We live in an era in which digital and phys-ical worlds not only coexist but also coop-

erate and complement each other. Ultimately,researchers hope to develop technologies that letusers cross the border between the two worldswithout a thought. This will radically changehow we communicate, interact, work, and play.

Mixed-reality environments are new inhabit-able spaces realized through the combined effortsand investment of major research councils andindustry. In a broad sense, mixed-reality envi-ronments merge physical and virtual worldsusing mobile wireless and ubiquitous technolo-gies. Probably the most widely known instantia-tion of these environments is in the gamingcontext. Figures quoted in the press increasinglyshow patterns of massive investment and con-sumption budgets in this domain. For example,

❚ the European Union’s Sixth Framework Pro-gram and British Engineering and PhysicalSciences Research Council (EPSRC) is invest-ing millions of euros in projects and initiativessuch as the Integrated Project of PervasiveGames (IPERG, http://iperg.sics.se) and Equa-tor (http://machen.mrl.nott.ac.uk).

❚ major companies such as Nokia, Sony, andMicrosoft have assembled large advertising,marketing, and development teams to pro-mote and realize these technologies on a mas-sive scale.1

❚ more than 100,000 players participated in theNokia Game ( http://www.nokiagame.com/game/index.htm) last year, approximately 48percent of whom were 25−40 years old.1

Although the game’s popularity might beattributable to powerful marketing campaignsand large investments, it also points to asignificant trend: Rather than simply toys for

teenagers, mixed-reality games are increasinglybecoming an entertainment and communi-cation medium for adults.

Interweaving the digital and physical worldsin the early stages of mixed-reality productionintroduced at least three obvious research chal-lenges: understanding interactions (that is, meth-ods needed to design and evaluate systems in thisarea), building devices, and understanding infra-structures for dynamic assembly of new devicesinto coherent user experiences. As mixed-realitytechnologies matured, research challengesincreasingly shifted to how people use them.Postpervasive game research revealed that con-sumers wanted to communicate directly, freely,and creatively with others and to build commu-nities.1,2 Through their interaction, sharing, andcollaboration, consumers created much of thegame content. Consequently, a major researchquestion has been how to build incentives intothe game to encourage idea sharing and team-work without constraining players with toomuch packaged content and thus inhibiting theircreativity (for example, BotFighters was moresuccessful than the Nokia Game because of thesimpler imposed content1).

This article focuses on the challenge of manag-ing the large amount of heterogeneous spa-tiotemporal mixed-reality data (such asaudio/video files, GPS logs, and text messages)generated in a distributed asynchronous fashionthat must be indexed, annotated, synchronized,and replayed in the postproduction phase. Asmixed-reality technologies grow and mature, thisprocess becomes increasingly difficult. We face avast amount of mixed-reality data as well as a vastnumber and diversity of services and tools (see the“Current Techniques and Limitations” sidebar).Producing meaningful content requires a system-atic and integrated approach to managing audio

12 1070-986X/05/$20.00 © 2005 IEEE Published by the IEEE Computer Society

Visions & Views

MilenaRadenkovicUniversity ofNottingham

Novel Infrastructures for SupportingMixed-Reality Experiences

13

Current Techniques and LimitationsHaving explored the production process for mixed-reality

television shows and demonstrated some early prototype pro-duction tools, Drozd et al.1 proposed a generic record-and-reuse infrastructure for automating mixed-reality production.Using the three key stages of mixed-reality production,researchers identified nine core services that a generic mixed-reality record-and-reuse facility must provide:

❚ logging for analysis,

❚ direct replay of an experience from start to finish,

❚ explicit queries over recording information,

❚ replaying with a changing viewpoint,

❚ replaying selected parts of a recording only,

❚ replaying with multiple simultaneous viewpoints,

❚ controlling replay timing,

❚ replaying recordings as part of live experiences, and

❚ making nested recordings.

Several communities, such as the gaming and VR communi-ties, have used record-and-reuse mechanisms to move from livead hoc experiences to more persistent environments. Althoughno work has explicitly addressed the problem of mixed-realityshow production, a wide range of relevant techniques use someform of the record-and-reuse technique and might be useful forbuilding a generic record-and-reuse infrastructure.

Over the last 10 years, the VR community has worked todevelop persistent collaborative virtual environments. This efforthas culminated in recent proposals of a flexible mechanism forrecording all of the activity in a virtual environment, manipu-lating these recordings, and later accessing them as new con-tent within other live virtual environments, including accessingrecordings within recordings.

At the heart of this mechanism is a technique for capturingall activities within a collaborative virtual environment (CVE),including the environment itself, multiple users’ movements,speech (over real-time networked audio), and interactions withvirtual objects, such that users could faithfully recreate theaction later. The producer could embed the resulting 3Drecordings in a live virtual environment. Application develop-ers and end users could then program and directly manipulatethe temporal, spatial, and presentational relationships betweenthe live environment and the recordings. Action within the liveenvironment could take place around and within the display of

the recorded activity, and the composition of the two coulditself generate further recordings. The community has demon-strated a variety of the mechanism’s applications, including hav-ing live actors improvise scenes to develop virtual world contentquickly; accessing virtual mail messages and flashbacks withinlive virtual worlds; and supporting both human−computerinteraction and system-level analysis of CVE experiences.

In multiplayer 3D games, researchers focused on developingrecord and replay techniques to display highlights of previousgame play. Examples include Electronic Arts’ FIFA Soccer and theGT Interactive Software’s automobile game Driver. Driver alsolets players create movies from recordings of their own actions.In a related area, recent work on virtualized reality captures liveaction in a physical environment by analyzing recordings frommultiple video cameras to produce a 3D graphical simulation.2

Examples of related work that refers to temporal propertiesin multimedia applications, but not specifically to VR, includethe Media Editor Toolkit (MET++), an application frameworkwith methods for manipulating temporal relations in multime-dia presentations. Trends are moving toward spatiotemporalmodels that provide a framework for composition and index-ing of multimedia objects. Systems are being developed to letusers incorporate recently recorded video and 2D sketches intoreal-time activities such as brainstorming meetings. The WorldWide Web Consortium has also adopted the Synchronized Mul-timedia Integration Language (SMIL) to deal with the tempo-ral aspects of authoring multimedia productions.3

The work discussed in this article as well as the vast amountof research in effective video summarization and scene and fea-ture extraction gives us a lot of tools to work with. Although thesetechniques and approaches can be useful in specific stages in ageneric record-and-reuse pipeline, achieving ease of deployment,interoperability, low cost, and scalability of such an infrastructurerequires that we address several fundamental limitations.

Currently, systems log all of the data produced in a typicalmixed-reality game or performance in a row format and store itcentrally, often without even globally synchronized time stamps.Consequently, the postproduction team must manually indexand cross-reference most of the files before they can apply any ofthe processing tools and techniques mentioned earlier.

References1. A. Drozd et al., “Using Record and Reuse Technologies to Create

a Mixed-Reality TV Show,” Proc. Equator Record and Reuse Work-

shop, 2004, http://www.mrl.nott.ac.uk/~sdb/r&rworkshop.

2. T. Kanade et al., “Virtualized Reality: Digitizing a 3D Time-Vary-

ing Event As Is and in Real Time,” Mixed Reality, Merging Real

and Virtual Worlds, Y. Ohta and H. Tamura, eds., Springer-Ver-

lag, 1999, pp. 41-57.

3. J. Ayers et al., eds., “Synchronized Multimedia Integration Lan-

guage (SMIL2.0),” World Wide Web Consortium Recommenda-

tion, Aug. 2001; http://www.w3.org/TR/smil20.

and video streams rather than sophisticated toolsor large development teams. We need an infra-structure to support the provenance and contextof (often) transient resources (for example, data ortools and services being changed and updated)that could support richer user interaction with theresources. More specifically, we identify key Gridand peer-to-peer capabilities that can bring us clos-er to such a large-scale generic record-and-reuseinfrastructure for mixed-reality experiences.

Mixed-reality environmentsMixed-reality environments often take the

form of games in which physical players (playersparticipating in the game from the physical worldusing maps such as those in Figure 1) and onlineplayers (that is, players participating in the gamefrom their home desktops using the interface inFigure 2) compete, collaborate, and try to establishan understanding of each other’s environment.Digital content mixes with live action to create acompelling experience for both player types. Inaddition to the Nokia Game, Majestic and Bon-Fighters are examples of games designed to envel-op consumers in a mixed-reality world.1

Some researchers have used mixed-realityenvironments to bring new kinds of artistic per-formances and cultural experiences to the streets,theatres, museums, and online.3,4 Creating high-quality artistic products for large-scale publicdeployment requires working with professionalartists and commissioning bodies.

Offline sharing and processing of previousexperiences in mixed-reality worlds is anotherinteresting context for mixed-reality environ-ments. For example, people could make personalrecords of their collaborative experiences. Moreinterestingly, postprocessing could be pushedtoward production of mixed-reality televisionshows, radically changing the TV industry. Mixed-reality TV shows combine fixed and wireless net-working with TV broadcasting in unconventional

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Multiple channels of information

Names of players (in red)

Names of runners (in blue)

Buildings

Area for text messages

(a) (b)

Figure 1. Maps used by physical players (or runners) in a mixed-reality game. (a) Handheld map shows online players’ and other

runners’ positions. (b) General location map and zoomed-in view of the street map.

Figure 2. Online player interface. The game drops online players into a 3D

model of the hosting city. Players move through the model with a fixed

maximum speed, access a city map view, and exchange text messages. They

also hear the runners’ walkie-talkie communication as a live audio stream.

ways. Inhabited TVa combination of collabora-tive virtual environments (CVEs) and broadcastTVhas been a topic of research since 1996through projects such as the Mirror (IlluminationsTelevision/BT/BBC), Heaven and Hell Live (Illumi-nations Television/BT/Channel 4), Out of ThisWorld (OOTW), and AvatarFarm (see http://machen.mrl.nott.ac.uk/home.htm). More recent-ly, mainstream television has started exploiting itcommercially through shows such as Fightbox(Richochet/BBC). Inhabited TV’s defining featureis that it lets an online audience socially partici-pate in a show that’s staged within a shared virtu-al world (or, more recently, a shared mixed-realityworld). The producer defines a framework, butaudience interaction and participation bring it tolife. The producer mixes the actions within thevirtual world into a broadcast stream that it trans-mits to a conventional viewing audience, either asa live event or as a postproduced and renderedbroadcast stream.

Mixed-reality show productionI use a mixed-reality production show as a tar-

get application because it highlights the mostimportant problems common to a range ofdesired interactions between users and multime-dia and mixed realities.

Mixed-reality television aims to move beyondtraditional broadcasting, in which viewers haveno control over what they see. This complexprocess poses a range of technical challenges. Forexample, individually broadcasting images fromeach camera lets viewers mix their own final pro-grams by switching between camera channels.

Alternatively, broadcasting the virtual world datalets viewers choose between the director’s mixand their own mix, and control their indepen-dent viewpoints. With a suitable networkbackchannel, a viewer could transition into aninhabitant, becoming embodied, active, and vis-ible within the event itself. At a more conceptuallevel, this work is similar to interactive digital art-works and installations, which combine com-puter graphics with aspects of live performance.An inhabited TV medium might make thesesame works available, although with an increasedconcern for the experiences of noninteracting(traditional) viewers.

Early mixed-reality showsEarly mixed-reality production processes

essentially involved creating a TV show from alive event with a production team consisting ofcamera operators, a director, and a technical sup-port crew working behind the scenes. Nonauto-mated approaches to camera control and mixingmainly relied on established human skills andwork patternssuch as the director and cameraoperators in Figure 3. Using a nonautomatedapproach, I explored how the change in tech-nology and medium influenced various produc-tion activities.

Existing TV-style broadcasting might be inap-propriate for 3D virtual worlds. For example, a1998 live inhabited TV show called Out of ThisWorld (University of Nottingham/IlluminationsTV/BT) demonstrated how dedicated virtual cam-era and participant-management technologiescould help create a relatively fast-paced and

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Figure 3. The director,

VT operator, and world

manager at work

during a show.

coherent game show within a collaborative vir-tual environment (CVE). A 2000 follow-up pro-ject called Avatar Farm attempted to create amore complex show. In the online drama, mem-bers of the public collaborated with professionalactors as part of a nonlinear drama consisting offour chapters roaming across four virtual worlds.In this work, researchers explored how inhabit-ed TV and 3D graphical environments can differfrom established experience with the physicalworld and identified the problems encounteredin combining multi-user virtual environmentswith television-style broadcasting.2 For example,in a normal television show, participants’ posi-tions and movements are tightly controlled tosupport the show’s presentation and timingwhereas in a multiuser virtual environmentachieving precise and coordinated movement isdifficult. A huge difference exists between thenatural pace of current virtual environments andthat of television: Television is typically tightlyscripted and directed to give an intense viewingexperience; interaction in general-purpose multi-user virtual environments is much more sedate.

Significant problems exist with camera controland navigation. More conservative researchershave sought to alleviate these problems usingtechniques such as appropriate world design,managed inhabitant and performer movement,and performance-oriented virtual camera controlinterfaces,5 while preserving a nonautomatedapproach. In contrast, some techniques attempt-ed, even in the early stages, to fully automatecamera work, direction, and mixing by applyingcinematic principles6,7 to computer graphics.These attempts usually prevented free navigationand interaction by using a constrained set ofhigh-level actions (such as “go to the bar”).

As our understanding of inhabited TVmatures, we’ll be able to integrate automation ina principled and informed way. This will let usdraw on the work discussed in the sidebar as wellas other work such as procedural interfaces forexpressing shots to use constraint-satisfaction,including path planning, camera placement, andshot composition for conveying information insemantically specified situations.8,9

Key activitiesThe production process can be considered a

pipeline of activities performed on one or moreinputs and producing one or more outputs. Foreach activity, there are a growing number of off-the-shelf production tools as well as tools devel-

oped in-house. The production process has threekey stages of activities:

❚ Designing and staging a (revised) liveexperience.

❚ Recording the live experience, including sys-tem-state recording of online action and videorecording of physical action using instru-mented fixed, steerable, and mobile cameras.

❚ Reviewing, selecting, and overdubbing thematerial.

In the recording stage, distributed infrastruc-ture records the online system state (avatarmovements, audio, video, text messages, and soon) as seen by a central server that provides thecanonical view of the experience. They also makevideo recordings with instrumented cameras sothey can cross-index themacross multipledimensions but primarily temporally and spa-tiallywith the system-state recordings.

In the reviewing stage, users and producersprimarily need to be able to analyze the record-ings to identify potential scenes of interest. Oncethey have a pool of scenes, they need to be ableto replay a short scene repeatedly, viewing itfrom different (virtual and physical) camera posi-tions. They also need to be able to overdub partsof the recordings. Overdubbing includes replay-ing the current recording, acting against it, andsaving a new version. All of the actions must benondestructive. Editing the recordings includes,for example, subtly changing an online player’strajectory through the model, removing certainplayers entirely, editing larger recordings intosmaller ones (in much the same way as in tradi-tional audio/visual media), and possibly mergingor joining recordings.

Early discussions with TV broadcasters con-sistently raised the concern that real-time com-puter graphics were of insufficient quality toprovide a compelling viewing experienceforexample, that avatars weren’t expressive enoughfor viewers to empathize with them. Currentinhabited TV shows mix computer graphicswith conventional video footage of real actorsand players. These shows are typically set in astudio environment, allowing producers to mixfootage of the human players and a studio audi-ence with computer graphics. During postpro-duction of the computer graphics, theproduction team creates offline rendered ani-

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mations that can match the quality of currentcartoons and animated films. Several tools andtechniques aim to support both approaches.Thus, we must export selected parts of therecordings in a format that’s useful to animationpackages and we need access to the state ofgiven item types at a given point in time.

Peer-to-peer grid approachWearable cameras and sensors, microphones,

virtual cameras, and various other ubiquitousdevices used in mixed-reality experiences providenew and exciting opportunities for querying, shar-ing, and monitoring mixed-reality worlds. Iexplore an approach for querying and using thearchived mixed-reality data and large number ofservices already being produced. To cope with largevolumes of mixed-reality data, large diversity ofservices, and potentially computationally inten-sive content-processing services, I propose a gener-ic middleware infrastructure that combines thebenefits of Grid10 and peer-to-peer11 paradigms.Both paradigms are overlay networks that attemptto solve the resource sharing problem. They differsignificantly in terms of application requirements,resource types, and user communities. My aim isto combine the benefits of the two paradigms togather mixed-reality resources, make them avail-able to end users and applications, and let userscollaborate securely by sharing processing and dataacross heterogeneous domains.

Peer-to-peer capabilitiesWhat capabilities of the emerging peer-to-peer

paradigm should we exploit? If we perceive theproduction of mixed-reality games and shows interms of numerous dynamically deployable het-erogeneous devices (such as cameras and iPaqs),then the dynamic discovery, assembly, and use ofthese devices over heterogeneous network con-nections requires a peer-to-peer layer. The basefunctionality of peer-to-peer systems supportsscalability, self-organization, robustness, andlightweight implementations, and layers built ontop of this layer would therefore support the samefeatures. For scalability, the system should storemixed-reality data close to the sources, but it cancache it elsewhere as dictated by the queries.

One of the most natural queries that usershave with such a system concerns rangeforexample, a user might be interested in all of themeetings that took place near a particular loca-tion within a certain time frame when the tem-perature was 20 degrees. The peer-to-peer

community has addressed this type of query andproposed several approaches for network-awared-dimensional range queries and approximaterange queries over distributed hash tables. Iassume that the necessary processing and meta-data attaching has already been done. This layerencourages public participation by giving com-plete autonomy to all peers.

Grid computing What can we learn from the Grid? Because

mixed-reality applications can involve complexand computationally intensive processing ofcommercial or private data, our infrastructureshould adopt the Grid’s approaches to security,its naming and binding model, resource man-agement virtualization abstractions, and ontolo-gies and data semantics. I aim to provideproduction teams, game developers, and ordi-nary users with a toolkit based on a high-levelmiddleware layer, enabling them to interact witha collection of semantically enriched servicesappropriate for mixed-reality show productions.More specifically, the middleware componentsaim to support construction, discovery, execu-tion, and management of the in silico produc-tion process, in which multiple services performthe workflow. A workflow is a pipeline of process-es, each representing a mixed-reality resource.The output from one resource can act as an inputto a successor resource.

The architecture exposes a pool of multimediaresources as services allowing rich interactionswith mixed-reality recordings. A recording can beabstracted as a mixed-reality resource and mod-eled consistently with the Global Grid Forum’s(GGF, http://www.ggf.org) Web ServicesResource Framework (WSRF). Mixed-realityresources include physical entities (such as a cam-era or global positioning system) and logical con-structs (a running workflow or a link betweenvideos, for example). They can be real or virtual,static (long lived) or dynamic (created anddestroyed as needed or on demand), alone or ina collection. They have distinguishable identitiesand lifetimes and are stateful (that is, they main-tain a specific state that can be materialized usingXML and accessed through one or more Web ser-vices). This statefulness is key to simplifyingprovenance capture and managementthat is,tracking down who has been working with a par-ticular recording and what he or she did with it.The Grid Security Infrastructure (GSI)10 serves asthe architecture’s security layer.

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Proposed infrastructureFigure 4 shows the proposed infrastructure. At

one end of the architecture are mixed-reality showproduction teams, game developers, ordinaryusers, and tool builders who require access tolarge-scale multimedia and computing resourcesand high-performance visualization back-end andsystem logs. At the other end are the physical andvirtual players, wearable (and nonwearable) sen-sors, GPSs, cameras, and iPaqs as well as toolbuilders that generate the data that will be storedin the (distributed) mixed-reality recordings repos-itory, service registry, and service-type registry.

The users in the architecture’s bottom layershare data in a peer-to-peer manner but if theywant to benefit from the Grid, they must firstpublish it in the system’s repositories.

The mixed-reality recordings repository lies atthe heart of the proposed architecture and con-tains rich data and metadata of heterogeneousrecordings. Several types of recordings have beenused across multiple projects: video and audiorecordings in different formats, real-time protocol(RTP) and transmission control protocol (TCP)dumps, sensors logs, VR platform recordings con-sisting of checkpoints and event logs, and consolelogs.12 The recordings share a common schemaand are associated with related resources such asgeometries, texture, and software components andtypes. Each recording (simple or compound)describes what the file is, where it came from, whatwe can do with it (for example, which types oftools to associate with them); specifies how therecordings relate to both the external/nominal ref-erences and to each other (that is, the dimensions

according to which of these relation-ships can exist, such as time, physicalspace, information, subject, andgenre); and finally describes the file’scontents and structure (that is, itallows for multiple substreams with-in the current stream with sequentialor random access).

Tool builders act as serviceproviders, publishing their tools andthe tool descriptions in the serviceand service-type registries. The ser-vice-type service describes what userscan do with their data (for example,extract scenes with meetingsbetween two people, visualize record-ings, or cross-index recordings), whattype of input the service expects, andwhat type of output it produces. The

service directory can then point the user to partic-ular instances of services performing that function,and the user can choose a service. Exposing toolsas services enhances interoperability but also helpsusers navigate the diversity of existing tools.

Because users might have complex queriesrequiring repeated assembly of a pipeline of toolsand humans in a loop to resolve, the architectureallows creation, storing, and enacting of suchcomplex processes, or workflows. A workflowrepository service and workflow engine servicestore (with full semantic descriptions) and enactthe workflows.

A notification service should be an integralpart of such an infrastructure. This service noti-fies users about events such as when someoneadds data to the mixed-reality recordings reposi-tory that contains information about a particu-lar location, or when someone uses your data fortheir workflow.

Clearly, much work remains before we can real-ize such an infrastructure. This is primarily becauseof the lack of ontology services that could be usedas glue between the mixed-reality recordings andservice-type repositories, workflow engine, andnotification service. Different ontologies would benecessary for different domainsfor example, arecently announced EU multimillion-euro six-yearproject (EPOCH) will use a similar approach butlimit it to the cultural heritage domain.

ConclusionEven if we meet the technical challenges, we

must still consider the ethics of creating experi-ences that could pervade people’s lives. There are

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Gateway

Distributed mixed- reality

recordings repository

Ordinary players Game developers

Peer-to-peer communication fabric

Workflow enactment engine

Service-typeregistry

Mixed-reality TV show production

teams

Recordings ontology

management service

Tool builders

QoS service

Notification service

Service registry

Tools, services,applications, componentsGPS, sensorsIPAQs PDAs cameras

Figure 4. Service-

oriented middleware

for mixed-reality TV

show production.

growing concerns that people involved in suchexperiences could become alienated from theirneighbors and friends, and thus damage theirsocial lives (in the traditional sense of the word).

The popularity of mixed-reality TV shows willundoubtedly increase and may enjoy even greatersuccess than the reality TV phenomenon. Supportfor richer means of communication between theaudience and the actors in a mixed-reality TVshow will replace the live chats and messageboards currently usedthat is, people will be ableto contribute content to these shows from any-where, anytime. If reality TV allows ordinary peo-ple to fulfill their fantasies of fame by being on TVand having millions of viewers, mixed-reality TVgoes one step further. It lets people produce morecreative and artistic forms of expression whileguaranteeing security and privacy. MM

References1. P. Guildford, A Persuasive Case for Pervasive Gaming,

http://www.analysys.com.

2. C. Greenhalgh et al., “Creating a Llive Broadcast

from a Virtual Environment,” Proc. Siggraph, ACM

Press, 1999, pp. 375-384.

3. S. Benford et al., “Coping with Uncertainty in a

Location-Based Game,” IEEE Pervasive Computing,

vol. 2, no. 3, July-Sept. 2003, pp. 34-41.

4. C. Greenhalgh, “Applications of Temporal Links:

Recording and Replaying Virtual Environments,”

Proc. IEEE Virtual Reality, IEEE CS Press, 2002, pp.

101-108.

5. S.M. Drucker, T.A. Galyean, and D. Zeltzer, “Cine-

ma: A System for Procedural Camera Movements,”

Proc. 1992 Symp. Interactive 3D Graphics, ACM

Press, 1992, pp. 67-70.

6. D. Arijon, “Grammar of the Film Language,” Com-

munication Arts Books, Hastings House, New York,

1976.

7. D. Seligmann and S. Feiner, “Automated Genera-

tion of Intent-Based 3D Illustrations,” Computer

Graphics (Siggraph 1991), vol. 25, no. 4, July 1991,

pp. 123-132.

8. D. Ritter, “The Intersection of Art and Interactivity,”

Ars Electronica Festival 96, Springer, 1996, pp. 274-

285.

9. L.-W. He, M.F. Cohen, and D.H. Salesin, “The Virtu-

al Cinematographer: A Paradigm for Automatic

Real-Time Camera Control and Directing,” Proc.

Siggraph, Addison Wesley, 1996, pp. 217-224.

10. I. Foster, The Grid: Blueprint for a New Computing

Infrastructure, 2nd ed., Morgan Kaufmann, 2004.

11. L. Garcés-Erice et al., “Data Indexing in Peer-to-

Peer DHT Networks,” Proc. 24th Int’l Conf. Distrib-

uted Computing Systems (ICDCS 04), IEEE CS Press,

2004, pp. 200-208.

12. M. Radenkovic and S. Benford, “A Multimedia

Framework for Mixed Reality TV Shows,” Proc.

Int’l Workshop Telecomm. (IWT), INATEL, 2004,

pp. 36-41.

Readers may contact Milena Radenkovic at mvr@cs.

nott.ac.uk.

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January–MarchComputing in Japan

This issue features an insider’s look at Hitachi’s role in the plug-compati-ble mainframe as well as IBM’s history of Far Eastern languages in com-puting.

July–SeptemberHistorical Reconstructions

With so many of the original artifacts of the original computing eragone or destroyed, some scientists are recreating old machines. Thisissue contains accounts of attempts to recreate old technology, such asthe Babbage Difference Engine and the IBM 1620, in new forms.

April–JuneBolt, Berenak, and Newman: Creating the Internet

Key players from BBN share their stories on how thecompany that created the Internet was formed.

October–DecemberFoundations in Computing

Take a look back to learn how computing hasevolved. Personal ancedotes, biographicalessays, and insightful commentaries round outthis issue.

2005Editorial Calendar

http://www.computer.org/annals