The purpose of the service role and name it to avoid having class names
in the topology files but still allow for the selection of service
plugins. Two levels of granularity are provided. The more general
"role" for a service is more common for example "WEBHDFS". For services
"name" isn't used much would potentially be used to disambiguate between
two services on the classpath that supported the same role.
The releavant pieces of code are the methods loadServiceContibutors and
selectContextServices in
gateway-server/src/main/java/org/apache/hadoop/gateway/deploy/DeploymentFactory.java
In loadServiceContributors you will see where the available services are
discovered on the classpath and loaded into a two level map by role/name.
In selectContextServices you will see how services referenced in a
topology file are resolved in that map during deployment.
On 12/9/14 10:15 AM, Sumit Gupta wrote:
While looking at the code for Service contribution and specifically the
ServiceDeploymentContributor interface in org.apache.hadoop.gateway.deploy, I
was wondering what the intent was behind the service role and name. The comment
says that the name is not used yet. Do we ever want to use it and how?
Sumit.
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