Details
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Improvement
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Status: Closed
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Minor
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Resolution: Fixed
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None
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None
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None
Description
Right now paths for services in service discovery hardcoded to pattern: /{basePath} /{serviceName}/{instanceId}. And that's impossible to configure paths this way: /{basePathPart1} /{serviceName}/{basePathPart2}/{instanceId}
For example:
If basePath = /base1/base2/base3, serviceName = serviceName, instanceId - serviceId
then path will be /base1/base2/base3/serviceName/serviceId, that can't be configured like this: /base1/base2/serviceName/base3/serviceId.
Because of strong encapsulation in ServiceDiscoveryImpl class (package private method modifiers)
@VisibleForTesting String pathForName(String name) { return ZKPaths.makePath(basePath, name); } @VisibleForTesting String pathForInstance(String name, String id) { return ZKPaths.makePath(pathForName(name), id); }
So, can we rethink visibility modifiers or add some extendable entity which would be responsible for constructing paths?
For example:
Create interface
/** * A constructor which constructs path to services for service discovering */ public interface DiscoveryPathConstructor { /** * Return the path where all service names registered * @return basePath */ String getBasePath(); /** * Return the path where all instances of service registered * @param name service name * @return path to service instances */ String getPathForInstances(String name); /** * Return the path where concrete instance registered * @param name service name * @param id concrete instance id * @return path to concrete instance */ String getPathForInstance(String name, String id); }
Also make a constructor and field in ServiceDiscoveryImpl:
private final DiscoveryPathConstructor pathConstructor;
/**
* @param client the client
* @param pathConstructor constructor for instances path
* @param serializer serializer for instances (e.g. {@link JsonInstanceSerializer})
* @param thisInstance instance that represents the service that is running. The instance will get auto-registered
* @param watchInstances if true, watches for changes to locally registered instances
*/
public ServiceDiscoveryImpl(CuratorFramework client, DiscoveryPathConstructor pathConstructor, InstanceSerializer<T> serializer,
ServiceInstance<T> thisInstance, boolean watchInstances)
{
this.watchInstances = watchInstances;
this.client = Preconditions.checkNotNull(client, "client cannot be null");
this.serializer = Preconditions.checkNotNull(serializer, "serializer cannot be null");
this.pathConstructor = Preconditions.checkNotNull(pathConstructor, "pathConstructor cannot be null");
if ( thisInstance != null )
{
Entry<T> entry = new Entry<T>(thisInstance);
entry.cache = makeNodeCache(thisInstance);
services.put(thisInstance.getId(), entry);
}
}
You can view commit in my fork of framework, if that's ok - I can make a pull request.
https://github.com/Me1kaa/curator/commit/6e6a34db7d71a84e3a53d284fc94e1fe2e3c10d8
