VO (value object) value of the object
is typically used to transfer data between the service layers, create a new keyword, recovered from the GC, and PO are as it only contains data. But it should be an abstract of a business object, and the table may correspond to, or may not, which based on business needs. Individual transfer the same feel as the DTO (data transfer objects) on the web.
PO (persistant object) persistent object
The concept appeared at the time o / r mapping, if not o / r mapping, no such concept exists. Generally corresponding to the data model (database), the processing section itself, there are business logic. It can be seen as java objects in the database appearances map. The simplest one PO is a corresponding database records in a table, the plurality of recording may be set PO. PO should not contain any database operation.
TO (Transfer Object) data transfer object
Object transfer between different TIE (relationship) application used for data communication
BO (business object) Business Objects
From a business point of view the model, see UML element domain object in the domain model. Encapsulate business logic java object by calling DAO methods, combined PO, VO business operations. The main role is to encapsulate business logic for an object. This object can comprise one or more other objects. For example, a curriculum vitae, educational experience, work experience, social relations, and so on. We can put educational experience corresponds to a PO, work experience corresponds to a PO, social relations corresponding to a PO. Establishing a resume process corresponding to the object BO resume, each of these comprising BO PO. In this way the business logic processing, we will be able to deal with for BO.
QO (Query object) query object
General Assembly for query parameters
POJO (plain ordinary java object) simple random java object
If some of the bean class that simple, or just as middleware, it can be classified as pojo
DAO (data access object) data access object
is a standard j2ee a design pattern of the sun, this mode is the DAO has interfaces, which operation lasting negative layer. It provides an interface for the business layer. This object is used to access the database. PO usually used in combination, DAO contains a method for operating the various databases. By its methods, PO binding to the database related operations. Caught in the middle of the business logic and database resources. With VO, providing database CRUD operations ...
DTO (Data Transfer Object) data transfer object
Mainly used for local transport objects requires a lot of long-distance calls and so on. For example, we have 100 fields in a table, then the corresponding PO have 100 properties. However, we only show the interface 10 fields, with the WEB service client to retrieve the data, there is no need to pass the entire client objects PO, then we can pass the results to the client 10 with the only attribute DTO, this also does not expose the server table structure. Upon arrival the client, if this object to the corresponding screen display, that at this time it's turned on the identity of VO