Friday, April 4, 2008

How To - 10.1.3 OWSM: Configure gateway to talk to failover enabled web services

It's a common use case to provide fail over for your web services. If OWSM Gateway is protecting such webservices then one of the following methods can be used for such configuration.

Method 1: Gateway -> Load Balancer (LBR) -> Web Services
This is the most commonly used approach of using a hardware load balancer between gateway and the web services. When performing service registration in the gateway, enter the load balancer endpoint.

Method 2: Gateway -> Oracle HTTP Server (OHS) -> Oracle Web Services
Here OHS acts as a software load balancer.

Method 3: Gateway -> Web Services
Gateway also has a built in mechanism to perform failover on the webservices by passing in bunch of failover urls. You can configure it at the time of service registration (page 2) or later on by editing service details, and clicking "Modify Protocol Parameters".
There are 3 relevant properties that need to be set.

  • FailoverURLs - List of comma separated web service urls. Gateway communicates with the web service endpoint in the order listed.
  • Attempts - Number of failed attempts before which Gateway tries to contact next url from the FailoverURLs list. The default value is 5, but you change it to 1 if you want to failover to next web service after first failed attempt.
  • RetryInterval - Gateway waits for this interval (ms) before retrying the same url based on the number of attempts set.