AGOCG logo
Graphics Multimedia VR Visualization Contents
Training Reports Workshops Briefings Index
This report is also available as an Acrobat file.
Back Contents

Appendix D - How LIVE-NET works

The main interface presented by livenet is a form containing the information relating to a booking. A typical form is shown below.
Booking Number: [05698]    Date: [07/10/93] (dd/mm/yy)   Start  Time: [17:00]
                                                         End    Time: [18:00]
                    Open/Closed: [o] (o/c)               Sw on  Time: [16:45]
                                                         Sw off Time: [18:15]
Series:   [BIOLOGY - PRE-TERM MEETING                                          ]
Session:  [                                                                    ]
          [                                                                    ]
Contact:  [Prof W G Chaloner                                                   ]

Locns:    [rhb.comp   ] [imp.main   ] [kcl.semr   ] [ucl.gower  ] [snt.rmb    ]
          [snt.quadb  ] [kcl.mon    ] [kcl.local  ] [kcl.recd   ] [snt.clock  ]
          [           ] [           ] [           ] [           ] [           ]
          [           ] [           ] [           ] [           ] [           ]

Notes:    [School: RHBNC - Dept. of Biology                                    ]
[Note: sites to be confirmed                                                   ]
[                                                                              ]
[                                                                              ]

The booking number is unique to each individual session and is allocated by the system in sequence. Date is the day the session is due to start. In the upper right corner are the start and end times of the session and the times at which the session actually switches. Normally a session will be scheduled to switch on a few minutes before the advertised start time (to allow for pre session tests, setting up of equipment etc) and will switch off a few minutes after the advertised end time (to allow for possible session overrun, discussion periods etc).

The session times used with LIVE-NET 2 tend to be more exact since the colleges have to pay for the time used and are therefore less keen to allow sessions to have extra time.

Open/Closed indicates if a session, once started, will allow other sites to connect to them. Normally sessions would be run as open however confidential sessions are run in closed mode. The series, session and contact fields contain optional information which though not needed to run the session is used for administrative purposes.

The notes field was originally used solely for optional administrative information. It is now used to hold information which is to be printed on the livenet update and commands to control the Codecs, Ascends and the VC700 videotelephone.

The locns fields contain a list of the rooms or equipment used in the session. In the example given ucl.gower is the UCL television studio in Gower Street and snt.clock is an Amiga computer used to produce a real time analogue clock. The first three characters of the field indicate where the location is, rhb for Royal Holloway and Bedford College, kcl for Kings College London, snt for Senate House etc.

Associated with the booking form of a session is a channel map which lists the connections to be made between the locations given. Channel maps can be generated automatically for certain types of sessions, entered by hand or by a combination of these two methods.

rhb.comp 1    > imp.main 1     kcl.semr 1     ucl.gower 1    snt.rmb 1     

imp.main 1    > rhb.comp 1     kcl.semr 2     ucl.gower 2    snt.rmb 2     

kcl.semr 1    > snt.quadb 1    imp.main 2     ucl.gower 3    kcl.mon 1     
                kcl.local 1    kcl.recd 3    

ucl.gower 1   > snt.quadb 2    imp.main 3     kcl.semr 3    

snt.rmb 1     > snt.quadb 3    imp.main 4     kcl.semr 4     ucl.gower 4   

snt.clock 1   > snt.quadb 4   

snt.quadb 3   > snt.rmb 3     

snt.quadb 5   > rhb.comp 3    

When a session starts the channel map is used to set crosspoints on the video switches. The crosspoints set are chosen to minimise the use of the trunk channels between sites. For the channel map given rhb.comp 1 is sent down a single trunk channel to the switch at Senate House and then to the other sites rather than using four separate trunk channels.

Once a session is inserted into the system it will start and finish at the set times without any further intervention. The start time can be immediately (in which case the switch on time is left blank) or any arbitrary time in the future.

Back Contents

Graphics     Multimedia      Virtual Environments      Visualisation      Contents