Add decorating "type" attr extension for service refs 82/36482/21
authorTom Pantelis <tpanteli@brocade.com>
Sun, 20 Mar 2016 04:06:08 +0000 (00:06 -0400)
committerTom Pantelis <tpanteli@brocade.com>
Thu, 7 Apr 2016 18:39:49 +0000 (18:39 +0000)
commit83c5bbb865803e0a06e0c24e9de849af10bb4993
tree995da728076de5001ae89d15a02b8fd612fa244c
parent36de1fd1c214d98ae97e6d7725f323dd01e34977
Add decorating "type" attr extension for service refs

Added an attribute extension to the <service> element that adds an
OSGi service property of the form "type=<value>". This allows providers
of a service to advertise the type of the service to distinguish it from
other services provided for the same interface.

Conversely, the extension can also be used in <reference> elements to allow
consumers of the service to specify which service implementation they
want.

As a convention, the "default" type should be used for the default
implementation of the service with other types being specialized
implementations. This allows consumers to obtain whichever
implementation the provider deems as the default without having to
explicitly know it and allows the provider to switch to a new
implementation without requiring all consumers to change their
referenced type.

If a consumer doesn't specify the "type" attribute, it may be ambiguous
as to which service is obtained. Rather than requiring that the "type"
attribute be specfied for every <reference> element, I added an attribute
extension attribute, "use-default-for-reference-types", to the <blueprint>
element that automatically adds a filter to all <reference> elements where
the "type" property is either not set or set to "default" if the "type"
attribute isn't explicitly specified. This ensures the default implementation
is imported if there are other implementations advertised with other types.

Change-Id: Ie61bb45da1c7539732cd31ab0f8130233c9696fc
Signed-off-by: Tom Pantelis <tpanteli@brocade.com>
opendaylight/blueprint/src/main/java/org/opendaylight/controller/blueprint/ext/ComponentProcessor.java
opendaylight/blueprint/src/main/java/org/opendaylight/controller/blueprint/ext/OpendaylightNamespaceHandler.java
opendaylight/blueprint/src/main/resources/opendaylight-blueprint-ext-1.0.0.xsd

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