Installing RHEL 4 Update 5 on Assembled Intel core2 duo

The installation of RHEL4 update 5 hangs during installation process while trying to probe devices. To get out of this problem while installation use the following command line:

linux pci=nommconf all-generic-ide

or

linux pci=conf1 all-generic-ide

Once the installation is complete do not forget to modify grub.conf, else it wont boot up.
Modify grub.conf file to pass "pci=nommconf" as additional parameter to kernel.
Example:

title Red Hat Enterprise Linux ES (2.6.9-55.ELsmp)
       root (hd0,0)
       kernel /boot/vmlinuz-2.6.9-55.ELsmp ro root=LABEL=/1 rhgb quiet pci=nommconf
       initrd /boot/initrd-2.6.9-55.ELsmp.img

Cannot find daemon loader issue with Apache common daemon

We had to write a daemon in Java and opted for using common daemon from Apache. It worked fine on Ubuntu Linux. One day we shifted to Fedora Core 6 and then the daemon stopped working.
While debugging the issue with -debug option for jsvc which is used to start and stop the daemon we figured out that even after providing commons-daemon.jar in the -cp (classpath) option for jsvc, it was unable to find the daemon loader.
"23/01/2007 15:42:33 9252 jsvc.exec error: Cannot find daemon loader org/apache/commons/daemon/support/DaemonLoader"

So after debugging, we did the following: Checked that the owner is root for all files (jars) and then ran the daemon, it ran (WOW, man this is kind of unusual, we need to make jsvc better).

Using Google AdSense API with Java and AXIS1.4

Was trying to use Google AdSense API via JAVA using AXIS1.4 and found that the example code provided by Google did not directly compile. As i did not want to move back and use AXIS1.1, i modified the Google AdSense API example code given at "Google AdSense API Developer Guide" to make it work.
Here's the modification:

Change the following line in the code:
AccountService accountService =
(new AccountServiceServiceLocator()).getAccountService();
 To:
AccountService_PortType accountService =
(new AccountServiceServiceLocator()).getAccountService();

Tomcat High Availability & Clustering

Tomcat High Availability & Clustering

 

Tomcat servers need to be clustered. This requirement is for constant uptime.

 

The following solution brings up 2 Tomcat servers and one Apache server. The customer web-sites will contact the Apache web server. The Apache web server will divert the traffic to a Tomcat server.

 

Here I describe the method and some reference web pages:

 

1.      Install 2 copies of Tomcat server, on the same host or different hosts, depending on your requirements. Here I have given the example of installing on the same host. I named the servers tomcat1 and tomcat2.

 

2.      Open server.xml files for tomcat1 and tomcat2. Change the following line in tomcat1/conf/server.xml to:

 

    <Connector port="8091" maxHttpHeaderSize="8192"

               maxThreads="150" minSpareThreads="25" maxSpareThreads="75"

               enableLookups="false" redirectPort="8443" acceptCount="100"

               connectionTimeout="20000" disableUploadTimeout="true" />

 

3.      Change the following line in tomcat2/conf/server.xml to:

    <Connector port="8092" maxHttpHeaderSize="8192"

               maxThreads="150" minSpareThreads="25" maxSpareThreads="75"

               enableLookups="false" redirectPort="8443" acceptCount="100"

               connectionTimeout="20000" disableUploadTimeout="true" />

 

4.      Also on the second server, change the port in the server entry at the top. For example:

<Server port="8006" shutdown="SHUTDOWN">

 

5.      Download sources of mod_jk from the following URL:

http://tomcat.apache.org/connectors-doc/

 

Build mod_jk. If required download the following rpms:

apr-devel-1.2.7-10.i386.rpm

apr-util-devel-1.2.7-3.i386.rpm

 

 

6.      Modify Apache’s httpd.conf to add following line:

LoadModule jk_module   modules/mod_jk.so

 

7.      Edit the workers.properties file inside tomcat1/conf directory.

Set workers.tomcat_home=<tomcat installation directory>

This is where the conf files are. This has to be set only once.

 

8.      Set workers.java_home=/usr/java/jdk1.5.0_10

This is the Java Home directory.

 

9.      Set worker.list=tomcat1, tomcat2, loadbalancer

Think of loadbalancer as the root node for tomcat1 and tomcat2 as worker nodes.

 

10.  Set the following properties for the first worker thread:

worker.tomcat1.port=8009

worker.tomcat1.host=192.168.1.101

worker.tomcat1.type=ajp13

worker.tomcat1.lbfactor=1

Note that the port is the AJP port, not the default tomcat port.

 

11.  Set the following properties for the second worker thread:

worker.tomcat2.port=8010

worker.tomcat2.host=192.168.1.101

worker.tomcat2.type=ajp13

worker.tomcat2.connection_pool_timeout=600

worker.tomcat2.socket_keepalive=1

worker.tomcat2.socket_timeout=60

worker.tomcat2.lbfactor=1

Note that the port is the AJP port, not the default tomcat port.

 

12.  Set the following properties for the loadbalancer thread:

worker.loadbalancer.type=lb

worker.loadbalancer.balance_workers=tomcat1, tomcat2

 

13.  Set the following properties for the status thread:

# Add the status worker to the worker list

worker.list=jkstatus

 

# Define a 'jkstatus' worker using status

worker.jkstatus.type=status

 

14.  Edit the Apache’s httpd.conf file and add the following lines:

 

# JkWorkersFile must be full pathname of the file you created above

# in my case it was tomcat1/conf/workers.properties

JkWorkersFile workers.properties

 

# LogLevel could be info, error, debug etc. debug seems to work best

JkLogLevel debug

JkLogFile /etc/httpd/logs/mod_jk.log

 

# Pathname of the redirection

# This means localhost/servlets-examples/* will go to tomcat[12]

JkMount /servlets-examples/* loadbalancer

 

# Add the jkstatus mount point

JkMount /jkmanager/* jkstatus

 

JkMountCopy off

 

15.  Having configured Apache as our dispatcher, we now need to configure the Tomcat workers.

Make sure the following line is uncommented in your tomcat1/conf/server.xml file:

    <Connector port="8009"

               enableLookups="false" redirectPort="8443" protocol="AJP/1.3" />

 

Make sure the following line is uncommented in your tomcat2/conf/server.xml file:

    <Connector port="8010"

               enableLookups="false" redirectPort="8443" protocol="AJP/1.3" />

 

16.  Edit the Engine entry to have a jvmRoute matching the tomcatId entry in workers.properties:

For tomcat1/conf/server.xml file:

<Engine name="Catalina" defaultHost="localhost" jvmRoute="tomcat1">

 

For tomcat2/conf/server.xml file:

<Engine name="Catalina" defaultHost="localhost" jvmRoute="tomcat2">

 

17.  Identify Tomcat server – create two different files called me.html inside tomcat1/webapps/servlets-examples and tomcat2/webapps/servlets-examples.

 

18.  Make sure you restart Apache server and the Tomcat servers before you test.

Load http://host_ip_address/servlets-examples/me.html in browser. Reload it, it should load balancer between the servers.

 

19.  For troubleshooting open /etc/httpd/logs/mod_jk.log file and try to understand what the error could be.

 

20.  Note:

 

a.      Set export JRE_HOME=/usr/java/jdk1.5.0_10 before you start Tomcat server.

b.      To stop Tomcat, kill the Java process, don’t do shutdown, that didn’t work for me.

 

Phew!

 

References in order of relevance

1.      http://www.javaworld.com/javaworld/jw-12-2004/jw-1220-tomcat.html?page=1

2.      http://publib.boulder.ibm.com/iseries/v5r2/ic2924/info/rzaie/rzaiemod_jk.htm#jkworkersfile

3.      http://tomcat.apache.org/connectors-doc/generic_howto/workers.html

4.      http://tomcat.apache.org/connectors-doc/

 

 

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