An Implementation Of Applying Integration Tier On J2EE Platform

These years, as the technology of database is developing drastically, besides of the traditional relation databases, some new types of databases such as XML database and object database are used in enterprises. On the other hand, as enterprises are continually developing by consolidation and regrouping, the new enterprises have to use the databases of the old enterprises, but these databases may not be the same in type. How to use and manage these different databases is the problem we have to face to. The paper puts forward a model to access and manage these different databases transparently. This model shields the differences among these database, and returns the DataObjects and TransferObjects uniformly. The software architecture is focused on what components should be used to set up software system and the relationships between these modules. This article analyzes the evolution of software architecture and points out both merits and demerits of them. It emphatically analyzes the popular multi-layer software architecture and B/S architecture. Then it explains the J2EE standard used in developing enterprise level application system based on multi-layer software architecture and related technology contained in it, then illuminates the layers in J2EE and the design patterns in every layer. This paper analyses the DAO pattern among these patterns and two implements of this pattern. Then in order to resolve our problem and according the actual context of web this paper puts forward the DDAO model, which means disconnected DAO. Then the frame and principle of the DDAO model is explained, contrasting to the EII. Following that, this paper analyses the function of the mediators, which are important modules in the DDAO model. The mediators draw data out of data sources and produce the TransferObjects, the changes the data sources according the changed DataObjects. This paper explains the mechanism of mediators using the RDB Mediator and XML Mediator. Then the paper analyses how to design some important Java APIs in DDAO model. The APIs are the interfaces of DataObject, Sequence, TransferObject, ChangeSummary, Type and Property. DataObject is an interface to access to business data of all the common types. Sequences are used when dealing with semi-structured business data. The TransferObject consists of a single root DataObject along with all the DataObjects that can be reached by recursively traversing the containment references of the root DataObject. The ChangeSummary provides access to change history information for the DataObjects in a TransferObject. The Type interface represents a common view of a data type. The Property is the Attribute of DataObject. At last this paper demonstrates how to use the DDAO model by an example.