A method, apparatus, and/or computer program product generates a predictive data structure for an application when operating offline in a network connected data processing system, the application comprising source code having an execution path. The method comprises: determining an exit point within the source code of the application; determining, from the exit point, an execution path comprising at least one conditional statement; identifying one or more branches of the at least one identified conditional statement and for each identified branch determining an expected response; for each determined expected response, generating a data structure from the response; continuing along the execution path of the source code from the exit point and replacing each request for a resource in the source code with a pointer to the generated data structure; and executing the source code with the pointer to the generated data structure from the determined exit point.