Depending on the needs of your GroupWise system, it might be necessary for you to have multiple Web servers running the WebAccess Application.
A basic installation of GroupWise WebAccess requires the WebAccess Application, a POA, and a DVA, as shown in the following diagram.
When you install the WebAccess Application, you configure it to communicate with a single POA. However, in this simple configuration, if that POA goes down, WebAccess users cannot access their mailboxes, even if all other the POAs in your GroupWise system are still running. Configuring the WebAccess Application for multiple POAs provides more stable access. Three POAs are recommended, but there is no limit to the number of POAs that you can configure the WebAccess Application to communicate with. When a POA stops responding, the WebAccess Application contacts the next POA in the list to provide uninterrupted access (except, of course, for the users whose mailboxes are in the post office where the POA is down).
When you install the WebAccess Application, you configure it to communicate with a single DVA. Again, in this simple configuration, if that DVA goes down, no WebAccess users can view attached documents until that DVA is running again. Configuring the WebAccess Application for multiple DVAs provides more reliable document conversion. Three DVAs are recommended, but there is no limit to the number of DVAs that you can configure the WebAccess Application to communicate with. When a DVA stops responding, the WebAccess Application contacts the next DVA in the list to provide uninterrupted document conversion.
In a larger GroupWise system, you can install the WebAccess Application to multiple Web servers.
There are various reasons why you might want to add additional WebAccess Applications, including:
Improving WebAccess reliability: One WebAccess Application might provide sufficient access and performance, but you want to protect against downtime that would occur if the WebAccess Application became unavailable because of Web server failure or some other reason. Installing more than one WebAccess Application enables you to set up failover support to make your system more reliable.
Improving WebAccess performance: The WebAccess Application is designed to be close to GroupWise post offices. It requires SOAP access to the POAs. For best performance, you should ensure that the WebAccess Application is on the same local area network as the POA that it communicates with. For example, in most cases you do not want a WebAccess Application in Los Angeles communicating with a POA in London.
Improving WebAccess availability: Adding additional WebAccess Applications enables GroupWise WebAccess users on an intranet to access GroupWise through an internal Web server and WebAccess users on the Internet to access GroupWise through an exposed Web server.
Improving Web server performance: Adding additional WebAccess Applications increases Web server performance by balancing the workload among several Web servers, especially if you are using the Web server for other purposes in addition to GroupWise WebAccess.