1. A computer-implemented process, comprising: instrumenting a program with a first aspect, wherein the first aspect is associated with a pointcut identifying data accesses and wherein the first aspect is associated with advice code that detects whether a data access will cause data from a first session to be accessed in conjunction with servicing a request associated with a second session, the first session and second session being distinct sessions; providing an associative data structure representing a mapping from objects into identifications of sessions, wherein the advice code consults the associative data structure to determine if in the associated data structure an object is associated with a session other than a current session; instrumenting the program with a second aspect, wherein the second aspect is associated with additional advice code that registers an object with the associative data structure in the event that the object becomes associated with a session; and executing the instrumented program, wherein executing the instrumented program includes raising an exception in response to detecting a data access that will cause data from one session to be accessed in conjunction with servicing a request associated with another, distinct session.