1. A computer-readable storage medium comprising computer-executable instructions for executing processes across multiple execution environments, the computer-executable instructions comprising instructions for: maintaining a memory invariance between a requesting process, hosted by a first hosting process and executing in a first execution environment, and a shadow process hosted by a second hosting process executing in a second execution environment, the shadow process being associated with the requesting process; receiving, in the first execution environment, a first request from the requesting process; communicating the first request to the second execution environment; and initiating, in the second execution environment, a second request, equivalent to the first request, from the shadow process to the second hosting process.