The concept of programmable nodes and active networks introduces programmability into communication networks. Code and data can be sent and modified on their routes to the destinations. Various research groups have designed and implemented their own design platforms. Each design has its own benefits and drawbacks. Moreover, there exists an interoperability problem among platforms. As a result, we introduce a concept that is similar to network socket programming. We intentionally establish a set of simple interfaces for programming active applications. This set of interfaces, known as active network socket programming (ANSP), will be working on top of all other execution environments in the future. Therefore, the ANSP offers a concept that is similar to "write once, run everywhere". It is an open programming model that active applications can work on all execution environments. It solves the heterogeneity within active networks. This is especially useful when active applications need to access all regions within a heterogeneous network to deploy a special service at critical points or to monitor the performance of the entire networks. Instead of introducing a new platform, our approach provides a thin, transparent layer on top of existing environments that can be easily installed for all active applications.