How to Access Client-Supplied SOAP Request Headers

Headers in SOAP requests can be obtained using a combination of the NEXT_SOAP_HEADER and SOAP_HEADER functions.

The NEXT_SOAP_HEADER function iterates through the SOAP headers included within a SOAP request envelope and returns the next SOAP header name. Calling it with NULL causes it to return the name of the first header. Subsequent headers are retrieved by passing the name of the previous header to the NEXT_SOAP_HEADER function. This function returns NULL when called with the name of the last header.

The following example illustrates the SOAP header retrieval:

SET hd_key = NEXT_SOAP_HEADER( hd_key );
    IF hd_key IS NULL THEN
      -- no more header entries
      LEAVE header_loop;
    END IF;

Calling this function repeatedly returns all the header fields exactly once, but not necessarily in the order they appear in the SOAP request.

The SOAP_HEADER function returns the value of the named SOAP header field, or NULL if not called from an SOAP service. It is used when processing an SOAP request via a web service. If a header for the given field-name does not exist, the return value is NULL.

The example searches for a SOAP header named Authentication. When it finds this header, it extracts the value for entire SOAP header and the values of the @namespace and mustUnderstand attributes. The SOAP header value might look something like this XML string:

<Authentication xmlns="CustomerOrderURN" mustUnderstand="1">
  <userName pwd="none">
    <first>John</first>
    <last>Smith</last>
  </userName>
</Authentication>

For this header, the @namespace attribute value would be CustomerOrderURN

Also, the mustUnderstand attribute value would be 1

The interior of this XML string is parsed with the OPENXML function using an XPath string set to /*:Authentication/*:userName.

SELECT * FROM OPENXML( hd_entry, xpath )
    WITH ( pwd LONG VARCHAR '@*:pwd',
        first_name LONG VARCHAR '*:first/text()',
        last_name LONG VARCHAR '*:last/text()' );

Using the sample SOAP header value shown above, the SELECT statement would create a result set as follows:

pwd	first_name	last_name
none	John	Smith

A cursor is declared on this result set and the three column values are fetched into three variables. At this point, you have all the information of interest that was passed to the web service.

Example

The following example illustrates how a web server can process SOAP requests containing parameters, and SOAP headers. The example implements an addItem SOAP operation that takes two parameters: amount of type int and item of type string. The sp_addItems procedure processes an Authentication SOAP header extracting the first and last name of the user. The values are used to populate a SOAP response Validation header via the sa_set_soap_header system procedure. The response is a result of three columns: quantity, item and status with types INT, LONG VARCHAR and LONG VARCHAR respectively.

// create the SOAP service
CREATE SERVICE addItems
    TYPE 'SOAP'
    FORMAT 'CONCRETE'
    AUTHORIZATION OFF
    USER DBA
    AS CALL sp_addItems( :amount, :item );

// create SOAP endpoint for related services
CREATE SERVICE itemStore
    TYPE 'DISH'
    AUTHORIZATION OFF
    USER DBA;

// create the procedure that will process the SOAP requests for the addItems service
CREATE PROCEDURE sp_addItems(count INT, item LONG VARCHAR)
RESULT(quantity INT, item LONG VARCHAR, status LONG VARCHAR)
BEGIN
    DECLARE hd_key LONG VARCHAR;
    DECLARE hd_entry LONG VARCHAR;
    DECLARE pwd LONG VARCHAR;
    DECLARE first_name LONG VARCHAR;
    DECLARE last_name LONG VARCHAR;
    DECLARE xpath LONG VARCHAR;
    DECLARE authinfo LONG VARCHAR;
    DECLARE namespace LONG VARCHAR;
    DECLARE mustUnderstand LONG VARCHAR;
 
  header_loop:
    LOOP
        SET hd_key = next_soap_header( hd_key );
        IF hd_key IS NULL THEN
            // no more header entries.
            leave header_loop;
        END IF;
        IF hd_key = 'Authentication' THEN
            SET hd_entry = soap_header( hd_key );
            SET xpath = '/*:' || hd_key || '/*:userName';
            SET namespace = soap_header( hd_key, 1, '@namespace' );
            SET mustUnderstand = soap_header( hd_key, 1, 'mustUnderstand' );
            BEGIN
                // parse for the pieces that you are interested in
                DECLARE crsr CURSOR FOR SELECT * FROM
                    OPENXML( hd_entry, xpath )
                        WITH ( pwd LONG VARCHAR '@*:pwd',
                               first_name LONG VARCHAR '*:first/text()',
                               last_name LONG VARCHAR '*:last/text()');
                OPEN crsr;
                FETCH crsr INTO pwd, first_name, last_name;
                CLOSE crsr;
            END;
            // build a response header, based on the pieces from the request header
            SET authinfo = XMLELEMENT( 'Validation',
                XMLATTRIBUTES(
                    namespace as xmlns,
                    mustUnderstand as mustUnderstand ),
                    XMLELEMENT( 'first', first_name ),
                    XMLELEMENT( 'last', last_name ) );
            CALL sa_set_soap_header( 'authinfo', authinfo);
        END IF;
    END LOOP header_loop;
    //  code to validate user/session and check item goes here...
    SELECT count, item, 'available';
END;