com.bigdata.rdf.sail.webapp.lbs.policy

Class NOPLBSPolicy

java.lang.Object

com.bigdata.rdf.sail.webapp.lbs.AbstractLBSPolicy

com.bigdata.rdf.sail.webapp.lbs.policy.NOPLBSPolicy

All Implemented Interfaces:

QuorumListener, IHALoadBalancerPolicy, IHAPolicyLifeCycle, Serializable

public class NOPLBSPolicy
extends AbstractLBSPolicy

This policy proxies all requests for update operations to the leader but forwards read requests to the local service. Thus, it DOES NOT provide a load balancing strategy, but it DOES allow update requests to be directed to any service in an non-HA aware manner. This policy can be combined with an external round-robin strategy to load balance the read-requests over the cluster.

Author:

Bryan Thompson

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class com.bigdata.rdf.sail.webapp.lbs.AbstractLBSPolicy

AbstractLBSPolicy.InitParams

Field Summary

Fields inherited from class com.bigdata.rdf.sail.webapp.lbs.AbstractLBSPolicy

journalRef, serviceIDRef, serviceTableRef

Constructor Summary

Constructors

Constructor and Description
NOPLBSPolicy()

Method Summary

Methods

Modifier and Type	Method and Description
String	getReaderURI(javax.servlet.http.HttpServletRequest req) Note: This method is not invoked.
boolean	service(boolean isLeaderRequest, HALoadBalancerServlet servlet, javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) Invoked for each request.

Methods inherited from class com.bigdata.rdf.sail.webapp.lbs.AbstractLBSPolicy

conditionallyForwardReadRequest, conditionallyUpdateServiceTable, destroy, getJournal, getLeaderURI, getLocalServiceScore, getServiceScoreForHostname, init, notify, toString, toString, updateServiceTable

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

NOPLBSPolicy

public NOPLBSPolicy()

Method Detail

service

public boolean service(boolean isLeaderRequest,
              HALoadBalancerServlet servlet,
              javax.servlet.http.HttpServletRequest request,
              javax.servlet.http.HttpServletResponse response)
                throws IOException,
                       javax.servlet.ServletException

Description copied from interface: IHALoadBalancerPolicy

Invoked for each request. If the response is not committed, then it will be handled by the HALoadBalancerServlet.

Specified by:

service in interface IHALoadBalancerPolicy

Overrides:

service in class AbstractLBSPolicy

Parameters:

isLeaderRequest - true iff this request must be directed to the leaeder and false iff this request may be load balanced over the joined services. UPDATEs MUST be handled by the leader. Read requests can be handled by any service that is joined with the met quorum.

servlet - The HALoadBalancerServlet. This is exposed in order to allow the IHALoadBalancerPolicy to perform a local forward of the request.

request - The request.

response - The response.

Returns:

true iff the request was handled.

Throws:

IOException

javax.servlet.ServletException

getReaderURI

public String getReaderURI(javax.servlet.http.HttpServletRequest req)

Note: This method is not invoked.

Parameters:

req - The request.

Returns:

The proxyTo Request-URI -or- null if we could not find a service to which we could proxy this request.