Access log sampler Step-by-step
This is a short tutorial on Jmeter's access log sampler. The purpose of the access log sampler is to provide an easy way to simulate production traffic. There are several benefits to using access logs.
1. rather than guess what users are doing, the test plan is using real traffic data
2. as the traffic pattern changes, the access log provides a record of individual changes and general shifts in usage
3. access logs contain a lot of useful data, which may provide some insight
4. access logs can be minded to determine different types of users
5. access logs can capture detailed session information
The down side of using access logs for test plans is you have to configure the webserver to output the request information. This may not be appropriate where security is an issue. For example, if the webserver dumps the post data from each request to the access logs, users login and password would be stored in plain text. Here are some general cases where access logs might be inappropriate.
1. security sensitive applications where the data is encrypted
2. the application does not allow fine grain control of which request parameters are written to the access logs
3. the webserver cannot be configured to append the post data to the access log
4. the webserver is hosting multiple applications, but doesn't provide a way to log the requests of one application to a separate file
To take advantage of access logs, the first thing is the webserver needs to be configured to use extended log format. Links for configuring the popular containers are provided below.
BEA Weblogic - http://e-docs.bea.com/wls/docs70/adminguide/web_server.html#113868
Tomcat - http://jakarta.apache.org/tomcat/tomcat-5.0-doc/config/valve.html
Websphere - http://e-docs.bea.com/wls/docs61/adminguide/web_server.html#113868
Resin - http://www.caucho.com/resin-3.0/config/log.xtp#access-log
In some cases, it may be desirable to write custom logging, so that