• Station Monitor Design
• Scenario
• CORBA Objects
• Running the Station Monitor
• Pre-Requisites
• Starting Stations and the Collector
• Single Station Monitor Applet
• Multiple Station Monitor Client (Command-line)
• Building the Station Monitor
• Pre-Requisites
• Files and Directory Structure
• Building
• Reference

SCENARIO

This code example implements a simple station monitor applet that is capable of monitoring the status of a single station, and a standalone Java application that monitors multiple stations at once.

CORBA OBJECTS

Station

The Station object is a standalone Java application whose purpose is to monitor the characteristics of a station.  When queried through its get_status() method, the station object returns to the caller the current status of the station in the form of a structure.  In "real life", the station object would probably get the current station status from a database, or from querying a set of hardware sensors set up to monitor the station.  In this example, the station object simulates the operation of a station.  It has a thread named SimTimer (StationServer.java) that calls a private method on the station object (updateIt)once per second.  The updateIt() method then updates the current station status based on assumptions of the inital input bin size and time to complete a single operation.  These assumptions are settable through command-line options.

If started with the "-r" option, the Station will register itself with a running Collector object (see below)

The Station object is implemented in the following source files:

• mfgDemo.idl: Contains the Station object's interface defintion in IDL
• StationSource/StationImpl.java: Implementation of the Station object
• StationSource/StationServer.java: Server startup, Station instantiation and registration with the ORB and Web Naming service
• StationSource/StationOptions.java: Command-line option processing

Collector

The Collector is a standalong Java application that implements an object used to allow the monitoring of multiple stations at once.  It's basic job is to periodically query all running stations for their statuses, and to pass those statuses in the form of an array of structures, to a multi-station monitor (an application capable of monitoring multiple stations at once.  When the collector starts up, it does nothing except register itself with the Web Naming service.  Thereafter, whenever a station is started with the "-r" option, the station registers itself with the collector through a method called register_station().  The collector maintains a running list of all running stations.  Later, when a multi-monitor client starts, the monitor registers itself with the collector through the register_monitor() method.  Once a monitor is registered, the collector will periodically query each of the stations for their status, assemble those statuses into an array of structures, and then perform a callback onto the monitor (method update()), passing the stations statuses.

The Collector object is implemented in the following source files:

• mfgDemo.idl: Contains the Collector object's interface defintion in IDL
• CollectorSource/CollectorImpl.java: Implementation of the Collector object
• CollectorSource/CollectorServer.java: Server startup, Collector instantiation and registration with the ORB and Web Naming service
• CollectorSource/CollectorOptions.java: Command-line option processing

Single-Station Display Applet

An applet that can query the status of any single running station.  The applet queries the selected station through the station's get_status() method, and displays the results each time the button is pressed.

The Single-Station Display Applet is implemented in the following source files:

• MonitorSource/DisplayStationApplet.java

Multiple-Station Display Client

A standalone Java application that implements a multi-station monitor.  When it starts, creates an instance of a Monitor object, whose purpose is to receive callbacks from the collector.  It then registers itself with a running Collector, and then waits for the Collector to notify it of station statuses.  It prints out a subset of the information it receives.

The Multiple-Station Display Client is implemted in the following source files:

• mfgDemo.idl: Contains the Monitor object's interface defintion in IDL
• MonitorSource/MonitorImplCmd.java: Implementation of the Monitor object used for receiving callbacks
• MonitorSource/MonitorClient.java: Application startup, Monitor instantiation and registration with the ORB and Collector
• MonitorSource/MonitorOptions.java: Command-line option processing

• Windows NT
• Enterprise Server 3.0
• Web naming needs to be configured so that IORs can be written to the directory tree starting at iiop_objects.
• A standalone Java VM supporting the JDK1.1 installed.  (Ex: JDK1.1.X from JavaSoft, or Symantec's Visual Cafe for Java 1.1)
• The Java VM is used by idl2java to process the IDL file
• Your CLASSPATH should include the following directories (in this order)
• <JDK 1.1 Libraries>  (Location dependent on your vendor.)
• <Enterprise Server Install Directory>\wai\java\nisb.zip
• <Enterprise Server Install Directory>\wai\java\wai.zip
• Your PATH should include the directory for your Java VM  (So that you can just type "java" to run it)

• Communicator 4.0.X installed and configured

• Bring-up a DOS-box and verify that your PATH and CLASSPATH are correctly set
• Navigate to the root demo directory
• Type "run" from the root demo directory.
• The Collector and stations will each start in a separate, minimized DOS box

• From Communicator, navigate to the demo directory and select the file "sglStClasses.html".

• Bring-up a DOS-box and verify that your PATH and CLASSPATH are correctly set
• Type "runmmclt" from the root demo directory
• The monitor will start.  Press Ctl-C to quit it.

• Enterprise Server 3.0
• A standalone Java VM supporting the JDK1.1.  (Ex: JDK1.1.X from JavaSoft, or Symantec's Visual Cafe for Java 1.1)
• Your CLASSPATH should include the following directories (in this order)
• <JDK 1.1 Libraries>  (Location dependent on your vendor.)
• <Enterprise Server Install Directory>\wai\java\nisb.zip
• <Enterprise Server Install Directory>\wai\java\wai.zip
• Your PATH should include:
• The directory for your Java VM  (So that you can just type "java" to run it)
• The directory for your Java compiler (javac)

• <root dir>:    Batch files to run and build example.  HTML files for running applet.  Readme.  IDL source file.
• amd:    Source files for a freeware progress bar widget
• CollectorSource:    Source files for the Collector
• MonitorSource:    Source files for the Single-Station Monitor applet and Multi-Station Monitor Client
• StationSource:    Source files for the Station
• classes:    Directory tree of class files created from the example source

• Open a DOS box and verify your PATH and CLASSPATH variables are correctly set
• Type "makeidl" to call the IDL compiler
• Type "make" to compile all the source

Batch files

mm1.bat
call idl2java -no_comments -no_examples -no_tie mfgDemo.idl

mm2.bat
md classes
javac -d classes .\StationModule\*.java
javac -d classes .\MonitorModule\*.java
javac -d classes .\CollectorModule\*.java
javac -d classes .\amd\AMD*.java
javac -d classes Collector*.java
javac -d classes Station*.java
javac -d classes Monitor*.java
javac -d classes Display*.java
 
stObject.bat
start "Collector" /min java -DDISABLE_ORB_LOCATOR CollectorModule.CollectorServer -n Collector
start "StationR" /min java -DDISABLE_ORB_LOCATOR StationModule.StationServer -n StationR -i R -d "Airplane Assembly" -u 100 -t 4 -s 5 -r -c Collector
start "StationT" /min java -DDISABLE_ORB_LOCATOR StationModule.StationServer -n StationT -i T -d "Airplane Finishing" -u 25 -t 8 -s 5 -r -c Collector