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Example: Read-read consistency checking

Read-read consistency checking only applies to LifeTimeInCache beans whose data is read from another transaction.


Usage scenario

For the access intents that are for repeatable read (RR), this means the product checks that the data is consistent with that in the data store and ensures that no one updates it after the checking. For the Access Intents that are for read committed (RC), this means the product checks that the data is consistent at the point of checking, but it does not guarantee that the data does not change after the checking. This makes the behavior of the LifeTimeInCache bean the same as non-LifeTimeInCache beans.

We have three options for setting consistency checking, as shown in the following scenarios concerning the calculation of interest in "Ann's" bank account. In each case, the data store is shared by this EJB container managed persistence (CMP) application to calculate the interest and other applications, such as EJB bean managed persistence (BMP), JDBC, or legacy applications. Also in each case, the EJB account is configured as a long-lifetime bean.


NONE


Read-read checking AT_TRAN_BEGIN


Read-read checking AT_TRAN_END


Related:

  • Enterprise beans
  • Concurrency control
  • Developing applications that use JNDI
  • WebSphere extensions to the Enterprise JavaBeans specification
  • Enterprise bean development best practices