Simon Laws wrote:
On Nov 20, 2007 6:47 PM, Jean-Sebastien Delfino <[EMAIL PROTECTED]>
wrote:
Simon Laws wrote:
On Nov 20, 2007 3:59 PM, Jean-Sebastien Delfino <[EMAIL PROTECTED]>
wrote:
Are you sure that this is the right semantics? Can you help me
understand why we need to change the naming of the service if there's a
a callback?
Thanks.
[EMAIL PROTECTED] wrote:
Author: slaws
Date: Tue Nov 20 06:35:45 2007
New Revision: 596692
URL: http://svn.apache.org/viewvc?rev=596692&view=rev
Log:
TUSCANY-1914
Construct URLs as ComponentName/ServiceName if callbacks have been
added
causing the number of services to be greater than 1
Modified:
incubator/tuscany/java/sca/modules/assembly/src/main/java/org/apache/tuscany/sca/assembly/builder/impl/CompositeConfigurationBuilderImpl.java
Modified:
incubator/tuscany/java/sca/modules/assembly/src/main/java/org/apache/tuscany/sca/assembly/builder/impl/CompositeConfigurationBuilderImpl.java
URL:
http://svn.apache.org/viewvc/incubator/tuscany/java/sca/modules/assembly/src/main/java/org/apache/tuscany/sca/assembly/builder/impl/CompositeConfigurationBuilderImpl.java?rev=596692&r1=596691&r2=596692&view=diff
==============================================================================
---
incubator/tuscany/java/sca/modules/assembly/src/main/java/org/apache/tuscany/sca/assembly/builder/impl/CompositeConfigurationBuilderImpl.java
(original)
+++
incubator/tuscany/java/sca/modules/assembly/src/main/java/org/apache/tuscany/sca/assembly/builder/impl/CompositeConfigurationBuilderImpl.java
Tue Nov 20 06:35:45 2007
@@ -280,7 +280,8 @@
String bindingURI;
if (binding.getURI() == null) {
- if (componentServices.size() > 1) {
+ //if (componentServices.size() > 1) {
+ if (component.getServices().size() > 1) {
// Binding URI defaults to component URI
/
binding name
bindingURI = String.valueOf(
binding.getName
());
bindingURI = URI.create(component.getURI
()
+ '/').resolve(bindingURI).toString();
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--
Jean-Sebastien
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Maybe I'm getting the wrong end of the stick here.
When a callback is encountered on a component reference a new callback
service is now created to represent the endpoint of the callback
[createCallbackService(Component, ComponentReference) in the
CompositeConfigurationBuilder].
I believe the intention is to treat these new services in the same way
as
any other service that the component may be providing.
There's a difference, they cannot be wired to using <reference
target="...">.
They can't be wired, but they can be looked up using createSelfReference()
and getService(). This is necessary to allow them to be passed as
service references on the setCallback() API.
For wiring, createSelfReference(), and getService(), it is always
possible to identify services by the fully qualified component/service
name. In addition, if there is only one service on the component
(counting both regular explicit services and implicit services for
callbacks), it should be possible to specify the component name
alone as a shorthand.
So far so good. Now we get to the trickier case of how URIs are
constructed for these services. For regular explicit services, the
approach in the spec is inconsistent with how this works for wiring
etc. as described above. The difference is that you either get a
fully qualified component/service name or you get a shorthand
component name only.
The either/or/only part of the last sentence has very undesirable
consequences in the following scenario:
1. A component has a single service A exposed via the shorthand URI.
2. Other bindings or non-SCA clients refer to it using the shorthand URI.
3. Another service B is added to the component. Now both A and B
are exposed via fully qualified URIs.
4. Everyone who was referring to A by the shorthand URI is now broken.
It's just as bad in the reverse scenario:
1. A component has a two services A and B exposed via fully qualified URIs.
2. Other bindings or non-SCA clients refer to A using a fully qualified URI.
3. Service B is removed from the component. Now A is only exposed via
a shorthand URI.
4. Everyone who was referring to A by the fully qualified URI is now broken.
The problem can be solved by always exposing services by the fully qualified
URI. In the case where there's a single service on a component, it would
be possible to also provide an "unsafe" alias shorthand URI that cannot be
relied on for forward compatibility, but I can't see that it's worth adding
this complexity for so little benefit.
I have raised a spec issue for this.
Simon
I think it would be worth checking the intention with the spec group.
Perhaps we should also check that the spec's intention is to continue to
have this one service vs multiple services distinction. I can't seem to
find it now on the mailing lists but I think I remember a discussion
around that and people suggesting to remove that distinction.
--
Jean-Sebastien
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Yes - I remember that too. I'll raise a question with Mike Edwards or
someone on the spec group and see if we can get some resolution to this.
Resolving the second question makes the first a moot point.
Regards
Simon
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