Database Reference
In-Depth Information
• Protocol-specific services, which represent the protocols supported by the co-
ordinator's coordination type
• The coordinator controller service of this composition, also known as the coordin-
ation service
A key element of the coordination context is the correlation key, which is common for all
activities in a particular composition. WS-Addressing's elements
wsa:ReferenceParameters
and
wsa:ReplyTo
could be employed as a container
for correlation ID and address, where the response will be sent:
<soap:Header>
<wsa:MessageID>uuid:35f19ca8-c9fe</wsa:MessageID>
<wsa:Action>http://erikredcarrier.com/ship</wsa:Action>
<wsa:To>http://www.portaquaba.com:7070/
ShippingService</wsa:To>
<wsa:ReplyTo>
<wsa:Address>
http://www.portbremen.com:7777/response
</wsa:Address>
<wsa:ReferenceParameters>
<customHeader>correlationKey</customHeader>
</wsa:ReferenceParameters>
</wsa:ReplyTo>
...
Combined together, these elements form the SOA pattern called
Service Callback
, which
is most commonly used in asynchronous communications.
Another pattern that is common to all types of service interactions related to the service is
the
Policy Centralization SOA
pattern. The
WS-Policy
specification is a machine-
readable language for representing these web service capabilities and requirements as
policies. A policy makes it possible for providers to represent such capabilities and re-
quirements in a machine-readable form. A separate policy file such as
policy.xml
can
contain several policy expressions that are grouped under different WS-Utility identifiers
(
wsu:Id
) for simplified referencing, both external (
ht-
tp://erikredcarrier.shipping.com/policy.xml#common
) and internal
(just
#common
); please see the
PolicyReference
examples shown in the following
code snippet:
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