The TORGA.net - Trans Portugal Galicia
Network - project is funded by Interreg III-A Community Initiative, Galicia North of Portugal Subprogramme involving the following partners: University of Vigo and Centro de Supercomputación de Galicia(CESGA) from Spain and University of Minho and Centro de Computação Gráfica (CCG) from Portugal. Its main objective is to build an efficient communication platform between the research and innovation communities of the South of Galicia and the North of Portugal, in order to encourage the collaboration between them and simplify the economic and social integration of this bordering zone

Castro, Rui

Lima, Ana

Marcos, Adérito

The Repositório Aberto

Introduction
The TORGA.net - Trans Portugal Gali-
cia Network - project is funded by
Interreg III-A Community Initiative,
Galicia North of Portugal Subpro-
gramme involving the following part-
ners: University of Vigo and Centro
de Supercomputación de Galicia
(CESGA) from Spain and University of
Minho and Centro de Computação
Gráfica (CCG) from Portugal. Its main
objective is to build an efficient com-
munication platform between the
research and innovation communities
of the South of Galicia and the North
of Portugal, in order to encourage
the collaboration between them and
simplify the economic and social inte-
gration of this bordering zone. In
practical terms, this project involves
the installation of several Access Grid
rooms. The Access Grid is an ensem-
ble of resources including multimedia
large-format displays, presentation
and interactive environments, and
interfaces to Grid middleware and
visualization environments.
These resources are used to sup-
port group-to-group interactions
across the Grid. For example, the
Access Grid is used for large-scale
distributed meetings, collaborative
work sessions, seminars, lectures,
tutorials, and training. Therefore, the
Access Grid technology differs from
desktop-to-desktop tools that focus
on individual communication.
Access Grid technology
A Grid is a set of hardware and soft-
ware resources distributed over the
Internet that provide services accessi-
ble through a set of protocols and
open interfaces (resource manage-
ment, remote process management,
communication libraries, security,
monitoring support, etc) organized
by well defined proceedings and
good practices. The virtual organiza-
tions that interconnect through a
Grid are responsible for their own
security and resource management
policies. This means that the technol-
ogy used to build a Grid is comple-
mentary to other technologies
enabling the use of distributed
resources from the intranet of those
organizations.
The need to use resources already
available in the systems connected to
the Internet and to simplify their
usage created an opportunity for a
new information technology known
as Grid. The idea for this new tech-German Abstract
Dieser Beitrag gibt einen allgemei-
nen Überblick über die Access-
Grid-Technologie mit Hinweisen
auf ihre technischen Aspekte und
einer kurzen Beschreibung der
Architektur eines Access Grid
Node. Er stellt die Unterschiede
zwischen der Access-Grid-Techno-
logie und anderen herkömmlichen
Technologien für Videokonferen-
zen dar und zeigt einige der Grün-
de auf, weshalb sich das
TORGA.net-Konsortium für diese
Technologie zur Durchführung
von Videokonferenzen zwischen
der Universität von Minho im Nor-
den Portugals und der Universität
von Vigo im spanischen Galizien
entschieden hat.
Grid Technology in TORGA.net Context
Rui Castro, Ana Lima, Adérito Marcos
CG topics 5/200514
Figure 1: Access Grid
room in university of
Minho (Braga)
CG topics 5/2005 15
nology is to offer access to various
resources geographically dispersed,
such as supercomputers, clusters,
storage, information sources, tools,
etc. Therefore, the distributed sys-
tems can be used as a single virtual
system by various applications.
A Grid system is defined by the
dependency in a centralized control,
for being based on open standards
and for providing quality of service.
As such, the objective of the Grid
technology is to bind resources of
distinct administration domains,
respecting the policies and internal
management tools of those domains.
Access Grid is a framework of
hardware and software resources
over multicast networks with middle-
ware interfaces, used to make
human interaction and collaboration
between local and remote spaces
easier.
Each Access Grid Node connects to
other nodes, creating a flexible Col-
laborative Virtual Environment that
makes possible for multiple users
located in different physical locations
to communicate and collaborate as if
they were working in the same
room.
In an Access Grid Node, audio,
video and data create environments
that make other participant nodes
feel like they were working in the
same physical space.
In order to create this environment
some aspects must be taken into
account, like the room space, equip-
ment layout and the construction
and configuration of the Access Grid
Node.
An Access Grid Node is composed
of four components:
– Audio System,
– Video System,
– Visualization System, and
– Network
Access Grid vs. Conventional
Videoconferences
What are the advantages of an
Access Grid Videoconference Sys-
tem? What are the differences
between Access Grid and conven-
tional videoconferencing technology?
Table 1 presents a comparison made
between a videoconference taking
place in an Access Grid Node versus
a videoconference in a conventional
room.
In a traditional videoconference
session we have a peer-to-peer
topology in which every peer estab-
lishes a connection with every other
peer in the conference that usually
resumes to one. This is mandatory
with unicast networks, while in an
Access Grid session, since it is based
on a multicast network, one node
(peer) broadcasts video, audio and
data stream(s) only once and every
other node (peer) receives that
stream, repeated as many as it
wants, only limited by its own band-
width. This means that the Access
Grid technology is scalable in terms
of the number of participants in a
particular session.
The possibility to share resources
and applications is another important
issue compared to other technolo-
gies. Some technologies allow at the
most the sharing of a virtual board in
which the participants can write and
make simple drawings. However,
with Access Grid, the participants
can share applications like web
browsers, slide show presentations,
etc. More, the resources of each
node can be shared and used by
applications as a single virtual sys-
tem.
Access Grid Node: Software Archi-
tecture
The Access Grid infrastructure has
the following components (figure 3):
– Venue Server: is where virtual
rooms are created, modified and
removed using a tool called
»venue management tool«.
Figure 2: Structure
of an Access Grid
Node
Service
Manager
Node
Service
Service
Manager
Video Visualization Audio
Video
Producer
Service
Audio
Service
Video
Consumer
Service
Service
Manager
Figure 3: Client-server structure in virtual rooms
Service
Manager
Service
Manager
Service
Manager
Service Service Service
Node
Service
Access Grid Node
Node
Management
Client
Venue
Client
Venue
Server
Management
Network
Service
Network
Service
Network
Service
Venue Server
Venue 1
Venue 2Venue 3
Venue 4 Venue 5
Lobby
CG topics 5/200516
Therefore, the Venue Server con-
nects different Access Grid Nodes.
– Venue Client: software that serves
as a connection between the
node and the virtual class room
(»virtual venue«)
Allows:
- To share data,
- To share applications, such as
Remote PowerPoint Presenta-
tion Tool, Whiteboard,
GridFTP, distributed Web
Browser, distributed Chat
Room, shared Bookmarks,
Voting Tool, Question &
Answer Tool, etc.
– Virtual Venue: cooperative virtual
space.
– Node: collection of hardware and
software resources.
As seen in Figure 2, the Node Service
connects to the Service Manager in
each machine. The Node Service
exposes to the outside the resources
of each machine of the Node. There-
fore, the components are:
– Node Service: central point of
contact in a node.
– Service Manager: manager that
controls the services in each
machine. There is one for each PC
to control the service execution.
– Service: include the hardware and
software resources needed to
provide a certain service (such as
audio and video streaming).
The functionalities of each Node are
determined by the services installed.
Conclusion
The experience provided by the
Access Grid technology is very differ-
ent from the traditional videoconfer-
encing systems. In the domain of rich
and interactive remote collabora-
tions, Access Grid has an excellent
performance when compared to oth-
er technologies. 
Another feature that makes Access
Grid stand up over other systems is
its scalability; a session can be estab-
lished between several nodes, each
with the possibility to see the others;
events with up to 100 participant
nodes have already taken place using
Access Grid technology. This is possi-
ble because Access Grid is based on
multicast networks, meaning that
one node has only one outgoing
audio/video stream that flows over
the multicast network to every other
participant node.
Summarizing, the Access Grid tech-
nology offers the following capabili-
ties:
– high-quality multichannel digital
video and audio
– prototypic large-format display
– integrated presentation technolo-
gies (PowerPoint slides, mpeg
movies, shared OpenGL windows)
– prototypic recording capabilities
– integration with Globus for basic
services (directories, security, net-
work resource management)
– macroscreen management
– integration of local desktops into
the Grid 
– multiple session capability 
Points of Contact
Rui Castro 
Ana Lima 
Prof. Adérito Marcos
Centro Computação Gráfica,
Guimarães, Portugal
E-mail: Rui.Castro@ccg.pt
Ana.Lima@ccg.pt
Aderito.Marcos@ccg.pt
Videoconference Access Grid:
Characteristics
Conventional Videoconference: 
Characteristics
Requires Broadband Networks 
(Internet2, GÉANT)
Require conventional networks: 
Internet, RDSI, ADSL
Multicast networks Unicast networks
Multiple open source software
resources
Require multiple hardware resources Require few hardware resources
Multiple audio/video streaming
Projection of high quality image Image of variable quality and small
dimensions
Complex collaborative virtual spaces Simple collaborative virtual spaces
Great interactivity Poor interactivity
Table 1: Comparison between Access Grid and conventional videoconferences


English

Grid technology in TORGA.net context

Repositório Aberto da Universidade Aberta

IntroductionThe TORGA.net - Trans Portugal Gali-cia Network - project is funded byInterreg III-A Community Initiative,Galicia North of Portugal Subpro-gramme involving the following part-ners: University of Vigo and Centrode Supercomputación de Galicia(CESGA) from Spain and University ofMinho and Centro de ComputaçãoGráfica (CCG) from Portugal. Its mainobjective is to build an efficient com-munication platform between theresearch and innovation communitiesof the South of Galicia and the Northof Portugal, in order to encouragethe collaboration between them andsimplify the economic and social inte-gration of this bordering zone. Inpractical terms, this project involvesthe installation of several Access Gridrooms. The Access Grid is an ensem-ble of resources including multimedialarge-format displays, presentationand interactive environments, andinterfaces to Grid middleware andvisualization environments.These resources are used to sup-port group-to-group interactionsacross the Grid. For example, theAccess Grid is used for large-scaledistributed meetings, collaborativework sessions, seminars, lectures,tutorials, and training. Therefore, theAccess Grid technology differs fromdesktop-to-desktop tools that focuson individual communication.Access Grid technologyA Grid is a set of hardware and soft-ware resources distributed over theInternet that provide services accessi-ble through a set of protocols andopen interfaces (resource manage-ment, remote process management,communication libraries, security,monitoring support, etc) organizedby well defined proceedings andgood practices. The virtual organiza-tions that interconnect through aGrid are responsible for their ownsecurity and resource managementpolicies. This means that the technol-ogy used to build a Grid is comple-mentary to other technologiesenabling the use of distributedresources from the intranet of thoseorganizations.The need to use resources alreadyavailable in the systems connected tothe Internet and to simplify theirusage created an opportunity for anew information technology knownas Grid. The idea for this new tech-German AbstractDieser Beitrag gibt einen allgemei-nen Überblick über die Access-Grid-Technologie mit Hinweisenauf ihre technischen Aspekte undeiner kurzen Beschreibung derArchitektur eines Access GridNode. Er stellt die Unterschiedezwischen der Access-Grid-Techno-logie und anderen herkömmlichenTechnologien für Videokonferen-zen dar und zeigt einige der Grün-de auf, weshalb sich dasTORGA.net-Konsortium für dieseTechnologie zur Durchführungvon Videokonferenzen zwischender Universität von Minho im Nor-den Portugals und der Universitätvon Vigo im spanischen Galizienentschieden hat.Grid Technology in TORGA.net ContextRui Castro, Ana Lima, Adérito MarcosCG topics 5/200514Figure 1: Access Gridroom in university ofMinho (Braga)CG topics 5/2005 15nology is to offer access to variousresources geographically dispersed,such as supercomputers, clusters,storage, information sources, tools,etc. Therefore, the distributed sys-tems can be used as a single virtualsystem by various applications.A Grid system is defined by thedependency in a centralized control,for being based on open standardsand for providing quality of service.As such, the objective of the Gridtechnology is to bind resources ofdistinct administration domains,respecting the policies and internalmanagement tools of those domains.Access Grid is a framework ofhardware and software resourcesover multicast networks with middle-ware interfaces, used to makehuman interaction and collaborationbetween local and remote spaceseasier.Each Access Grid Node connects toother nodes, creating a flexible Col-laborative Virtual Environment thatmakes possible for multiple userslocated in different physical locationsto communicate and collaborate as ifthey were working in the sameroom.In an Access Grid Node, audio,video and data create environmentsthat make other participant nodesfeel like they were working in thesame physical space.In order to create this environmentsome aspects must be taken intoaccount, like the room space, equip-ment layout and the constructionand configuration of the Access GridNode.An Access Grid Node is composedof four components:– Audio System,– Video System,– Visualization System, and– NetworkAccess Grid vs. ConventionalVideoconferencesWhat are the advantages of anAccess Grid Videoconference Sys-tem? What are the differencesbetween Access Grid and conven-tional videoconferencing technology?Table 1 presents a comparison madebetween a videoconference takingplace in an Access Grid Node versusa videoconference in a conventionalroom.In a traditional videoconferencesession we have a peer-to-peertopology in which every peer estab-lishes a connection with every otherpeer in the conference that usuallyresumes to one. This is mandatorywith unicast networks, while in anAccess Grid session, since it is basedon a multicast network, one node(peer) broadcasts video, audio anddata stream(s) only once and everyother node (peer) receives thatstream, repeated as many as itwants, only limited by its own band-width. This means that the AccessGrid technology is scalable in termsof the number of participants in aparticular session.The possibility to share resourcesand applications is another importantissue compared to other technolo-gies. Some technologies allow at themost the sharing of a virtual board inwhich the participants can write andmake simple drawings. However,with Access Grid, the participantscan share applications like webbrowsers, slide show presentations,etc. More, the resources of eachnode can be shared and used byapplications as a single virtual sys-tem.Access Grid Node: Software Archi-tectureThe Access Grid infrastructure hasthe following components (figure 3):– Venue Server: is where virtualrooms are created, modified andremoved using a tool called»venue management tool«.Figure 2: Structureof an Access GridNodeServiceManagerNodeServiceServiceManagerVideo Visualization AudioVideoProducerServiceAudioServiceVideoConsumerServiceServiceManagerFigure 3: Client-server structure in virtual roomsServiceManagerServiceManagerServiceManagerService Service ServiceNodeServiceAccess Grid NodeNodeManagementClientVenueClientVenueServerManagementNetworkServiceNetworkServiceNetworkServiceVenue ServerVenue 1Venue 2Venue 3Venue 4 Venue 5LobbyCG topics 5/200516Therefore, the Venue Server con-nects different Access Grid Nodes.– Venue Client: software that servesas a connection between thenode and the virtual class room(»virtual venue«)Allows:- To share data,- To share applications, such asRemote PowerPoint Presenta-tion Tool, Whiteboard,GridFTP, distributed WebBrowser, distributed ChatRoom, shared Bookmarks,Voting Tool, Question &Answer Tool, etc.– Virtual Venue: cooperative virtualspace.– Node: collection of hardware andsoftware resources.As seen in Figure 2, the Node Serviceconnects to the Service Manager ineach machine. The Node Serviceexposes to the outside the resourcesof each machine of the Node. There-fore, the components are:– Node Service: central point ofcontact in a node.– Service Manager: manager thatcontrols the services in eachmachine. There is one for each PCto control the service execution.– Service: include the hardware andsoftware resources needed toprovide a certain service (such asaudio and video streaming).The functionalities of each Node aredetermined by the services installed.ConclusionThe experience provided by theAccess Grid technology is very differ-ent from the traditional videoconfer-encing systems. In the domain of richand interactive remote collabora-tions, Access Grid has an excellentperformance when compared to oth-er technologies. Another feature that makes AccessGrid stand up over other systems isits scalability; a session can be estab-lished between several nodes, eachwith the possibility to see the others;events with up to 100 participantnodes have already taken place usingAccess Grid technology. This is possi-ble because Access Grid is based onmulticast networks, meaning thatone node has only one outgoingaudio/video stream that flows overthe multicast network to every otherparticipant node.Summarizing, the Access Grid tech-nology offers the following capabili-ties:– high-quality multichannel digitalvideo and audio– prototypic large-format display– integrated presentation technolo-gies (PowerPoint slides, mpegmovies, shared OpenGL windows)– prototypic recording capabilities– integration with Globus for basicservices (directories, security, net-work resource management)– macroscreen management– integration of local desktops intothe Grid – multiple session capability Points of ContactRui Castro Ana Lima Prof. Adérito MarcosCentro Computação Gráfica,Guimarães, PortugalE-mail: Rui.Castro@ccg.ptAna.Lima@ccg.ptAderito.Marcos@ccg.ptVideoconference Access Grid:CharacteristicsConventional Videoconference: CharacteristicsRequires Broadband Networks (Internet2, GÉANT)Require conventional networks: Internet, RDSI, ADSLMulticast networks Unicast networksMultiple open source softwareresourcesRequire multiple hardware resources Require few hardware resourcesMultiple audio/video streamingProjection of high quality image Image of variable quality and smalldimensionsComplex collaborative virtual spaces Simple collaborative virtual spacesGreat interactivity Poor interactivityTable 1: Comparison between Access Grid and conventional videoconferences

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Grid technology in TORGA.net context

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