17. A computer program product for use in a federated environment in which a token service fulfills request by executing a trust chain comprising a set of modules, comprising: a non-transitory computer-readable medium having computer program instructions that, when executed by a data processing system, perform the following steps: responsive to receipt of a token, initiating processing of the module chain; during processing of the module chain, attempting to validate a value of a name-value pair based on a rule, wherein the rule is determined based on one or more invocation parameters of the module chain; and returning a response.
17. A computer program product for use in a federated environment in which a token service fulfills request by executing a trust chain comprising a set of modules, comprising: a non-transitory computer-readable medium having computer program instructions that, when executed by a data processing system, perform the following steps: responsive to receipt of a token, initiating processing of the module chain; during processing of the module chain, attempting to validate a value of a name-value pair based on a rule, wherein the rule is determined based on one or more invocation parameters of the module chain; and returning a response. 19. The computer program product as described in claim 17 wherein, if the value of the name-value pair is validated, the response is an output token.