Kathryn H. Britton

Transcoding: extending e-business to new environments

The promise of e-business is coming true: both businesses and individuals are using the Web to buy products and services. Both want to extend the reach of e-business to new environments. Customers want to check accounts, access information, and make purchases with their cellular phones, pagers, and personal digital assistants (PDAs). Banks, airlines, and retailers are competing to provide the most ubiquitous, convenient service for their customers. Web applications designed to take advantage of the rich rendering capabilities of advanced desktop browsers on large displays do not generally render effectively on the small screens available on phones and PDAs. Some devices have little or no graphics capability, or they require different markup languages, such as Wireless Markup Language (WML), for text presentation. Transcoding is technology for adapting content to match constraints and preferences associated with specific environments. This paper compares and contrasts different approaches to content adaptation, including authoring different versions to accommodate different environments, using application server technology such as JavaServer pagesTM (JSPTM) to create multiple versions of dynamic applications, and dynamically transcoding information generated by a single application. For dynamic transcoding, the paper describes several different transcoding methodologies employed by the IBM WebSphereTM Transcoding Publisher product, including HyperText Markup Language (HTML) simplification, Extensible Markup Language stylesheet selection and application, HTML conversion to WML, WML deck fragmentation, and image transcoding. The paper discusses how to decide whether transcoding should be performed at the content source or in a network intermediary. It also describes a means of identifying the device and network characteristics associated with a request and using that information to decide how to transcode the response. Finally, the paper discusses the need for new networking benchmarks to characterize the server load and performance characteristics for dynamic transcoding.

Two-phase commit optimizations and tradeoffs in the commercial environment

Eleven two-phase commit (2PC) protocol variations that optimize towards the normal case are described and compared with a baseline 2PC protocol. Environments in which they are most effective are discussed. The variations are compared and contrasted in terms of number of message flows, number of log writes (both forced and non-forced), probability of heuristic damage, how damage is reported, and other tradeoffs.<<ETX>>

Two-phase commit optimizations in a commercial distributed environment

An atomic commit protocol can ensure that all participants in a distributed transaction reach consistent states, whether or not system or network failures occur. The atomic commit protocol used in industry and academia is the well-known two-phase commit (2PC) protocol, which has been the subject of considerable work and technical literature for some years.Much of the literature focuses on improving performance in failure cases by providing a non-blocking 2PC that streamlines recovery processing at the expense of extra processing in the normal case. We focus on improving performance in the normal case based on two assumptions: first, that networks and systems are becoming increasingly reliable, and second, that the need to support high-volume transactions requires a streamlined protocol for the normal case.In this paper, various optimizations are presented and analyzed in terms of reliability, savings in log writes and network traffic, and reduction in resource lock time. The papers unique contributions include the description of some optimizations not described elsewhere in the literature and a systematic comparison of the optimizations and the environments where they cause the most benefit. Furthermore, it analyzes the feasibility and performance of several optimization combinations, identifying situations where they are effective.

Multiprotocol transport networking: a general internetworking solution

The multiprotocol transport networking (MPTN) architecture proposed in this paper is a general solution to providing interconnectivity for applications. The MPTN architecture provides a protocol-independent system interface that includes most functions provided by existing transport protocols. As a result, the MPTN architecture decouples higher-layer protocols, application programming interfaces, and applications from protocols at the transport layer and below. Using the MPTN architecture, current and new applications can function unmodified over any transport supported under the MPTN interface. In addition, MPTN transport-layer gateways provide an end-to-end communication facility across a number of networks running different protocols. Therefore, a collection of networks running different protocols can serve as a single logical network.<<ETX>>