Saturday, April 23, 2005
J2EE, 2PC and XA
Excellent blog on transaction management in J2EE world - a wonderful article on 2PC, XA and the implemention of transaction log - key to transaction management.
Mike Spille Blog on XA.
Mike Spille Blog on XA.
Saturday, April 09, 2005
Default Isolation Levels for Various Databases
SQL SERVER - READ COMMITTED
Sybase - READ COMMITTED
Oracle - READ COMMITTED (supports only READ COMMITTED, SERIALIZABLE and the non-standard READ ONLY)
DB2 - REPEATABLE READ (supports REPEATABLE READ, UNCOMMITTED READ and 2 non-standard levels)
PostgreSQL - REPEATABLE READ (only supports REPEATABLE READ and SERIALIZABLE)
Mysql InnoDB - REPEATABLE READ
Sybase - READ COMMITTED
Oracle - READ COMMITTED (supports only READ COMMITTED, SERIALIZABLE and the non-standard READ ONLY)
DB2 - REPEATABLE READ (supports REPEATABLE READ, UNCOMMITTED READ and 2 non-standard levels)
PostgreSQL - REPEATABLE READ (only supports REPEATABLE READ and SERIALIZABLE)
Mysql InnoDB - REPEATABLE READ
Caching in Service Locator Can Be Harmful
J2EE 1.3 introduced the concept of resource references. Resource references are helpful in breaking down coupling between systems but it also introduced an unintended problem when cached via Service Locator pattern. See this article for reasons why? From the article's introduction - "This article shows how implementations of the Service Locator pattern that include a resource cache can cause code to run incorrectly in J2EE 1.3 and later versions. While the Service Locator pattern itself is still useful, this article will show how caching with this pattern is harmful rather than helpful, why it should be eliminated from service locator implementations, and offer some practical alternatives."
