Example: Setting custom properties for an HTTP transport

WebSphere Application Server - Express has several transport properties that are not shown in the WebSphere administrative console in the settings page for an HTTP transport. They are as follows:

• ConnectionIOTimeout
  Specifies the maximum number of seconds to wait when trying to read or process data during a request. Data type: Integer.

• ConnectionKeepAliveTimeout
  Specifies the maximum number of seconds to wait for the next request on a keep-alive connection. Data type: Integer.

• MaxKeepAliveConnections
  Specifies the maximum number of concurrent keep-alive (persistent) connections across all HTTP transports. To make a particular transport close connections after a request, you can set MaxKeepAliveConnections to 0 (zero) or you can set KeepAliveEnabled to false on that transport.

  The Web server plug-in keeps connections open to the application server as long as it can. However, if the value of this property is too small, performance is negatively impacted because the plug-in has to open a new connection for each request instead of sending multiple requests through one connection. The application server may not accept a new connection under a heavy load if there are too many sockets in TIME_WAIT state. If all client requests are going through the Web server plug-in and there are many TIME_WAIT state sockets for port 9080, the application server is closing connections prematurely, which decreases performance. The application server closes the connection from the plug-in, or from any client, for any of the following reasons:

  • The client request was an HTTP 1.0 request when the Web server plug-in always sends HTTP 1.1 requests.
  • The maximum number of concurrent keep-alives was reached. A keep-alive must be obtained only once for the life of a connection, that is, after the first request is completed, but before the second request can be read.
  • The maximum number of requests for a connection was reached, preventing denial of service attacks in which a client tries to hold on to a keep-alive connection forever.
  • A time out occurred while waiting to read the next request or to read the remainder of the current request.

  Data type: Integer. Default: 90% of the maximum number of threads in the Web container thread pool. This prevents all of the threads from being held by keep alive connections so that there are threads available to handle new incoming connect requests.

• MaxKeepAliveRequests
  Specifies the maximum number of requests which can be processed on a single keep alive connection. This parameter can help prevent denial-of-service attacks when a client tries to hold on to a keep-alive connection. The Web server plug-in keeps connections open to the application server as long as it can, providing optimum performance. Data type: Integer. Default: 100.

• KeepAliveEnabled
  Specifies whether to keep connections alive or not. Data type: Boolean. Default is true.

  You can set these properties on either the Web Container or HTTP Transport Custom Properties pages. When set on the Web container Custom Properties page, all transports inherit the properties. Setting the same properties on a transport overrides like settings defined for a Web container.

To specify values for these custom properties for a specific transport on the HTTP Transport Custom Properties page:

1. Access the settings page for transport properties in the WebSphere administrative console:

   1. In the navigation menu, click Servers --> Application Servers --> server --> Web Container --> HTTP Transport, where server is the name of your application server.
   2. Click the host whose properties you want to set.
   3. Under Additional Properties click Custom Properties.
   4. On the Custom Properties page, click New.

2. On the settings page for a new property, enter the name of the transport property and the value to which you want it set. For example, if you want the transport to wait a maximum of 60 seconds when trying to read or write data during a request, enter ConnectionIOTimeout for the name and 60 for the value. Then click OK.

3. Click Save on the console taskbar and save the changes to the configuration.

4. Restart the server.

5. Regenerate the Web server plug-in.