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There is a very large body of knowledge on the subject of metadata, much of which pre-dates the development of information webs. Metadata is essentially data about data, an example being the card index catalogue in a library; where the information on that card is metadata about a particular publication. The application of solutions based on metadata may solve many of the problems associated with content identification and delivery on information webs. It is from the standpoint of: "metadata being used by anyone to make their material more accessible", that much of the relevant research is based.
A paper entitled: "Metadata for the masses: what is it, how can it help me, and how can I use it?", by Paul Miller provides much of the background to research efforts so far, and provides details (and links) to a number of metadata schemes, however concentrating on the Dublin Core Metadata Element Set, or Dublin Core (DC). The Dublin Core has also been translated into in French.
URL: DC http://purl.org/metadata/dublin_core
URL: DC French http://www-rocq.inria.fr/~vercoust/METADATA/DC-french.html
An additional approach is provided by the Warwick framework and this, along with the Dublin Core, should: "provide a comprehensive infrastructure for network resource description". A report from the workshop held in Warwick, UK to which the framework refers and an explanation of the framework itself are published on the web.
The focus of a great deal of activity worldwide is based on the approach of describing 'Document Like Objects' - the aim being to agree a scheme capable of describing the majority of resources available on the Internet, and suitable for inserting the widest range of file types: from simple HTML files to complex Postscript files and other image formats. An additional starting point providing a description of the form and content of resources concerned with Metadata is available on the web.
There are also a number of conference reports and proceedings:
- Proceedings of the OCLC Internet Cataloging Colloquium, San Antonio, Texas January 19, 1996
- Report from the Metadata Workshop II, Warwick, UK, April 1-3, 1996
- Report from the Distributed Indexing/Searching Workshop, Cambridge, Massachusetts, May 28-29, 1996
- Conference proceedings from the The Second IEEE Metadata Conference, Silver Spring, Maryland, USA, September 16 - 17, 1997 papers online.
In a paper entitled: "Towards a theory of meta-content", R.V. Guha argues for the use of a single expressive language for encoding meta-content irrespective of the source, location or format of the content itself. It seems from the thread of Guha's arguments that the his use of the term metacontent is in fact a synonym for metadata.
Meta-content is defined broadly in the paper as "anything about content", it is descriptive of content - where content can include anything from the documents on hard disks, pages on the WWW, to messages in email folders. Whilst the paper recognises there is no clear line between content and meta-content, it argues that the application of a more principled approach to the definition and use of meta-content will ensure far more effective management and manipulation of information.
Guha, postulates a potential meta-content language and characterises some of the benefits as:
- enhanced ability to search on the context of information;
- richly structured meta-content, enables searching to be transformed into structured query processing and inferencing;
- meta content could be used to provide background context maps, particularly in hypertext environments (eg. the Web) where context can sometimes be lost through hyperlinking.
This paper lead to a proposed standard language for describing meta-content, Meta Content Framework (MCF).
Educom, a nonprofit US-based consortium of higher education institutions which concentrates on the synthesis of education and information technology, along with a coalition of US academic, industry and government organisations is developing a metadata specification for materials used in higher education, corporate and government training programs.
Through the proposed metadata specification the project aims to provide a common vocabulary for educational resources, making them easier to find on the Web. Educom is also developing a Java-based tool that will assist content developers in applying the metadata labels to their materials.
URL: metadata specification http://www.imsproject.org/metadata/
The concept of metadata/metacontent has received increasing attention from the major vendors in the web market. The W3C coordinates these often disparate metadata activities, through a working group - the W3C Metadata Activity.
The specification for Meta Content Framework (MCF), an application of XML proposed by Apple and adopted now by Netscape, is based on the draft proposal developed by R.V Ghua (see above). The drafts have been heavily reworked with the latest specification. This document provides the specification for a data model for describing information organization structures (metadata) for collections of networked information. It also provides a syntax for the representation of instances of this data model using XML. There is also a tutorial which introduces MCF.
URL: tutorial http://www.textuality.com/mcf/MCF-tutorial.html
The World Wide Web Consortium have published a draft of the Resource Description Framework (RDF), a vendor-neutral and operating system-independent system for metadata. RDF is an extension of the work on PICS content description technology, drawing on XML technology along with the submissions to the W3C by Microsoft (XML Web Collections and XML-Data) and Netscape (XML/MCF) . The design of RDF has also been influenced by the Dublin Core/Warwick Framework - see information above.
RDF will allow different application communities to define the metadata property set that best serves the needs of each community. A variety of application areas are envisaged including:
- in resource discovery to provide better search engine capabilities;
- in cataloging for describing the content and content relationships available at a particular Web site, page, or digital library;
- by intelligent software agents to facilitate knowledge sharing and exchange;
- in content rating for child protection and privacy protection;
- in describing collections of pages that represent a single logical "document";
- for describing intellectual property rights of Web pages.
Implemented with digital signatures, the W3C believes that: "RDF will aid in building the 'Web of Trust' for electronic commerce, collaboration, and other applications". The RDF specification has been produced as part of the W3C Metadata Activity, which includes the work on PICS and DSig and has seven major areas of focus:
- A metadata model and syntax specification, RDF;
- A language for writing RDF schemas;
- A language for expressing processing rules (sometimes called "filters", "preferences", or "profiles" in various applications of metadata) for the use of RDF statements;
- A language for expressing a general query for RDF information;
- An algorithm for canonicalizing RDF for digital signature;
- A syntax for digitally signing RDF; A vocabulary for expressing PICS labels in RDF, and a conversion algorithm from PICS 1.1.
Useful references for RDF include:
- Introduction to RDF
- A "lighter" introduction to RDF
- The RDF Specification current draft
- "An Introduction to the Resource Description Framework"
For more on PICS and rating systems see the Social aspects topic page.
For more on XML see the Interoperability and standards topic page.
A Proposed Convention for Embedding Metadata in HTML - the problem is to identify a simple means of embedding metadata within HTML documents without requiring additional tags or changes to browser software, and without unnecessarily compromising current practices for robot collection of data.
A vendor in the web application development market, has implemented an extension of HTML aimed at tagging information. The Identify system is based on the company's own specification for representing semantics information, called IDML. There is a tutorial on IDML and also a discussion document entitled: "Why not use META tags?"
The Metadata Coalition, a group of database and database application vendors are proposing the definition, implementation and ongoing evolution of a metadata interchange format (MIF). This group views the emergence of metadata as a critical element in effective data management and plans to standardise the metadata generated from various application domains including: data warehousing and databases (relational, OLAP, OLTP).
Online virtual reality: stretching the technologies is the title of the paper presented at the Online '97 Conference, 9 December 1997, London, UK by Geoffrey Stephenson (IESERV) and Roger Frampton, Cyber-Wizard, UK. The paper is available for download (PC zipped, 21KB).
Abstract of the paper: The success of the Internet and, in particular the World Wide Web, has led to an explosion in the use of online technology for information dissemination and both inter-company and inter-personnel communication. The imminent arrival of tele-shopping, electronic commerce, web-TV, network games, tele-working and other new applications are widely forecast. Many of these applications require simultaneous improvements in the underlying technologies that are not immediately available. The paper considers the requirements for the new applications and some proposed solutions. There are further resources available for download from this site, see the download page.
Over 40 US companies including Microsoft, Progressive Networks, Intel and Adobe have proposed that the Advanced Streaming Format (ASF) draft specification, be adopted as the file format "of choice" for storing and streaming multimedia content on intranets and the Internet, replacing data types such as WAV and AVI.
The developers claim that: "ASF provides for integration of different media types, optimization for delivery over networks, and support for multiple bandwidths within a single media file. ASF also supports synchronization of different media types on a common time line allowing images, HTML pages or scripted events to be synchronized with an audio track". Progressive Networks have announced that ASF will become the primary and default file format in future releases of RealAudio and RealVideo. A draft specification of the ASF, along with the live proceedings of the design review are available.
Lotus intends to integrate Microsoft's Windows Media Technologies into Notes Release 5 and Domino Release 5 (R5) collaboration software products, via IBM's HotMedia Connect for Domino, middleware technology. The agreement between the companies covers distribution, development and licensing of Microsoft's streaming multimedia technology.
URL: Windows Media Technologies http://www.microsoft.com/windows/windowsmedia/
URL: Lotus http://www.Lotus.com/
URL: IBM http://www.IBM.com/
An addition to the array of web technologies is real-time audio. The main system that seems to be in use is RealAudio, an add-in for web browsers. The 'viewer' ('listener'?) is available at the company's web site for free download.
The development of audio on the Web created a deal of controversy as the potential for Internet telephony became apparent. In a move which signals enhanced developments in this area, ETSI (European Telecommunications Standards Institute) plans to help establish enhanced voice communications over the Internet. Code named Tiphon (Telecommunications and Internet Protocol Harmonisation Over Networks) the work is divided into three phases:
- Phase 1 focuses on calls relayed between IP terminals and fixed and mobile phones
- Phase 2 addresses calls relayed between fixed and mobile phones and IP terminals
- Phase 3 will look at the use of the Internet as a means to carry dialogue between phones.
The Java Media Framework (JMF) specifies a unified architecture, messaging protocol, and programming interface for media players, media capture, and conferencing. The Java Media Player APIs support the synchronisation, control, processing, and presentation of compressed streaming and stored time-based media, including video and audio.
The Java Media Player APIs are being developed by Sun Microsystems, Silicon Graphics, and Intel. Version 1.0 of the Java Media Player API Specification is now available.
The Synchronized Multimedia Integration Language specification (SMIL 1.0) is a W3C Recommendation, which represents cross-industry agreement on a wide range of features for putting multimedia presentations on the Web.
SMIL promises to offer the following features:
- Easy-to-learn synchronization primitives - 90% of the power of SMIL can be tapped by mastering only two tags, "parallel" and "sequential".
- Temporal hyperlinking - offers all the capabilities of hyperlinks in HTML, and adds capabilities required in time-based presentations.
- Reusability of media objects - all components of the multimedia presentation are referenced via URLs rather than physically embedded into SMIL file.
- Load balancing - different media objects in a presentation can be stored on different servers.
- Bandwidth selection - authors can express that a media object such as an audio track is available in different versions, each having been encoded for a different transmission bandwidth.
Additional information on SMIL is available at:
- the Audio, Video, and Synchronized Multimedia Web Site
- SMIL 1.0 Specification
- Webdeveloper.com's SMIL tools links
- SMIL syntax validator
- JustSMIL, a web site dedicated to the standard
- Allaire's SMIL resources page
The World Wide Web Consortium (W3C) has released a public working draft of Synchronized Multimedia Integration Language (SMIL), known as SMIL Boston. SMIL Boston builds upon the SMIL 1.0 Recommendation, and adds a number of extensions, including reusable modules, generic animation, improved interactivity, and TV integration, all written in the eXtensible Markup Language (XML).
"With SMIL Boston, anyone can make multimedia for the Web. Using your own digital snapshots and audio commentary, SMIL, and a simple text editor, you can make multimedia presentations that can immediately go live", claimed Philipp Hoschka, Chair of the SYMM Working Group.
The Synchronized Multimedia (SYMM) Working Group, responsible for the development of SMIL, runs a public mailing list for comments from developers, regarding the recommendation.
URL: SMIL Boston spec. http://www.w3.org/1999/08/WD-smil-boston-19990803/
URL: public mailing list mailto:email@example.com
Intel run a website, Mediadome, that acts as a digital stage for the newest web-based technology. The site features video, audio and VR - programming is changed every couple of weeks.
One of the consequences of the growth of client-server computing and particularly of the Web, is a growth in asymmetric software systems with different capabilities at the server and client ends. The differences arise because generally the client is less secure, the client is less powerful, and the design of the distributed application uses asymmetry to improve efficiency.
To meet the needs of such asymmetric applications plugins have been developed. Essentially these are modules that are attached to a standard piece of software, such as a Web browser, and enable the browser to communicate with some specific software or protocol supported by the server. Plugins are available both for business applications over Intranets and for general Internet applications.
Initially plugins were used to provide support for data types - sound and images - that were not supported by the browser but for which the protocol provided a means of identification through standards such as MIME types.
Plugins have extended their scope so that they now support, for example:
- proprietary multimedia data types, Shockwave from Macromedia supports Freehand vector graphic files, Authorware multimedia and Flash animations
- Virtual Reality worlds in proprietary formats such as Viscape from Superscape , or VRML standard formats as supported by Cosmo
- VR chat environments demonstrated by OnLive
- and group productivity and interworking - BSCW from GMD and Netopia Virtual Office from Farallon
A recent trend in plugins is to support better utilisation of bandwidth in an effort to raise the standard of sound and video and to reduce the time the client waits to download files for these media types.
The plugin supports 'streamed' audio or video which means that the application begins to play the input stream from the server before it has been fully downloaded. The stream is usually compressed using some proprietary algorithm.
These types of plugins initially required dedicated proprietary software at the server, making it difficult for many small sites to support them. More recent solutions only require the files stored on the server side to be in proprietary formats for downloading. The creator still needs to generate these formats using proprietary software, but they can be delivered from a standard server system.
A number of Web sites exist that specialise in providing plugin downloads. These include:
- Browserwatch which has an amazing number of plugins indexed in a variety of ways to make access easier
- The Netscape plugin page
- The Microsoft plugin page simply claims that IE downloads plugins automatically as required.
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Last up-dated: 26 March 2021
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