Comments inline.
Thanks,
Raymond
----- Original Message -----
From: "Simon Laws" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Thursday, August 09, 2007 3:46 PM
Subject: Re: Accessing global domain information
On 8/9/07, Simon Laws <[EMAIL PROTECTED]> wrote:
On 8/9/07, Jean-Sebastien Delfino <[EMAIL PROTECTED] > wrote:
>
> Simon Laws wrote:
> > I need some advice on the way the code is structures. In various
> places in
> > the code I need to get at some information that logically belongs to
> the sca
> > domain. For example,
> >
> > CompositeWireBuilderImpl.connectComponentReferences()
> >
> > Tries to resolve services. In the distributed case this resolution
> > may
> > validly fail and I need to ask the domain whether the service is
> available
> > elsewhere. So I need access to some domain management services.
> Ideally I
> > would like to have access to a domain interface but am unsure how to
> plumb
> > it in as this kind of thing isn't generally available now. Anyone
> > care
> to
> > offer some advice how I get at such an interface without breaking the
> SPIs?
> >
> > Thanks
> >
> > Simon
> >
> >
> WireCompositeBuilderImpl is not an SPI, so you can pass whatever you
> want to its constructor without breaking any SPI.
>
> But I have a preliminary question: Why do you need to ask the domain
> (management service) about remote services at that specific point in
> WireCompositeBuilderImpl?
>
> --
> Jean-Sebastien
>
>
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>
> Hi Sebastien
I was thinking about this on the drive home. Just looking back at the
code
I had missed the important point that a reference target remains
unresolved
if the target component cannot be found. I could use this instead of the
actual service lookup at this point. The issue I have though is that the
CompositeWireBuilder dumps the bindings from the reference if it can't
find
a matching service/binding. This will be the case if the model for the
references service/binding is not read into the model for the current
node,
i.e. if the target component is not included in the current nodes
contributions.
Is it valid to only replace the current bindings with "selectedBindings"
if some selected bindings have actually be found?
Simon
Have been looking into this a little more and it seems that the list of
matched bindings takes into account the reference multiplicities and then
is
used during activation to create the runtime wires so we do have to be a
little cleverer in terms of creating a dummy resolved target to keep the
bindings in play.
Let's assume the reference is wired to a remote SCA service for this
discussion. For non-SCA services, it's simpler as we just have to pick a
binding locally for the reference and the binding URI will be good enough
for the routing.
There are two factors here:
1) What information is required from the service side for the reference side
to choose the right binding?
service: {service uri in the domain, a list of bindings} (I intentionally
skip the intent/policy stuff here). The key is that should be able to build
a call routing to this service endpoint.
2) When should we try to do the matching between the reference and the
service?
In some cases, the remote service information is not available when the
runtime wires are constructed. It means we have to defer the process when
the reference is used.
Anyone out there intimately familiar with the resolution process? What I
want to be able to do is have an sca binding (or any other binding for
that
matter) remain in place even in the case where the referenced target is
not
available in the local domain composite. Come runtime wire generation time
the binding itself can take responsibility for creating the correct
providers and invokers so that, assuming the referenced service is
remoteable, the request can be routed to the correct node.
Simon
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