In mobile Internet applications, data can be transcoded, updated, and transferred across heterogenous clients. The problem then arises where updates made in the context of an initial transcoding results in content too stringently transcoded for subsequent clients, thereby causing loss of semantic value. We solve this problem by suggesting that the updates themselves can be transformed so that they can be applied directly to the original data instead of to the transcoded data; this approach allows the data to preserve as much semantic value as possible across all heterogeneous clients without unnecessary transcoding artifacts. We define reconciliation rules that can govern the interaction between client updates and transcoding, demonstrate a complete middleware architecture that supports our methodology, and provide two case studies using content-transferring applications. We show that our resulting middleware system executes our reconciliation approach with acceptable latency (under 5 seconds for 200 kbytes of layered content), good scalability, and well-organised modularity.

Mobile computing research has often focused on untethering an in-use computing device, rather than enabling the mobility of the computation task itself. This paper presents an architecture, implementation, and experimental evidence that together validate a new continuous computing concept, application session handoff. The iMASH architecture leverages previous work on proxies, content adaptation, and client awareness to provide a unique, middleware-enable capability for continuous computing. Implementation in both socket- and RPC-based environments shows that very fast, secure session handoff of non-trivial client/server applications across heterogeneous client devices and network is feasible: experiments on a number of applications yielded handoff latencies ranging from 0.5s to 2s.

The importance of middleware and content adaptation has previously been demonstrated for pervasive use of Web-based applications. In this paper we propose a modular extensible, and scalable middleware component called the Content Adaptation Pipeline that performs content adaptation on arbitrarily complex data types not limited to text and graphic images. Furthermore, the architecture can be used as part of many client-server applications, not just Web browsers. In our work we leverage the XML language as a uniform means to describe all the elements in our architecture, including the client device and user profiles, the data characteristics, the transcoding operations performed on the data, and the resultant adapted data. We illustrate the flexibility of our architecture to support new data types and adaptation operations by first showing its use with data from a real-world medical application and then extending its capabilities to handle animated graphics and also real-time streaming RTP data. Finally, we demonstrate scalability in our architecture by executing the Content Adaptation Pipeline over a distributed set of servers running an efficient protocol.