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https://issues.apache.org/jira/browse/UIMA-5385?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Jerry Cwiklik closed UIMA-5385.
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Resolution: Fixed
Assignee: Jerry Cwiklik
Added support for targeting specific instance of uima-as service. The service
uses a default selector with a format <IP>:<PID> and will process messages that
match the value of property TargetServiceId. Optionally, a service deployer can
override default selector with a -DTargetServiceId command line property
> UIMA-AS: add support for targeting specific service instance via JMS
> --------------------------------------------------------------------
>
> Key: UIMA-5385
> URL: https://issues.apache.org/jira/browse/UIMA-5385
> Project: UIMA
> Issue Type: New Feature
> Components: Async Scaleout
> Reporter: Jerry Cwiklik
> Assignee: Jerry Cwiklik
> Fix For: 2.10.0AS
>
>
> With multiple service instances getting messages from a shared JMS queue
> there is no way to know which instance gets a particular message. By design,
> the JMS queue provides natural load balancing and a broker routes a message
> to a service which has capacity (ready thread) to process it.
> Targeting services would support interesting use cases. For example, sending
> a message to a specific service instance could be used to determine if the
> service is viable or not. Targeted messages can also be considered of high
> processing priority and processed ahead of 'normal' priority messages.
> JMS supports targeting with selectors. A message listener is configured to
> indicate which messages it wants to receive. The selection is based on a
> value of a JMS property included in a message. The JMS selector syntax is
> based on SQL 92 spec which allows for compound expressions that include: AND,
> OR, NOT, etc. The message selection is done by the broker not the consumer.
> The broker will route messages to a consumer whose selector matches property
> values in a message.
> Current UIMA-AS already supports two selectors, one for handling Process
> requests and the other for GetMeta. Each of these has a dedicated listener
> and thread(s) to process messages. The proposal is to add yet another
> listener with a new selector to support targeting. The service selector value
> can be user defined via -DHighPriorityServiceId=XXX. If the -D is not
> present, the UIMA-AS will create a new listener with a selector = [Node IP:
> PID] which would uniquely identify a service.
> It would be up to the client application to determine value for the targeting
> string (selector). The UIMA-AS client will provide a way for an application
> to specify targeting string via a Map which is passed into the initialize( )
> method of the UIMA-AS client. This would allow for pinning a client to a
> specific service instance. All messages from the client would be processed by
> that service. If targeting string is not present, targeting will not be
> enabled and messages will be processed by an arbitrary service instance.
> As mentioned, targeted messages will have a high priority and will be
> processed first. A new java priority queue will be added to the UIMA-AS
> service to enable sorting of messages according to the priority.
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