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The basic function of the CLF system is to provide a set of common system
services to Java based Applets and Servlets (referred to as Applications in the
rest of this article)
The 4 basic requirements are:
- Provide an interface to the Common Error Handler.
- Provide a Web server based Metrics Gathering System.
- Provide a Web server based Debug Logging System.
- Minimize the performance impact on Java Applications.
Provide an interface to the Common Error Handler
Union Pacific
Railroad has developed a centralized Common Error Handler (CEH). This service
provides UNIX based applications a centralized facility to monitor errors as
they happen. When critical situations occur within an application, a mechanism
pro-actively notifies support groups, thereby minimizing system outages. Java
applications also need to have an interface into this service. The CLF will
provide the interface to CEH service.
Provide a Web server base Metrics Gathering System
As Union
Pacific Railroad starts to deploy business to business applications significant
audit questions are being asked:
- How often is an application accessed?
- How much information is transferred?
- How long does the application take to handle a request?
- Who is using the application?
The CLF system will provide the interface, server functions, and repository
where the appropriate application execution information can be recorded.
Provide a Web server based Debug Logging System
Web server
applications (also called CGI programs or Servlets) usually run for only a few
seconds while Applets may run much longer. Presently, when an unexpected
situation arises within a Java application there is no practical way to start
gathering debugging information while the program is executing. The only
possibility is to use a Try/Catch block around the main body of the program.
The difficulty is that the programs (i.e. Servlets) are relatively short lived
and it is difficult to restart the program at the same logical point in which
the exception was caught. A Try/Catch block is more realistic for an Applet
that may be run for a very long time. This alternative for Applets will be
tested as RMI is implemented in the major Web browsers. The CLF system will
provide a means to turn on/off debug gathering at execution time and provide a
repository on the server to store the debug messages. Normally, debugging will
be turned off since it may impact overall application performance.
Minimize the performance impact on Applications
The CLF system
should not noticeably impact overall application performance, except when debug
gathering has been turn on.
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