Tuesday, November 22, 2011

Apache CXF STS documentation - part XII

A previous blog post detailed the AbstractOperation class that provides some core functionality for the STS operations, such as parsing the client request into a format that the TokenProviders/TokenValidators/TokenCancellers can consume. In this, the final post of this series of articles on the Apache CXF STS, we will examine an extension of AbstractOperation that is used to cancel tokens. Finally, we will look at the STS sample that ships with the CXF 2.5.x distribution.

1) The TokenCancelOperation

TokenCancelOperation is used to cancel tokens in the STS. It implements the CancelOperation interface in the STS provider framework. In addition to the properties that it inherits from AbstractOperation (detailed previously), it has a single property that can be configured:

  • List<TokenCanceller> tokencancellers - A list of TokenCanceller implementations to use to cancel tokens.

Recall that AbstractOperation uses the RequestParser to parse a client request into TokenRequirements and KeyRequirements objects. TokenCancelOperation first checks that a "CancelTarget" token was received and successfully parsed (if so it will be stored in the TokenRequirements object). If no token was received then an exception is thrown.

TokenCancelOperation then populates a TokenCancellerParameters object with values extracted from the TokenRequirements and KeyRequirements objects. It iterates through the list of defined TokenCanceller implementations to see if any "can handle" the received token. If no TokenCanceller is defined, or if no TokenCanceller can handle the received token, then an exception is thrown. Otherwise, the received token is cancelled. If there is an error in cancelling the token, then an exception is also thrown. A response is constructed with the context attribute (if applicable), and the cancelled token type.

2) The STS sample in Apache CXF

Finally, we'll take a brief look at the STS sample that ships with Apache CXF. Download and extract the Apache CXF 2.5.x distribution. Navigate into "samples/sts" and take a look at the README.txt. The service provider has a policy that requires a SAML 2.0 token issued by an STS. The client authenticates itself to the STS with a UsernameToken over the symmetric binding. The STS issues a SAML 2.0 token to the client, which sends it to the service. The IssuedToken is defined as an InitiatorToken of an Asymmetric binding in the policy of the service, and so the client will use the secret key associated with the Subject of the Assertion to sign various parts of the message.

Build the sample with "mvn install", and then open up three separate command prompts. Start the STS with "mvn -Psts" in one, and start the service with "mvn -Pserver" in another. Finally, start the sample in the other window with "mvn -Pclient". You will see the (encrypted) messages flowing first between the client and the STS, and then between the client and the service provider.

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