Extended Monitoring Guide
The ZenWebTx ZenPack allows you to test the availability and performance of Web sites by performing some of the same activities performed by your user community. You create one or more tests that mimic user actions in a Web browser. Zenoss then performs these tests periodically, creating events when a test fails or exceeds a time threshold.
Additionally, Zenoss can record data for each test run, such as:
Time required for the test to execute
Time taken for any portion of the test to complete
Values extracted from Web pages during the test
ZenWebTx uses a scripting language called Twill to describe the steps of a test. These steps include actions such as:
Clicking a link
Completing form fields
Assertions, which check for the presence or absence of text on a page. In addition, you can extract data from the Web page and record the numeric values that are a part of these patterns
Descriptions of data to collect during the test
You can write Twill commands manually. You also can use a Firefox add-on called TestGen4Web to record a browser session that ZenWebTx then translates into Twill commands. The zenwebtx daemon processes the Twill commands periodically, recording data and creating events as appropriate.
Data produced by any Zenoss data source are called data points. WebTx data sources contain two default data points:
totalTime – Number of seconds taken to complete the entire transaction.
success – Returns 1 (success) or 0 (failure), depending on whether or not the transaction succeeded.
You can create other data points by using the extract and printTimer twill commands, which output data values when the twill commands are run. You must create new data points with the same name you used in those commands to bring that data into Zenoss. For more information about the extract and printTimer twill commands, refer to the appendix titled Appendix A, twill Commands Reference.
ZenWebTx supports using XPath queries to extract data from XML documents. For more information about this feature, refer to the appendix in this guide titled Appendix A, twill Commands Reference.
There are several situations for which ZenWebTx will create events in Zenoss. These events use the component and event class specified on the Data Source tab. These situations are:
ZenWebTx is unable to retrieve a page during the transaction.
One of the twill commands fails, such as finding text that does not exist or following a link that does not exist.
The timeout (specified on the Data Source tab) is exceeded.
A threshold defined for one of the data points in this data source is exceeded. Thresholds are defined in the performance template that contains the data source.