WebSphere Application Server - DB2 RS Transaction Isolation Level is Default

In WebSphere, the default transaction level is set to something very restrictive.

It’s likely that they haven’t changed this in their app server configuration.

Have them check the webSphereDefaultIsolationLevel custom property on their data sources.

https://www.ibm.com/support/pages/determining-and-changing-isolation-level

“If the database connection is obtained in a servlet, JSP, or session bean, TRANSACTION_REPEATABLE_READ is used by default.”

JDBC Isolation Level

              

DB2 Isolation Level

TRANSACTION_SERIALIZABLE      Repeatable Read (RR)

TRANSACTION_REPEATABLE_READ           Read Stability (RS)  ← Deafult

TRANSACTION_READ_COMMITTED          Cursor Stability (CS) ← What we want

TRANSACTION_READ_UNCOMMITTED    Uncommitted Read (UR)

“In WebSphere Application Server V6.1 and above, the webSphereDefaultIsolationLevel custom property can be set on a data source to change the default isolation level that is used even if indirect JNDI lookups and resource references are not used by the application.”

Procedure for changing this setting in WAS 8.5.5 can be found here:
https://www.ibm.com/support/knowledgecenter/en/SSWLGF_8.5.6/com.ibm.sr.doc/twsr_setwebspheredefaultisolationlevelproperty.html

Detecting Transaction Isolation Level through Profiler Trace and other means on MS SQL Server 2005

I doubt that this comes up often, but I find myself in a bit of an argument about what isolation level will be used for transactions in our SQL Server database when the transaction is initiated by WebSphere.  There are various documents that indicate how WebSphere can over ride this value.

I decided to dig into this a bit further.

TRACE:

In doing so, I found that I could monitor our SQL Server DB to determine this.

I have only found two places where the transaction isolation level is appearing:
1 - Sessions:Existing Connection.Text Data
2 - In a deadlock trace as part of the XML output.

If anyone can find it elsewhere, I'd love to hear from you.  However, this makes sense, since this is more-or-less controlled at the session level.

QUERY:
If found that 

DBCC USEROPTIONS

would give me the *default* TIL for the db, but that if that TIL was altered by the session, it would not reflect that.

To get the TIL for *your session*, you can run the following query:

SELECT CASE transaction_isolation_level WHEN 0 THEN 'Unspecified' WHEN 1 THEN 'ReadUncomitted' WHEN 2 THEN 'Readcomitted' WHEN 3 THEN 'Repeatable' WHEN 4 THEN 'Serializable' WHEN 5 THEN 'Snapshot' END AS TRANSACTION_ISOLATION_LEVEL FROM sys.dm_exec_sessions

Credit to StackOverflow question and answer here: http://stackoverflow.com/questions/1038113/how-to-find-current-transaction-level 

Auto Starting WebSphere Network Deployment V8 on AIX

We have very basic AIX, with no bells or whistles installed.
To create a launch script, the startmanager, startserver, and starnode scripts will generate this for you.  The command is

./startManager.sh -script -background

or

./startNode.sh -script -background

or

 ./startServer.sh -script -background

.. as appropriate...

In my case, I'm going to auto-start the deployment manager and the node agent, and then use the WAS monitoring policy to handle the individual app servers.

So, the steps are:

1. Generate the startup scripts using the above commands.
2. make a copy of rc.was (found in the was bin directory) for the deployment manager, and another for the node agent.  I called these rc.dm.was and rc.na.was.
1. Edit these to point to the start_dmgr.sh and start_nodeagent.sh scripts generated above
3. create entry in etc/Inittab for the two files created in step 2
1. was:2:once:/usr/WebSphere/AppServer/bin/rc.dm.was >/dev/console 2>&1
2. was:2:once:/usr/WebSphere/AppServer/bin/rc.na.was >/dev/console 2>&1

And, that should do it.  Let's see if it works :-)

 

Starting WebSphere Certification

I'm starting work on my WebSphere certification.
I'm beginning my work with the IBM WebSphere website.

WebSphere main page:
http://www-01.ibm.com/software/websphere/

WebSphere Application Server V8.0 Administration Curriculum:
http://www-01.ibm.com/software/websphere/education/curriculum/appserv/index.html


Several courses are offered.
1 - Administration on Windows
2 - Administration on Linux
3 - Technical Overview
4 - Problem Determination
5 - Transition to V8

I think that this is a good place to start focusing.  No budget to actually TAKE these courses, but this makes a fantastic outline.

The Certification page (http://www-01.ibm.com/software/websphere/education/certification/#free-was-cr) lists quite a few resources as well.

Available certifications include
"IBM Certified System Administrator - WebSphere Application Server Network Deployment V8.0"
The Recommended prerequisite section is telling:

Recommended Prerequisite Skills

(*Knowledge and skills one needs to possess before beginning to prepare for this job role certification; skills not measured on test) 

• basic Java Enterprise Edition 6 knowledge
• basic Web application architecture and deployments
• network and operating system security concepts
• network or operating system administration and problem determination skills
• understanding of operating systems

There is an assessment test which I think will be a very, very useful tool, found here: http://www-03.ibm.com/certify/tests/sam317.shtml.  Cost is $30 / practice test.

There is also a "Training Resources" section (http://www-03.ibm.com/certify/tests/edu317.shtml) that lists several redbooks and Web Resources.

REDBOOKS:
http://www.redbooks.ibm.com/abstracts/sg247957.html?Open
http://www.redbooks.ibm.com/redpieces/abstracts/sg247971.html?Open

There are about a bazillion web resources.  Probably worth checking out.