rfc1614.txt

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   making about 30 sample scientific articles available over the
   SuperJANET network, using a range of different software products. The
   demonstrator project is being managed by IOP Publishing and is being
   carried out at Edinburgh University Computing Service.

   Existing tools, particularly WAIS and WWW, are relevant, but adequate
   security and charging mechanisms are required if commercial
   publishers are to use them.  Many research groups are now making the
   text of preprints and published research papers available on Gopher
   servers.

   It is interesting to note that the proceedings of the Multimedia 93
   conference run by the ACM will be published electronically (on CD
   ROM), using a multimedia document format designed specifically for
   the event.

   Computer-aided Learning

   The ready availability of user-friendly multimedia authoring tools
   such as AuthorWare Professional, Asymmetrix Multimedia Toolbook,
   Macromind Director and many more, has stimulated much interest in
   multimedia for computer-aided learning applications within the user
   community.  Sophisticated interactive multimedia courseware
   applications are being developed in many disparate subjects
   throughout the European academic community.  Users are now beginning
   to ask network technologists, "how can I make my multimedia
   application available to others across the network?".

   There is considerable interest in using the network to enhance
   delivery of multimedia teaching materials - for instance to allow
   students to take courses remotely (distance learning) and for their
   learning process to be supported, monitored and assessed remotely.

   The requirements which flow from this type of network application
   include the ability to identify and authenticate the students using
   the material, to monitor their progress, and to supply on-line
   assessment exercises for the student to complete.  Multimedia
   authoring tools allow very attractive presentation environments to be
   created, which encourages learning; this is viewed as essential by
   course developers.  Easy-to-use authoring tools (preferably existing
   commercial ones) are also essential.

   Finally, some learning applications involve simulations - examples
   include meteorological modelling and economic simulations.  Network



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   delivery of teaching materials should cope with this requirement
   (perhaps by acknowledging that executable scripts are just another
   media type).

   General Information Services

   There are many other possible uses of multimedia data in networked
   information servers which don't conveniently fall into any of the
   above categories. Some examples are given below.

      o    On-line documentation.  Manuals and instruction books often
           rely heavily on pictorial information, and are enhanced by
           dynamic media types (sound, video).  The ability to access
           centrally-held manuals across a network makes it much easier
           to keep the information up-to-date.

      o    Campus-wide information systems (CWIS) are an important
           growth area.  The opportunities for enhancing such a
           service with multimedia data (e.g., maps) is obvious.

      o    Multimedia news bulletins (e.g., the Internet Talk Radio,
           which is sound only).

      o    Product information (the multimedia equivalent of paper
           advertising matter).

      o    Consumer systems - e.g., tourist information servers.  The
           utility of such systems in an academic/research environment
           is perhaps questionable, but it is likely that such systems
           will address problems which will also be met in this
           environment.  We should be prepared to learn from such
           projects.

2.2. Data Characteristics

   Some of the characteristics which make data more appropriate for
   network publication rather than publication on physical media are
   listed below.

      o    The data may change frequently.

      o    Implementing corrections and improvements to the data is
           very much easier.

      o    It is more readily available to the data user - no
           purchase/delivery cycle need exist.





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      o    Publication on physical media may not be cost-effective for
           very large volumes of data.  (Of course, there is a cost in
           networking the data as well, but the research/academic user
           is normally insulated from this.)

      o    Access for large user communities can be established without
           requiring each user to purchase a potentially expensive
           physical media peripheral (such as a laser disk player).
           This is particularly helpful in classroom situations.

      o    It may require less effort from the data publisher to make
           data available over a network, rather than set up a manual
           mechanism for distributing physical media.

      o    If related data from many different sources is to be
           published, it may be more efficient to leave the data in
           situ, and simply publish the network addresses of the data.

   There are counter-reasons which may make physical media distribution
   more appropriate:

      o    Easier to charge for.  (However, charging mechanisms do
           exist in some network information systems.  It may be that
           potential information providers need to be made more aware
           of this.)

      o    Easier to deter or prevent copyright infringement, using
           traditional copy-protection techniques.

2.3. Requirements Definition

   From studying the applications described in the preceding section,
   and from discussions with the people involved with the applications,
   it is possible to draw up a list of general requirements which a
   distributed multimedia information system for the academic and
   research community should satisfy.  These requirements are informally
   described in the following subsections.  The descriptions are
   necessarily informal and incomplete: every individual application
   will have its own detailed requirements, which would take a great
   deal of effort to determine (and indeed some of the requirements may
   not become apparent until the application is into its development
   phase).

   Platforms

   It is clear that the European academic community, in common with
   other such communities, requires support for three main platforms:
   UNIX, Apple Macintosh, and PC/Windows.  For multimedia client/server



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   systems, the latter two are less appropriate as server platforms, but
   client support for all three is vital.  UNIX will be most often used
   as the server platform.

   There are other systems, such as VAX/VMS, which are also important in
   some sectors.

   Media Types

   Unsurprisingly, all applications require text data to be supported as
   a basic media type.  Image and graphic media types are next in
   importance, followed by "application-specific" data (such as tabular
   scientific data, mathematical equations, chemical data types, etc).
   Sound and video media types are becoming more important as users
   discover how these can enhance applications.

   Many different encodings are possible for each media type (e.g.,
   image data can be encoded as TIFF, PCX, GIF, PICT and many more).  An
   information system should not constrain the type of encoding used,
   and should ideally offer either a range of alternative encodings, or
   conversion facilities between the stored encoding and an encoding
   suitable for display by the client workstation.

   Hyperlinks

   It is clear that many applications require their users to be able to
   navigate through the information base according to relationships
   determined by the information provider - in other words, hyperlinks.
   Academic publishing, CAL, on-line documentation and CWIS systems all
   require this capability.  The user should be able, by some action
   such as clicking on a highlighted word in a text node or on a button,
   to cause another node or nodes to be retrieved and displayed.

   Some "hypermedia" systems are in fact simply hypertext, in that they
   require the source anchor of a hyperlink to be in a text node.  A
   true hypermedia system allows hyperlinks to have their source anchors
   in nodes of any media type.  This allows a user to click the mouse on
   a component of a diagram or on part of a video sequence to cause one
   or more related nodes to be retrieved and displayed.

   Some hypermedia systems allow target anchors of a hyperlinks to be
   finer-grained than a whole node - e.g., the target anchor could be a
   word or a paragraph within a text document.  Without such a
   capability, it is necessary for target nodes to be quite small if
   precision is required in a hyperlink.  This may be difficult to
   manage, and fine-grained target anchors are therefore better.





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   Additional structure above or orthogonal to the underlying
   hyperlinked data is required in some applications.  This allows the
   same (generally non-textual) data to be used in several different
   applications, or the implementation of different access paradigms.

   Presentation

   Related information of different media types must be capable of
   synchronised display.  Commercial multimedia authoring packages
   provide many different ways of presenting, synchronising and
   interacting with media elements.  Some of these are summarised below.

      o    Backdrops.  An application may present all its visual
           information against a single background bitmap - e.g.,
           a CAL application might use a background image of an open
           textbook, with graphics, text and video data all presented
           on the open pages of the book.

      o    Buttons.  A "button" can be defined as an explicitly-
           delimited area of the display, within which a mouse click
           will cause an action to occur.  Typically, the action will
           be (or can be modelled as) a hyperlink traversal.
           Applications use different styles of button - some may use
           "tabs" as in a notebook, or perhaps "bookmarks" in
           conjunction with the open textbook backdrop mentioned above.
           Others may use plain buttons in a style conforming to the
           conventions of the host platform, or may simply highlight a
           word or phrase in a text display to indicate it is "active".

      o    Synchronisation in space.  When two or more nodes are
           presented together (e.g., because a link with more than one
           target anchor has been traversed), the author of the
           hyperdocument may wish to specify that they be presented in
           a spatially-related way.  This may involve: x/y
           synchronisation - e.g., a video node being displayed
           immediately above its text caption; it may involve
           contextual synchronisation - e.g., an image being displayed in
           a specific location within a text node; or it may involve z-
           axis synchronisation as well - for instance a text node
           containing a simple title being displayed on top of an
           image, with the text background being transparent so that
           the image shows through.

      o    Synchronisation in time.  Isochronous data may require
           synchronisation - the obvious case being audio and video
           tracks (where these are held separately).  Other examples
           are: the synchronisation of an automatically-scrolling text
           panel to a video clip (for subtitling); or to an audio clip



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           (e.g., a translation); or synchronising an animation to an
           explanatory audio track.

   Searching

   Database-type applications require varying degrees of sophistication
   in retrieval techniques.  For applications addressed in this report,
   non-text nodes form the major data of interest.  Such nodes have
   associated descriptions, which may be plain text, or may be
   structured into fields.  Users need to be able to search the
   descriptions, obtain a list of "hits", and select nodes from that
   list to display.  Searching requirements vary from simple keyword
   searching, via full-text indexing (with or without Boolean
   combinations of search words), to full SQL-style database retrieval
   languages.

   Interaction

   The user must be able to annotate documents retrieved from the
   information server.  The annotations may be stored locally.
   Similarly, the user may wish to add his own (locally-held) hyperlinks
   to documents.  (Actual modification of documents in the information
   system itself, or shared annotations to documents - i.e., the
   information system as a CSCW environment - is viewed as separate
   issue which this report does not address.)