Java Dictionary 
Purpose
The SAP Web Application Server provides varied options for all aspects of application development. Different techniques, such as JDBC, are provided also for the database connection for applications. Central storage for neutral platform definition of data types and database objects is very helpful if you are programming extensive SAP applications. SAP provides this storage area in the form of the Java Dictionary.
The Java Dictionary enables the following:
· Data type descriptions for Web applications can be described centrally, redundancy-free, and independently of the program code.
In standard J2EE programming, there are three layers: presentation layer, business layer, and database layer. Cross-layer, reusable storage of data descriptions is possible.
· You can define platform-independent data types.
The provided type system is based on XML.
· In the Java Dictionary, you can store metadata and services for database objects and user interfaces (Web Dynpro).
The Java Dictionary provides additional data compared to the database catalog of the respective database system being used. Data type definitions for fields, for example, can be given an input help or a field label.
Features
The Java Dictionary supports you when defining elementary types, structures, and database objects (tables and indexes).
Elementary data types and structures are used in the SAP programming model for user interfaces, Web Dynpro. Information from the Java Dictionary can be used in many ways:
· If a type from the Dictionary is assigned to an input field, the Web Dynpro runtime automatically checks whether the values entered match the type.
· If there is a fixed set of values for a type, this value set is proposed to the user in a dropdown list.
· The label texts for input fields and the heading of a table column can be derived, on the basis of the respective language, from the Dictionary information on the field (or column). This is done through the generation of suitable Properties files.
· Structures can be reused in different Web Dynpro contexts.
With Open SQL for Java, SAP offers a persistence framework that ensures automatic portability in all database systems. All tables and indexes that are created in the database must be defined first in the Java Dictionary. The tables defined in the Java Dictionary are accessed using Open SQL/JDBC or Open SQL/SQLJ. For SQLJ, SAP provides additional utilities (SQLJ Editor, Translator, and so on). Type checks that are executed in Open SQL for Java are based on the definitions in the Java Dictionary.
The Java Dictionary provides central storage for all application development levels.
See also: