to provide resource
>> classes themselves are returned by a sub-resource locator of a root resource
>> (such classes are analyzed at runtime). It is also possible to dynamically
>> reload root resource classes.
>>
>> If there is a common pattern to all business process you can write general
>> resource classes with careful use of URI templates e.g. @Path("{id}"}
>>
>
> I think I can work with the assumption of having a process engine level
> root resource, processes being sub-resources and process execution related
> resource being sub-sub-resources. Only the second and third level resources
> would need to be dynamic (we don't instantiate several engines). Does that
> sound possible?
>
>
> I think something is possible here, for example the sub-resource locator of
> the engine could do:
>
> @Path("{process}")
> public Object getProcess(@PathParam("process") String process) {
> Object o = ProcessEngine.lookup(process);
> if (o == null) throw NotFoundException();
> return o;
> }
>
Yep, that works. I got a small prototype working yesterday.
>
>
> On thing I forgot to mention is that sub-resources would need to be
> removable as processes can get undeployed.
>
>
> This is an area that requires some work. There needs to be a way to say
> "please remove all information about and references to these components that
> you may know about)". I can add support for that. But it may work for
> sub-resources since it is the application that decides, the issue is Jersey
> will retain references to the sub-resource classes, which may not be good.
>
At least in my case I would only need to remove sub-resources and I would
know which ones to remove. So I wouldn't use something like sub-resource
automatic deletion or anything fancy.
>
> Are the class definitions and/or implementations for processes likely to
> change over redeployment?
>
The class definitions shouldn't, They'll have to be dynamic enough to handle
changes in the process. But the resources under which those classes are
published are going to change. New ones could be created, old ones removed.
By the way just to clarify, what I'm working on is RESTful support for BPEL
processes in Apache ODE (
http://ode.apache.org). We have a small spec to
extend BPEL with REST primitives (
http://ode.apache.org/restful-bpel-part-ii.html), replacing the dependencies
to WSDL and adding some REST-specific semantics
Thanks a lot for your help,
Matthieu
>
>
> Also would you have an example of reloading a root resource class?
>
>
> See here [1]. Currently the reloading functionality reloads the whole
> Jersey app. I need to work on a more granular level.
>
> In general this area is non-trivial for frameworks that leverage and cache
> reflection information and store references. One area that might be useful
> to investigate here is using OSGi to manage the notification of
> loading/unloading of modules that contain JAX-RS/Jersey components. To me
> leveraging OSGi seems like the right thing to do in general here.
>
> Paul.
>
> [1]
> http://markmail.org/search/?q=list%3Anet.java.dev.jersey.users+ContainerNotifier#query
> :list%3Anet.java.dev.jersey.users%20ContainerNotifier+page:1+
> mid:ztw4htppadrxh2rj+state:results
>
> Thanks!
> Matthieu
>
>
>>
>> Paul.
>>
>>
>> On Oct 15, 2008, at 5:13 PM, Matthieu Riou wrote:
>>
>> Hi,
>>>
>>> I have a need to create resources dynamically instead of having
>>> predefined static classes. The use case is I'm implementing a server where
>>> users can deploy business processes. Those should be exposed using a RESTful
>>> web service. But of course I don't know beforehand the resource address or
>>> even how many resources I'm going to have.
>>>
>>> Is there an API in Jersey that I could use to handle this use case?
>>>
>>> Thanks,
>>> Matthieu
>>>
>>
>>
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>
>