Location-Mediated Service Coordination in Ubiquitous Computing

Transcription

1 Locaton-Medated Servce Coordnaton n Ubqutous Computng Ako Sashma CARC, AIST / CREST, JST Aom, Koto-ku, Tokyo, , Japan sashma@carc.ast.go.p Norak Izum CARC, AIST / CREST, JST Aom, Koto-ku, Tokyo, , Japan nz@n.ast.go.p Koch Kurumatan CARC, AIST / CREST, JST Aom, Koto-ku, Tokyo, , Japan kurumatan@socsys.org ABSTRACT We propose locaton-medated servce coordnaton n ubqutous computng. In the coordnaton, mddle agents determne bestmatched servces for a user by consderng the user s locaton based on locaton-ontology for ubqutous computng. Introducng such locaton-aware mddle agents and locaton-ontology nto ubqutous computng, we can extend applcaton areas of software agents from the Internet to the real world. In ths paper, we frst llustrate the dea of locaton-aware mddle agents and locaton-ontology. Second, we descrbe a multagent archtecture, called CONSORTS, as an mplementaton of the agents. In order to brdge the gap between devce-orented physcal nformaton n the real world and web-based conceptual nformaton n the dgtal world, CONSORTS agents can translate sensor-based raw representaton of the locatons nto conceptual one. Fnally, we descrbe two applcatons of CONSORTS, an ntellgent nformaton assst system at a museum and wreless-lan based locaton system. Keywords Web Agents, Semantc Web, Ubqutous Computng, Servce Coordnaton 1. INTRODUCTION Two ntellgent servce frameworks, Ubqutous (or Pervasve) computng [25] and Semantc Web[2], receved much nterest n both research and applcaton n the past years. In order to mprove the current web-based servce frameworks, the Ubqutous computng handles devce-orented physcal nformaton; the Semantc Web handles ontologcal nformaton. Ubqutous computng enables computers to be aware of the context of users n the real world. The ubqutous computng envronment has numerous sensor devces and computers connectng to the networks. In the framework, the computers manage not only explct nformaton of the user nteracton but also physcal nformaton from sensors n the real world. For example, the ntellgent gude systems n a museum should manage both locaton and commands of the users n order to nteractvely offer nformaton about the exhbtons there. On the other hand, the Semantc Web enables computers to read the web contents by addng meta-data to the documents. The meta-data are developed on XML. One of such meta-data frameworks s RDF (Resource Descrpton Framework) [18] and RDFS (RDF Schema) [19]. In ths framework, the computers manage not only nformaton explctly descrbed n the content but also ontologcal nformaton of the content, whch are shared wth the computers on the Internet. For example, the computers handle the meta-data and the doman ontologes to understand the contents meanngs, such as dentfyng my father s father wth my grand father n a document. Although there are many researches nvolved n the Semantc Web and the Ubqutous computng, stll few researches [8] [20] try to brdge the gap between devce-orented physcal nformaton n the Ubqutous computng and web-based ontologcal nformaton n the Semantc Web. In order to realze ntellgent nformaton servces for our daly actvtes (e.g. shoppng assstants, museum gude, etc.), we need a servce framework that can seamlessly manage both of the nformaton because our actvtes are comprehensble wthn the physcal and ontologcal context. For such seamless servce framework, we have been developng a multagent archtecture named CONSORTS (Archtecture for cogntve resource management wth physcally-groundng agents) [5]. In the archtecture, mddle agents, locaton-aware mddle agents, can handle physcal and conceptual nformaton of envronments, and determne the best-matched servce accordng to the user s locaton. Brdgng the gap between devce-orented physcal nformaton n the real world and web-based conceptual nformaton n the dgtal world, CONSORTS agents can translate sensor-based raw representaton of the locatons nto conceptual one. In ths paper, we descrbe a framework of servce coordnaton mechansm n Ubqutous computng. We frst llustrate the dea of locaton-aware mddle agents and locaton-ontology. Second, we descrbe an mplementaton of CONSORTS archtecture. Fnally, we descrbe two applcatons of CONSORTS, an ntellgent nformaton assst system at a museum and wreless- LAN based locaton system. 2. LOCATION-MEDIATED SERVICE COORDINATION Although the ubqutous computng s a promsng framework of the ntellgent servces, t s stll premature and has many problems. One of the problems s about coordnaton among

2 servces. In a ubqutous computng envronment, a lot of servces are usually co-located (e.g. navgaton, gude, advertsng, nformaton retreval, controllng devces, etc.). When numerous servces can be smultaneously provded to a user, a servce coordnaton s requred to provde proper servces then and there. How can we realze such a servce coordnaton n ubqutous computng? One possble answer s to ntroduce mddle agents [21]. Mddle agents are matchmaker agents that match servce agents wth servce requester agents. The mddle agents medate the communcaton between the agents to acheve the good performance on the Internet. For example, Paolucc et al. [17] show the potental of the mddle agents by the orchestraton of Web Servces [24]. Ths mddle agents work effcently on the Internet, but t s not suffcent for the mddle agents n the Ubqutous Computng. Most researches focus on the problem how the software agents properly serve the user who operates a computer termnal connected to the Internet [13][16]. However, the mddle agents n the Ubqutous Computng must handle the nformaton of the locaton where servce provders and servce requesters communcate wth each other. If a servce s semantcally matched to a request but the servce resource s far removed from the requestng user, the servce should not be provded n the context of Ubqutous computng; the nearer servce resource to the user s often better than any other servces. 2.1 Locaton-Aware Mddle Agents In order to realze the servce coordnaton sutable for ubqutous computng, we propose locaton-medated servce coordnaton, and ntroduce new type of agent, spato-temporal reasoner. The spato-temporal reasoner manages sensor-based raw nformaton and conceptual nformaton of the envronment, such as physcal locatons of obects, and reasons of ther spatal relatons1. Usng the spato-temporal reasoner, we extend the conventonal mddle agent framework to realze the locaton-medated coordnaton n the Ubqutous computng. The locaton-medated coordnaton process conssts of followng agents: Requester Requester Requester request Servce Content Matchmakng Locaton-Aware Mddle Agent Spato-Temporal Reasoner Servce Provder advertse Servce Provder Query about Spato-Temporal Relaton Servce Provder Fgure 1. Locaton-medated servce coordnaton 1 To track the obect s locaton, we assume usng sensor devces (e.g. RF- ID tags, GPS, etc.) and ther nformaton are avalable. Servce Provder Agent: the agent that provdes some types of servce, such as problem solvng, medatng Semantc Web servces; Servce Requester Agent: the agent that needs provder agents to perform some servces for them; Locaton-Aware Mddle Agent: the agent that helps locate other agents along wth Spato-Temporal Reasoner; Spato-Temporal Reasoner: the agent that manages physcal locatons of Servce Provders and Servce Requesters, and reason about ther spatal relaton n cogntve way. The coordnaton s as follows: 1) provder agents advertse ther capabltes and physcal servce areas to mddle agents; 2) mddle agents store these advertsements, and nform ther servce areas to spato-temporal reasoners; 3) spato-temporal reasoners store these servce areas; 4) a requester asks some mddle agents whether they know provders wth desred capabltes; 5) the mddle agents ask some spato-temporal reasoners whether the stored servce areas cover the requester s locaton or not, and get the results, a subset of the stored servce areas; 6) takng account of the results, the mddle agent matches the request wth the stored advertsements, and returns the result, a subset of the stored advertsements (see Fgure 1.). In ths framework, the descrptons of locaton are separately managed n the spato-temporal reasoners, so servce contents modfcaton s not requred even f the servce areas are changed. For example, the content for an nformaton servce n a museum can be used n exhbtons n other museums, by only adustng the locaton nformaton to the museum. Addtonally, ths process s a natural extenson of matchng process proposed by Sycara et al.[21]. By ntegratng above agents wth ordnal web agents on the Internet, we can extend applcaton areas of Web agents (and Web Servces) to ubqutous computng envronment. 3. MODELING SPACE IN COGNITIVE WAY 3.1 Conceptual Representaton of Locatons To realze the locaton-medated servce coordnaton, the agents must share representatons of locatons (e.g. servce area, the requester s locaton, etc.). Moreover, the representaton must be human-frendly, conceptual ones. For example, to nform the user s locaton to others, the agents should understand the user was n a museum on the mornng, rather than the user was at Longtude: E, Lattude: N at Mon Jan 13 07:47: JST. Such human understandng of spatal

3 concept s generally called mereologcal thnkng [23], reasonng about part-of relaton. To realze ths knd of spatal reasonng as a basc functon of our agent archtecture, especally of Spatotemporal reasoner, we model ubqutous computng envronment wth a mereologcal, tree representaton. The representaton conssts of part-of relatons among 4-dmentonal spato-temporal regons n the real world Locaton and Regon Frst, we formularzed locatons of obects wth the spatotemporal regons usng the formalzaton by Bttner [3]. The formalzaton s as follows. The symbol o ( o O ) denotes an obect, and the doman of obects, o. The symbol x ( x X ) denotes a spato-temporal regon, and the doman of the regons, X. The doman of the s regons conssts of 3-dmentonal (spatal) regons, x, and 1- dmenatonal (temporal) regon x t. An obect o s exactly located at the regon x s formalzed as follows; o O : x s X : L ( o, x where the symbol τ denotes an nstance of tme. Weaker defnton of obect s locaton s as follows: t s L(o,x,x ) t s x':x' x τ x' : x : L ( o, x) x x where the symbol denotes the part-of relaton of the domans. Hence, L (John, hs room, ths mornng) means John was n hs room n ths mornng Tree Representaton We formularze the ubqutous computng envronments as a treestructure of spato-temporal regons based on Bttner [3]. A tree structure of spato-temporal regons s denoted by G : G = ( R, ) where R: ( r R) denotes a set of spato-temporal regons, denotes a part-of relaton between two regons. The regons n G have followng natures. where 1) r : r r k 2) r, r : r r r r r = r 3) r, r, r : r r r r r r r,, r rk s a regon. 3.2 Mereologcal Reasonng Now, we can nfer and query the obect s locaton usng ths notaton. For example, gven two statements: John was n hs room n ths mornng, and Hs room s part of ths buldng, we can nfer John was n ths buldng n ths mornng, we can nfer the Jhon s locaton as follows. τ τ k s ) k L(John, h s room, th s mornng ) hs room L(John, th s buldn g, ths mo rnng) ths bul dng Smlarly, we can defne the users that can receve the servce n ubqutous computng envronment, denoted by C, as: C = U{ Person : L( Person, anarea, aperod)} By usng ths knd of logcal nference, Spato-Temporal Reasoner can reason about ther spato-temporal relaton. Replyng results, a subset of the stored servce areas, denoted by SR, Spato- Temporal Reasoner can reason as SR = U{ r : L( person, r, aperod)} servce servce where rservce : rservce Rservce denotes a servce area of a set of servce areas n the envronment. Ontology of Spatal Regon (An example) Buldng Spatal Regon Property GUID:<Global Unque ID> Part -of:<spatal Regon> A-knd -of:<type of Regon> Includes: <Obect> Part-of a-knd-of Floor Entrance Part - of Buldng Floor Room Entrance Part - of a - knd - of Fgure 2 A part of locaton ontology Room Obect Includes Bed Room Class Room 3.3 Locaton Ontology Based on the above formalzaton, we defne a locaton ontology for the ubqutous computng. Fgure 2 shows the locaton ontology for descrbng spatal regon. We defne smlar type of ontology for descrbng temporal regon. We defne the relaton of spatal regons, and ther property n the ontology. Part-of relaton n the fgure s the relaton denoted by n before secton. The agents can descrbe obect s locaton, and reason about spatalrelaton based on the ontology. 3.4 Spato-Temporal Reasoner Spato-Temporal Reasoner manages spato-temporal nference engne and spatal nformaton repostory. The repostory manages the devce-orented physcal nformaton of the ubqutous computng envronments, such as locaton of users and

4 surroundng sensor devces. Locaton data are constantly updated, gven by devce wrapper agents. Spato-temporal reasoner also manages conceptual representaton of the envronment, tree-structure ( G n Secton 3.1.2). The mddle agent and varous servce agents, such as navgaton plannng, searchng the nearest devce to the user, use the treerepresentaton of envronment, and do not use the devce-orented raw representaton. It means that the reasoner hdes such complex representatons from other agents and humans. Hence, one of mportant functon of spato-temporal reasoner s brdgng the gap between sensor-based nformaton n the real world and cogntvely comprehensve annotated nformaton n the dgtal world (see Fgure 3.). For the translaton between two representatons, we defne statc mappng functons beforehand. Devce-orented Raw Representaton Fgure 3 Data representatons of spato-temporal reasoner 4. LOCATION-AWARE MIDDLE AGENT Locaton-aware mddle agent s an agent that help locate other agents along wth Spato-Temporal Reasoner The mddle agent orchestrates the varous servces of agents that manage sensor nformaton of the physcal envronment and ontologcal nformaton of the web servces. Although the mddle agents control the matchmakng process, the spato-temporal reasonng s outsourced to Spato-Temporal Reasoner. 4.1 Matchmakng The locaton-aware mddle agent matches the request aganst the stored advertsements wth takng account of the results from Spato-Temporal Reasoner. In our prototype system, we tentatvely defne the matchmakng process as followng expresson. S Trackng User Locaton wth Sensor Devce (e.g. RF - ID Tag, etc.) Conceptual Representaton 1 st Floor Entrance Pantng A = argmax= 1,2..n { u( S )} u( S ) = λ f ( SC ) + (1.0 λ) g( SR ) Translaton 2 nd Floor Room A Museum 3 rd Floor Room B Pantng B Room C Pantng C (0.0 λ 1.0) Where S denotes one of avalable servces n current stuaton. u( S ) represents a utlty functon of the servce S. λ denotes a constant value for a normalzed weght to matchng degree of contents for utlty functon u ( S ). f ( SC ) represents a matchng degree of a servce content SC. g ( SR ) represents a matchng degree of servce area SR. The mddle agent selects the most sutable servce whch has the maxmum utlty value among the servces. Ths coordnaton scheme s a basc functon n We can mplement complex servces, such as servce composton, as facltes of the mddle agents. Because the matchmakng process that we proposed s an extenson of the ordnal matchmakng process among agents on the Internet, the process model of DAML-S[7] can be apply to the descrpton of servce content. Therefore, we omt the descrptons for servce contents, and ther matchmakng process f ( SC ) n ths paper. We concentrate to descrbe the locaton based matchmakng process g ( SR ). 4.2 Locaton-based Matchmakng Locaton-based matchmakng process has two methods: the method that calculates matchng degree by part-of relatons, and by a-knd-of relatons. Each of two functons calculates the matchng degrees between servces and a user Matchng Degrees by Part-of Relatons Each of servces has a servce area that corresponds to a node of the tree representaton of the envronment. Ths matchng method calculates the matchng degrees based on part-of relatons of spato-temporal regons, whch nclude the servce areas, or the requester are located at. At frst, the agent flters the servce areas where the requester s located, then, calculates matchng degrees of each servce areas. The matchng degrees of the servce areas are dscrete values correspondng to the path lengths from root node to the nodes of the servce areas on a part-of relaton tree. In the tree representaton n Fgure 2, f the user s located at Entrance, the matchng degree s 2. In other words matchng degree of narrower regon has hgh value (e.g. g(room A) >g(1 st Floor) n Fgure 3) Matchng Degrees by a-knd-of Relatons Ths matchng method enables the requester to access the nformaton generally related to facltes of the place. For example, when a user s located at a lbrary, the user would lke to access sorts of book gudance servces. Ths servce s not related to the physcal locaton of the lbrary but related to the cogntve facltes of the lbrary. Ths knd of locaton-medated coordnaton s sutable for assst servces n a lot of places where human actvtes take place (e.g. staton, lbrary, museum, etc.). The matchng degrees are calculated based on a-knd-of relatons. When the servce provders and the requester are located at the dfferent place, a-knd-of relatons are used. At frst, the agent looks at the a-knd-of property of the regon where requester s located, and pck up the servces that have the same a-knd-of property. Then, the agent calculates the matchng degree of each servce provder.

5 The matchng degrees of the servce areas are dscrete values correspondng to the path lengths from root node to the nodes of the servce areas on a a-knd-of relaton tree. In the tree representaton n Fgure 2, f the user s located at Bedroom, the matchng degree s 2. Matchng degree of narrower regons have hgh values (e.g. g(bedroom ) >g(room) n Fgure 2).So the user receves the nformaton servces related to bedrooms rather than rooms. CONSORTS Archtecture Physcal World Moble User 1 Moble User n Camera, Wreless LAN RFID, etc. Communcaton and Sensng Devces Personal Agent Devce Wrapper Agents Locaton Aware Mddle Agent Inference Engne Agent Communcaton API Physcal Lnk Servce Agents Physcally Groundng Mechansm Spato-Temporal Reasoner Content Server Spatal Informaton Repostory Locaton-Ontology-based Semantc Informaton Devce-orented Physcal Informaton Fgure 4 Outlne of CONSORTS archtecture 5. IMPLEMENTATION In order to realze human-centered ntellgent nformaton servces n ubqutous computng, we have been developng CONSORTS (Archtecture for cogntve resource management wth physcallygroundng agents), an agent-based software archtecture that medates the real world and a dgtal world, for assstng human n accessng ntellgent nformaton servces. In ths secton, we descrbe the CONSORTS archtecture as an mplementaton of the locaton-aware mddle agents, and confrm the functonalty of the mddle agents n context-aware nformaton assst servce n a museum. 5.1 CONSORTS Archtecture The key concepts of CONSORTS are physcally-groundng and cogntve resources [15]. By usng sensory nformaton brought by ubqutous envronment, agents have a groundng n physcal world, and manage physcal resources (especally spato-temporal resources) n a cogntve way,.e., they can recognze, reorganze, and operate raw physcal resources as conceptual resources. Fgure 4 shows an outlne of CONSORTS Archtecture, whch conssts of followng type of agents. Servces Agents (Servce Provder Agent) provde servces, such as tour gude, navgaton, and nformaton presentaton. Servces agents realze the flexble servce by usng semantc nformaton through the content servers. The content servers are resources on the Internet, especally Semantc Web and Web Servces. Personal Agents (Servce Requester Agent) request servce behalf of a user. The agents communcate wth Devce wrapper agents, and manage them as user nterface devces. Locaton-aware Mddle Agents manage to nteracton to medate between agents and a user. The agent sends the request to the mddle agents, and controls the nteracton between servce agents and the user. In current verson, Matchng by a-knd-of Relaton s not mplemented. Spato-Temporal Reasoners manage physcal locatons of Servce Provders and Servce Requesters, and reason about ther spatal relaton n cogntve way. The agents manage both devce-orented physcal nformaton n the real world and cogntvely comprehensve nformaton n the dgtal world Devce Wrapper Agents hde the dversty of physcal devce and legacy applcaton. Devce Wrapper Agents realze devce-ndependent applcatons by wrappng the raw nformaton, whch s derved from legacy devces and applcatons, wth the standardzed agent communcaton language. 5.2 Context-Aware Informaton Assst Servce n a Museum Based on the CONSORTS archtecture, we have mplemented context-aware nformaton assst servce n a museum. In ths system, the agents are aware of the dstance between a user and pantngs n the museum. The servce system s that when the user approaches a pantng, the agents automatcally provde nformaton of the pantng va the user's portable dsplay devce. In the museum, user can access general museum nformaton based on the procedure of matchng degrees by a-knd-of Relatons. In addton, when a user s located near a pantng, the user can receve the nformaton of the pantng va the user s portable dsplay devce from the agents. Ths servce s based on the procedure of matchng degrees by part-of Relaton. Snce, the nformaton of the pantng s derved from the Internet resources (e.g. Web servces, Search Engne, etc.).for example, f the user needs more nformaton of the pantng, the user should push the tell me button of the portable devce. The CONSORTS agents notce the user's request, make a search query about the pantng wth the necessary nformaton they've already had, e.g. the pantng's name and user s preference, and access the nternet search engne, e.g. Google Web Servces [10], behalf of the user. Fgure 5 shows a snapshot of the montor dsplay of the system. You can see a museum map n a man wndow, two nformaton wndows wth some pctures, and a message wndow dsplayng agent communcaton. In the map, human cons represent current locatons of the users; the yellow zones represent servce zones of the museum servce agents; the blue lnes represent users traectores. The nformaton wndows correspond to the screen of users' portable devces. In ths demonstraton program, the users randomly roam n the museum. If a user enters the yellow zone, an nformaton wndow pops up n the screen to dsplay the pcture nformaton. Currently, users, users behavor, and a museum n ths system are smulated ones. However, we have desgned the devce wrapper agent to hde the dversty of the devces API, we can ntegrate the physcal devces nto the system on the CONSORTS.

6 Table 1 A message n the assstance system at the museum Fgure 5 Snapshot of the assstance system at the museum Physcal World Moble User 1 Interface and Sensng Devces Personal Agent wth User ID 8 Content Informaton Devce Wrapper Agents 6 7 Matched Servce User ID + Locaton Servce Request Content Informaton 3 5 Museum Servce Agents Content Database Request Rule-based Acton: If (Person on the Regon) then Inform Person of Servce Name. Locaton-Aware Mddle Agent Spato-Temporal Reasoner Fgure 6 Message flows n the assstance system at the museum Fgure 6 outlnes the agent communcaton n the museum system. Frst, the servce agent requests the mddle agent to contnuously nfer whether users are located on a servce regon assocated wth a servce name ([1] n Fgure 6). The mddle agent requests the Spato-Temporal Reasoner to request to nform when users are located on a servce regon ([2] n Fgure 6). On the other hand, the devce wrapper agent nforms the spato-temporal reasoner where a user wth unque d s located ([3] n Fgure 6). When the spato-temporal reasoner notce a user s located on a servce regon, the reasoner nforms the mddle agent of the user d ([4] n Fgure 6). The mddle agents tell the personal agents of the user avalable servce name ([5] n Fgure 6). Then, the personal agent requests a servce based on the servce name ([6] [7] n Fgure 6). Fnally, the personal agent requests the devce wrapper agent to show the servce content on a user s portable dsplay devce ([8] n Fgure 6). (REQUEST :sender PersonalAgent :recever MuseumAgent :content "((acton (agent-dentfer :name MuseumAgent) (provde (person :name PersonalAgent) (servce :name Monalsa :provder MuseumAgent)))" :language fpa-sl :ontology locaton-ontology ) All messages of the agent communcaton are descrbed wth FIPA-ACL (Foundaton for Intellgent Physcal Agents Agent Communcaton Language)[9]. The message content s descrbed wth FIPA-SL. Table 1 shows a message whch represents Personal Agent request to Museum Servce Agent to provde the servce named Mona Lsa (showng nformaton about the pantng of the Mona Lsa). Ths message flows at arrow-lne [6] n Fgure 6. Although we have already mplemented RDF-based descrptons as a content part of the message, we adopt FIPA-SL as the content language for nteroperablty wth other agent platform n ths system. We are also plannng to adopt DAML famles [11][6] n the near future. We have mplemented the CONSORTS agents usng JADE [12], a software framework to develop the agent system that conforms to FIPA specfcatons. Usng standardzed ACL lke FIPA-ACL, the system can connect to open agent systems, such as AgentCtes [1]. Hence, usng the CONSORTS archtecture, FIPA-agents can share the physcal nformaton and devces n the museum, and open the possblty of new servces whch use the physcal resources over the world. In ths demonstraton system, we have shown the potental of the dstrbuted open agent systems that can brdge devce-orented physcal nformaton n the real world and web-based conceptual nformaton n the dgtal world. 5.3 Wreless-LAN based Locaton System Based on the CONSORTS archtecture, we have mplemented Wreless-LAN (IEEE b) based Locaton System. In ths system, the agents are aware of user locaton by watchng the status of the wreless-lan statons. The servce system s that when the PC or PDA wth a user connects wth one of the statons, the system detects the connecton, and store a MAC address of the network card of the PDA wth physcal locaton of the staton. Because a MAC addresses s a globally unque, the system can track the locaton of the card (wth the user) globally. Fgure 7 shows an outlne of the locaton system. In the system, Web servces, whch provde locaton nformaton lke sensor

7 devces, are ntegrated wth a FIPA-agent platform, and the locaton nformaton s shared wth FIPA-agents. Users Real World Wreless-LAN based Locaton System Wf Card Web Browser CONSORTS FIPA Agent Networks Frewall Web Servce HTTP Wreless-LAN Wf Card Access Pont Wf Card Montor Wrapper Agent Spato-Temporal Reasoner SOAP HTTP FIPA-ACL FIPA-ACL Wreless-LAN Wrapper Agent Web Servce Access Pont Wf Card SOAP Fgure 7 Outlne of wreless-lan based locaton system We have expermentally confrmed the functonalty wth real wreless-lan statons that located on varous ctes, (e.g. Barcelona, Tokyo, etc.) n the world. Fgure 8 shows a snapshot of the montor wndow of the locaton system n that experment. Fgure 8 Snapshot of the locaton repostory In ths experment, we have shown the potental of the dstrbuted open agent systems that can access and unfy the real world nformaton coverng all over the world. 6. RELATED WORK CoolAgent [4] s a context-aware software agent system. The agents can share the context nformaton descrbed by RDF that can be an ontology descrpton framework for the Semantc Web. However, CoolAgent system does not provde the desgn framework of ubqutous agents, such as locaton-aware mddle agent. In ths paper, we formally descrbe the desgn pattern of the coordnaton of ubqutous agents. There are some researches for mddle agents[21][22][17]. As we descrbed before, the work n ths paper s extenson of ther works n ubqutous computng. Hence, ther results, such as ntegraton of DAML-S, must be useful for our future research. 7. FUTURE WORK As future work, we are plannng to ntroduce the concept of Mass User Support [15]. Exstng context-aware applcatons provde nformaton for a sngle user. However, f the applcatons provde some users wth the same nformaton at the same tme, serous conflct wth users behavor, such as a long queue formed n front of a tourst attracton, may be aroused. In that stuaton, the total performance to assst users actvtes wll decrease. Thus, we are plannng to realze the servce whch has faclty to resolve the conflct wth mult users requrements and to mplctly modfy the provdng nformaton for each user n order to mantan the performance of the whole system. We are mplementng the faclty usng market mechansm, called user ntenton market. [14] 8. CONCLUSION In ths paper, we descrbed a framework of servce coordnaton mechansm n Ubqutous computng. We frst llustrated the dea of locaton-aware mddle agents and locaton-ontology. Second, we descrbed an mplementaton of CONSORTS archtecture. Fnally, we descrbed two applcatons of CONSORTS, an ntellgent nformaton assst system at a museum and wreless- LAN based locaton system. In our demonstraton systems, we have shown the potental of the dstrbuted open agents n the real world. In the Semantc Web[2], an agent s defned as the program that collects nformaton from dverse sources, processes the nformaton and exchanges the results wth other programs. We have realzed such agents n the context of the Ubqutous computng, and extended applcaton areas of the agents from the Internet to the real world. 9. REFERENCES [1] AgentCtes Web, [2] Berners-Lee, T., Hendler, J. and Lassla, O., the Semantc Web. Scentfc Amercan, [3] Bttner, T., Reasonng about qualtatve spato-temporal relatons at multple levels of granularty. In F. van Harmelen (ed.): ECAI Proceedngs of the 15th European Conference on Artfcal Intellgence, IOS Press, Amsterdam, 2002 [4] Chen, H. and Tola, S., Steps towards creatng a contextaware agent system. TR-HPL , HP Labs, [5] CONSORTS Archtecture Web, [6] DAML+OIL (March 2001) Reference Descrpton, [7] DAML Servce, [8] Fnn, T. and Perch, F., edtor. Proc. of the AAMAS Workshop on Ubqutous Agents on embedded, wearable, and moble devces, 2002

8 [9] The Foundaton for Intellgent Physcal Agents (FIPA), [10] Google Web APIs, [11] Hendler, J. and McGunness, D. L., DARPA Agent Markup Language (DAML). IEEE Intellgent Systems, 15 (6), 72 73, [12] Java Agent DEvelopment Framework (JADE), [13] Jennngs. N., An agent-based approach for buldng complex software systems. Communcatons of the ACM, 44 (4): 35-41, [14] Kurumatan. K., User Intenton Market for Mult-Agent Navgaton - An Artfcal Intellgent Problem n Engneerng and Economc Context; Kurumatan, K., Chen, S.-H.,Ohuch, A. (eds.), Proceedngs of The AAAI-02 Workshop on Mult- Agent Modelng and Smulaton of Economc Systems, Techncal Report WS-02-10, pp.1-4, AAAI Press, [15] Kurumatan. K., Socal Coordnaton n Physcally-Grounded Agent Archtecture, to appear n Proceedngs of Landscape Fronter Internatonal Symposum, [16] Maes, P., Agents that Reduce Work and Informaton Overload. Communcatons of the ACM, 37(7): pp.31-40, ACM Press, July [17] Paolucc, M., Kawamura, T., Payne, T. R., and Sycara, K., Semantc Matchng of Web Servces Capabltes. In Proceedngs of the 1st Internatonal Semantc Web Conference (ISWC2002), 2002 [18] Resource Descrpton Framework (RDF), [19] RDF Vocabulary Descrpton Language 1.0: RDF Schema, [20] Sashma, A., Kurumatan, K., and Izum, N., Physcally- Groundng Agents n Ubqutous Computng, Proc. of Jont Agent Workshop (JAWS2002), pp , [21] Sycara, K., Decker, K., and Wllamson, M., Mddle-Agents for the Internet, Proceedngs of IJCAI-97, January [22] Sycara, K., Klusch, M., Wdoff. S., and Lu, J., Dynamc Servce Matchmakng among Agents n Open Informaton Envronments, SIGMOD Record (ACM Specal Interests Group on Management of Data), Vol. 28, No. 1, , March, 1999 [23] Varz, A., C. and Casat, R., Parts and Places. The Structures of Spatal Representaton, Cambrdge, MA, and London: MIT Press, [24] Web Servces Actvty, [25] Weser, M., The computer for the 21st century. Scentfc Amercan, , Sep 1991.