XML has become one of the core technologies for contemporary business applications, especially web-based applications. To facilitate processing of diverse XML data, we propose an extensible, integrated XML processing architecture, the XML Virtual Machine (XVM), which connects XML data with their behaviors. At the same time, the XVM is also a framework for developing and deploying XML-based applications. Using component-based techniques, the XVM supports arbitrary granularity and provides a high degree of modularity and reusability. XVM components are dynamically loaded and composed during XML data processing. Using the XVM, both client-side and server-side XML applications can be developed and deployed in an integrated way. We also present an XML application container built on top of the XVM along with several sample applications to demonstrate the applicability of the XVM framework.

A composite multimedia presentation may be represented by a sequence of virtual media data packets. An algorithm is presented for ordering these virtual media data packets so as to minimize the initial delay required to transfer the composite stream from a media server to a client. This algorithm has been implemented as part of the IBM Toolkit for MPEG-4.

The feasible-region is a simple and optimal framework for scheduling the transmission of data with deadlines. We establish the fundamental relationship between the bandwidth requirement and the initial delay in feasible-region-based transmission scheduling. The relationship represents the optimal bandwidth/delay tradeoff. In the process, we identify the essential bandwidth, the exact bandwidth lower bound regardless of the initial delay. Efficient algorithms are given to calculate the essential bandwidth as well as the optimal bandwidth/delay tradeoff. The results extend the previous results on feasible-region-based scheduling, most of which were derived in the context of video traffic smoothing. When applied to the problem of scheduling scalable multimedia, we show that the feasible-region framework enables the integrated scheduling of presentation and transmission and is a new and promising approach of dealing with scalable multimedia. We establish the presentation feasibility condition and present some initial results on scheduling spatial scalability.

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Time is an essential component i n i n teractive m ultimedia documents (or systems).We present the elastic time model for multimedia documents.Using the metaphor of a spring system, it allows authors to associate with each multimedia object a minimum and a maximum length and a length at rest.Authors can connect the (elastic) objects by de ning temporal relationships among them.If the given specication is consistent, a document is produced which is also elastic, with a minimum, a maximum, and an optimal length.As such, our elastic model associates with a document a range of feasible solutions in addition to an optimal one.The author can then select from the acceptable range an alternative length for the document, and the system will compute a revised solution that takes the additional global constraint i n to eect.The system can answer questions, such as: \Can I show this multimedia presentation in 10 minutes?If so, how should all the objects be scheduled?"Furthermore, the system also takes fairness into consideration and distributes any necessary stretching or shrinking across multimedia objects contained in a document.As such, the elastic time model provides expressive p o w er and exibility in document au-The author's current address is:

The performance implications of asynchronous disk interleaving are examined. In an asynchronous system, adjacent subblocks are placed independently of each other. Since each of the disks in such a system is treated independently while being accessed as a group, the access delay of a request for a data block in an n-disk system is the maximum of n access delays. Using approximate analysis, a simple expression for the expected value of such a maximum delay is obtained. The analysis approximation is verified by simulation using trace data; the relative error is found to be at most 6%.>

A group of disks may be interleaved to speed up data transfers in a manner analogous to the speedup achieved by main memory interleaving. Conventional disks may be used for interleaving by spreading data across disks and by treating multiple disks as if they were a single one. Furthermore, the rotation of the interleaved disks may be synchronized to simplify control and also to optimize performance. In addition, check- sums may be placed on separate check-sum disks in order to improve reliability. In this paper, we study synchronized disk interleaving as a high-performance mass storage system architecture. The advantages and limitations of the proposed disk interleaving scheme are analyzed using the M/G/1 queueing model and compared to the conventional disk access mechanism.