Wednesday, February 27, 2008


Open STA is an open source software developed in C++, and released under the GPL licence.
It is an HTTP load test application with scenario creation and monitoring, which can be
distributed on different computers. The version evaluated below is the v1.4.1 from July 2002.
More information can be found on the web site home page:
OpenSTA provides a script language which permits to simulate the activity of a user
(sequence of accessed files, form filling, delay between each user interaction (think time), …).
This language can describe HTTP/S scenario, with OpenSTA you can only build load tests for
web applications.
You can write scripts with an editor provided with the application or you can use a module
which records the request and response of a browser and generate a script automatically. To
simulate a great number of users, this script is executed by each virtual user at the same time.
Script editor
You cannot randomise the think time1, the form filling or the user action like choosing a link
in an HTML response.
All the test configuration is managed in the graphical interface. The composition of the test is
very simple (drag & drop of elements…). You choose scripts for a test, a remote computer
that will execute each test, the number of users, different monitoring possibilities and you can
launch the test.
During the test execution, you can monitor a great number of parameters like CPU idle time,
network traffic, number of processes, disk usage, error in HTTP response… For each user
configured in the test, OpenSTA creates one thread which executes the script.
Composition of test
The test can be distributed on several computers. OpenSTA provides a name server for
registering the different computers. During the building of the test we choose on which
computer each scenario will be launched.
1The "think time" is a delay representing the time spent by the user thinking between two consecutive clicks.
All the distribution is based on CORBA. It uses the omniORB Object Request Broker (ORB)
and Naming Service from AT&T Laboratories Cambridge.
A great number of data can be caught during the test. First, all information of system
monitoring (WinNT performance monitor or with SNMP). We can also catch information on
the test, like number of requests, error, throughput of client…). All information can be
reviewed with customizable graphics. All information can be exported in a file in order to be
used with other software like Excel.
Result and analysis
You can make a lot of queries to monitor the computer. Two systems can be used for this:
Windows performance monitor or SNMP server. You can only use the first one if the
computer uses Windows NT and if OpenSTA is launched (with registration in the name
server), it is not really a problem for all the clients because OpenSTA is designed only for
Windows. The second solution needs a SNMP server in the network and SNMP agent on each
computer monitored.
Positive part of this software are the following:
-A user-friendly graphical interface.
-The script capture from the browser.
-The monitoring functionality
-You can make very complete test with the script language
Negative part of this software are the following:
-Only designed for Windows
-Only for HTTP

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