Hierarchical model for web multimedia documents retrieval and periodical updates

Purpose - The purpose of this paper is to propose a four-level hierarchy model for multimedia documents representation to be used during the dynamic scheduling and altering of multimedia contents. Design/methodology/approach - The four-level hierarchy model (object, operation, timing, and precedence), offers a fine-grain representation of multimedia contents and is embedded within a research tool, which is called WEBCAP. WEBCAP utilizes the four-level hierarchy to synchronize the retrieval of objects in the multimedia document employing Allen's temporal relations, and then applies the Bellman-Ford's algorithm on the precedence graph to schedule all operations (fetch, transmit, process, and render), while satisfying the in-time updating and all web workload's resources constraints. Findings - The experimental results demonstrate the effectiveness of the model in scheduling the periodical updating multimedia documents while considering a variety of workloads on web/TCP. Research limitations/implications - WEBCAP should be enhanced to automatically measure and/or approximate the available bandwidth of the system using sophisticated measurement of end-to-end connectivity. In addition, WEBCAP should be expanded and enhanced to examine system infrastructure for more real-time applications, such as tele-medicine and e-learning. Practical implications - WEBCAP can be used as an XML markup language for describing multimedia presentations. It can be used to create online presentations similar to PowerPoint on desktop environment, or used as an interactive e-learning tool. An HTML browser may use a WEBCAP plug-in to display a WEBCAP document embedded in an HTML/XML page. Originality/value - This paper proposed a dynamic scheduling of multimedia documents with frequent updates taking into consideration the network's workload to reduce the packet lost ratio in the TCP flow, especially in the early stages. WEBCAP can be used to guide distributed systems designers/managers to schedule or tune their resources for optimal or near optimal performance, subject to minimizing the cost of document retrieval while satisfying the in time constraints.