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Integration Example #1
Integrating an application for which you have source code

This integration example (the roulette application) is available for download in Solaris and Windows versions. The download includes full source code.

Integrating an application for which you have source code is almost trivial. Remember that you need not modify your source code. OC Systems' patented application patching technology instruments the application at runtime, when it is in memory.

For a larger view please click the image.

Here you see a Node View of the Universal Agent showing an integration of application roullette.exe. The specific resources that are being monitored are Bet, Debt, and BankTotal. These resources represent program variables within the application.

How did we extract the program variable values from the application without modifying the source code, and how did we integrate those values into Unicenter NSM?

At the bottom left of the screenshot we see a portion of file roullette.c, the source code for the application. We are interested in extracting the following program variables:

• The parameter "Amount" that is passed to function "Bet()".

• The return value from function "BankTotal()".

• Variable "Debt" (not shown—declared as a static global variable).

At the bottom right of the screenshot we see the complete contents of file roullette.apc. This is the code that was developed to instrument the application and integrate it into NSM. Let's take a look at what the code does:

• "probe extern:Bet()" indicates that function "Bet()" is to be instrumented.

• "on_entry" indicates that the following code is to be executed when this function is called, before the function's existing code is executed.

• "probe extern:BankTotal()" indicates that function "BankTotal()" is to be instrumented.

• "on_exit" indicates that the following code is to be executed when this function returns, after the function's existing code is executed.

The code that is executed in these probes is the Universal Agent API. Let's look at the UA_api() calling sequence. The first parameter identifies the resource name; the third parameter specifies its value. Notice how each individual portion (separated by dots) of the resource name is mapped into distinct nodes in Node View.

The resource values being passed in the UA_api() calls are as follows:

• "$Amount" is the value of parameter "Amount" in function "Bet()".

• "$return" is the value returned by function "BankTotal()".

• "$Debt" is the value of global variable "Debt" as it exists when function "BankTotal()" returns.

The Universal Agent application instrumentation technology allows you to inject code into your application at any location: program entry and exit, function entry and exit, even down to the source code line level! Although the original application source code is never modified, the injected code is written as though, and behaves exactly as if, it were a part of the original source code.

Now take a look at Integration Code Example #2: Integrating an application for which you have NO source code.

Even if you have source code for an application, you may still want to use the "no-source" instrumentation/integration techniques. For example, if you are interested in overall resource usage by the application, you may only be able to obtain this data by instrumenting the system API layer. In other cases, it is simply easier to extract the desired resource data by instrumenting the API layer.

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