How do you know its working?
Use A Log Analysis Tool
You can verify that Web Performance TrainerTM is working by running
a log analysis tool that will verify that the statistics reported from Web
Performance TrainerTM are actually in the log files. While log analysis programs do a good
job if counting hits, keeping track of users is another thing. Many log analysis programs
use the IP address of the the browser to track users, which isn't accurate. For example,
thousands of users coming from a company web site may appear to be the same IP address.
Because the IP address of the request isn't used by any web servers or application servers
to track users, Web Performance TrainerTM generates all
its requests from the same IP address as the computer its running on. Instead, it uses
the standard cookie technique of simulating multiple users, which is used by every web
server and application server. In order for the log analysis tool to report the same
number of virtual users as the web server, you'll have to configure the tool to work
with the particular cookie that your web server supports.
WebTrends is a popular log analysis
tool that supports cookies, and it can be configured to accurately track users for
any web server. We've created a short set of instructions to save you some time.
Examine the Web Server Logs
You verify that Web Performance TrainerTM is working by checking the web server's log files, which are located on
the computer that is running your web server.
Apache:
If you're using Apache
with RedHat,
the log file is /var/log/httpd/access_log. You can execute a "tail -f access_log" command to watch exactly
what's happening during a performance test. If you have cookie tracking turned on, you'll see that each virtual
user has received its own cookie for the duration of each business case. Note that log analysis tools such as WebTrends
may not count users generated by our tool since we don't do IP spoofing, and some log analysis tools use the IP
to count users.
Another thing you can do with the logs is use the "wc" to check the
number of lines before and after the tests. Each line represents a hit, and the numbers will match up with the
number of hits reported by the test case if no one else is accessing the server at the same time the test was executed.
IIS:
Normally the log files are located directories under C:\WINNT\System32\LogFiles
. You can use whatever tool you like to view the files, but be careful the file isn't 100
megabytes in size before you load it into MS Word!
Realtime Statistics Displays
Its also possible to see what the web server thinks its doing performance-wise to verify what Trainer is telling
you.
IIS:
On Windows use the Performance Tool to monitor web server performance on the server itself. To start the program
on Windows 2000 use Start->Programs->Administrative Tools->Performance. On Windows NT the command is Start->Programs->Administrative
Tools (common)->Performance Monitor.
The way the program works is you have to select different statistics to view in
real time. Click on the "+" button bar to bring up the "Add Counters" dialog. Select "Web
Service" from the "Performance object" pulldown, and a list of statistics will be displayed. Start
by selecting "Anonymous Users/sec".
Apache:
Apache has
a much simpler tool that works on both NT and UNIX operating systems. See the documentation for
mod_status for more information.
Check your Database Logs
If you've written a web application that includes transactions, chances are you keep track of them in a database.
You can view the tables before and after a test to verify that the test tool is actually executing the transactions.
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