Migrating WSE 3.0 Web Services to WCF
The benefits of migrating WSE 3.0 Web services to Windows Communication Foundation (WCF) include improved performance and the support of additional transports, additional security scenarios, and WS-* specifications. A Web service that is migrated from WSE 3.0 to WCF can experience up to a 200% to 400% performance improvement. For more information about the transports supported by WCF, see Choosing a Transport. For a list of the scenarios supported by WCF, see Common Security Scenarios. For a list of the specifications that are supported by WCF, see Web Services Protocols Interoperability Guide.
The following sections provide guidance on how to migrate a specific feature of a WSE 3.0 Web service to WCF.
WSE 3.0 and WCF applications include wire-level interoperability and a common set of terminology. WSE 3.0 and WCF applications are wire-level interoperable based on the set of WS-* specifications that they both support. When a WSE 3.0 or WCF application is developed there is a common set of terminology, such as the names of the turnkey security assertions in WSE and the authentication modes.
Although there are many similar aspects between the WCF and ASP.NET or WSE 3.0 programming models, they are different. For details about the WCF programming model, see Basic Programming Lifecycle.
To migrate a WSE Web service to WCF the ServiceModel Metadata Utility Tool (Svcutil.exe) tool can be used to generate a client. That client however contains interfaces and classes that can be used as a starting point for a WCF service too. The interfaces that are generated have the OperationContractAttribute attribute applied to the members of the contract with the ReplyAction property set to
WCF services can use a configuration file to secure a service and that mechanism is similar to a WSE 3.0 policy file. In WSE 3.0 when securing a Web service using a policy file, you use either a turnkey security assertion or a custom policy assertion. The turnkey security assertions map closely to the authentication mode of a WCF security binding element. Not only are the WCF authentication modes and WSE 3.0 turnkey security assertions named the same or similarly, they secure the messages using the same credential types. For instance, the
usernameForCertificate turnkey security assertion in WSE 3.0 maps to the
UsernameForCertificate authentication mode in WCF. The following code examples demonstrate how a minimal policy that uses the
usernameForCertificate turnkey security assertion in WSE 3.0 maps to a
UsernameForCertificate authentication mode in WCF in a custom binding.
<policies> <policy name="MyPolicy"> <usernameForCertificate messageProtectionOrder="SignBeforeEncrypt" requireDeriveKeys="true"/> </policy> </policies>
<customBinding> <binding name="MyBinding"> <security authenticationMode="UserNameForCertificate" messageProtectionOrder="SignBeforeEncrypt" requireDerivedKeys="true"/> </binding> </customBinding>
To migrate the security settings of a WSE 3.0 Web service that are specified in a policy file to WCF, a custom binding must be created in a configuration file and the turnkey security assertion must be set to its equivalent authentication mode. Additionally, the custom binding must be configured to use the August 2004 WS-Addressing specification when WSE 3.0 clients communicate with the service. When the migrated WCF service does not require communication with WSE 3.0 clients and must only maintain security parity, consider using the WCF system-defined bindings with appropriate security settings instead of creating a custom binding.
The following table lists the mapping between a WSE 3.0 policy file and the equivalent custom binding in WCF.
|WSE 3.0 Turnkey Security Assertion||WCF custom binding configuration|
For more information about creating custom bindings in WCF, see Custom Bindings.
Whether WSE 3.0 or WCF is used, the security requirements can be specified in application code instead of in configuration. In WSE 3.0, this is accomplished by creating a class that derives from the
Policy class and then by adding the requirements by calling the
Add method. For more details about specifying the security requirements in code, see How to: Secure a Web Service Without Using a Policy File. In WCF, to specify security requirements in code, create an instance of the BindingElementCollection class and add an instance of a SecurityBindingElement to the BindingElementCollection. The security assertion requirements are set using the static authentication mode helper methods of the SecurityBindingElement class. For more details about specifying security requirements in code using WCF, see How to: Create a Custom Binding Using the SecurityBindingElement and How to: Create a SecurityBindingElement for a Specified Authentication Mode.
In WSE 3.0 there are two types of custom policy assertions: those that secure a SOAP message and those that do not secure a SOAP message. Policy assertions that secure SOAP messages derive from WSE 3.0
SecurityPolicyAssertion class and the conceptual equivalent in WCF is the SecurityBindingElement class.
An important point to note is that the WSE 3.0 turnkey security assertions are a subset of the WCF authentication modes. If you have created a custom policy assertion in WSE 3.0, there may be an equivalent WCF authentication mode. For example, WSE 3.0 does not provide a CertificateOverTransport security assertion that is the equivalent to
UsernameOverTransport turnkey security assertion, but uses an X.509 certificate for client authentication purposes. If you have defined your own custom policy assertion for this scenario, WCF makes the migration straightforward. WCF defines an authentication mode for this scenario, so you can take advantage of the static authentication mode helper methods to configure a WCFSecurityBindingElement.
When there is not a WCF authentication mode that is equivalent to a custom policy assertion that secures SOAP messages, derive a class from TransportSecurityBindingElement, SymmetricSecurityBindingElement or AsymmetricSecurityBindingElementWCF classes and specify the equivalent binding element. For more details, see How to: Create a Custom Binding Using the SecurityBindingElement.
The WCF programming model for creating a custom token is different than WSE 3.0. For details about creating a custom token in WSE, see Creating Custom Security Tokens. For details about creating a custom token in WCF, see How to: Create a Custom Token.
The programming model for creating a custom token manager is different in WCF than WSE 3.0. For details about how to create a custom token manager and the other components that are required for a custom security token, see How to: Create a Custom Token.
If you have created a custom
Like a WSE 3 application, a WCF application can specify the MTOM message encoding in configuration. To migrate this setting, add the <mtomMessageEncoding> to the binding for the service. The following code example demonstrates how MTOM encoding is specified in WSE 3.0 for a service that is equivalent in WCF.
<messaging> <mtom clientMode="On"/> </messaging>
<customBinding> <binding name="MyBinding"> <mtomMessageEncoding/> </binding> </customBinding>
When the WSE Messaging API is used to gain direct access to the XML that is communicated between the client and Web service, the application can be converted to use "Plain Old XML" (POX). For more details about POX, see Interoperability with POX Applications. For more details about the WSE Messaging API, see Sending and Receiving SOAP Messages Using WSE Messaging API.
By default, WSE 3.0 clients and Web services that send SOAP messages using the TCP transport do not interoperate with WCF clients and Web services. This incompatibility is due to differences in the framing used in the TCP protocol and for performance reasons. However, a WCF sample details how to implement a custom TCP session that interoperates with WSE 3.0. For details about this sample, see Transport: WSE 3.0 TCP Interoperability.
To specify that a WCF application uses the TCP transport, use the <netTcpBinding>.
The equivalent of a WSE 3.0 custom transport in WCF is a channel extension. For details about creating a channel extension, see Extending the Channel Layer.