Modifying the starting weight of applications using scripting (jython)

1. Update the starting weight of an Enterprise Application:

AdminConfig.modify
(AdminConfig.showAttribute
(AdminConfig.getid("/Deployment:myApps/"),
"deployedObject"),[['startingWeight','20']])

Note: Valid range for 'startingWeight': 0 and 2147483647

2. Update the class loader mode of an Enterprise Application:

AdminConfig.modify
(AdminConfig.showAttribute(AdminConfig.showAttribute
(AdminConfig.getid('/Deployment:myApps/'),'deployedObject'),
'classloader'),[['mode','PARENT_LAST']])

Note: Valid values for 'mode' : PARENT_FIRST, PARENT_LAST

3. Update the WAR class loader policy of an Enterprise Application:

AdminConfig.modify
(AdminConfig.showAttribute
(AdminConfig.getid('/Deployment:myApps/'),
'deployedObject'),[['warClassLoaderPolicy','SINGLE']])

Note: Valid values for 'warClassLoaderPolicy':
SINGLE (Application), MULTIPLE (Module;default)

4. Update the starting weight of individual modules (Web or EJB) within an EAR -->

def modifyModStartingWeight(appName, modStWeight, modName):
    global AdminConfig
    try:
        refParam = "/Deployment:" + appName + "/"
        depRef = AdminConfig.getid(refParam)
        depObjectRef = AdminConfig.showAttribute(depRef, 'deployedObject')
        modules = AdminConfig.showAttribute(depObjectRef, 'modules')
        arrayModules = modules[1:len(modules)-1].split(" ")
        for module in arrayModules:
        tmpStr = AdminConfig.showAttribute(module,'uri')
                if tmpStr == modName:
                        AdminConfig.modify(module, [['startingWeight', modStWeight]])
                        print "New starting weight for " +
AdminConfig.showAttribute(module,'uri') + "is " +
AdminConfig.showAttribute(module,'startingWeight')
        try:
            AdminConfig.save()
        except:print "AdminConfig.save() caught exception. \n"
    except: print "AdminConfig.modify(" + appName + ") caught 

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New Rules For Cricket

I just got a mail forward from one of my friend.

After watching the test match, someone has written some rules have to be incorporated by ICC to give the other teams a perfect clarification

(1)    Ricky Ponting – (THE TRULY GENUINE CRICKETER OF THE CRICKET ERA AND WHOSE INTEGRITY SHOULD NOT BE DOUBTED) should be considered as the FOURTH UMPIRE. As per the new rules, FOURTH UMPIRE decision is final and will over ride any decisions taken by any other umpires. ON-FIELD umpires can seek the assistance of RICKY PONTING even if he is not on the field. This rule is to be made, so that every team should understand the importance of the FOURTH UMPIRE.

(2)    While AUSTRALIAN TEAM is bowling, If the ball flies anywhere close to the AUSTRALIAN FIELDER(WITHIN 5 metre distance), the batsman is to be considered OUT irrelevant of whether the catch was taken cleanly or grassed. Any decision for further clarification should be seeked from the FOURTH UMPIRE. This is made to ensure that the cricket is played with SPORTIVE SPIRIT by all the teams.

(3)    While BATTING, AUSTRALIAN players will wait for the ON-FIELD UMPIRE decisions only (even if the catch goes to the FIFTH SLIP as the ball might not have touched the bat). Each AUSTRALIAN batsman has to be out FOUR TIMES (minimum) before he can return to the pavilion. In case of THE CRICKETER WITH INTEGRITY, this can be higher.

(4)    UMPIRES should consider a huge bonus if an AUSTRALIAN player scores a century. Any wrong decisions can be ignored as they will be paid huge bonus and will receive the backing of the AUSTRALIAN team and board.

(5)    All AUSTRALIAN players are eligible to keep commenting about all players on the field and the OPPONENT TEAM should never comment as they will be spoiling the spirit of the AUSTRALIAN team. Any comments made in any other language are to be considered as RACIALISM only.

(6)    MATCH REFREE decisions will be taken purely on the AUSTRALIAN TEAM advices only. Player views from the other teams decisions will not be considered for hearing. MATCH REFREES are to be given huge bonus if this rule is implemented.

(7)    NO VISITING TEAM should plan to win in AUSTRALIA. This is to ensure that the sportive spirit of CRICKET is maintained.

(8)    THE MOST IMPORTANT RULE: If any bowler gets RICKY PONTING – “THE UNDISPUTED CRICKETER WITH INTEGTIRY IN THE GAME OF CRICKET” more than twice in a series, he will be banned for the REST OF THE SERIES. This is to ensure that the best batsman/Captain will be played to break records and create history in the game of CRICKET.

  These rules will clarify better to the all the teams VISITING AUSTRALIA.

Custom User Registry

To enable security in WebSphere Application Server, you need to logon to WAS admin console. The default URL for accessing WAS admin console would be http://localhost:9060/admin in your local machine. When the security is not enabled WAS would ask you for a username and you can provide any username you want. When enabling security in WAS 6.0 there are three different types of user registries available.
1. Custom User Registry
2. LDAP
3. Local OS.
Here I will be talking about enabling security using Custom User Registry as the Active User Registry. The first step in enabling security using Custom user registry is to create one user file and a group file. The group file will be of the following format.

name:gid:users:display name
For eg:
admins:1:admin,admin1:Administrative group
operators:2:operator,operator1:Operators group
users:3:user1,user2,user3,bobby:

The groups file will be saved with name groups.props in directory D:\IBM\security.
Then create a users file using the following format.

name:passwd:uid:gids:display name
admin:admin:10:1:Admin
admin1:admin1:11:1:Admin 1
user:user:12:2,3:User

The users file will be saved with name users.props in directory D:\IBM\security. (This cane be any directory)
The next fist step is to click on Global Security link under security menu.

 The security configuration page opens up.

Once the security configuration page got opened click on Custom under user registries section. The custom user registry page opens.

Under general properties enter the server admin username and password you want and click on the custom properties link under Additional properties section. Click on new button in the custom properties page.

Enter groupsFile as the name and D:/IBM/security/groups.props as the value. Save the custom property value and create another custom property and enter usersFile as the name D:/IBM/security/users.props as the value. Save the values you will be returned to the custom properties page. Now the custom properties page would look like the one in the below picture.

Save the changes made and return to the security configuration page.
Now select custom user registry under active user registry and select the ‘Enable global security’ checkbox. Uncheck ‘Enforce Java 2 Security’

Save the changes. Restart your server. Once global security is enabled on the WAS server, we need to provide the admin username and password for starting and stopping the server. The command for starting the server once the security is enabled is
startServer.bat server1 -user admin -password admin
where server1 is the name of your server. If your server is integrated with an IDE like RAD, double click on the server from the server perspective and enter the username and password after selecting ’security is enabled on this server’ checkbox under security section in your server configuration window.

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Memory leak detection and analysis in WebSphere Application Server: Part 1: Overview of memory leaks

Overview of memory leaks

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WebSphere Cluster Member crashed

Have you ever been asked this question in the interview?
how do you find out which cluster member was crashed/down?
The general answer we give is to go to administration console and check the individual server status or the cluster member status.
The other option is to use a third-party monitoring tool such as ITCAM, wily introscope, UniCenter and Nagios etc..
Have you ever checked the system.out log file of any individual server when one of the cluster member was stopped?
WebSphere has Distribution & Consistency Services (DCS), which is a part of the HA architecture. Using these DCS messages we can find which member of the cluster is down.
Here is an example:


I’ve a cell with name Test-Cell, which has a cluster with 6nodes each having 2 servers.
I’ve stopped one of cluster members. Then if you see the System.Out log file, you see message similar to the below:

[3/3/10 18:00:37:758 CET] 00000026 RoleMember    W   DCSV8104W: DCS Stack DefaultCoreGroup.TestRepln at Member Test-Cell\node01\server01: Removing member [Test-Cell\node02\server02] because the member was requested to be removed  by member Test-Cell\node02\server01. Internal details VL suspects others: CC-Situation Normal
[3/3/10 18:00:38:176 CET] 00000023 VSyncAlgo1    I   DCSV2004I: DCS Stack DefaultCoreGroup at Member Test-Cell\node01\server01: View synchronization completed successfully. The View Identifier is (22898:0.Test-Cell\node02\server01). The internal details are None.
[3/3/10 18:00:38:207 CET] 00000023 VSyncAlgo1    I   DCSV2004I: DCS Stack DefaultCoreGroup.TestRepln at Member Test-Cell\node01\server01: View synchronization completed successfully. The View Identifier is (331:0.Test-Cell\node02\server01). The internal details are None.
[3/3/10 18:00:38:537 CET] 00000024 CoordinatorIm I   HMGR0218I: A new core group view has been installed. The core group is DefaultCoreGroup.
[3/3/10 18:00:39:228 CET] 00000026 DataStackMemb I   DCSV8050I: DCS Stack DefaultCoreGroup.TestRepln at Member Test-Cell\node01\server01: New view installed, identifier (332:0.Test-Cell\node02\server01), view size is 11 (AV=11, CD=12, CN=12, DF=12)
[3/3/10 18:00:39:343 CET] 00000021 DRSBuddyManag A   CWWDR0006I:  Replication instance terminated : Test-Cell\node02\server02

So, from the above messages, it is clear that server02 of Node02 was down and is removed from the coregroup.
After some troubleshooting/changes, i started the server which was down earlier. Now, if you observe the SystemOut.log, you can see the following:

[3/3/10 18:17:13:245 CET] 00000026 RoleMember    I   DCSV8051I: DCS Stack DefaultCoreGroup.TestRepln at Member Test-Cell\node01\server01: Core group membership set changed. Added: [Test-Cell\node02\server02].
[3/3/10 18:17:13:315 CET] 00000023 MbuRmmAdapter I   DCSV1032I: DCS Stack DefaultCoreGroup.TestRepln at Member Test-Cell\node01\server01: Connected a defined member Test-Cell\node02\server02.
[3/3/10 18:17:30:337 CET] 00000023 VSyncAlgo1    I   DCSV2004I: DCS Stack DefaultCoreGroup.TestRepln at Member Test-Cell\node01\server01: View synchronization completed successfully. The View Identifier is (333:0.Test-Cell\node02\server01). The internal details are None.
[3/3/10 18:17:30:353 CET] 00000026 DataStackMemb I   DCSV8050I: DCS Stack DefaultCoreGroup.TestRepln at Member Test-Cell\node01\server01: New view installed, identifier (334:0.Test-Cell\node02\server01), view size is 12 (AV=12, CD=12, CN=12, DF=12)
[3/3/10 18:17:30:354 CET] 00000027 DRSBuddyManag A   CWWDR0007I:  Replication instance group membership changed: Test-Cell\node02\server02
[3/3/10 18:17:30:356 CET] 00000027 DRSBuddyManag A   CWWDR0002I: Replication instance is active : Test-Cell\node02\server02
[3/3/10 18:17:30:358 CET] 00000010 ViewReceiver  I   DCSV1033I: DCS Stack DefaultCoreGroup.TestRepln at Member Test-Cell\node01\server01: Confirmed all new view members in view identifier (334:0.Test-Cell\node02\server01). View channel type is View|Ptp.

You can a meesage which is showing that it added a new member to the coregroup.

About DCS:
There are two main versions of DCS: Core DCS and Data DCS. There is one Core DCS per process and it provides membership services among peer processes. These processes together form a Core Group. A process may be a member in one or more named Core Groups. Applications running on these processes can be members of application groups. Application groups are subsets of a particular named core group. A Data DCS component can be associated with each member of an application group.
DCS provides a mechanism for communicating information (distribution) among members with a given quality of service. Failure detection mechanisms that support and allow guaranteed quality of service are an inherent part of DCS and its services. DCS supports WebSphere components’ state replication requirements (like http session and stateful beans) as well as the distribution and synchronization of WebSphere artifacts for performance, scalability, and availability.
I’ll soon write about ‘Core Groups” of WebSphere to understand the DCS and high availability architecture of the WebSphere.

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WebSphere Core Groups

What is a core group?

A core group encapsulates processes in a Network Deployment cell to create high availability domains.
A core group is a grouping of WebSphere Application Server cell processes. A core group can contain standalone servers, cluster members, node agents, and the deployment manager. A core group must contain at least one node agent or the deployment manager.
DefaultCoreGroup is a core group that is created by default at installation time and can be used out-of-the-box; that is, all processes will know about each other.
Note:
1. A core group cannot extend beyond a cell
2. All JVMs in a core group must able to communicate (they use heartbeat messages to know each other)

Core group coordinator

Once the core group stabilizes at runtime, one of the member will be elected to act as an coordinator. That member called as Coregroup coordinator is responsible for managing the high availability with in that core group.
1. It maintains all group information like group name, members and policy of the group
2. It maintains a record state of the group members as they start, stop or fail
3. Assigning singleton services to group members and handling failover based on policy specified.
We can change the default core group coordinator by going to:
servers –>coregroups->coregroup settings->Default Coregroup ->preferred coordinator servers.
When a member becomes active coordinator, you can see the following messages in the SystemOut:

[3/3/10 18:00:37:758 CET] 00000013 CoordinatorIm I HMGR0206I: The Coordinator is an Active Coordinator for core group DefaultCoreGroup.

If a member was failed/stopped in the core group:

[3/3/10 18:00:37:758 CET] 00000026 RoleMember    W   DCSV8104W: DCS Stack DefaultCoreGroup.TestRepln at Member Test-Cell\node01\server01: Removing member [Test-Cell\node02\server02] because the member was requested to be removed  by member Test-Cell\node02\server01. Internal details VL suspects others: CC-Situation Normal
[3/3/10 18:00:38:176 CET] 00000023 VSyncAlgo1    I   DCSV2004I: DCS Stack DefaultCoreGroup at Member Test-Cell\node01\server01: View synchronization completed successfully. The View Identifier is (22898:0.Test-Cell\node02\server01). The internal details are None.
[3/3/10 18:00:38:207 CET] 00000023 VSyncAlgo1    I   DCSV2004I: DCS Stack DefaultCoreGroup.TestRepln at Member Test-Cell\node01\server01: View synchronization completed successfully. The View Identifier is (331:0.Test-Cell\node02\server01). The internal details are None.
[3/3/10 18:00:38:537 CET] 00000024 CoordinatorIm I   HMGR0218I: A new core group view has been installed. The core group is DefaultCoreGroup.
[3/3/10 18:00:39:228 CET] 00000026 DataStackMemb I   DCSV8050I: DCS Stack DefaultCoreGroup.TestRepln at Member Test-Cell\node01\server01: New view installed, identifier (332:0.Test-Cell\node02\server01), view size is 11 (AV=11, CD=12, CN=12, DF=12)
[3/3/10 18:00:39:343 CET] 00000021 DRSBuddyManag A   CWWDR0006I:  Replication instance terminated : Test-Cell\node02\server02

If a new member joins the core group, you can see the following message

[3/3/10 18:17:13:245 CET] 00000026 RoleMember    I   DCSV8051I: DCS Stack DefaultCoreGroup.TestRepln at Member Test-Cell\node01\server01: Core group membership set changed. Added: [Test-Cell\node02\server02].
[3/3/10 18:17:13:315 CET] 00000023 MbuRmmAdapter I   DCSV1032I: DCS Stack DefaultCoreGroup.TestRepln at Member Test-Cell\node01\server01: Connected a defined member Test-Cell\node02\server02.
[3/3/10 18:17:30:337 CET] 00000023 VSyncAlgo1    I   DCSV2004I: DCS Stack DefaultCoreGroup.TestRepln at Member Test-Cell\node01\server01: View synchronization completed successfully. The View Identifier is (333:0.Test-Cell\node02\server01). The internal details are None.
[3/3/10 18:17:30:353 CET] 00000026 DataStackMemb I   DCSV8050I: DCS Stack DefaultCoreGroup.TestRepln at Member Test-Cell\node01\server01: New view installed, identifier (334:0.Test-Cell\node02\server01), view size is 12 (AV=12, CD=12, CN=12, DF=12)

What happens when coordinator went down?
When the active coordinator is not available (stopped/crashed), the HA manager will elect the first inactive server in the preferred coordinator servers list. If preferred list is not specified, it will select lexically lowest named server.
The newly selected coordinator initiates a state rebuild by sending a message to all core group members to report their states.

Core group settings

1. Number of coordinators

Specifies the number of coordinators for this core group. The default value is one coordinator, although multiple coordinators are advisable for large core groups. All of the group data must fit in the memory of the allocated coordinators. One coordinator can run out of memory in a system with a large core group, which can cause the system to work improperly.

2. Transport type

Specifies the transport mechanism to use for communication between members of a core group.

Channel framework

Channel framework is the default transport type. It uses the channel framework service to incorporate port reusability and shared port technology into the communication system.

Unicast

Unicast is a targeted network model that focuses on a direct recipient for communication. This type of communication is most suitable when the intended message is sent to a specific set of recipients.

Multicast

Multicast consists of a broadcast network model. This model broadcasts communication across the defined network, depending upon the values that are provided for the multicast settings. Multicast settings are suitable when there are many recipients for the intended message; otherwise broadcast communication tends to overload the network with traffic, and can impact performance goals.

3. Channel chain name

Specifies the name of the channel chain if you select channel framework for the transport type.
If you select Multicast transport type

• Multicast port
  The port setting tells the coordinator where to scan for transmissions. When setting this value, verify that you are specifying a port that is not used by another network communication device. Setting a port value that has conflicts causes problems with your high availability manager infrastructure.
• Multicast group IP start
  Specify the starting Internet Protocol (IP) address of the intended communication area.
• Multicast group IP end
  Specify the ending IP address of the intended communication area. Plan the network to accommodate scalability.

4. Additional Properties
Core group servers
Specifies the server processes that belong to the core group. Server processes include the deployment manager, node agents, application servers, and cluster members. You can use the panel that displays to move server processes to a different core group.

Policies

Use to define the policies that determine which members of a high availability group are made active.

Preferred coordinator servers

Specifies which core group servers are preferred coordinator servers.

Core Group policies:

Servers > Core groups > Core group settings > New or existing core group > Policies.

Policy types

All active	The All active policy indicates that the high availability manager keeps all of the application components that are running on all of the servers in the high availability group active at all times
M of N	The M of N policy is similar to the One of N policy. However, it enables you to specify the number (M) of high availability group members that you want to keep active if it is possible to do so. The number of active members must be greater than one and less than or equal to the number of servers in the high availability group. If the number of active servers is set to one, this policy is a match for the One of N policy
No Operation	The No operation policy indicates that no high availability group members are made active
One of N	The One of N policy keeps one member of the high availability group active at all times. This is used by groups that desire singleton failover. If a failure occurs, the high availability manager starts the singleton on another server
Static	The Static policy allows you to statically define or configure the active members of the high availability group

Match Criteria
Specifies one or more name-value pairs that are used to associate this policy with a high availability group. These pairs must match attributes that are contained in the name of a high availability group before this policy is associated with that group.

Is alive timer
In seconds, the interval of time at which the high availability manager will check the health of the active group members that are governed by this policy. If a group member has failed, the server on which the group member resides is restarted.
Quorum
Specifies whether quorum checking is enabled for a group governed by this policy. Quorum is a mechanism that can be used to protect resources that are shared across members of the group in the event of a failure. The quorum mechanism is designed to work in conjunction with a hardware control facility that allows application servers to be shut down if a failure causes the group to be partitioned.
note: The Quorum setting in the policy will only have an effect if the following items are true:
* The group members are also cluster members.
* GroupName.WAS_CLUSTER=clustername must be specified as a property in the group name of any high availability group matching this policy.
Fail back
Specifies whether work items assigned to the failing server are moved to the server that is designated as the most preferred server for the group if a failure occurs. This field only applies for M of N and One of N policies.
Preferred servers only
Specifies whether group members are only activated on servers that are on the list of preferred servers for this group. This field only applies for M of N and One of N policies.

Core group servers:

 

Use this to move servers into a different core group. All members of a cluster must be in the same core group. If you select one or more members of a cluster, all of the members of that cluster must be moved.

Preferred coordinator servers:

 

 

Use Add and Remove to move servers into and out of the list of preferred servers. Use Move up and Move down to adjust the order within the list of preferred servers. Make sure that the most preferred server is at the top of the list and the least preferred server is at the bottom.

Core group member Failure detection

HA manager monitors all the core group members. It uses 2 settings to detect the failure
1. Active failure detection
If the heartbeat from a JVM is failing for specified interval of time, then it will be marked as failed. When using default settings, heartbeats are sent every 10sec and 20times (200sec) should be failed before marking the JVM as failed. When a JVM is marked as failed, a new view is installed and you can see that in the SystemOut log.
2. TCP Keep Alive
If one member is not able to contact other member, and if gets closed socket error, it will signal the other members to treat that member as failed. Say, if one jvm is panics or network issue etc, as soon as the TCP settings allow, the failure will be detected.
Note: TCP Keep alive setting is of the operating system.
About DCS and finding which core group member crashed/stopped. Here


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Quick hit JVM heap size change

I was tasked to change the JVM heap size in approximately 2,500 servers today. I created a quick little script that I will share for you.

#
# Update the Heap size
# Mike Huffsteder 5/5/2008
#
# ./wsadmin.sh -lang jython -f updateJVM.py
#

as = AdminConfig.getid('/Cell:YOUR_CELL_NAME/Node:YOUR_NODE_NAME/Server:YOUR_SERVER_NAME/')
jvm = AdminConfig.list('JavaVirtualMachine', as)
AdminConfig.modify(jvm, [['initialHeapSize', '512'], ['maximumHeapSize', "768"]])
AdminConfig.save()
# set the newly saved config to variables to place entries in logging
i = AdminConfig.showAttribute(jvm, "initialHeapSize")
m = AdminConfig.showAttribute(jvm, "maximumHeapSize")
print "The initial heap size is now" + i
print "The max heap size is now" + m

Of course, you can change the heap to whatever size you would like.

wsadmin rotate jvm log files

Simple, working, rotates logs at 10mb saving max 5 files.

# rotateWasLogEPRN.py
# Setup WAS Log file rotations
# for yourserver
# 9/10/2008
# Mike Huffsteder - WTA
#
# Implement:
# ./wsadmin.sh -lang jython -f $FILE_LOCATION/rotateWasLogEPRN.py >> $TO_LOG_FILE
#
# You can add this as you have other scripts in the deployment script
# if you need help please let me know.
#
#

print "Changing the SystemOut & SystemErr log file rotation settings"
var1 = AdminConfig.getid('/Cell:yourcell/Node:yournode/Server:yourserver/')

log = AdminConfig.showAttribute(var1, 'outputStreamRedirect')
log2 = AdminConfig.showAttribute(var1, 'errorStreamRedirect')

AdminConfig.modify(log, '[[rolloverSize 10] [maxNumberOfBackupFiles 5]]')
AdminConfig.modify(log2,'[[rolloverSize 10] [maxNumberOfBackupFiles 5]]')

AdminConfig.save()

print "New SystemOut settings 9-10-08"
AdminConfig.show(log).split("\n")
print "New SystemErr settings 9-10-08"
AdminConfig.show(log2).split("\n")

Analyze JVM Logs

ystemOut.log and SystemErr.log files are text files

so you can view them using simple text editor.
The Application server writes formatted messages to the SystemOut.log file and this is how a sample log message looks like

[7/2/09 9:12:22:645 PDT] 00000017 ApplicationMg A WSVR0221I: Application started: SchedulerCalendars
Each entry can be deciphered as follows

• Time Stamp: The first part of the log message in sample code is [7/2/09 9:12:22:645 PDT]. It is the time stamp when the message was written. The time stamp is formatted using the locale of the process and it is 24 hour time stamp with milli-second precision


• Thread ID: The next part in the log message is 00000017, which represents the thread id. The thread ID is an eight-character hexadecimal value that is generated from the hash code of the thread that issued the message


• Short name: The short name is the abbreviated name of the component that issued the message. This name is typically the class name of a WAS component and would be some other identifier for the application. In our sample the ApplicationMg is component name


• Event Type: The event type is a one character field that indicates the type of the message. The possible values are
  
  
  
  • F- Fatal message
  
  
  • E- Error message
  
  
  • W- Warning message
  
  
  • A- Audit message
  
  
  • I- Informational message
  
  
  • C- Configuration message
  
  
  • D- detail message
  
  
  • O- Messages that are written directly to System.out by an application or server component
  
  
  • R- Messages that are written directly to System.err by the user application or internal component.
  
  
  • Z- Place holder to indicate type was not recognized
  
  In my sample message A indicates this is audit message

.ear files deployment descriptor

The deployment descriptor of the EAR file is stored in the META-INF directory in the root of the EAR and is called application.xml. It contains information about the modules that makeup the application.

I have a HelloWorld.ear that contains one HelloWorldEJB module, which is a EJB project and HelloWorldWeb module which is a web module. The HelloWorldWeb module calls methods of HelloWorldEJB

<?xml version="1.0" encoding="UTF-8"?>
<application id="Application_ID" version="1.4" xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/application_1_4.xsd">
 <display-name>
 HelloWorld</display-name>
 <module id="EjbModule_1251662896937">
  <ejb>HelloWorldEJB.jar</ejb>
 </module>
 <module id="WebModule_1251663065906">
  <web>
   <web-uri>HelloWorldWeb.war</web-uri>
   <context-root>HelloWorldWeb</context-root>
  </web>
 </module>
</application>

In addition to the standard J2EE deployment descriptors, EAR files produced by the Application Server Toolkit can also include additional WebSphere-specific information used when deploying applications to WebSphere environments. This supplemental information is stored in files called ibm-xxx-xxx-xxx.xmi, also in the META-INF directory.

WebSphere Application Server V6.0 and V6.1 can also store deployment-related information (such as data sources, class loader settings, and so on) as part of an Enhanced EAR file. This information is stored in an ibmconfig subdirectory of the EAR file’s META-INF directory.

Trouble shooting errors during profile creation

The successful installation of the Network Deployment product is a two-part process:

• The first step is using the installation wizard to install a shared set of core product files.


• The second step is to create a deployment manager profile, an application server profile, or a custom profile.

If the installation failed during the creation of profile then check app_server_root/logs/manageprofiles/<profilename>_create.log for further information on what went wrong. The <profilename>_create.log file is an XML file that contains a record of the events that occur during the creation of the last profile.

In addition to the logs created within the core product files, the following logs are created in the app_server_root/logs/manageprofiles/profile_name directory.

• activity.log: Compiled activity log from various installation activities


• amjrte_config.log: Tivoli Access Manager configuration log for its Java Runtime Environment


• collect_metadata.log: Collects metadata information about managed objects in the system to evaluate and prevent potential installation conflicts


• createDefaultServer.log: A log from wsadmin recording the creation of the server1 process in the default profile


• createshortcutforprofile.log:Windows tool log for creating menu entries and shortcuts


• defaultapp_config.log:JACL script log from configuring default application resources


• defaultapp_deploy.log:Application DefaultApplication installation log


• node_name Service.log:Start and stop events for server1


• filetransfer_config.log:Application filetransfer installation log


• hamanager_config.log: Configuration log for the high availability application


• ivt_config.log:Application ivtApp installation log


• mejb_config.log: Application ManagementEJB installation log


• query_config.log: Application Query installation log


• samples_config.log: Configuration log for the PlantsByWebSphere Samples application


• samples_install.log: Installation log for the SamplesGallery and PlantsByWebSphere Samples applications


• scheduler.cal_config.log: Application SchedulerCalendars installation log


• SIBDefineChains.log: Creation log for service integration bus endpoints, inbound channels and channel chains, outbound thread pool, and outbound channel and channel chains


• SIBDeployRA.log: Deployment log for the service integration bus function


• webui_config.log: Application administrative console installation log

The no. and logs that get created might vary based on the profile that your creating. The same set of logs get created irrespective of how your creating profile, i.e. either at the time of installation, using Profile Management tool or using the manageprofile command.

Interview questions

What is deadlock?When two threads are waiting for each other and can’t proceed until the first thread obtains a lock on the other thread or vice versa, the program is said to be in a deadlock.

What are synchronized methods and synchronized statements?Synchronized methods are methods that are used to control access to an object. A thread only executes a synchronized method after it has acquired the lock for the method's object or class. Synchronized statements are similar to synchronized methods. A synchronized statement can only be executed after a thread has acquired the lock for the object or class referenced in the synchronized statement.

What is the difference between process and thread?A thread is a separate path of execution in a program. A Process is a program in execution.

What do you understand by Synchronization?
Or
What is synchronization and why is it important?
Or
Describe synchronization in respect to multithreading?
Or
What is synchronization?With respect to multithreading, Synchronization is a process of controlling the access of shared resources by the multiple threads in such a manner that only one thread can access a particular resource at a time. In non synchronized multithreaded application, it is possible for one thread to modify a shared object while another thread is in the process of using or updating the object's value. Synchronization prevents such type of data corruption which may otherwise lead to dirty reads and significant errors.

E.g. synchronizing a function:
public synchronized void Method1 ()
{
// method code.
}
E.g. synchronizing a block of code inside a function:
public Method2 (){
synchronized (this) {
// synchronized code here.
}
}

Java Garbage Collection

Explain Garbage collection mechanism in Java?
Garbage collection is one of the most important features of Java. The purpose of garbage collection is to identify and discard objects that are no longer needed by a program so that their resources can be reclaimed and reused. A Java object is subject to garbage collection when it becomes unreachable to the program in which it is used. Garbage collection is also called automatic memory management as JVM automatically removes the unused variables/objects (value is null) from the memory. Every class inherits finalize() method from java.lang.Object, the finalize() method is called by garbage collector when it determines no more references to the object exists. In Java, it is good idea to explicitly assign null into a variable when no more in use. In Java on calling System.gc() and Runtime.gc(), JVM tries to recycle the unused objects, but there is no guarantee when all the objects will garbage collected. Garbage collection is an automatic process and can't be forced. There is no guarantee that Garbage collection will start immediately upon request of System.gc().

What kind of thread is the Garbage collector thread?It is a daemon thread.

Can an object’s finalize() method be invoked while it is reachable?An object’s finalize() method cannot be invoked by the garbage collector while the object is still reachable. However, an object’s finalize() method may be invoked by other objects.

Does garbage collection guarantee that a program will not run out of memory?Garbage collection does not guarantee that a program will not run out of memory. It is possible for programs to use up memory resources faster than they are garbage collected. It is also possible for programs to create objects that are not subject to garbage collection.

What is the purpose of finalization?The purpose of finalization is to give an unreachable object the opportunity to perform any cleanup, before the object gets garbage collected. For example, closing an opened database Connection.

If an object is garbage collected, can it become reachable again?Once an object is garbage collected, It can no longer become reachable again.
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WMSG1603E - An error occurred trying to read the bundle

WMSG1603E - An error occurred trying to read the bundle


I encountered a strange error this weekend whilst installing multiple fix packs across numerous WAS systems. Despite installing these fixes numerous times, this error only occurred on one system.


I was upgrading from WAS 6.1.0.21 to 6.1.0.27 - that included WAS, SDK, IHS and Plugin fixes.


After installing the fix packs when I restarted the server I got the following error:


WMSG1603E: An internal error occurred. It was not possible to register the WebSphere MQ JMS client with the application serve

r due to exception org.osgi.framework.BundleException: An error occurred trying to read the bundle



followed by a java stack which included the following:

WMSG1603E: An internal error occurred. It was not possible to register the WebSphere MQ JMS client with the application serve

r due to exception org.osgi.framework.BundleException: An error occurred trying to read the bundle

A quick search and the reason was obvious. This WAS system does not run as root but when I checked the file permissions on the org.osgi.framework bundles in {WAS_INSTALL_DIR}/profiles/{PROFILE_NAME}/configuration the bundle in question was owned by root:


drwxr-x--- 2 wasadm wasadm 256 07 Feb 10:25 org.eclipse.update

drwxr-xr-x 4 root system 256 07 Feb 10:26 org.eclipse.osgi

drwxr-x--- 3 wasadm wasadm 256 04 Jan 11:24 org.eclipse.core.runtime


A quick change of permissions on the directory and all sub directories followed by a restart and everything came up fine.

Test connection on each node for cell scope datasource

Test connection on each node for cell scope datasource


I am sure pretty much every WAS administrator has used the "test connection" button in the WAS console to prove a JDBC datasource has been set up correctly.

Although not a problem, something that always got me and didn't seem to be as good as it could be, is the fact that if you work in a large scale enironment you may well end up setting the datasource at a cell level as this would cut down on the time it takes to set up a datasource on each node or appserver and also redude the likelihood of something being mis typed. Hoever, if you do this and then run test connection, the connection is just from the dmgr as you can see by lookiig in the dmgr logs.


So what happens if you have 10, 20 or more nodes and you want to make sure that all of them can connect correctly to the database. You could telnet from each box to the DB server on the correct port, but that just shows network connectivity rather than a full databsee connection.

I assumed this could be done in a jython script but it took me a day or 2 to figure this out. If I connected to the nodeagent in wsadmin, I couldn't get the config details of the datasources as these are accessed from a wsadmin session connected to the dmgr. But running a test connection when in a wsadmin session connected to the dmgr just does the same as the "test connection" through the admin console.

In the end, I managed to write a simple unix script, which does the following:

1. Open a wsadmin session to the dmgr to get the datasource ids and write these to a file, passing in the name of the cell

2. open a wsadmin session to each nodeagent, read the datasource id's from the file, then run a test connection.


This is the basic unix script:

###########################################################################

CELL=epwsdr21Cell

NODES="epwsdr21 epwsdr22 epwsdr23 epwsdr24 epbtdr21"

PORT=8878

echo "Running connection from each node to the datasources in WAS"

echo "Connecting to dmgr through wsadmin....."


# Connect to the dmgr through wsadmin - pass in the name of the cell - and run scropt dsconnect.py


/usr/was6/WebSphere/AppServer/bin/wsadmin.sh -lang jython -f ./jython/dsconnect.py $CELL


echo "Connecting to each nodeagent to run test connections....."


for node in $NODES;do

echo "Connecting to ${node} on port ${PORT} through wsadmin"



# Connect to each nodeagent in my list of nodes above - and run script dsconnect2.py


/usr/was6/WebSphere/AppServer/bin/wsadmin.sh -lang jython -conntype SOAP -host $node -port $PORT -f ./jython/dsconnect2.py $node


done

echo 'Complete '

#############################################################################

And here is what is in the first jython script - dsconnect.py


# Jython script to get the datasource id's once connected to the dmgr through wsadmin

import sys

print ' '

print "Getting datasources for cell " + sys.argv[0]

# First build the cell name we are interested in fromm the cell name passed from the main script

constructcell ="/Cell:" + sys.argv[0] + "/"

# get the cell id

cellid = AdminConfig.getid( constructcell )

# Get the datasource id's

print 'Datasources found are listed below:'


# In this instance I am after v4 datasources for v5 datasources use "dsid = AdminConfig.list("DataSource", cellid).splitlines()"

dsid = AdminConfig.list("WAS40DataSource", cellid).splitlines()


print dsid


# Now open a tmp file and write the list of dsid's to tfe file - this will be a string rather than a jython list


f=open('/tmp/dsconnect.out','w')

s=str(dsid)


f.write(s)

f.close()


##############################################################################

So the list of ids is written to /tmp/dsconnect.out, now the second script is called for each nodeagent I want to connect to and then run a test connection. The list that has been put into a file will be seen as a jython string rather than a list which is why I use the eval statment so it goes back into string format

# Jython script to run a test connection on a list of datasources

import sys
#

# Open temp file to get string of datasource ids and assign to a jython list

f=open('/tmp/dsconnect.out')

test=f.read()

dsids=eval(test)

f.close()


for ds in dsids:

print ' '

print 'Testing connection from ' + sys.argv[0] + ' to ' + ds

try:

outp=AdminControl.testConnection(ds)

except:

print 'Error connecting to datasource'


print outp

else:
print outp


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