The DADX wizard supports the creation of a DADX file from a combination
of one or more SQL statements, stored procedures, and DAD files. A DADX file
is an XML file that is used to create a Web service that accesses a relational
database. The DADX File wizard creates a DADX file in a DADX group of a Web
Project.
Prerequisites:
- Before creating a DADX file you need to create a DADX group as described
in: Create a DADX group configuration.
- Your SQL statement or stored procedure must exist in the Workbench for
you to be able to complete the DADX wizard. For more information on creating
SQL statements or stored procedures, refer to the related tasks such as Working
with SQL statements.
- If you are generating a DADX file from an SQL statement that contains
parameters, the parameters must be in simple column expressions in order for
a parameter type to be properly generated in the DADX file. If you have parameters
in complex column expressions (for example, in a function) you have to add
them manually to the generated DADX code yourself. This is a known problem.
A Document Access Definition (DAD) file is a user-specified file
that provides control over the mapping of XML document elements to DB2
® database columns
for storage and retrieval. The DADX wizard supports only Xcollection DAD.
The types of mappings and operations supported by the DADX wizard are as follows:
- SQL statement operations (query and update operations based on SQL statements
are supported)
- RDB_node mapping (storeXML and retrieveXML operations based on DAD file
mappings are supported).
- Stored procedure calls
If the DAD file that you select defines a SQL statement (SQL_stmt)
mapping, you may need to customize the SQL_override information to specify
the parameters you want to override from the SQL host variables. See the http://publib.boulder.ibm.com/infocenter/db2help/index.jsp and
look under Developing > Database Applications > Web services and Federated
Web Applications for more information.
To generate a DADX file:
- Click .
- In the New window, expand the Web Services node,
click DADX File, and then click Next.
- On the DADX Generation page:
- Select the Web project and DADX group for the output location
of the DADX file. For your Web service to function properly, you
must create your DADX file in your DADX group. If necessary, you can generate
it elsewhere without using the wizard and move it to your DADX group later;
however, we recommend that you place it in your DADX group when you first
generate it.
- Enter a name for the new DADX file and optionally a description.
- Select to create the DADX file using Dynamic Query Services
or from a list of SQL queries or stored procedures.
- If you select to use the Dynamic Query Service click Finish.
A DADX file with the <DQS/> operation tag is generated.
- If you select to create a file from a list of SQL queries or stored procedures
click Next.
- Select the SQL statements and stored procedures to include in the
DADX file. You can select only SQL statements, only stored procedures,
or both SQL statements and stored procedures. The SQL statement or stored
procedure must exist in the Workbench. Click Next or Finish.
- (Optional) Use this page to select one or more DAD files to include
in your DADX file:
- To import a DAD file from your file system, click Import
Files.
- In the Workbench Files list, click a
DAD file, and then click >. Repeat this
step to add more DAD files.
- To remove one or more DAD files from the Selected
Files list, click the < or << button.
- After you have added all of the DAD files required to the list, Selected
Files, click Next
Note: You must create or import your DADX files into your DADX group:
WebProject\JavaSource\groups\DADXGroup. Any relevant DAD files
also need to be in this folder. At runtime, this is where these files are
expected to be located. If this is not true, you may experience database or
server errors.
- (Optional) Modify or add text to the Operation or Description fields
by selecting the row, then selecting the cell that you want to modify. Type
your changes, and then press Enter. The Operation field
provides a name for the name attribute of the operation tag in the generated
DADX file and the Description field provides a description
text for the document tag. Click Finish.
The DADX file is generated and opens in the XML editor where you
can edit it, as necessary. If you selected to use Dynamic Query Service a db2WebRowSet.xsd file
is copied to the WebContent directory.
Note: For DADX files based on
stored procedures, result set metadata is generated for the DADX and used
in the call element. Only stored procedures that have result sets with fixed
metadata can be invoked from a DADX in order to have a well-defined WSDL file
for the Web service.
A <result_set_metadata> element is generated
in the DADX for each result set returned by the stored procedure. This is
true even if they share the same metadata characteristics. You can modify
the generated code to use a single <result_set_metadata> tag if you want.
If you modify the metadata name where the metadata is used in a <result_set>
child element of a <call> element, make sure that you modify its name in
the corresponding <result_set_metadata> definition.
Once you have created the DADX file, you can create a Web service
as described in: Create a DADX Web
service.
For additional information about DADX files, refer to
the DB2 information center (an online version can be found here: http://publib.boulder.ibm.com/infocenter/db2luw/v9//index.jsp),
under Developing > Database applications > Web services and federated Web
applications > Creating a Web services provider from a database.