SDSU CS 580 Client-Server Programming
Fall Semester, 2002
Configuration Files
Previous    Lecture Notes Index    Next    
© 2002, All Rights Reserved, SDSU & Roger Whitney
San Diego State University -- This page last updated 17-Oct-02

Contents of Doc 17, Configuration Files



References


SDSU Java Library, http://www.eli.sdsu.edu/java-SDSU/docs/

VisualWorks Application Developers Guide, pages 219-223

CommanlLineInterest class>>example 

Doc 17, Configuration Files Slide # 2

Application Parameters & Configuration Files


Applications normal have configuration files to store


Some programs use environment variables 

   cvs co assignment2

Command line program/servers/utilities have flags 

   ls -la
   ps -aux




Doc 17, Configuration Files Slide # 3
Servers

Servers normally use configuration files & command line flags

Environment variables are uses much in servers (why?) 




Doc 17, Configuration Files Slide # 4

Java


Some systems have libraries to handle config files & command line arguments

JDK does not seem to have such classes

There should be a number of Java libraries that provide such support

sdsu Java library is one such library 


Doc 17, Configuration Files Slide # 5

sdsu.util.ProgramProperties


Parses
Configuration files
Command line arguments
Command Line argument

-flag=value
-flag value
-flag
--xyz
-- (ignore rest of the command line )

File Formats
properties format
#A comment to the end of the line
key1=value1
key2=value2 with spaces
key3 with spaces=value3 #part of the value
sdsu.util.LabeledData format
#A comment to the end of the line,
key1 = value1;
key2='value2 with spaces';
'key3 with spaces'=value3; # a comment 

Doc 17, Configuration Files Slide # 6
Simple Example 

import sdsu.util.ProgramProperties;
public class ConfigurationExample {
   public static void main(String args[]) {
      try
         {
         ProgramProperties flags = 
            new ProgramProperties( args, "configurationFile");
         String nameValue = 
            flags.getString( "name" , "No name given");
         int size = flags.getInt( "size", 0);
         boolean switchOn = flags.containsKey( "s");
         System.out.println( " nameValue: " + nameValue);
         System.out.println( " size: " + size);
         System.out.println( " switchOn: " + switchOn);
         
         }
      catch (java.io.IOException readParseProblem)
         {
         System.err.println( "Program aborted on error " + 
         readParseProblem);
         }
   }
}

File "configurationFile.labeledData" 
name=Roger;
size=12;

Doc 17, Configuration Files Slide # 7
Sample Runs

java ConfigurationExample

Output
nameValue: Roger
size: 12
switchOn: false


java ConfigurationExample -s -name Pete

Output
nameValue: Pete
size: 12
switchOn: true


java ConfigurationExample -conf=otherFile

Output
nameValue: Sam
size: 8
switchOn: true 

Doc 17, Configuration Files Slide # 8

VisualWorks


Command Line Arguments

CEnvironment

Cenvironment class>>commandLine

Returns array of String of flags in order they were specified

Starting VisualWorks with: 

   visual script.im -port 5 -host=rohan.sdsu.edu -xyz
CEnvironment commandLine returns 

    #('visual' 'script.im' '-port' '5' '-host=rohan.sdsu.edu' '-xyz')


Doc 17, Configuration Files Slide # 9
CEnvironment class>> userEnvironment

Returns CEnvironment object with user’s environment variables 

| user |
user :=CEnvironment userEnvironment. 
user at: 'CVSROOT'

returns value of CVSROOT environment variable

CEnvironment is a subclass of Dictionary 

Doc 17, Configuration Files Slide # 10
Registering for Flags

To avoid parsing the command line array

Classes can register to be informed of individual flags

To register add method to CommanlLineInterest class
In dependencies-pragma protocol 

Doc 17, Configuration Files Slide # 11
Example 

CommanlLineInterest class>>port: aTokenReadStream
   <triggerAtSystemEvent: #returnFromSnapshot option: '-port'>
   | port |
   port := aTokenReadStream next asNumber.
   SimpleDateServer port: port.
   
   “Now make SimpleDateServer>>port: set the port.


aTokenReadStream next returns the value after the flag

CommanlLineInterest class>>port: is called on startup when flag -port exits on command line

Only supports -flag value options

Can have method triggered at

#earlySystemInstallation flags are handled from left to right

Then #returnFromSnapshot flags are handled from left to right 
Doc 17, Configuration Files Slide # 12
Configuration Files


VisualWorks servers use configuration files

No system wide classes for supporting them

Too easy to create own system?



Copyright ©, All rights reserved.
2002 SDSU & Roger Whitney, 5500 Campanile Drive, San Diego, CA 92182-7700 USA.
OpenContent license defines the copyright on this document.
Previous    visitors since 17-Oct-02    Next