Monitoring the Availability of Web Pages with GRMG Lite 

Use

You can monitor the availability of a URL by creating a GRMG Lite scenario. You do not need to implement a GRMG application to use this function check. Instead, GRMG Lite uses standard capabilities of the HTTP protocol.

To create a GRMG Lite scenario, you must enter a complete URL. You do not require any property values unless authentication is required.

GRMG Lite allows you to economically ping a Web server and a particular Web page. No implementation or installation of a GRMG application on the monitored server is required. Network traffic and server load is reduced, since the content of the page is not returned.

Procedure

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       1.      Start transaction GRMG. The Generic Request and Message Generator screen appears.

       2.      Choose the button  Edit/Delete ® Create GRMG Lite Scenario, and confirm the subsequent query.

       3.      On the following screen, Create GRMG Scenario, enter details about the name and description of the scenario and the component in the Scenario Specifications group box. In this way, you determine the name under which the scenario is displayed in the Alert Monitor, and the MTE classes to which the corresponding nodes belong. You can enter the following data:

Input Field	Description
Scenario Name	Determines the MTE class of the monitoring context (the MTE class of the monitoring context is GRMG_<scenario name>)
Version (Scenario)	Field, which you can leave empty, since GRMG has automatic version numbering
Description (Context Name)	Name of the monitoring context and therefore of the root node under which the scenario is displayed in the Alert Monitor
URL/RFC Destination	Defines whether a URL or an RFC connection is to be monitored using the scenario You can only monitor RFC destinations of types G and H (HTTP connections) in a GRMG Lite scenario.
Component name	Determines the MTE class of the summary node (GRMG_<scenario name>_<component name>) and of the monitoring object (GRMG_<component name>_OBJ)
Version (Component)	Field, which you can leave empty, since GRMG has automatic version numbering
Description (Superordinate Name)	Name of the summary node and therefore of the subtree that contains the availability and the status messages for the monitored URL

Use the names of the MTE classes to create your own rule-based monitors (see Creating a Rule-Based GRMG Monitor).

       4.      In the group box HTTP Test Method, you can decide whether you want to monitor only the header data (HTTP HEAD) or also the content of an HTML page (HTTP GET). To move to the next screen, choose the button  Create.

This assigns the value GET or HEAD to the property GET_OR_HEAD.

       5.      If you want to monitor the contents of the page, you can decide on the next screen which character strings are to be specifically monitored. To do this, enter up to three character strings in the corresponding three input fields.

If a red alert is to be displayed if the character string does not appear in the Web page, choose must exist; if a red alert is to be displayed if the character string does appear on the Web page, choose the radio button must not exist.

To move to the next screen, choose the button  Create.

This assigns the respective character strings to the properties CHECK_STRING_1 – CHECK_STRING_3. If an alert is to be generated if the character string exists, the corresponding property is assigned the value !<character string>.

       6.      On the screen Edit GRMG Customizing, enter the name of the URL or RFC destination to be monitored in the URL/Destination input field.

If you want to monitor a URL, ensure that it is actually a page that exists on the Web server. Although Web servers should response with HTTP header data for the default page if they are called without a page, most servers do not. Instead, they often return the return code 404 (Page not found), if the URL does not define a page.

This error does not occur if you assign the value GET to the property GET_OR_HEAD (see below).

In this way, for example, pinging http://www.cnn.com (we do not recommend that you try this) returns the return code 404 and the message that the scenario cannot be executed due to an HTTP communication error. On the other hand, pinging http://www.cnn.com/index.html returns a return code 200 (ok).

       7.      If you want to enter additional information for user authentication for the call of the URL or RFC destination, enter this information in the Editable Properties table.

If you enter passwords in the editable properties, assign these the type PW. Properties of this type are stored in an encrypted format in the secure storage, displayed with asterisks (*), and protected with additional security measures.

To monitor the availability of a Web page that requires a user/password logon, make the following entries:

Property Name	Type	Property Value
LOGON_USER		<user>
LOGON_PASSWORD	PW	<Password>
USE_BASIC_AUTHENTICATION		X

       8.      You can also check the contents of Web pages if they have a complex structure (for example, with frames). In this case, you can specify yourself to what depth tags of this type are to be resolved. To do this, set the property RECURSION_LIMIT to the desired depth of analysis.

The property is only evaluated if GET_OR_HEAD is assigned the value GET, that is, if the content of the page is analyzed.

       9.      The availability of a URL is determined by the HTTP return code. By default, a return code 2xx (OK) or 3xx (redirect) in the response header is interpreted as available. The status code 4xx (client error) or 5xx (server error) is interpreted as unavailable. You can use the values of the property name AVAILABLE_RESPONSE_CODES to determine the HTTP return codes with which the URL is regarded as available. When doing so, you can use the plus character as a placeholder for any individual character or individual number in that position. Separate the different valid return codes using commas.

In addition to the availability itself, you can also determine the response time of the Web site (see Measuring the Runtime of Availability Monitoring with the GRMG).

   10.      Save your entries and exit the editing screen by choosing  Exit.

   11.      To start the scenario, select the corresponding row, and choose the  Start button.

Result

You have created a GRMG Lite scenario for monitoring a URL or an RFC destination. The availability is displayed in the Availability and Performance Overview monitor (see Displaying the Availability Monitoring with the GRMG in the Alert Monitor).

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