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Contract

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A service contract carries metadata that defines how a service to handles channel messages.

A WS_SERVICE_CONTRACT carries metadata for a service to handle a WS_MESSAGE.

Diagram showing WS_SERVICE_CONTRACT metadata in a message to a service endpoint.

It has a WS_CONTRACT_DESCRIPTION and a function table. An application can optionally specify WS_SERVICE_MESSAGE_RECEIVE_CALLBACK.

If a WS_CONTRACT_DESCRIPTION and a function table are not given, the application is required to specify WS_SERVICE_MESSAGE_RECEIVE_CALLBACK.

Diagram showing the Add and Subtract service operations in the ICalculator service contract.

static WS_SERVICE_CONTRACT calculatorContract = 
{
    &calculatorContractDescription, 
    NULL, 
    &calculatorFunctions, 
};

See the calculator example for details.

Contract Description

WS_CONTRACT_DESCRIPTION is metadata defining the type-contract of the service. Generated by wsutil.exe.

In terms of WSDL, a WS_CONTRACT_DESCRIPTION maps to a wsdl:portType. For each wsdl:portType in the WSDL document a separate WS_CONTRACT_DESCRIPTION will be generated.

A contract description is made up of one or more service operations. These operations are given as an array of WS_OPERATION_DESCRIPTION.

Diagram showing a WS_CONTRACT_DESCRIPTION as an array of WS_OPERATION_DESCRIPTIONs.

<wsdl:definitions xmlns:soap="https://schemas.xmlsoap.org/wsdl/soap/" 
xmlns:wsu="https://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd" 
xmlns:soapenc="https://schemas.xmlsoap.org/soap/encoding/" xmlns:tns="https://Example.org" 
xmlns:wsa="https://schemas.xmlsoap.org/ws/2004/08/addressing" xmlns:wsp="https://schemas.xmlsoap.org/ws/2004/09/policy" 
xmlns:wsap="https://schemas.xmlsoap.org/ws/2004/08/addressing/policy" xmlns:xsd="https://www.w3.org/2001/XMLSchema" 
xmlns:msc="http://schemas.microsoft.com/ws/2005/12/wsdl/contract" xmlns:wsaw="https://www.w3.org/2006/05/addressing/wsdl" 
xmlns:soap12="https://schemas.xmlsoap.org/wsdl/soap12/" xmlns:wsa10="https://www.w3.org/2005/08/addressing" 
xmlns:wsx="https://schemas.xmlsoap.org/ws/2004/09/mex" targetNamespace="https://Example.org" 
xmlns:wsdl="https://schemas.xmlsoap.org/wsdl/">
 <wsdl:portType name="ICalculator">
  <wsdl:operation name="Add">
   <wsdl:input wsaw:Action="https://Example.org/ICalculator/Add" 
   message="tns:ICalculator_Add_InputMessage" />
   <wsdl:output wsaw:Action="https://Example.org/ICalculator/AddResponse" 
   message="tns:ICalculator_Add_OutputMessage" />
  </wsdl:operation>
 </wsdl:portType>
</wsdl:definitions>

For details of wsdl:portType to WS_CONTRACT_DESCRIPTION conversion, see the WSDL output section.

Example: WS_CONTRACT_DESCRIPTION

static WS_CONTRACT_DESCRIPTION contractDescriptionICalculator =
{
    WsCountOf(serviceOperationsICalculator),
    serviceOperationsICalculator
};

Function Table

Function Table is a struct of function pointers representing each of the service operations in the service contract. The function table definition is also generated by wsutil.exe.

Example: Function Table

 // Function Table
struct CalculatorServiceFunctionTable
{
      AddOperation Add;
      SubtractOperation Subtract;
};

// Populate the Function Table
static const CalculatorServiceFunctionTable calculatorFunctions = {Add, Subtract};

Using the WS_SERVICE_MESSAGE_RECEIVE_CALLBACK

WS_SERVICE_MESSAGE_RECEIVE_CALLBACK has a dual mutually exclusive role.

If a WS_CONTRACT_DESCRIPTION is specified on the WS_SERVICE_CONTRACT, this becomes the default message handler for all the actions which are not supported by the specified WS_CONTRACT_DESCRIPTION. Otherwise, if WS_CONTRACT_DESCRIPTION is not specified on the WS_SERVICE_CONTRACT, and the WS_SERVICE_MESSAGE_RECEIVE_CALLBACK is specified on the WS_SERVICE_CONTRACT all in coming messages are passed to this callback.

For more examples, please see

The following callbacks are part of the contract:

The following structures are part of the contract: