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Difference between revisions of "EclipseLink/Development/DBWS/ParseDDLDS"
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For Oracle databases, <tt>DBWSBuilder</tt> uses a modified cut-down version of the JPublisher classes to send SQL queries to Data Dictionary views (<tt>ALL_OBJECTS</tt>, <tt>ALL_ARGUMENTS</tt>, etc.) that is then converted to an in-memory object-graph of all relevant information about the specific database artifact required for the Web Service. This object-graph is then ''walked'' and the required DBWS runtime artifacts generated. | For Oracle databases, <tt>DBWSBuilder</tt> uses a modified cut-down version of the JPublisher classes to send SQL queries to Data Dictionary views (<tt>ALL_OBJECTS</tt>, <tt>ALL_ARGUMENTS</tt>, etc.) that is then converted to an in-memory object-graph of all relevant information about the specific database artifact required for the Web Service. This object-graph is then ''walked'' and the required DBWS runtime artifacts generated. | ||
| − | Unfortunately, the information in the Data Dictionary views can be (under certain circumstances) incomplete or inaccurate, or the in-memory object-graph constructed from the views can be distorted. | + | Unfortunately, the information in the Data Dictionary views can be (under certain circumstances) incomplete or inaccurate, or the in-memory object-graph constructed from the views can be distorted. For example, the arguments to a StoredProcedure may have a default thus making it optional. This in turn means that the calling sequence can change: |
| + | <source lang="sql"> | ||
| + | CREATE OR REPLACE PACKAGE SOMEPKG AS | ||
| + | |||
| + | TYPE EMP_REC IS RECORD( | ||
| + | EMPNO EMP.EMPNO%TYPE, | ||
| + | FNAME EMP.FNAME%TYPE, | ||
| + | LNAME EMP.LNAME%TYPE | ||
| + | ); | ||
| + | |||
| + | PROCEDURE DOSOMETHING(MYREC IN OUT EMP_REC, STUFF IN VARCHAR2, | ||
| + | P_EMPNO IN NUMBER := 20, FLAG IN BOOLEAN default FALSE, | ||
| + | WHATEVER IN VARCHAR2 default 'bogus'); | ||
| + | END; | ||
| + | </source> | ||
Revision as of 16:25, 31 May 2011
Parsing DDL for Metadata
The primary job of the DBWSBuilder utility is to extract metadata from the database about some artifact (i.e. a Table or a StoredProcedure) that is to be used as the basis of a (JAX-WS compliant) Web Service. The DBWSBuilder translates the information (fields, arguments, scalar or complex datatypes, etc.) into DBWS runtime artifacts (e.g. EclipseLink Project XML files, JAX-WS Provider class, etc.) Thus it is crucial that DBWSBuilder get complete and accurate metadata from the database.
For Oracle databases, DBWSBuilder uses a modified cut-down version of the JPublisher classes to send SQL queries to Data Dictionary views (ALL_OBJECTS, ALL_ARGUMENTS, etc.) that is then converted to an in-memory object-graph of all relevant information about the specific database artifact required for the Web Service. This object-graph is then walked and the required DBWS runtime artifacts generated.
Unfortunately, the information in the Data Dictionary views can be (under certain circumstances) incomplete or inaccurate, or the in-memory object-graph constructed from the views can be distorted. For example, the arguments to a StoredProcedure may have a default thus making it optional. This in turn means that the calling sequence can change:
CREATE OR REPLACE PACKAGE SOMEPKG AS TYPE EMP_REC IS RECORD( EMPNO EMP.EMPNO%TYPE, FNAME EMP.FNAME%TYPE, LNAME EMP.LNAME%TYPE ); PROCEDURE DOSOMETHING(MYREC IN OUT EMP_REC, STUFF IN VARCHAR2, P_EMPNO IN NUMBER := 20, FLAG IN BOOLEAN DEFAULT FALSE, WHATEVER IN VARCHAR2 DEFAULT 'bogus'); END;