ADF BC: Making Your Application Module Activation-Safe
By Sandra Muller on Sep 19, 2006
In our project we found out that a certain error only occurred in the
deployment environment, and then only sometimes. Those are the worst
problems to solve! The error message was:
JBO-30003: The application pool (...name...) failed to checkout an application module due to the following exception:
oracle.jbo.JboException: JBO-29000: JBO-25000: Unknown SQL type: null.
After debugging, googling, and metalinking, we found that the error was
related to the State Management mechanism of ADF Business
Components. The error only occurred when on certain pages an Application Module instance's state
had to be passivated to the database, and later activated again.
Steve Muench gave us a great tip: you can enforce this Application
Module (AM) passivation and activation in your development environment
by temporarily setting a configuration parameter. See section 28.8, "Testing to Ensure Your Application Module is Activation-Safe" of the ADF Developer's Guide.
This enabled us to reproduce the error in JDeveloper, and to verify that the patch for bug 5191597 you can download from MetaLink did indeed solve the problem!