Web Services transactions, firewalls and intermediary nodes
You can configure your system to enable propagation of Web Services Atomic Transactions (WS-AT) message contexts and Web Services Business Activities (WS-BA) message contexts across firewalls or outside the WebSphere Application Server domain. With this configuration, you can distribute Web service applications that use WS-AT or WS-BA across disparate systems. The topology that you use can affect the high availability and affinity behavior of the transactions.
The topologies that are available to you are as follows:
- Direct connection
No intermediary node exists in this topology. The client communicates directly with a specific WAS. This topology supports high availability for transactions on requests made in a cluster, and affinity of transactions.
- Proxy Server for IBM WAS
In this topology, the client communicates with a Proxy Server for IBM WAS, which dynamically routes the client requests to the appropriate server in a WAS cluster.
The proxy server supports high availability, workload management, and affinity of transactions. After creating the proxy server, you do not have to perform any extra additional steps to enable these features.
- HTTP server, such as IBM HTTP Server
In this topology, the client communicates with an HTTP server, which always routes the client requests to a specific server in a WAS cluster. You configure the HTTP server to specify the WAS to route requests to. The HTTP server cannot provide either affinity or high availability for transactions. However, transactional integrity is assured, because recovery processing occurs after the failed server restarts.
You can still enable high availability on the WAS. Clients that access this server through an HTTP server cannot have high availability of transactions, but other clients that access the same server can.
If you have an existing HTTP server, but want the high availability and workload management capabilities of a Proxy Server for WebSphere, create a Proxy Server for IBM WebSphere Application Server and configure the HTTP server to route all requests to the proxy server, as in the following scenario.
- HTTP server in conjunction with a Proxy Server for IBM WebSphere Application Server
The client communicates with an HTTP server, which you configure to forward the client's requests to a Proxy Server for IBM WebSphere Application Server. The proxy then dynamically routes the requests to the appropriate server in WAS.
The proxy server provides the client with the high availability and affinity behavior that the HTTP server cannot.
Related concepts
Support for Web Services protocols
Related tasks
Configure an intermediary node for Web services transactions
Enabling WAS to use an intermediary node for Web services transactions
Installing Web server plug-ins
Planning to install ND
Creating a proxy server