Web Services Wrappers

Virtual DataPort supports the creation of wrappers for SOAP Web services. Through the data contained in a WSDL of a Web service (which was indicated when creating the Web service data source), the wrapper selects a specific operation to be modeled as a base view, defines how the different parameters required for executing the operation are established and which output data will form part of the wrapper result.

Syntax of the CREATE WRAPPER WS statement
CREATE [ OR REPLACE ] WRAPPER WS <name:identifier>
    [ FOLDER = <literal> ]
    DATASOURCENAME = <name:identifier>
    SERVICENAME = <literal>
    PORTNAME = <literal>
    OPERATIONNAME = <literal>
    [ INPUTMESSAGE = <literal> OUTPUTMESSAGE = <literal> ]
    [ TUPLEROOT = <literal> ]
    [ FROMEXAMPLE ]
    [ OUTPUTSCHEMA ( <field> [, <field> ]* ) ]
    [ SOURCECONFIGURATION ( [ <source configuration property>
                            [, <source configuration property> ]* ] ) ]

<field> ::=
       <name:identifier> = <mapping:literal> [ VALUE <literal> ]
          [ ( { OBL | OPT } ) ]
          [ ( DEFAULTVALUE <literal> ) ]
          [ EXTERN ]
          [ <inline constraints> ]*
     | <name:identifier> = <mapping:literal> : ARRAY OF ( <register field> )
          [ ( DEFAULTVALUE <literal> ) ]
          [ <inline constraints> ]*
     | <name:register field>

<register field> ::=
    <name:identifier> = <mapping:literal> :
       REGISTER OF ( [ <field> [, <field> ]* ] )
          [ ( DEFAULTVALUE <literal> ) ]
          [ <inline constraints> ]*
<inline constraint> ::=
     [ NOT ] NULL
   | [ NOT ] UPDATEABLE
   | { SORTABLE [ ASC | DESC ] | NOT SORTABLE }

<source configuration property> ::=
      DATAINORDERFIELDSLIST = { DEFAULT | ( <name:identifier> { ASC | DESC }
                                      [, <name:identifier> { ASC | DESC } ]* ) }
    | DELEGATEOPERATORSLIST = { DEFAULT | ( <operator:identifier>
                                        [, <operator:identifier> ]* ) }

The modification syntax of a Web service wrapper is similar (see Syntax of the ALTER WRAPPER WS statement).

Syntax of the ALTER WRAPPER WS statement
ALTER WRAPPER WS <name:identifier>
    [ DATASOURCENAME = <name:identifier> ]
    [ SERVICENAME = <name:literal> ]
    [ PORTNAME = <name:literal> ]
    [ OPERATIONNAME = <operation:literal> ]
    [ INPUTMESSAGE = <input:literal> OUTPUTMESSAGE = <output:literal> ]
    [ TUPLEROOT = <literal> ]
    [ OUTPUTSCHEMA ( <field> [, <field> ]* ) ]
    [ SOURCECONFIGURATION ( [ <source configuration property>
    [, <source configuration property> ]* ] ) ]

<field> ::= (see Syntax of the CREATE WRAPPER WS statement)

<source configuration property> ::= (see Syntax of the CREATE WRAPPER WS statement)

  • DATASOURCENAME: Name of the data source used by the wrapper.

    When creating the wrapper, the Server retrieves the WSDL of the Web service. If the WSDL specified by the data source cannot be found, the Server creates the wrapper but marks it as incomplete and the queries to it will fail. Once you execute a query over this wrapper and the Server can retrieve the WSDL, the wrapper is marked as complete and the wrapper will be “queryable”.

  • SERVICENAME: Name of the Web service on which the operation is to be invoked. A WSDL file can contain the definition of various Web services.

  • PORTNAME: Name of the port containing the specific operation.

  • OPERATIONNAME: name of the operation. There may be several different operations with the same name, which are distinguished because of the input/output messages they allow. These are indicated in the following parameters.

  • INPUTMESSAGE: Name of the message that defines the input parameters of the operation of the search method to be modeled (optional).

  • TUPLEROOT: If present, it means that the wrappers will use the “Stream output at the specified level” approach to transform the data returned by the Web service operation. The section XML Sources of the Administration Guide explains how this option works.

  • OUTPUTMESSAGE: Name of the message that defines the output parameters of the operation of the search method to be invoked (optional)

The attributes of the messages of the selected operation define the Web services wrapper schema, i.e. a Web service wrapper has as a schema the input, output and input-output attributes with the names defined in the WSDL file.

Note

Operations can also use compound parameters in the input message. These parameters will be converted to Virtual DataPort compound types (see section Management of Compound Values) in the same way as those of the output message and you may specify conditions on them using the compound value constructors ROW and { } (see section Conditions with Compound Values).

From the list of conditions received the wrapper will create the parameters required to invoke the Web service and obtain the required results.

As with the other wrappers, it is possible to explicitly indicate the output schema of the wrapper (OUTPUTSCHEMA) together with the associations between the external attributes and the parameters of the Web service. The attribute “name” of a field of the OUTPUTSCHEMA indicates the name with which the wrapper will export the element. The “mapping” attribute indicates the name used by the Web service. To reference the different elements of a Web service in the mappings to be made the following notation is used:

  • $<parameterNumber> -> references the parameter of the indicated position of the Web service operation.
  • $$ -> references the output parameter returned through invocation of the Web service operation.

This is the notation used for the elements of the first level (input and output parameters and output of the Web service). For the other elements (fields of a result object or of a Web Service parameter) the mapping is obtained from the name of the property in the corresponding object.

The wrapper creation statement accepts the OR REPLACE modifier. Where specified, if there is already a wrapper with the same name, its definition is replaced by the new one.

Lastly, certain wrapper properties can be specified (SOURCECONFIGURATION). Virtual DataPort takes them into account to determine the operations that can be made on the wrapper. The applicable properties are indicated in the corresponding statement declaration (Syntax of the CREATE WRAPPER WS statement), and are explained in section Wrapper Configuration Properties.