Glossary
A comprehensive, structured, commented, glossary is
available at: http://www.titan.be.
The following glossary refers to the most important entries
needed to be understood in order to fill the questionnaires
in.
Application
The word "application" covers the type of service
with its content of information.
Cache
The word "cache" corresponds to the cases where data
are duplicated on the bases of the last requested parts,
simply limited by the cache size, extracted in the original
server. The purpose is to speed up the access to the data
for the local users. The cache server works on behalf of the
local server in a full automatic and transparent way. It
means that the searches, queries, modifications, Ö
could be done with use of the original data when the size of
the cache is not large enough for avoiding that too often
the requested data have been overwritten by more recent
requests.
See also "proxy", "mirroring" and "cache" which could be
used combined through "squid redirector". For more
information find a very understandable document written by
John Heaton john@manchester.ac.uk
available on http://www.mcc.ac.uk/John.
You can also ask the proceedings of the WWW caching
work-shop at http://wwwcache.ja.net
Duplicated data
The word "duplicated data" covers the cases when
services of a specific common type are supplied at several
places but that the data are supplied from several sources.
The approach is a particular case of mirror services.
Encapsulation
The word "encapsulation" covers the transfer of a
set of data from one place to another where the server uses
one protocol to ensure the transfer, addressing and other
controls to the client, while the client open the "capsule"
to recover the data for further processing according to a
structuration and representation according to another
protocol. The most current encapsulations cover the transfer
of data coded with the Internet Protocol (IP) on broadcast
networks according to the DVB-ETSI broadcast standard format
and protocol.
Interaction
The word "interaction" covers the fact that the
service is given in a way that the "client" has the feeling
that he can receive responses or reactions depending of his
choices. This can be obtained in several ways:
a real time link exist between the "server" and the
"client". It is called "full interaction". It means that the
service is given from end to end in real time;
a real time link exist between a local "server" and the
"client". It is called "interaction in
proxy/cache/mirror mode". It means that the service
is possibly given from end to end in real time through the
use of ancillary servers;
Carousel
a carousel of information is permanently sent to
the client(s). The client tool selects what the client has
requested from the carrousel when the requested information
passes.
Download
A download of data occurs in the client tool. The
client operates in stand alone, as long as the local data
suffice.
Note: several of those modes can be combined for performing
one service! A typical example is the Internet browsing in
full interaction with downloads of Java applets from the
Server to the PC of the Client.
ISDN
The word "ISDN" covers the "Integrated Services
Digital Network", the well known universal interactive
network which, for the capillary part could used the PSTN
two wires infrastructure with its addressing scheme. For the
professional use and for the interconnection between
exchanges, fibre optics is the most common solution.
Formats
The word "formats" cover all ways in which "sense"
can be expressed: i.e. the semiotic, syntactical and
semantic elements of documents or messages, as well as the
interaction types between people through such documents or
messages possibly exchanged via telecommunication. In
particular, the format means:
In which natural language the document is expressed (French,
English, Spanish, etc)
In which way it is represented (MicrosoftÒ Word,
WordPerfect, etc)
In which way it is coded (ASCII, ISO G2, etc)
In particular, the encoding and representation techniques
used within a specific format cover the interface protocols
for the various layers of the tri-axes analysis model
proposed below.
In particular, the analysis of the content of a message and
legal monitoring could be based on these formats.
Hybrid
The word "hybrid" covers the cases when a service is
given using more than one network: for instance the PSTN for
interaction in the requests and the Satellite for the
broadcast of huge set of data.
Media Home Platform
The word "media home platform" (MHP) covers
the way in which hybrid and mixed services could be obtained
at home, in particular in liaison with cable networks. The
MHP is planned to be release by the DVB in mid 1998.
Mirror
The word "mirror" corresponds to the cases where data
are duplicated with their structure and content. The purpose
is to speed up the access to the data for the local users.
It means that the searches, queries, modifications, Ö
could be done without using necessarily the original data.
In simple mirroring, the update is made on the initiative of
the master server. So there is a risk that the local data
will not be at the last revision.
See also "proxy", "mirroring" and "cache" which could be
used combined through "squid redirector". For more
information find a very understandable document written by
John Heaton john@manchester.ac.uk
available on http://www.mcc.ac.uk/John.
Mixed
The word "mixed" covers the type of service which is
given through one type of equipment for several types of
services. For example, the access to the TV broadcast and
the Internet Web service through an IRD connected to the
cable network.
Piping
The word "piping" covers the transfer of a set of
data from one place to another where the client is listening
and the server sends them when it want to.
Proxy
The word "proxy" corresponds to the cases where data
are duplicated with their structure and content with
reference to the original. The purpose is to speed up the
access to the data for the local users. The proxy server
works on behalf of the master server. It means that the
searches, queries, modifications, Ö could be done with
limited use of the original data (simply checking that the
local data are up-to-date and, if not download of the
updating).
See also "proxy", "mirroring" and "cache" which could be
used combined through "squid redirector". For more
information find a very understandable document written by
John Heaton john@manchester.ac.uk
available on http://www.mcc.ac.uk/John.
PSTN
The word "PSTN" covers the "Public Switched Telephone
Network", the well known two wires infrastructure with its
addressing scheme.
Rooming
The word "rooming" covers the fact that a telecom
service provider supply a service of world type (like GSM or
Digital TV) by him self for his own subscribers and supplies
it also to the customers/subscribers of colleagues when,
casually, they enter in his sphere of action.
Service
The word "service" covers all types of multimedia
services and programmes, whatever medium they use: CD-ROM,
etc. (in non-real time), Satellite, Cable, Fibre Optic,
terrestrial radio, etc. (in real-time); whatever the mode:
broadcast, addressed, with interaction, client-server,
client-server-client, etc.
Stage
The word "stage" covers the main phases of a
project:
M stage: Management "go" given on the bases of a
"strategy" document;
F stage: Functional definition ready;
P stage: Product ready and validated;
T stage: Trial for evaluation before launch at large
scale;
O stage: Running operations and maintenance;
E stage: End of life; date for end of service
decided
Squid Director
The word "squid redirector" corresponds to the cases
where the techniques of "proxy", of "cache" and/or "mirror"
are combined to make profit of the advantages of all those
facilities. The purpose is to speed up the access to the
data for the local users and to optimize the use of the
resources. The squid redirector works on behalf of the local
server on contract with the master servers boosted by the
redirector.
See also "mirror", "proxy" and "cache". For more information
find a very understandable document written by John Heaton
john@manchester.ac.uk
available on http://www.mcc.ac.uk/John.
Streaming
The word "streaming" covers the transfer of data from
one place to another where the client is listening the
stream as it comes. The stream can include data intended to
be sent for different clients (including broadcast to all
listeners); the stream can include several consistent set of
data called "programs".
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