Content Based Routing (CBR) component

CBR works with Caching Proxy to proxy client requests to specified HTTP or HTTPS (SSL) servers. Use CBR to manipulate caching details for faster web document retrieval with low network bandwidth requirements. CBR and Caching Proxy examines HTTP requests by using specified rule types.

[8.5.5.0 or later] CBR gives you the ability to specify a set of servers that handle a request that is based on regular expression matching of the content of the request. Because CBR can specify multiple servers for each type of request, the requests can be load balanced for optimal client response. CBR also detects when one server in a set fails, and stops routing requests to that server. The load-balancing algorithm that is used by the CBR component is identical to the proven algorithm used by the Dispatcher component.

When a request is received by Caching Proxy, it is checked against the rules that are defined in the CBR component. If a match is found, then one of the servers that are associated with that rule is chosen to handle the request. Caching Proxy then continues its normal processing to proxy the request to the chosen server.

CBR has the same function as Dispatcher, except for high availability and a few other configuration commands.

Caching Proxy must be installed, configured, and running on the same machine before CBR can begin load balancing client requests.

With the CBR component, you can provide the following advantages to your clients:
Features of Content Based Routing:

Functions that provide load balancing

The primary functions of CBR interact with each other and Caching Proxy to balance network traffic in your environment. CBR consists of the following functions:
  • The cbrserver command handles requests from the command line to the executor, manager, and advisors.
  • The executor supports content-based load balancing of HTTP, HTTPS, and FTP connections. The executor always runs when the CBR component is being used for load balancing.
  • The manager sets weights that are used by the executor, which is based on:
    • Internal counters in the executor
    • Feedback from the servers that are provided by the advisors
    • Feedback from a system-monitoring program, such as Metric Server or WLM.
    • Using the manager is optional; however, if the manager is not used, load balancing is performed by using weighted round-robin scheduling that is based on the current server weights, and advisors are not available
  • The advisors query the servers and analyze results by protocol before it calls the manager to set weights as appropriate. Currently there are advisors available for the following protocols: HTTP, HTTPS, and FTP. You also have the option of writing your own advisors (read the Creating a custom advisor topic). Using the advisors is optional but recommended.

Configure and manage the executor, advisors, and manager, by using the command line (cbrcontrol) or the graphical user interface (lbadmin).

The three key functions of CBR (executor, manager, and advisors) and Caching Proxy interact to balance and dispatch the incoming requests between servers. Along with load balancing requests, the executor monitors the number of new connections, active connections, and connections in a finished state. The executor also does garbage collection of completed or reset connections and supplies this information to the manager.

The manager and advisor functions are similar to that of the Dispatcher.

Managing local servers with CBR

The CBR component uses Caching Proxy to forward client requests (HTTP or HTTPS) to the servers based on the content of the URL. This figure shows a logical representation of a site in which CBR is being used to proxy some content from local servers.

CBR used to proxy content from local servers
Concept topic    

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Last updated: April 16, 2014 11:59 AM EDT
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