Web Client Function and Procedure Requirements and Recommendations

Web service client procedures and functions require the definition of a URL clause to identify the web service endpoint. A web service client procedure or function has specialized clauses for configuration but is used like any other stored procedure or function in every other respect.

You can use the CREATE PROCEDURE and CREATE FUNCTION statements to create web client functions and procedures to send SOAP or HTTP requests to a web server.

The following list outlines the requirements and recommendations for creating or altering web client functions and procedures. You can specify the following information when creating or altering a web client function or procedure:

• The URL clause, which requires an absolute URL specifying the web service endpoint. (Required)

• The TYPE clause to specify whether the request is HTTP or SOAP over HTTP. (Recommended)

• Ports that are accessible to the client application. (Optional)

• The HEADER clause to specify HTTP request headers. (Optional)

• The SOAPHEADER clause to specify SOAP header criteria within the SOAP request envelope. (Optional. For SOAP requests only)

• The namespace URI. (For SOAP requests only)

• Web Client URL Clause
  You must specify the location of the web service endpoint to make it accessible to your web client function or procedure. The URL clause of the CREATE PROCEDURE and CREATE FUNCTION statements provides the web service URL that you want to access.
• Web Service Request Types
  You can specify the type of client requests to send to the web server when creating a web client function or procedure. The TYPE clause of the CREATE PROCEDURE and CREATE FUNCTION statements formats requests before sending them to the web server.
• Web Client Ports
  It is sometimes necessary to indicate which ports to use when opening a server connection through a firewall. You can use the CLIENTPORT clause of the CREATE PROCEDURE and CREATE FUNCTION statements to designate port numbers on which the client application communicates using TCP/IP. It is recommended that you not use this feature unless your firewall restricts access to a particular range of ports.
• HTTP Request Header Management
  HTTP request headers can be added, changed, or removed with the HEADER clause of the CREATE PROCEDURE and CREATE FUNCTION statements. You suppress an HTTP request header by referencing the name. You add or change an HTTP request header value by placing a colon after the header name following by the value. Header value specifications are optional.
• SOAP Request Header Management
  A SOAP request header is an XML fragment within a SOAP envelope. While the SOAP operation and its parameters can be thought of as an RPC (Remote Procedure Call), a SOAP request header can be used to transfer meta information within a specific request or response. SOAP request headers transport application metadata such as authorization or session criteria.
• SOAP Namespace URI Requirement
  The namespace URI specifies the XML namespace used to compose the SOAP request envelope for the given SOAP operation. The domain component from URL clause is used when the namespace URI is not defined.
• Web Client SQL Statements
  The following SQL statements are available to assist with web client development: