WSMon
WebSite Server Monitor Applet

Introduction

This applet monitors a remote WebSite or WebSite Pro server (only), with three moving graphs displaying:

• number of requests per second
• response data volume in KBytes/sec
• number of current connections

If you are reading this page from a WebSite-powered site, you should begin to see the graphs appearing by now. This document sets the applet to sample every 10 seconds. Normally, you would set this to at least 30 seconds between samples. The full-scale values for each graph are adjustable via applet parameters:

Downloading and Installing

There are three steps to making WSMon available from your site:

1. Download the package
2. Unzip it into a web-visible directory, for example /java/
3. Using a Java compatible browser, fetch the URL http://your.site.name/java/wsmon.html

Customizing

To display the monitor graph within an HTML document, you must insert the <applet> tag and its parameters like this:

<applet code="WSMon.class" width=479 height=92>
	<param name=num_samples     value=16>
	<param name=sample_interval value=10>
	<param name=max_req_rate    value=5>
	<param name=max_byte_rate   value=16384>
	<param name=max_conns       value=20>
<blockquote>
<em>
You're viewing this page with a browser that doesn't understand the APPLET tag.
You need to upgrade to a Java-enabled browser in order to view this Java
applet. Right now, this means Netscape 2.0. Expect more browsers to support
Java in the future!
</em>
</blockquote>
</applet>

num_samples

The number of sample points across each graph. There is not much point in setting this to a value that exceeds the number of screen pixels within the width of a graph. The default is 60.

sample_interval

The time, in seconds, between samples. Don't set this too short. Each sample requires completion of an HTTP request to the server. Take into account network delays. Also, the data volume gets updated only on completion of an HTTP request by the server, so you will not see the effects of a large data transfer until it's over. Then it will all show at once. It's best to set the sample interval to at least 30 sec. The default is 30 sec.

max_req_rate

The full-scale value for the requests/sec. graph (default 30)

max_byte_rate

The full-scale value for the KBytes/sec. graph (default 150)

max_conns

The full-scale value for the current connections graph (default 60)

server_host (not shown above)

The DNS host name or IP address of the host to monitor. This is configurable only if the WSMon classes are loaded from a local file path, resulting in the applet being trusted (see below). Defaults to the host from which the applet classes were loaded (in accordance with Java security policy).

The non-applet HTML within the <applet> tag (the stuff in <blockquote> above) will be displayed by non-Java browsers. You can put anything in there you want.

Monitoring Specific Servers

In order to monitor a server or servers other than the one from which the applet classes are loaded, you must load the classes from your local hard disk. By loading classes locally, you inform the Java security monitor that the applet is trusted and may fetch documents from any server host. A detailed explanation of the local Java environment is beyond the scope of this document. There are a few key things you need to know:

• The <applet> tag must specify codebase=... that has a local file path in it.

• You must have the Java Developer's Kit 1.0 or later installed, and your CLASSPATH environment variable appropriately configured. The foundation class package that comes with the Netscape Navigator 2.0 browser appears to have the trusted applet feature of the security manager disabled.

• You can embed several copies of the applet in a single HTML document, providing you with a view of the activity on several servers at once.

• If you do have the JDK, you can use the applet viewer to display stats on one or more servers without the overhead of running a full-blown browser. The applet viewer is quite lightweight.

Final Notes