Open System Testing Architecture




An OpenSTA Collector is a set of user-defined queries which determine the performance data that is monitored and recorded from target Hosts when a Test is run. They are used to monitor and collect performance data from the components of Web Application Environments (WAEs) and production systems during Test-runs to help you evaluate their performance.

Collectors are stored in the Repository and are included in Tests by reference, so any changes you make to a Collector will have immediate affect on all the Tests that use them.

The HTTP/S Load release of OpenSTA (Open Source release) supplies the NT Performance Module and the SNMP Module for Collector creation.

NT Performance Collectors are used for collecting performance data from Hosts running Windows NT or Windows 2000.

SNMP Collectors are used for collecting SNMP data from Hosts and other devices running an SNMP agent or proxy SNMP agent.

Collector Pane

The Collector Pane is the workspace used to create and edit Collectors. It is displayed in the Commander Main Window when you open a Collector from the Repository Window.


OpenSTA Commander is the Graphical User Interface used to develop and run HTTP/S Tests and to display the results of Test-runs for analysis.

Each OpenSTA Module, provides its own Plug-ins and supplies Module-specific Test Configuration, data collection, Test-run monitoring and Results display facilities. All Plug-in functionality is invoked from Commander.


A packet of information sent by a Web server to a Web browser that is returned each time the browser accesses the Web server. Cookies can contain any information the server chooses and are used to maintain state between otherwise stateless HTTP transactions.

Typically cookies are used to store user details and to authenticate or identify a registered user of a Web site without requiring them to sign in again every time they access that Web site.


Common Object Request Broker Architecture.

A binary standard, which specifies how the implementation of a particular software module can be located remotely from the routine that is using the module. An Object Management Group specification which provides the standard interface definition between OMG-compliant objects. Object Management Group is a consortium aimed at setting standards in object-oriented programming. An OMG-compliant object is a cross-compatible distributed object standard, a common binary object with methods and data that work using all types of development environments on all types of platforms.

Document Object Model or DOM

The Document Object Model (DOM) is an application programming interface (API) for HTML and XML documents (Web pages). It defines the logical structure of documents and the way a document is accessed and manipulated.

With the Document Object Model, programmers can build documents, navigate their structure, and add, modify, or delete elements and content. Anything found in an HTML or XML document can be accessed, changed, deleted, or added using the Document Object Model, with a few exceptions - in particular, the DOM interfaces for the XML internal and external subsets have not yet been specified.

For more information:


The OpenSTA Gateway interfaces directly with the Script Modeler Module and enables you to create Scripts. The Gateway functions as a proxy server which intercepts and records the HTTP/S traffic that passes between browser and Web site during a Web session, using SCL scripting language.


An OpenSTA Host is a networked computer or device used to execute a Task Group during a Test-run. Use the Test Pane in Commander to select the Host you want to use a to run Task Group.

Host also refers to a computer or device that houses one or more components of a Web Application Environment under Test, such as a database. Use Collectors to define a Host and the type of performance data you want to monitor and collect during a Test-run


Hypertext Markup Language. A hypertext document format used on the World-Wide Web. HTML is built on top of SGML. Tags are embedded in the text. A tag consists of a <, a case insensitive directive, zero or more parameters and a >. Matched pairs of directives, like <TITLE> and </TITLE> are used to delimit text which is to appear in a special place or style.

.HTP file

See Script.


HyperText Transfer Protocol. The client-server TCP/IP protocol used on the World-Wide Web for the exchange of HTML documents. HTTP is the protocol which enables the distribution of information over the Web.


HyperText Transmission Protocol, Secure. A variant of HTTP used by Netscape for handling secure transactions. A unique protocol that is simply SSL underneath HTTP. See SSL.


Reference to HTTP and HTTPS.


This release of OpenSTA includes the following Modules/components:

The release includes:

HTTP/S Load User's Guide

Hard copy and on-line versions of this guide are available.

In Commander click Help > Commander Help > Contents.

You can view or download a copy from

Load Test

Using a Web Application Environment in a way that would be considered operationally normal with a normal to heavy number of concurrent Virtual Users.


See OpenSTA Modules.

Monitoring Window

The Monitoring Window lists all the display options available during a Test-run or a single stepping session in a directory structure which you can browse through to locate the monitoring option you need. Each Task Group included in the Test is represented by a folder which you can double-click on to open and view the display options contained.

Use the Monitoring Window to select and deselect display options in order to monitor the Task Groups included in your Test and to view additional data categories, including summary data and an error log. The monitoring display options available vary according on the type of Task Groups included in a Test.

The Monitoring Window is located on the right-hand side of the Monitoring Tab by default, but can be moved or closed if required.

Name Server

See OpenSTA Name Server.


Object Management Group. A consortium aimed at setting standards in object-oriented programming. In 1989, this consortium, which included IBM Corporation, Apple Computer Inc. and Sun Microsystems Inc., mobilized to create a cross-compatible distributed object standard. The goal was a common binary object with methods and data that work using all types of development environments on all types of platforms. Using a committee of organizations, OMG set out to create the first Common Object Request Broker Architecture (CORBA) standard which appeared in 1991. The latest standard is CORBA 2.2.

Open Source

A method and philosophy for software licensing and distribution designed to encourage use and improvement of software written by volunteers by ensuring that anyone can copy the source code and modify it freely.

The term Open Source, is now more widely used than the earlier term, free software, but has broadly the same meaning: free of distribution restrictions, not necessarily free of charge.

OpenSTA Dataname

An OpenSTA Dataname comprises between 1 and 16 alphanumeric, underscore or hyphen characters. The first character must be alphabetic.

The following are not allowed:

Note: Where possible avoid using hyphens in the names you give to Tests, Scripts and Collectors. The hyphen character functions as an operator in SCL and conflicts can occur during Test-runs.

OpenSTA Modules

OpenSTA is a modular software system that enables users to add additional functionality to the system by installing new OpenSTA Modules. When a new Module is installed existing functionality is enhanced, enabling users to develop their configuration of OpenSTA in line with their performance Testing requirements. Each Module comes complete with its own user interface and run-time components.

OpenSTA Modules are separate installables that bolt on to the core architecture to add specific functionality, including performance monitoring and data collection for all three layers of Web Application Environment activity:

OpenSTA Name Server

The OpenSTA Name Server allows the interaction of multiple computers across a variety of platforms in order to run Tests. The Name Server's functionality is built on the Object Management Group's CORBA standard.

Performance Test

One or more Tests designed to investigate the efficiency of Web Application Environments (WAE). Used to identify any weaknesses or limitations of target WAEs using a series of stress Tests or load Tests.

Proxy Server

A proxy server acts as a security barrier between your internal network (intranet) and the Internet, keeping unauthorized external users from gaining access to confidential information on your internal network. This is a function that is often combined with a firewall.

A proxy server is used to access Web pages by the other computers. When another computer requests a Web page, it is retrieved by the proxy server and then sent to the requesting computer. The net effect of this action is that the remote computer hosting the Web page never comes into direct contact with anything on your home network, other than the proxy server.

Proxy servers can also make your Internet access work more efficiently. If you access a page on a Web site, it is cached on the proxy server. This means that the next time you go back to that page, it normally does not have to load again from the Web site. Instead it loads instantaneously from the proxy server.


The OpenSTA Repository is where Scripts, Collectors, Tests and results are stored. The default location is within the OpenSTA program files directory structure. A new Repository is automatically created in this location when you run Commander for the first time.

You can create new Repositories and change the Repository path if required.
In Commander click Tools > Repository Path.

Manage the Repository using the Repository Window within Commander.

Repository Host

The Host, represented by the name or IP address of the computer, holding the OpenSTA Repository used by the local Host. A Test-run must be started from the Repository Host and the computer must be running the OpenSTA Name Server.

Repository Window

The Repository Window displays the contents of the Repository which stores all the files that define a Test. Use the Repository Window to manage the contents of the Repository by creating, displaying, editing and deleting Collectors, Scripts and Tests.

The Repository Window is located on the left-hand side of the Main Window by default and displays the contents of the Repository in three predefined folders  Collectors,  Scripts, and Tests. These folders organize the contents of the Repository into a directory structure which you can browse through to locate the files you need.

Double-click on the predefined folders to open them and display the files they contain.

Right-click on the folders to access the function menus which contain options for creating new Collectors, Scripts and Tests.

Results Window

The Results Window lists all the results display options available after a Test-run or a single stepping session is complete. The display options are listed in a directory structure which you can browse through to locate the results option you need. Each Collector-based Task Group included in the Test is represented by a folder which you can double-click on to open and view the display options contained.

Use the Results Window to select and deselect display options in order to view and analyze the results data you need. The results display options available vary according on the type of Task Groups included in a Test.

The Results Window is located on the right-hand side of the Results Tab by default, but can be moved or closed if required.


See Script Control Language.

SCL Reference Guide

Hard copy and on-line versions of this guide are available.

In Script Modeler click Help > SCL Reference.


Scripts form the basis of HTTP/S load Tests using OpenSTA. Scripts supply the HTTP/S load element used to simulate load against target Web Application Environments (WAE) during their development.

A Script represents the recorded HTTP/S requests issued by a browser to WAE during a Web session. They are created by passing HTTP/S traffic through a proxy server known as the Gateway, and encoding the recorded data using Script Control Language (SCL). SCL enables you to model the content of Scripts to more accurately generate the Web scenario you need reproduce during a Test.

Scripts encapsulate the Web activity you need to test and enable you to create the required Test conditions. Use Commander to select Scripts and include them in a Test then run the Test against target WAEs in order to accurately simulate the way real end users work and help evaluate their performance.

Scripts are saved as an .HTP file and stored in the Repository.

Script Control Language

SCL, Script Control Language, is a scripting language created by CYRANO used to write Scripts which define the content of your Tests. Use SCL to model Scripts and develop the Test scenarios you need.

Refer to the SCL Reference Guide for more information.

Script Modeler

Script Modeler is an OpenSTA Module used to create and model Scripts produced from Web browser session recordings, which are in turn incorporated into performance Tests by reference.

Script Modeler is launched from Commander when you open a Script from the Repository Window.

Single Stepping

Single stepping is a debugging feature used to study the replay of Script-based Task Groups included in an HTTP/S load Test. Run a single stepping session to follow the execution of the Scripts included in a Task Group to see what actually happens at each function call, or when a process crashes.


Simple Network Management Protocol. The Internet standard protocol developed to manage nodes on an IP network. SNMP is not limited to TCP/IP. It can be used to manage and monitor all sorts of equipment including computers, routers, wiring hubs, toasters and jukeboxes.

For more information visit the NET_SNMP Web site:


Secure Sockets Layer. A protocol designed by Netscape Communications Corporation to provide encrypted communications on the Internet. SSL is layered beneath application protocols such as HTTP, SMTP, Telnet, FTP, Gopher, and NNTP and is layered above the connection protocol TCP/IP. It is used by the HTTPS access method.

Stress Test

Using a Web Application Environment in a way that would be considered operationally abnormal. Examples of this could be running a load test with a significantly larger number of Virtual Users than would normally be expected, or running with some infrastructure or systems software facilities restricted.


An OpenSTA Test is comprised of one or more Task Groups which in turn are composed of Tasks. The Scripts and Collectors included in Task Groups are known as Tasks. Script-based Task Groups can contain one or multiple Tasks. Tasks within a Script-based Task Group can be managed by adjusting the Task Settings which control the number of Script iterations and the delay between iterations when a Test is run.

Collector-based Task Groups contain a single Collector Task.

Task Group

An OpenSTA Test is comprised of one or more Task Groups. Task Groups can be of two types, Script-based or Collector-based. Script-based Task Groups represent one or a sequence of HTTP/S Scripts. Collector-based Task Groups represent a single data collection Collector. Task Groups can contain either Scripts, or a Collector, but not both. The Scripts and Collectors included in Task Groups are known as Tasks.

A Test can include as many Task Groups as necessary.

Task Group Definition

An OpenSTA Task Group definition constitutes the Tasks included in the Task Group and the Task Group settings that you apply.

Task Group Settings

Task Group settings include Schedule settings, Host settings, Virtual User settings and Task settings and are adjusted using the Properties Window of the Test Pane. Use them to control how the Tasks and Task Group that comprise a Test behave when a Test is run.

Schedule settings determine when Task Groups start and stop.

Host settings specify which Host computer is used to run a Task Group.

Virtual User settings control the load generated against target Web Application Environments during specifying the number of Virtual Users running a Task Group. Set Logging levels to determine the amount of performance statistics collected from Virtual Users running the Tasks. You can also select to Generate Timers for each Web page returned during a Test-run.

Task settings control the number of times a Script-based Tasks are run including the delay you want to apply between each iteration of a Script during a Test-run.


An OpenSTA Test is a set of user controlled definitions that specify which Scripts and Collectors are included and the settings that apply when the Test is run. Scripts define the test conditions that will be simulated when the Test is run. Scripts and Collectors are the building blocks of a Test which can be incorporated by reference into many different Tests.

Scripts supply the content of a Test and Collectors control the type of results data that is collected during a Test-run. Test parameters specify the properties that apply when you run the Test, including the number of Virtual Users, the iterations between each Script, the delay between Scripts and which Host computers a Test is run.

Commander provides you with a flexible Test development framework in which you can build Test content and structure by selecting the Scripts and Collectors you need. A Test is represented in table format where each row within it represents the HTTP/S replay and data collection Tasks that will be carried out when the Test is run. Test Tasks are known as Task Groups of which there are two types, either Script-based and Collector-based.

Test Pane

The Test Pane is the workspace used to create and edit Tests, then run a Test and monitor its progress. After a Test-run is complete results can be viewed and compared here. The Test Pane is displayed in the Commander Main Window when you open a Test from the Repository Window.


A unit of interaction with an RDBMS or similar system.


Uniform Resource Identifier. The generic set of all names and addresses which are short strings which refer to objects (typically on the Internet). The most common kinds of URI are URLs and relative URLs.


Uniform Resource Locator. A standard way of specifying the location of an object, typically a Web page, on the Internet. Other types of object are described below. URLs are the form of address used on the World-Wide Web. They are used in HTML documents to specify the target of a hyperlink which is often another HTML document (possibly stored on another computer).


Variables allow you to vary the fixed values recorded in Scripts. A variable is defined within a Script. Refer to the Modeling Scripts section for more information.

Virtual User

A Virtual User is the simulation of a real life user that performs the activity you specify during a Test-run. You control the activity of your Virtual Users by recording and modeling the Scripts that represent the activity you want. When the Test that includes the Script is run, the Script is replayed exactly as the browser made the original requests.

Web Application Environment, WAE

The applications and/or services that comprise a Web application. This includes database servers, Web servers, load balancers, routers, applications servers, authentication/encryption servers and firewalls.

Web Applications Management, WAM

Consists of the entirety of components needed to manage a Web-based IT environment or application. This includes monitoring, performance testing, results display, results analysis and reporting.

Web Site

Any computer on the Internet running a World-Wide Web server process. A particular Web site is identified by the host name part of a URL or URI. See also Web Application Environment, WAE.
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