Aleksander Melnichnikov created CURATOR-457:
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Summary: Configuring service discovery paths
Key: CURATOR-457
URL: https://issues.apache.org/jira/browse/CURATOR-457
Project: Apache Curator
Issue Type: Improvement
Reporter: Aleksander Melnichnikov
Assignee: Jordan Zimmerman
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)
{code:java}
@VisibleForTesting
String pathForName(String name)
{
return ZKPaths.makePath(basePath, name);
}
@VisibleForTesting
String pathForInstance(String name, String id)
{
return ZKPaths.makePath(pathForName(name), id);
}
{code}
So, can we rethink visibility modifiers or add some extendable entity which
would be responsible for constructing paths?
For example:
Create interface
{code:java}
/**
* 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);
}
{code}
And make a constructor and field in ServiceDiscoveryImpl:
{code:java}
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);
}
}
{code}
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
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