com.bigdata.rdf.sail.webapp.lbs

Interface IHALoadBalancerPolicy

All Superinterfaces:

IHAPolicyLifeCycle

All Known Implementing Classes:

AbstractHostLBSPolicy, AbstractLBSPolicy, CountersLBSPolicy, GangliaLBSPolicy, NOPLBSPolicy, RoundRobinLBSPolicy

public interface IHALoadBalancerPolicy
extends IHAPolicyLifeCycle

Load balancer policy interface.

Author:

Bryan Thompson

See Also:

HALoadBalancerServlet, HA Load Balancer

Method Summary

Methods

Modifier and Type	Method and Description
String	getLeaderURI(javax.servlet.http.HttpServletRequest req) Return the Request-URI to which a non-idempotent request will be proxied.
String	getReaderURI(javax.servlet.http.HttpServletRequest req) Return the Request-URL to which a read-only request will be proxied.
boolean	service(boolean isLeaderRequest, HALoadBalancerServlet servlet, javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) Invoked for each request.

Methods inherited from interface com.bigdata.rdf.sail.webapp.lbs.IHAPolicyLifeCycle

destroy, init

Method Detail

service

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

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

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:

javax.servlet.ServletException

IOException

getLeaderURI

String getLeaderURI(javax.servlet.http.HttpServletRequest req)

Return the Request-URI to which a non-idempotent request will be proxied.

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.

getReaderURI

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

Return the Request-URL to which a read-only request will be proxied. The returned URL must include the protocol, hostname and port (if a non-default port will be used) as well as the target request path.

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.