Other Operating Systems

• Solaris users have a free T.120 communications application called SunForum available for download. Tests have shown that this interoperates very well with NetMeeting, and the simultaneous use of NetMeeting on a PC and SunForum on a Solaris workstation allows the control of Unix applications from a PC and vice versa. SunForum 3.2, the current version, includes support for video, audio, and interactive data sharing (chat, whiteboard and application sharing) between users of the software. It can also log on to, and make use of, ILS servers. Further Information can be found at: http://www.sun.com/desktop/products/software/sunforum/ and SunForum can be downloaded from http://www.sun.com/desktop/products/software/sunforum/download.html/
• HPUX workstation users can find details of the T.120 data sharing product HP visualize conference at: https://h20392.www2.hp.com/portal/swdepot/displayProductInfo.do?productNumber=B7580AA. Interoperability with NetMeeting, ILS servers, and other H.323/T.120 programs is offered.
• SGImeeting is a collaborative data sharing product for Silicon Graphics IRIX workstations. The current version is SGImeeting 2.0 and this is available at: http://www.sgi.com/software/sgimeeting/ Again, full interoperability is offered.
• There is currently development work in producing H.323 software for Linux and open source users. Pointers and further information can be found at: http://www.openh323.org/. Initiatives include GnomeMeeting which does not yet include data sharing (apart from a text chat tool for use with other GnomeMeeting users). Further details are available from: http://www.gnomemeeting.org/
• There are no applications that the author is aware of that currently offer Apple Mac users T.120-based data sharing. There is at least one commercial H.323 program available: VideoLink Pro, from Smith Micro Software, at: http://www.smithmicro.com/. This offers only a chat program, not full T.120 services.

The Access Grid, Multicast Videoconferencing and Data Sharing

Multicast videoconference users have a different set of applications available for videoconferencing and data sharing. Information on this subject can be accessed at: http://www.ja.net/development/network-engineering/multicast/

Data sharing applications that are used in multicast videoconferencing include:

• wb a shared whiteboard, available at:
  

  http://mice.ed.ac.uk/mice/archive/wb.html

• NetText is a shared text editor. More information is available from:
  

  http://mice.ed.ac.uk/mice/archive/nt.html

Large-scale pooling of computing resources and sharing of data over the Internet are realised by the use of multicast and the Access Grid. Further details can be found at the Access Grid Home Page: http://www.accessgrid.org/

T.120 Servers

In H.320 and unicast H.323, calls involving only two participants are point-to-point, from one endpoint to another. In order to take part in calls involving more than two endpoints, each of the endpoints needs to be in conference with an Multipoint Control Unit (MCU) which acts as the hub of the meeting. The T.120 data-collaboration element of a conference can be routed through the MCU as well. This allows the session to scale to a far larger number of users than would otherwise be possible, but it means that all network traffic (video/audio and data sharing) is routed through the same server. The use of T.120 servers or 'conference servers' would appear to be most appropriate for internal use by organisations on an intranet for example. JANET does not have a T.120 server, and there are currently no plans to implement one. The current situation, of non-centralised, out-of-band data sharing is the most appropriate for the JANET network.