Christopher Lindblad

The VuSystem: a programming system for compute-intensive multimedia

In compute-intensive multimedia applications, the computer not only manipulates media, but also digests it and performs independent actions based on media content. We present a design approach that applies the programming techniques of visualization systems to the development of compute-intensive multimedia applications. We describe an implementation based on this approach, and report performance measurements that demonstrate it is practical. We conclude with a description of some applications that have been implemented and a discussion of the implications for the design and engineering of operating systems.

The VuNet desk area network: architecture, implementation, and experience

The VuNet is a gigabit-per-second desk-area ATM network that interconnects general-purpose workstations, network-based multimedia devices, and bridges to other networks, workstations access the multimedia devices over the network and coordinate the movement of information streams among the different parts of the system. This architecture presents several advantages over the traditional workstation-centric models, including the ability to easily share network-based devices, to access nonlocal devices, and to relieve the workstation of a portion of the I/O work. This paper describes the philosophy, implementation choices, advantages, and limitations of the VuNet ATM network implementation, as well as performance and current status. >

The ViewStation: a software-intensive approach to media processing and distribution

The ViewStation architecture embodies a software-intensive approach to the support of interactive media-based applications. Starting from the premise that the raw media data, e.g., the video pixels themselves, must eventually be made accessible to the application, we have derived a set of architectural guidelines for the design of media-processing environments. The resultant ViewStation architecture, as described in this paper, consists of the VuSystem, a complete media-programming environment, and the VuNet, a substrate for the acquisition, communication, and rendering of video and closed caption text. We describe a set of computer-participative applications that demonstrate the present day viability of applications that actively process live media-based information. Early performance results illustrate the affordability and benefits of our software-intensive approach.

VuSystem Performance Measurements

In this paper I discuss some performance measurements made of the VuSystem, a programming system for the software-based processing of audio and video data. The VuSystem is designed to run on ordinary Unix workstations with no specific support for the manipulation of multimedia data. Measurements made of processing times of representative filter modules demonstrate the viability of the approach.

Active pages: Intelligent nodes on the World Wide Web

Active pages provide a common interface to World Wide Web applications, crossing browser, platform and operating system boundaries. They are hypertext documents that present a front−end to intelligent applications. Typically implemented as interpreted programs with an associated database, they use the forms extension for application input. There are three advantages to the active pages approach for application interfaces. Application interfaces are widely accessible because they leverage off of the accessibility of the Web by using HTTP to bridge application and interface. Applications are self−documenting. The hypertext model of the Web makes it simple for active pages to contain embedded documentation and links to auxiliary material. Finally, applications integrate seamlessly with the Web. Active pages may be accessed in the same way and with the same browser as other pages. In this paper, we present our active page design methodology and demonstrate it with two examples from our server: WEBDNS, a facility for editing Internet Domain Name System master files; and The People Directory, an editable personnel database that includes hypertext links to biographical pages. Introduction The World Wide Web can be an interface to shared applications, as well as a mechanism for electronic publishing and collaboration. Applications on the Web can leverage off of the portability of the Web for access. In turn, Web users can leverage off of the flexibility of programs to improve their collaboration. The pages of a shared application change in appearance and content as viewers progress through them. Input from one viewer can become visible to others. The same information can be presented differently, depending on the viewer and their preferences. From the viewers’ perspective, the pages appear active and intelligent. These active pages contrast with other pages, which appear the same from invocation to invocation. We developed an approach to the design of active pages suited to shared applications. To implement the active pages, a server interface for executing programs and a client interface for accepting input is required. We adopted the Common Gateway Interface (CGI) extension to HTTP servers and the forms extension to Web browsers, respectively, because they were immediately available and in widespread use. In this paper, we describe our design and illustrate it with two examples. The first, WEBDNS, facilitates the interactive update of Domain Name System (DNS) master files. The second, The People Directory, presents an editable personnel database. The Advantages of Active Pages Active pages provide several advantages to shared applications. They are widely and conveniently accessible, especially suited to collaborative tasks, encourage documentation, and are seamlessly integrated with other Web pages. Accessiblity The broadest feature of active pages compared to other application interfaces is widespread accessibility. The Web is portable across platform and operating system and network boundaries. Just as for other Web pages, active pages may be accessed interactively, across the network, and from a variety of computer platforms. This makes them appropriate for services that benefit from being freely available to a hetrogeneous community. Collaboration Many users may simultaneously access one active page. This, coupled with the fact that the application executes on the server, rather than the client, allows many users to share few special resources. This type of access is especially useful for collaboration within a user community, and can be applied to many database systems. Two large examples of database systems that can be interfaced to the Web with active pages are SABRE, the United Airlines reservations system, and Lotus Notes.