Extending Service-Oriented Architecture with Hierarchical Composition of Client-Side Asynchronous Event-Processing Logic

There is a growing need for a new type of WS-*/SOA standards that could facilitate hierarchical, object-oriented composition of client-side executable code. This is especially true for the sorts of client-side logic embedded in AJAX and rich Internet applications, virtual worlds and MMORPGs; code that deals with issuing requests to servers, processing their responses, rendering UI, interacting with users, and processing asynchronous events from other client nodes. The paper offers an analysis of client-side composition patterns, a brief explanation why they lack adequate support from the existing web technologies, and design guidelines for client-side component integration environments to follow. The proposed guidelines have been successfully implemented in a prototype system. Our analysis is thus strongly rooted in reality; it is based on real experiences with concrete application scenarios. The paper concludes by highlighting the key architectural aspects of our implementation with respect to the principles listed earlier.