13.28. Web Services Translator

The Web Services translator exposes stored procedures for calling web services.

The Web Services translator is implemented by the org.teiid.translator.ws.WSExecutionFactory class and known by the translator type name ws.

The corresponding resource adapter may optionally be configured to point at a specific WSDL. Results from this translator will commonly be used with the TEXTTABLE or XMLTABLE table functions to use CSV or XML formatted data. See Section 3.6.8, “Nested Tables: TEXTTABLE” and Section 3.6.9, “Nested Tables: XMLTABLE” for more details.

There are no importer settings for this translator, but it does provide metadata for dynamic VDBs. If the connection is configured to point at a specific WSDL, the translator will import all SOAP operations under the specified service and port as procedures.

The WS translator exposes two low level procedures for accessing web services: invoke and invokeHttp.

Invoke allows for multiple binding, or protocol modes, including HTTP, SOAP11, and SOAP12.

Procedure invoke(binding in STRING, action in STRING, request in XML, endpoint in STRING) returns XML

The binding may be one of null (to use the default) HTTP, SOAP11, or SOAP12. Action with a SOAP binding indicates the SOAPAction value. Action with a HTTP binding indicates the HTTP method (GET, POST, etc.), which defaults to POST.

A null value for the binding or endpoint will use the default value. The default endpoint is specified in the WS resource adapter configuration. The endpoint URL may be absolute or relative. If it is relative then it will be combined with the default endpoint.

Since multiple parameters are not required to have values, it is often more clear to call the invoke procedure with named parameter syntax.

call invoke(binding=>'HTTP', action=>'GET')

The request XML should be a valid XML document or root element.

If the stream parameter is set to true, the resulting value document can only be read once. This is appropriate when directly passing the XML into XMLQUERY or XMLTABLE and only a single pass against the document is needed. If stream is null or false, then the engine may need to save a copy of the document for repeated use.

invokeHttp can return the byte contents of an HTTP or HTTPS call.

Procedure invokeHttp(action in STRING, request in OBJECT, endpoint in STRING, contentType out STRING) returns BLOB

Action indicates the HTTP method (GET, POST, etc.), which defaults to POST.

A null value for endpoint will use the default value. The default endpoint is specified in the WS resource adapter configuration. The endpoint URL may be absolute or relative. If it is relative then it will be combined with the default endpoint.

Since multiple parameters are not required to have values, it is often more clear to call the invoke procedure with named parameter syntax.

call invokeHttp(action=>'GET')

The request can be one of SQLXML, STRING, BLOB, or CLOB. The request will be sent as the POST payload in byte form. For STRING/CLOB values this will default to the UTF-8 encoding. Use the TO_BYTES function to control the byte encoding.

The optional headers parameter can be used to specify the request header values as a JSON value. The JSON value should be a JSON object with primitive or list of primitive values.

call invokeHttp(... headers=>jsonObject('application/json' as ContentType, jsonArray('gzip', 'deflate') as "Accept-Encoding"))

The procedures above give you anonymous way to execute any web service methods by supplying an endpoint, with this mechanism you can alter the endpoint defined in WSDL with a different endpoint. However, if you have access to the WSDL, then you can configure the WSDL URL in the web-service resource-adapter's connection configuration, Web Service translator can parse the WSDL and provide the methods under configured port as pre-built procedures as its metadata. If you are using Dynamic VDB's you will see the procedures in your web service's source model.

If the stream parameter is set to true, then the resulting lob value may only be used a single time. If stream is null or false, then the engine may need to save a copy of the result for repeated use. Care must be used as some operations, such as casting or XMLPARSE may perform validation which results in the stream being consumed.

The resource adapter for this translator is a Web Service Data Source.