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EclipseLink/Development/DBWS/MetadataGenerationFromDDLMetaModel
Contents
Generating JAXB and JPA Metadata From DDL Parser Meta-model
The EclipseLink DBWS design time component (a.k.a. DBWSBuilder) generates OR and OX projects for use by the runtime component - these project instances are built using DDLParser generated meta-model objects. Since EclipseLink 2.5, DBWS generates and writes out JAXB and JPA metadata (DBWS Metadata Support) based on the OR/OX projects. When considering JAXB/JPA metadata generation consolidation among various components, it would make sense to have the ability to generate metadata directly from the DDLParser generated metamodel, then bootstrap DBWS builder, JPA-RS, etc. from this metadata. This would allow the DDLParser and metadata generation piece proposed here to be standalone components, available to whomever requires this generated metadata.
Basic DDLParser Usage
The DatabaseTypeBuilder
class (part of the DDLParser package) is responsible for generating the required statement to be used to retrieve the DDL from the database, then parsing the returned DDL into the meta-model objects. The type builder can build TableTypes, ProcedureTypes, and PLSQLPackageTypes based on user provided schema(s) and table/procedure/package name(s), and a database connection. The build methods can take a single schema & table/procedure/package name, or lists of each when multiple artifacts are to be parsed.
Table
// use DatabaseTypeBuilder to generate a list of TableTypes DatabaseTypeBuilder dbTypeBuilder = new DatabaseTypeBuilder(); try { List<TableType> dbTables = dbTypeBuilder.buildTables(conn, "SCOTT", "EMPLOYEE_TABLE"); ... } catch (ParseException e) { // handle exception }
Top-level StoredProcedure
// use DatabaseTypeBuilder to generate a list of ProcedureTypes DatabaseTypeBuilder dbTypeBuilder = new DatabaseTypeBuilder(); try { List<ProcedureType> dbProcedures = dbTypeBuilder.buildProcedures(conn, "TOPLEVEL", "GetAllEmployees"); ... } catch (ParseException e) { // handle exception }
Top-level StoredFunction
// use DatabaseTypeBuilder to generate a list of FunctionTypes DatabaseTypeBuilder dbTypeBuilder = new DatabaseTypeBuilder(); try { List<FunctionType> dbFunctions = dbTypeBuilder.buildFunctions(conn, "TOPLEVEL", "GetEmployeeById"); ... } catch (ParseException e) { // handle exception }
PL/SQL Stored Functions/Procedures
Retrieving meta-model instances for PL/SQL procedures and functions involves retrieving the PL/SQL package meta-model, then getting the procedure and/or function objects from it.
// add desired PL/SQL stored function/procedure names List<String> procedurePatterns = new ArrayList<String>(); // PL/SQL stored procedures procedurePatterns.add("COPYTABLE"); procedurePatterns.add("COPYPHONECOLLECTION"); // PL/SQL stored functions procedurePatterns.add("CREATETABLE"); procedurePatterns.add("GETALLTABLES"); // use DatabaseTypeBuilder to generate a list of PLSQLPackageTypes DatabaseTypeBuilder dbTypeBuilder = new DatabaseTypeBuilder(); try { List<ProcedureType> dbProcedures = new ArrayList<ProcedureType>(); // process the package List<PLSQLPackageType> packages = dbTypeBuilder.buildPackages(conn, "SCOTT", "PACKAGE2"); for (PLSQLPackageType pkgType : packages) { // now get the desired procedures/functions from the processed package for (ProcedureType procType : pkgType.getProcedures()) { if (procedurePatterns.contains(procType.getProcedureName())) { dbProcedures.add(procType); } } } ... } catch (ParseException e) { // handle exception }
Multiple PL/SQL Packages
// schema names List<String> schemaNames = new ArrayList<String>(); schemaNames.add("HR"); schemaNames.add("SCOTT"); schemaNames.add("SCOTT"); // package names List<String> packageNames = new ArrayList<String>(); packageNames.add("HR_DATA"); packageNames.add("MATH_FUNCTIONS"); packageNames.add("EMPLOYEE"); // procedure names List<String> procedurePatterns= new ArrayList<String>(); procedurePatterns.add("findAllEmployees"); procedurePatterns.add("findEmployeeByPK"); procedurePatterns.add("getPersonalData"); procedurePatterns.add("removeEmployee"); procedurePatterns.add("calculateMaxAngle"); // use DatabaseTypeBuilder to generate a list of PLSQLPackageTypes DatabaseTypeBuilder dbTypeBuilder = new DatabaseTypeBuilder(); try { // process the packages List<PLSQLPackageType> packages = dbTypeBuilder.buildPackages(conn, schemaNames, packageNames); for (PLSQLPackageType pkgType : packages) { // now get the desired procedures/functions from the processed package for (ProcedureType procType : pkgType.getProcedures()) { if (procedurePatterns.contains(procType.getProcedureName())) { dbProcedures.add(procType); } } } ... } catch (ParseException e) { // handle exception }
JPA Metadata Generation
The EclipseLink JPA meta-model will be utilized to generate the JPA metadata. The proposed JPAMetadataGenerator
class will be responsible for building an instance of org.eclipse.persistence.internal.jpa.metadata.xml.XMLEntityMappings
. The entity mapping writer class (org.eclipse.persistence.internal.jpa.metadata.xml.XMLEntityMappingsWriter
) will then be used to marshal the generated metadata.
JAXB Metadata Generation
- TBD
Open Issues
- What should the default package name for generated Entities (or anything not in a PL/SQL package) be? Ideally the user would be permitted to set this on the generator.
- Query names - what would be the default name for a query generated from a stored procedure, etc.? Perhaps the user could provide a Map of query names > procedure names. Currently, the query name is the stored proc/function name.
- For non-Oracle databases, JDBCHelper returns meta-model objects that extend the DDLParser meta-model - should this functionality be taken into consideration here as well?
- Automatic CRUD operation generation for tables; by default, DBWS generates CRUD query operations for a given database table - is this something we should include by default? Perhaps it could be configurable.