Web-farm Monitoring

The aim of the Web farm tool is to ensure availability of your web farms by letting you know how many of your servers are responding with the correct web content.

One of the main goals of web farms is to assure availability of the web site. The biggest challenge is to successfully measure and monitor the web farm’s overall availability to determine its success, and drive its improvement. Monitoring Studio essentially groups HTTP requests all together, allowing you to use all the tools of the SW_HTTP_REQUESTS class to monitor your web-farms.

To create a new web farm monitoring, right-click the application icon in the PATROL Console and select KM Commands > New > Web farm monitoring…

Editing the webfarm instance is not feasible; but you can edit individual hosts (web –requests) under this web farm. You can add, edit and delete the hosts grouped under the webfarm icon at any time.

Step 1: Enter the URL, select the type of HTTP request and specify desired output

After the welcome panel of the Web farm monitoring wizard, you are asked to enter the URL to query and the type of HTTP request.

URL to query: Enter the URL of the web site that needs to be monitored. From a Windows agent, it is possible to poll a secure web site by using the "https" method.

HTTP Request type: Enter the HTTP request, there are two different modes: "GET" and "POST".

▪	The "GET" mode (HTTP GET method) is the standard way to query a Web page from a Web server.

▪	The "POST" mode (HTTP POST method) is classically used to post a form to a Web server and obtain the result of the processing of the form data. If you choose this mode, you must specify the variables and values to be transmitted to the Web server.

Some Web forms can be passed to the server with the HTTP GET method. In such case, the form data is passed through the URL (http://server/form.php?varA=valueA&varB=valueB&…). You must check the Web form HTML source to know which method needs to be used (GET or POST).

When posting a form to a Web server, you have to enter the URL of the script/CGI/page that will actually process the data, which may be different from the Web page URL that shows the form itself. Again, you need to check the Web form HTML source to identify the URL to query.

A Web form HTML source should contain a statement like the following one: <FORM METHOD="POST" ACTION="/urlToQuery.php">

Timeout after: Enter the connection timeout period. The default is set to 30 seconds. When this timeout is reached, Monitor Studio considers the host to be unreachable and triggers an alert on the ServerConnectionState parameter.

Proxy settings (optional): If your environment uses a proxy server, click to enter the proxy settings required to execute the HTTP request.

Web Server Authentication (optional): See section below on HTTP authentication for details.

Authenticate as: Enter the user name as required by the HTTP server (see note below for more information)

Specify what should be shown in the ReturnOutput parameter: Select what you would like to retrieve from the Web page returned by the Web server: the entire HTTP response; only the Web page (with HTML tags) or only the content text (no HTMP tags).

Some Web applications request a user name and password in order to access resources available on the Web server.

Starting with version 8.5.00, Monitoring Studio supports HTTP authentication. The HTTP authentication is a login/password-based mechanism implemented in the HTTP protocol itself.

HTTP authentication has nothing to do with an authentication system of a Web page with a form asking for user credentials like on Hotmail or Yahoo mail or any public webmail service.

A Web server that requires an HTTP authentication will result in the following dialog box in Internet Explorer:

Please note that this depends on where Monitoring Studio is running, and not on the platform the Web server is running on.

On a Windows machine, Monitoring Studio supports Basic, Digest and NTLM authentication schemes.

On UNIX or Linux, Monitoring Studio only supports Basic HTTP authentication (password is sent in a base 64-encoded form, i.e. very easily decoded).

If you need to test a Web page or retrieve information from a Web server that requires HTTP Digest or NTLM authentication, we recommend that you install Monitoring Studio on a Windows system and set up the Web requests from this machine (Web requests can be sent to remote systems).

If the "GET" method is selected in the first panel, the following panel comes up:

Since a web-farm is composed of several servers, in this panel, you can enter up to 10 hosts that make-up the web-farm.

To edit or delete a host, right-click the host icon > KM commands > Edit host or Delete as the case may be.

If the "POST" method is selected in the first panel, the following panel comes up:

Here, up to eight variables to post can be entered. For each variable, enter its name in the first box and its value in the second one.

Since a web-farm is composed of several servers, in this panel, you can enter up to 10 hosts that make-up the web-farm.

To edit or delete a host, right-click the host icon > KM commands > Edit host or Delete as the case may be.

•	Object display name: Label displayed in the PATROL Console for this web-farm monitoring.

What thresholds do you want to set for the newly created instance? A drop-down list allows you to select the mode of setting alert thresholds:

•	Use default thresholds: Uses the default thresholds set by Monitoring Studio

•	Set custom thresholds: Allows you to customize the thresholds for all parameters of the instance

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Use default thresholds and customize them: Sets the default Monitoring Studio thresholds on certain parameters (see list of parameters with default thresholds) and then allows you to customize any/all of them. This is mainly intended to help save time if you wish to customize the thresholds of just one of many parameters for the instance, and leave the default settings for the others.

If you select Use default thresholds and customize them; on clicking Finish, the Set Thresholds panel will appear, and certain parameters for the instance may appear with an asterisk symbol - indicating that they already have thresholds. You can then customize (any/all) the thresholds of the parameters as per your specific needs.

•	Do not set any thresholds for now: No thresholds will be set on any parameter of the instance, and as a result no alerts will be triggered. Monitoring Studio will poll the object and return the output of the polling, but will not raise any alerts until you set thresholds.

Thresholds can be set or modified at anytime by right-clicking on the instance > KM commands > Set Thresholds.