J2SE: 1.4.1 boosts garbage collection

A pretty good article on 1.4.1 GC from JavaWorld.

Other 1.4.1 GC Tutorials:
1. From java.sun.com.
2. From Wireless Java. Note that this replaces the famous GC Article for 1.2.2
3. From JavaPerformanceTuning.

Some Benchmarks:
1. From JavaLobby.
2. From NetBeans.

JSF: EA3 Released

JavaServer Faces Early Access 3 has been posted at java.sun.com. Tutorial for JSF is available here.

Weblogic: Starting ManagedServer Programmatically

Weblogic6.1 Node Manager do *not* attempt to restart a Managed Server when its goes down or provide a mechanism where user can use some compand line tool to start the managed server using Node Manager. The following is the example code to start a managed server using nodemanager programmatically. This code when used in combination with script that detects when a server goes down (Example: SNMP management tools which get a trap when managed server goes down), will automate server restart when a problem occurs.

Tested with weblogic6.1SP4.

import java.util.Properties; import javax.naming.Context; import javax.naming.InitialContext; import weblogic.management.MBeanHome; import weblogic.management.configuration.ServerMBean; /** * This tools starts a managed server when node manager corresponding * to that server is already running. * Usage : StartManagedServer -adminurl <> -user <> -pass <> -domain <> -managedserver <> */ public class StartManagedServer { public static void main(String[] args) { ServerMBean serverMBean = null; String url = "t3://localhost:7001"; String username = "system"; String password = "password"; String domain = "yourdomain"; String managedServer = "Server1"; int i = 0; try { for (; i < args.length; i++) { if (args[i].equals("-adminurl")) url = args[++i]; else if (args[i].equals("-user")) username = args[++i]; else if (args[i].equals("-pass")) password = args[++i]; else if (args[i].equals("-domain")) domain = args[++i]; else if (args[i].equals("-managedserver")) managedServer = args[++i]; } } catch (ArrayIndexOutOfBoundsException aio) { log("Missing value for arguement '" + args[--i] + "'"); log("Usage : StartManagedServer -adminurl <> -user <> -pass <> -domain <> -managedserver <>"); return; } try { Properties props = new Properties(); props.put(Context.INITIAL_CONTEXT_FACTORY, "weblogic.jndi.WLInitialContextFactory"); props.put(Context.PROVIDER_URL, url); props.put(Context.SECURITY_PRINCIPAL, username); props.put(Context.SECURITY_CREDENTIALS, password); Context ctx = new InitialContext(props); MBeanHome home = (MBeanHome) ctx.lookup("weblogic.management.adminhome"); serverMBean = (ServerMBean) home.getMBean(managedServer, "Server", domain); } catch (Exception e) { log("Exception in getting Admin home & serverMBean: " + e); } try { log("Sending a start command to the AdminServer ..."); serverMBean.start(); } catch (weblogic.rmi.extensions.RemoteRuntimeException rre) { //The java.io.Reader returned which is not serializable :-) log("Ignorable Exception occured ..."); } catch (Exception e) { //InsufficientConfigurationException?? Couldn't find JavaDocs for exception //mentioned in javadocs.:-) log("Unexpected exception: " + e); return; } log("NodeManager initiated the server"); } private static void log(String s) { System.out.println(s); } }

Starting weblogic7 Node Manager attempts to restart a Managed Server whose health state is "failed".

General: Redirecting Std err

Most Java Programmers I know are unaware of how to redirect Stderr to a file. Here is a 1 minute tutorial on the same. For both Unix and Windows:

When writing shell scripts, you can control input/output redirection. Input redirection is the ability to force a command to read any necessary input from a file instead of from the keyboard. Output redirection is the ability to send the output from a command into a file or pipe instead of to the screen.
Each process created by a shell script begins with three file descriptors associated with it:

0 stdin

1 stdout

2 stderr

You can use the file descriptor numbers 0 (standard input), 1 (standard output), and 2 (standard error) together with the redirection metacharacters to control input and output in the Bourne and Korn shells.

Bourne and Korn Shell Redirection

Description	Command
Take STDIN from file	<file, or 0<file
Redirect STDOUT to file	> file, or 1>file
Redirect STDERR to file	2> file
Append STDOUT to end of file	>> file
Redirect STDERR to STDOUT	2>&1
Pipe standard output of cmd1 as standard input to cmd2	cmd1 | cmd2
Use file as both STDIN and STDOUT	<> file
Close STDIN	<&-
Close STDOUT	>&-
Close STDERR	2>&-

When redirecting STDIN and STDOUT in the Bourne and Korn shells, you can omit the file descriptors 0 and 1 from the redirection symbols. You must always use the file descriptor 2 with the redirection symbol.


The 0 and 1 file descriptors are implied, and not used explicitly for the C shell. The C shell representation for standard error (2) is an ampersand (&). STDERR can only be redirected when redirecting STDOUT.

C Shell Redirection Metacharacters

Description	Command
Redirect STDOUT to file	> file
Take input from file	< file
Append STDOUT to end of file	>> file
Redirect STDOUT and STDERR to file	>& file
Append STDOUT and STDERR to file	>>& file

For windows:
The command shell provides facilities to change the default stream input and output. These facilities are accessed by placing special command redirection symbols in a command.

Windows Command Redirection Symbols

Symbol	Description
>file	Redirects command output to the file specified. You can also use a standard device name such as LPT1, CON, PRN or CONOUT$ as the file name. Any preexisting contents of the file are lost.
>>file	Redirects command output to the file specified. If the file already exists, all command output is appended to the end of the file.
<file	Redirects command input from the file specified. You can also use a standard device name such as CON or CONIN$.
2>file	Redirects command error output to the file specified. You can also use a standard device name such as LPT1, CON, PRN or CONOUT$ as the file name. Any preexisting contents of the file are lost.
2>&1	Redirects command error output to the same location as command output. This makes any command output redirection also apply to command error output.
cmd1 | cmd2	Pipes the command output of cmd1 to the command input of cmd2. Multiple pipe characters are allowed, creating a chain of commands, each sending output to the next command in the chain.