Dependable distributed and mobile computing - utilizing time to enhance recovery from failures

Abstract Mobile computing allows ubiquitous and continuous access to computing resources while users travel or work at a client's site. The flexibility introduced by mobile computing brings new challenges to dependability and fault tolerance. Failures that were rare with fixed hosts become common, and host disconnections make fault detection and message coordination difficult. This chapter describes checkpointing and failure recovery procedures that are well adapted to both distributed and mobile environments. The protocols use time to indirectly coordinate the creation of new global states and thereby avoid message exchanges. The mobile protocol uses two different types of checkpoints to adapt to network characteristics. Procedures for integrating adaptive mobile checkpointing with storage management are also described

Benchmarking on-line services industries

The Web Quality Analyser (WQA) is a new benchmarking tool for industry. It has been extensively tested across services industries. Forty five critical success features are presented as measures that capture the user’s perception of services industry websites. This tool differs to previous tools, in that it captures the information technology (IT) related driver sectors of website performance, along with the marketing-services related driver sectors. These driver sectors capture relevant structure, function and performance components.\ud An ‘on-off’ switch measurement approach determines each component. Relevant component measures scale into a relative presence of the applicable feature, with a feature block delivering one of the sector drivers. Although it houses both measurable and a few subjective components, the WQA offers a proven and useful means to compare relevant websites. The WQA defines website strengths and weaknesses, thereby allowing for corrections to the website structure of the specific business. WQA benchmarking against services related business competitors delivers a position on the WQA index, facilitates specific website driver rating comparisons, and demonstrates where key competitive advantage may reside. This paper reports on the marketing-services driver sectors of this new benchmarking WQA tool.\u