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An extended seal calculus language, ExtSealL, and its syntax is introduced in this paper. A frame structure is proposed for ExtSeal. A construction method for translating a seal definition into the frame definition is proposed and a transformation function is given based on the method. An operating semantics is developed basing on the frame structure, an example of a frame and its execution are given.

As a distributed process calculus with localities and mobility of computational entities, Seal calculus is playing an important role in expressing key features such as security and mobility of Internet programming directly. However, little implementation technique proposed for the calculus, partly due to the complication of mobile computation, which fusions three important techniques: concurrency, distribution and mobility at the same time. The abstract machine PSN for a distributed implementation of the Seal calculus is presented. In PSN the logical structure of a seal system and its physical distribution are separated which induces a more simple and clear implementation. Moreover, an operational semantics description of the Seat calculus based on PSN is given.

The Seal calculus is a calculus of mobile computations designed for programming secure distributed applications over large scale open networks such as the Internet. This paper presents a distributed implementation for the Seal calculus based on an abstract machine SAM, a translation from Seal terms to SAM term, a proof of the correctness of such a translation, which asserts that a Seal term and its translation exhibit the same observance behavior, and a prototype Java implementation. The implementation helps to speed up the development of programming languages based on Seal and experimentation of Seal on concrete examples.