Tutorials : J2EE Activity Service for Extended Transactions :

J2EE Activity Service for Extended Transactions

by: Benoy Jose

Introduction:

Today’s businesses are getting increasingly complex and sophisticated and their demands are increasing in a proportional manner. The solutions of the present day and the systems used to support them also need to improve to cater to the growing demand. Transactional systems have made great improvements from the non-interactive flat files to dynamic databases that can do real time processing. Still as the industry expands they demand transactional qualities that can be foolproof, persistent and atomic. Added to these requirements which are supported by most database systems, the need to span the scope of the transaction for a longer period of time. This might sound easy if we are working with a single non-dependent database. But the problem compounds when businesses need to do transactions spanning disparate systems across multiple businesses. Businesses would love to integrate with other businesses and reduce costs and improve efficiency but they would not want to do so at the expense of locking and slowing down their own systems. There lies the challenge to create transactional systems that don’t lock resources down while they satisfy the need of the businesses to interact with each other.

JTS (Java transaction Service), JTA (Java transaction API) already exists in the industry to take care of the independent transactions. They provide all the flexibility and robustness required by smaller transactions that are tightly coupled to a particular system. There is no high level API or a common specification which caters to providing loosely coupled, isolated transactions like the cruise scenario described above. The J2EE activity service provides a framework to address the shortcomings of the traditional transaction systems.

The J2EE Activity service provides a middleware framework to support the implementation of extended transaction models. It is a generic framework which allows different extended transaction models to be built on top of it. The J2EE Activity service provides an extended unit of work (UOW) that either groups a related set of tasks with no transactional attributes or groups them into a number of short duration transactions. The advantage of grouping tasks into short lived transactions within a longer activity is that the transaction as a whole does not lock up the other resources, used by individual sub transactions, and slow down the system. A typical problem with extended UOW models is that the failure scenarios may be quite complex, potentially involving the compensation of some or all of the smaller transactions that were committed before a long-running activity failed. The responsibility for providing the appropriate recovery from such a failure may be shared between the application itself, which is the component that understands what needs to be compensated, and the extended unit of work service provider, which might provide facilities to register compensating actions.

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