CXF WS-Security runtime token caching

CXF caches tokens in the security runtime in the following circumstances:

• When the IssuedTokenInterceptorProvider is invoked to obtain an Issued token from an STS.
• When the STSTokenValidator is used to validate a received UsernameToken, BinarySecurityToken or SAML Assertion to an STS.
• When the SecureConversation protocol is used.
• When the WS-Trust SPNEGO protocol is used.
• When tokens are obtained from a Kerberos KDC.

In each of these use-cases, the retrieved token is cached to prevent repeated remote calls to obtain the desired security token. There is no built-in support as yet to cache tokens in the WS-Security layer to prevent repeat validation. Of course this could be easily done by wrapping the existing validators with a custom caching solution.