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SOA Agent for Web Servers and Policy Server Interaction using Apache-based Web Server Pre-Fork Mode

When an Apache-based web server in pre-fork mode receives a request, the web server spawns a child process to communicate with the SOA Security Manager Policy Server. When more requests are received, more child-processes are spawned to handle them. Each child process spawned by the Apache-based web server has its own independent connections to the SOA Security Manager Policy Server.

The following illustration describes this process:

Multi-Process Web Servers create a parent process for the first policy server connection and spawn child processes for subsequent connections.

For Apache-based web servers, the value of the MaxClients parameter (in the httpd.conf file) determines the number of child processes spawned the web server. When a parent process from an Apache-based web server spawns a child process, the child process opens an initial connection to the SOA Security Manager Policy Server.

An important distinction exists between the number of SOA Agents for Web Servers, and the number of SOA Agent processes. Each SOA Agent requires its own web server instance. IIS web servers, for example, only operate as a single instance, so the number of IIS SOA Agents equals the number of IIS web servers. For other types of servers, it is possible to have multiple server instances listening on different ports within one physical web server.

The maximum number of sockets opened from an Apache-based web server to a SOA Security Manager Policy Server equals the value of the MaxClients parameter multiplied by the number of SOA Agent processes. For example, if the value of the MaxClients parameter of your server is set to 150, and you have five SOA Agent processes, then the maximum number of possible sockets opened is 750.

Using a multiprocess web server affects the ratio of SOA Agent processes to Policy Servers in your SOA Security Manager environment. The limiting factor often becomes the number of connections between the SOA Agent processes and the Policy Server, not the number of transactions per second.

Before deploying SOA Agents, verify that the SOA Security Manager Policy Servers receiving the requests can handle the maximum number of connections that the related web servers could open.

More information:

Failover and Load Balancing with Multi-Process Web and Application Servers