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Interactive Services TechnologiesFiscal 1995 Project Portfolio Report
J. Duane Northcutt
Overall ObjectiveThe Interactive Services Technologies (IST) group is comprised of several different projects, each of which pursues a different technical objective, but all sharing a common set of principles and working toward a common vision. The projects of the IST group are all aimed at providing technology in support of interactive services implemented on networked workstations. This direction suggests the need for technology in support of continuous media and high degree of user interaction-e.g., I/O capabilities that exhibit both high throughput and low latency. To provide the end-to-end support needed for this class of application requires work at a wide span of levels of abstraction, and therefore, the IST group has been working at many different system levels.
Objective for FY95The key objectives of the IST group for this year included the broadening of the explorations in areas begun in the previous fiscal year. Specifically, some technology developed by the group in the area of time-critical media was identified for potential productization, and the emphasis for the new year was aimed at media storage, retrieval, and synchronization. In the area of Agoric systems, the results of the previous year's work on the application of money, market institutions, and general micro-economic principles to the problems of system-level resource management proved so successful that the project's attentions are now directed at the application of this technology to the creation of more general, and higher-level, "electronic economies." Finally, the work done last year in getting I/O investigations underway in SMCC have resulted in the genesis of a new Lab project to explore the creation of a new I/O subsystem for our workstations, based on high-speed serial communications technology.
DescriptionThis year, each of the IST group's projects builds on work done in the previous fiscal year. The Indexed Media Streams work extends some of the earlier work in media synchronization done in the SML High Resolution Video Workstation project. The work in timestamp-based media synchronization was extended and coupled with the work that was done earlier on the decoding of closed-captioning data to provide an effective means of locating and retrieving desired video clips from archival storage on a server. The media server work done this year was an outgrowth of earlier video-over-ATM work done by the group. The key observation here is that average-case disk performance can be achieved (despite the wide disparity between average- and worst-case disk performance), through careful file layout and the scheduling of transfer operations. In the previous fiscal year, work had been done on a scalable video coding scheme that allowed the quality of video to scale with the bandwidth required to deliver it. However, this year a significant new coding scheme was developed that makes heavy use of precomputed lookup tables to speed the decompression stage, and achieves scalability through the use of successively larger/smaller table indexes.Most of the foundations for this year's work on the Agoric systems project was laid out in the previous year's work. The foundation for electronic market economies was initially implemented in C++, but this work was advanced this year by creating a CORBA-compliant rapid object prototyping environment as an extension to the Tcl/Tk scripting language. Similarly, all of the group's preceding work on system support for digital audio and video was put to work in the development of a suite of initial applications to fill the role of electronic goods and services for the experimental electronic economy being constructed in SML by the IST group. Finally, the IST group's experiments in new machine I/O architecture formed the foundations of the Gigabit DeskNet project initiated last year within the IST group.
AccomplishmentsThe major areas where significant accomplishments were seen this year were are in: Time-Critical Media Technology, Agoric Electronic Marketplaces, Gigabit DeskNet I/O Subsystem, and Datacast Technology Investigations. An overview of the main accomplishments in each of these areas is given below.Time-Critical Media Technology This year saw the transition into full product status of a number of the media-related technologies developed by the IST group. In particular, the computer-controlled video tuner (i.e., the SunTM Tuner), and the low-cost video capture (i.e., SlicVideo) prototype units were productized and made available via Sun Express. Furthermore, the first Media Server product offered by Sun (i.e., the SMS1000) was largely designed and implemented by members of the IST group for the Sun Interactive organization. The group also provided technical support to various Sun organizations including the World Cup multimedia kiosk work, and various field operations groups. In the area of time-critical media technology, the IST group shifted its attention from acquisition and network transport issues, to the problems of media storage, retrieval, and synchronization. The following is a description of the key technical contributions made by the group in each of these areas this year.
Indexed Media Streams
Media Server Technology This year, the IST group developed other media server technologies, in addition to that used in the Sun Media Server product. In particular, the group's work on scalable video coding technology was enhanced and extended to the storage area. A prototype scalable video server was constructed that takes advantage of the fact that useful video service can span a wide range of different quality levels in order to provide its users a higher degree of value, at lower costs, than would be possible if the video streams were all constrained to remain at the same quality level. Furthermore, this server is being used in conjunction with the Electronic Commerce experiments, where the notion of cost has been integrated with the quality of video to explore various issues related to graceful degradation of video quality in the face of resource contention, as well as the effectiveness of various dynamic market institutions on the problem of distributed resource management. Agoric Electronic Marketplaces Following the initial work with Agorics, Inc., which was focused on applying micro-economic principles to the problem of distributed system resource management, the project's focus shifted to the broader application of computational market institutions to the creation of complete electronic economies. This shift was in part due to the realization that, although there has been a great deal of activity in the area of "electronic commerce," the bulk of the work is focused on payment and currency mechanisms. These mechanisms represent a very small fraction of the diverse "ecosystem" of market institutions which comprise a complete economy (electronic, or otherwise). In order to explore electronic economies, the IST group, in conjunction with Agorics, Inc., developed a computational framework with which fully functional, self-sustaining, electronic economies can be constructed. This framework (named WebMart) makes use of secure languages and protocols (i.e., JavaTM, Safe-Tcl, Safe-C++, and SKIP) to create a secure distributed object-programming environment (through extensions to Java and Tcl, the creation of a secure object invocation mechanism, and a persistent object store), upon which various computational market institutions have been created (e.g., resource auctions, futures markets, escrow agents, etc.). This framework allows automated business to be constructed, and it is intended that this will also foster the emergence of new forms of market economies which are unique to the distributed computing environment. As it was recognized that there would be great difficulty in beginning to "charge" for goods or services previously thought of as being "free," an effort was made to implement a wide range of initial goods and services with which to bootstrap the first electronic economy in SML. For this reason, a series of application programs and related services were developed this year as part of the SML Interactive Services Network experiment in electronic economies. Included among the new electronic goods and services created this year are:
Gigabit DeskNet I/O Subsystem In order to realize the potential benefits of applying the full power of the workstation to continuous media streams, the I/O subsystem of the traditional workstation must be significantly enhanced. In order to support the demands of many of the applications within the interactive services class, the IST group's Gigabit DeskNet project has defined a new I/O subsystem that permits media-related devices (e.g., audio/video input/output units, motion/gesture sensors, etc.) to be connected to the system in the manner needed to fully integrate the media streams into the workstation as a "first-class datatype." This interconnection mechanism provides Sun with a number of other valuable opportunities-e.g., to simplify the large variation in peripheral connection mechanisms through the use of a single, common, interconnection scheme, and to explore new system configurations/partitionings made possible by the ability to separate the primary computing complex from the various (user-manipulatable) peripheral devices. This year, the initial design of the Gigabit DeskNet system was completed, along with simulations of the lower level protocols. In addition, progress was made towards the creation of a prototype system that makes use of DeskNet for all of its I/O functions. Key modules were developed and a wide range of physical-layer technologies were investigated (in addition to the high-speed serial link technology developed earlier by SML and being refined further by the SML Venturi project). Efforts are also being made to explore the possibility of having the Gigabit DeskNet technology be accepted as the high-performance branch of the P1394 serial communications standard. As part of this work, and in conjunction with other researchers in SML and STB, a study was conducted into the technologies related to the creation of highly-scalable/modular server-class machines. A number of industrial and academic projects were studied, key (internal and external) individuals were invited to make presentations on a range of different modular-server-related technologies, and an extensive internal report was generated as a result. Work in this area is continuing in conjunction with the DeskNet project in SML. Datacast Technology Investigations A series of investigations was performed this year to explore the potential for new business opportunities offered by the wide-area (wireless) broadcasting of digital data. In particular, a study of the technical and business issues related to datacast using the vertical blanking interval of various terrestrial and satellite video transmission systems was performed with staff from Sun's Corporate Development office. Various existing satellite data transmission services were examined as part of this study. Also, a series of hardware prototype units was developed which permit the insertion and reception of arbitrary digital data streams within standard analog video transmissions. While the investigations are still underway, and no definite decisions have been made concerning Sun and its use of datacasting technology, the IST project is continuing to explore the related technologies in order to better understand the technical aspects of this area.
ReferencesPublicationsAgorics, Inc. "Architectural Issues in Agoric Open Systems." Agorics Technical Report ADd007P (May 1994). Agorics, Inc. "An Automated Auction in ATM Network Bandwidth." Project Technical Report (December 1994). SML-94-0508. Agorics, Inc. "An Introduction to Agoric Computation." Agorics Technical Report ADd006P (May 1994). Chaddha, N., G. A. Wall, and B. K. Schmidt. "An End-to-End Software Only Scalable Video Delivery System." Proceedings of the Fifth International Workshop on Network and Operating System Support for Digital Audio and Video (April 1995). Also IEEE (April 1995). Also ACM (April 1995). SML-94-0490. Nieh, J. "Integrated Scheduling for Multimedia." Proceedings of the Fifth International Workshop on Network and Operating System Support for Digital Audio and Video (April 1995) Also IEEE (April 1995). Also ACM (April 1995). SML-94-0489. Nieh, J., M. S. Lam, and J. D. Northcutt. "A Practical Unified Approach to Processor Scheduling." Project Technical Report (December 1994). SML- 94-0488. Schmidt, B. K., J. D. Northcutt, and M. S. Lam. "A Method and Apparatus for Measuring Media Synchronization." Proceedings of the Fifth International Workshop on Network and Operating System Support for Digital Audio and Video (April 1995). Also IEEE (April 1995). Also ACM (April 1995). SML-94-0493.
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