Selecting a front end for your WebSphere Application Server topology

You can use either a Web server plug-in, or a WebSphere Application Server proxy server to provide session affinity, failover support, and workload balancing for your WebSphere Application Server topology .

After you install the product, you can set up either a Web server plug-in, or a WebSphere Application Server proxy server to establish communication between an application and a remote client.

You can also use the on demand router (ODR), that is provided with the WebSphere eXtended Deployment product, as a reverse proxy between an HTTP client and a clustered application, or a partitioned application. See the WebSphere eXtended Deployment Information Center at http://publib.boulder.ibm.com/infocenter/wxsinfo/v7r0/index.jsp for more information about using ODR.

The traditional topology, using your Web server of choice and the corresponding Web server plug-in, is recommended unless:

The following tables compare the core application server frontend functionality, and the non-core functionality of a Web server plug-in running in a modern Web server, such as the IBM HTTP Server, based on Apache HTTP Server, and a WebSphere Application Server proxy server.

Table 1. Core functionality. This table compares the functionality that a Web server plug-in, and a WebSphere Application Server proxy server provide.
Functionality Web server plug-in WebSphere Application Server proxy server
Session affinity Yes Yes1, 2
DMZ ready Yes No
Custom advisors are supported No No3
Service Level Agreement (SLA) No No
QoS/Throttling No No
SIP proxy No Yes
ESI dynamic Caching Yes Yes4
Managed from the administrative console Yes Yes
Stream caching (large response caching) Yes No5
Dynamically receive management events6 No Yes
Multi cells routing No Yes6
Performance monitoring Yes7 Yes7
Load Balancing (weighted round-robin) Yes8 Yes9
Routing rules are configurable No10 Yes
Interoperability with WLM Yes11 Yes12
Web service affinity and failover No Yes13
Generic server cluster (GSC) affinity and failover No Yes14
Table notes:
  1. Session affinity is supported for WebSphere Application Server managed resources. However, some session management custom properties, such as HttpSessionCloneId, are not supported.
  2. For generic server routing, where the resources are not WebSphere Application Server managed resources, active session affinity and passive session affinity need to be configured under generic server routing action.
  3. Custom advisors are supported in Version 7.0.
  4. WebSphere Application Server proxy servers do not support fragment caching. Only whole page caching, and the ESI invalidation servlet are supported.
  5. Stream caching is provided in Version 7.0
  6. Requires core group bridge setup between the proxy cell and other cells.
  7. The Web server plug-in statistics are obtained from request metrics.
  8. WebSphere Application Server proxy server statistics can be retrieved from Tivoli performance viewer, ARM, and performance mBeans.
  9. Random Load balancing is supported in addition to weighted round robin.
  10. Web server plug-in can only do static routing.
  11. A Web server plug-in indirectly has interoperability with WLM through the exchange of dynamic workload manager (DWLM) Partition Tables between the Web server plug-in and WebSphere Application Server. The plug-in uses these tables for dynamic routing and failover scenarios within a cluster.
  12. [Updated in July 2011] The proxy server uses the WebSphere Application Server WLM even if the proxy server is running on a z/OS operating system. [Updated in July 2011]
    jul2011
  13. The DataPower appliance manager provides faster Web service affinity and failover service than Java proxy provides.
  14. Proxy server supports load balancing and failover for generic server clusters with passive and/or active affinity.
Table 2. Functionality provided outside of the Web server plug-in. This table provides a comparison of the functionality that a typical Web server, that is hosting a Web server plug-in, and a WebSphere® Application Server proxy server provide outside of the core application server frontend functionality. See your Web server documentation for a complete description of the functionality that your particular Web server provides.
Functionality Web server plug-in used with either the IBM HTTP Server or the Apache Web Server WebSphere Application Server proxy server
Common Gateway Interface (CGI) Yes No
Request URI rewriting Yes No
Efficient static file serving Yes No1
Compression Yes Yes
Response filtering Yes No2
SSL termination Yes Yes
Cryptographic Accelerator3 Yes Yes4
FIPS Yes Yes
Third-party/customer-written plug-ins Yes No
Logging Yes Yes5
Custom Logging Yes No
Disk caching Yes Yes
Asynchronous request handling none or partial6 Yes7
Table notes:
  1. WebSphere Application Server proxy servers support basic static file serving in Version 7.0
  2. WebSphere Application Server proxy servers support HTML link rewriting in Version 7.0.
  3. This functionality only applies to Cryptographic Accelerators that WebSphere Application Server supports. See the Supported hardware and software Web page .
  4. The support is provided by IBM JDK/JCE.
  5. Only NCSA common format is supported.
  6. The connection between a Web server plug-in and an application server is synchronous and consumes a thread while reading/writing or waiting for data. See your Web server documentation for information about how your particular Web server handles client connections.
  7. Proxy server is optimized to handle AJAX long polling requests under large scale deployments.



Related tasks
Setting up the proxy server
Communicating with Web servers
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