April 30, 2004


What are we to believe in, then? Nothing. That is the beginning of Wisdom. It is time to rid ourselves of 'Principles' and to espouse Science, objective inquiry.

Gustave Flaubert
--Flaubert-Sand Correspondence

Posted at 11:18 AM

April 21, 2004

XA transactions

Java Technology Forums

A non-XA transaction is what you get (usually automatically) if you access JDBC connections and do statements over them. A non-XA (or local) transaction can only span one connection (if you rollback, it's the work on that connection only).

A JTA transaction is any transaction that you configure in the application server. For instance, if you use a bean with REQUIRED transaction settings in the deployment descriptor, then that will be a JTA transaction.
Same thing for UserTransaction.begin() (if you do that).

XA-compliant means that the JDBC or JCA driver you are using is compatible with the JTA transaction manager in the application server: the driver will listen to the instructions that the application server gives it to rollback or commit. non-XA-compliant JDBC or JCA drivers don't listen to this and do what they want.

Indeed, the tricky part is when you combine e.g. JDBC and JTA transactions: if you're not careful then the JDBC will still use its own,"separate" local (non-XA) transaction. That is the case for non-XA-compliant drivers. The effect is that when the application server calls rollback() then this will not be done properly. Simply because the application server is unable to rollback your "local, non-XA" transactions. This is not what you want and that's why the application server warns you.

XA and weblogic

X/Open Distributed Transaction Processing (DTP) XA interface

TPMs: (Transaction Processing Monitors): Tuxedo, CICS, NCR TopEnd, UniKix

Posted at 10:31 PM

MQ For Dummies

Quick summary of MQ Series (now known as Websphere MQ 5.3).

Messages, Queues: Self explanatory.

Types of queues: Predefined queues: Setup by admin, live past reboots
Dynamic queues: created programatically based on template queue definitions (using mqsc DEFINE QMODEL).

(attributes such as number of messages, etc).

object types are: queuemanagers, queues, process definitions, channels, namelists, authentication information objects.

Talk to MQ Using:
MQAI - MQ Admin Interface
PCF - Programmable Command Format
MQSC - Commands from the keyboard
MQAI - COM interface
ADSI interface

Process Definition - defines the process that is started in response to a trigger. Some queues can be set up to start a process when a message is posted to the queue

Channels: Abstraction mechanism to hide the details of distributed queueing. This could hide the fact that you are talking over different networks and protocols.

Cluster: A group of queuemanagers set up so that they can communicate with each other without requiring definitons.

Namelist: A list of names for MQ objects

XA compliant transaction managers: IBM TXSeries, BEA Tuxedo. XA compliant databases - two phase commits.

Posted at 10:24 PM

April 20, 2004

Types of MBeans

There are three types of MBeans; standard, dynamic,
and open. Only standard MBeans use reflection. Dynamic MBeans register their
methods, operations, etc.  OpenMBeans are dynamic MBeans but are restricted
to using OpenType objects (which are ArrayType, CompositeType, SimpleType,
or TabularType).  OpenMBeans allow complex objects to be returned to the GUI
without the GUI having to have knowledge of the "real" classes.  Since
OpenMBeans are dynamic MBeans they also do not use reflection but instead
register their methods, operations, etc.  
-- From the web

Types of beans

Intro to JMX

Posted at 09:15 PM

April 18, 2004

Tyranny in Democracies

Under the absolute sway of one man the body was attacked in order to subdue the soul; but the soul escaped the blows which were directed against it and rose proudly superior. Such is not the course adopted by tyranny in democratic republics; there the body is left free, and the soul is enslaved. The master no longer says: 'You shall think as I do or you shall die'; but he says: 'You are free to think differently from me and to retain your life, your property, and all that you possess; but you are henceforth a stranger among your people.'

Alexis de Tocqueville
--Democracy in America

Posted at 01:52 PM

Private Civilization

Civilization is the progress toward a society of privacy. The savage's whole existence is public, ruled by the laws of his tribe. Civilization is the process of setting man free from men.

Ayn Rand
--The Fountainhead

Posted at 01:50 PM

April 11, 2004

The Inner Ring

The Inner Ring, by C.S. Lewis

C.S. Lewis contends that people are not in fact driven by sexual impulses as they are by the desire to be part of a clique. This 'desire' is self propogating. Once an inner ring has been breached it no longer holds as a special place in your mind and you now seek another inner ring. Perhaps, the real problem is desire. Even if people were not involved (say climbing a tall mountain), it is desire that pushes you to the next big 'thing' (or mountain). If you gave up desire, then you would be content in the present.

Posted at 08:32 PM

Existentialist Happiness

The struggle itself towards the heights is enough to fill a human heart. One must imagine that Sisyphus is happy.

Albert Camus
--The Myth of Sisyphus

Posted at 06:47 PM


Hence, it will be found that the fundamental fault of the female character is that it has no sense of justice. This is mainly due to the fact, already mentioned, that women are defective in the power of reasoning and deliberation; but it is also traceable to the position which Nature has assigned to them as the weaker sex. They are dependent not upon strength, but upon craft, and hence their instinctive capacity for cunning, and their incredible tendency to say what is not true.

Arthur Schopenhauer
--Gedanken uber vielerlei Gegenstande

Posted at 06:45 PM

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