Killer apps are highly transformative technologies that create new markets and widespread patterns of behaviour. IT generally, and the Web in particular, has benefited from killer apps creating new networks of users. The Semantic Web community on the other hand, is still unsure whether any of their applications could become a killer app. This paper sheds some light on the main aspects of killer apps in general, and compares them with the features of Protégé as a killer app for ontology curation and management

Alani, Harith

O'Hara, Kieron

Shadbolt, Nigel

English

Open Research Online

Open Research OnlineThe Open University’s repository of research publicationsand other research outputsCommon features of killer apps: A comparison withProte´ge´Conference or Workshop ItemHow to cite:Alani, Harith; O’Hara, Kieron and Shadbolt, Nigel (2005). Common features of killer apps: A comparisonwith Prote´ge´. In: 8th International Prote´ge´ Conference, 18-21 Jul 2005, Madrid, Spain.For guidance on citations see FAQs.c© 2005 The AuthorVersion: Accepted ManuscriptLink(s) to article on publisher’s website:http://protege.stanford.edu/conference/2005/Copyright and Moral Rights for the articles on this site are retained by the individual authors and/or other copyrightowners. For more information on Open Research Online’s data policy on reuse of materials please consult the policiespage.oro.open.ac.ukCommon Features of Killer Apps: A Comparison with Prote´ge´Harith Alani, Kieron O’Hara, Nigel ShadboltIntelligence, Agents, Multimedia GroupSchool of Electronics and Computer ScienceUniversity of Southampton, UKha@ecs.soton.ac.ukAbstract. Killer apps are highly transformative technologies that create new markets and widespread pat-terns of behaviour. IT generally, and the Web in particular, has benefited from killer apps creating newnetworks of users. The Semantic Web community on the other hand, is still unsure whether any of theirapplications could become a killer app. This paper sheds some light on the main aspects of killer apps ingeneral, and compares them with the features of Prote´ge´ as a killer app for ontology curation and manage-ment.1 IntroductionFor a technology to develop a large user base, it is helpful to exist applications in which (a) the technologyis essential, and (b) many users can find profit or utility. Such an application is often called a ‘killer app’.Killer apps appear in the intersection between technology, society and business. In the first place, killer appsare technological, that is, artificial solutions to perceived problems or opportunities. They need not be hi-tech,they could be simple gadgets or even non-physical systems (such as double-entry book-keeping). The effect ofa killer app in a domain is to increase network effects so that a large community of users develops and reachescritical mass. This community will have enough members to attract new users, not by the underlying technolo-gies, but by the opportunities (whether commercial, scientific or just fashionable) created by the existence ofthe community itself.The development of the Web was greatly boosted by a number of killer apps that increased the usability,desirability and utility of the Web, thereby attracting users beyond the academic community. Applications suchas eBay allowed new forms of behaviour that users find attractive; Amazon extended the experience of shoppingfor books; Google made navigation through the web less hit-and-miss.It has often been observed that the Semantic Web (SW) needs to gain similar momentum to the Web;Metcalfe’s Law [1], which states that the utility of a community is proportional to the square of the number ofmembers, implies that a large network needs to be in place before the utility of the SW will become visible. Inthat case, SW research may well be aided by informed guesses about what a SW killer app would look like.Research in this area is not just an example of academics trying misguidedly to think like entrepreneurs; rather,the success of the SW as a technology depends to some extent on where the killer apps lie.However, mere innovation is not enough. A killer app must meet a need, or open up some opportunity,for enough people to create a critical mass of users; hence its use must integrate into people’s work or otherbehaviour patterns. And, as well as the social aspects of the user base, there must be sufficient economicadvantage for some businesses to take the risk of development and marketing.In this paper, we discuss the notion of killer apps in the SW, in the context of Prote´ge´. The idea of a killerapp sounds very broad, but there is quite a literature on the ways that killer apps transform business contexts. Inthe next section we will discuss potential features that killer apps are thought to require, and features thoughtto be desirable, and link these into the current state, and potential, of Prote´ge´, in relation to the SW, and itsinevitable needs for ontology management.2 Killer Apps on the Semantic WebSpotting a killer app is in reality as much art as science. However, there have been a number of academic andbusiness studies of the concept, e.g. [2][3], which tend to discuss and categorise killer apps by some of thefeatures they exhibit in relation to their environment; of course, context is very important to judging killer apps,an application that appears at the wrong time or in the wrong context is as good as useless.In the remainder of this section, we will think about killer apps in the context of both the SW as an envi-ronment, and Prote´ge´ as a technology applied in that environment. We will discuss some of the features thatwould be useful for the SW, and map these features onto general features that we might expect to see in a killerapp, and onto the current structure of, or potential for development for, Prote´ge´.Prote´ge´ has evolved over many years to become one of the most popular tools in ontology editing andmanagement, with more than 26K registered users at the time of writing. Prote´ge´ has certainly become a killerapp in its niche domain. For Prote´ge´ to reach this level of popularity it must have shown some superiorityover other similar tools, such as OntoEdit, Ontolingua, WebOnto, OilEd, and KAON, which all co-existed withProte´ge´ at some point in time. A comparison of earlier versions of these tools is detailed in [4]. Results showedthat Prote´ge´ has many superior features to most of its competitors at the time, such as open source, freelyavailable, extendible design, friendly user interface, range of plugins offering additional features, excellenttechnical support, etc. A quick look at the qualities that boosted Protege’s popularity may teach us some lessonsabout developing killer apps in general, and SW killer apps in particular.2.1 IndispensabilityThere is nothing better than being indispensable to make one wanted. This is as true of killer apps as it is inany other area of life. Such an app must grow into an essential part of an existing market (e.g. eBay, Amazon)or even create a new market of its own (e.g. Napster). Being first in a new market is a distinct advantage [2][3],but late entrants can also succeed if they outperform existing services [5].Support for Ontology Development: There is no doubt that ontologies will be one of the SW supportingpillars. The simplicity of Prote´ge´’s user interface made ontology development and management a much lesscostly and challenging task. Manually writing ontologies directly in RDF or OWL is out of the question, andhence a graphical tool to shield the complexity of SW languages is certainly very beneficial.In addition to editing an ontology schema, ontology developers often need to query it, compare it with otherontologies, extend it with further schemas, populate it with instances, etc. Prote´ge´ addressed such needs andexpanded its use to not only the edition of schemas, but also of building and managing entire Knowledge Bases(KB).2.2 Hitting the markOne important feature that a killer app must have is the ability to meet a range of requirements for a particulartask. The technology must also outstrip its opponents, usually in terms of costs, but also by doing the job better,or by providing extra services interleaved with the fundamental taskCost: Killer apps are often cheaper than similar, or alternative, market products [3]. The more affordablean application is to obtain and operate, the more users will be able to embrace it. Giving an application or asystem for free is probably the best cost-effective approach to make them ubiquitous [6].Superiority: A killer app has to provide higher service quality than other existing technologies to justifyits use and attract the masses (e.g. email vs post mail, broadband vs dial-up connection).Ease of Use: Easy to use, non-complex applications certainly increase the likelihood of their adoption andusage. Imagine where the Web would be now if everyone had to learn HTML before they could even browse it!Personalisation: Customers tend to become more loyal to services they can customise to their liking [2].Many of today’s killer apps have some level of personalisation. Amazon for example makes recommendationsbased on what the customer buys or looks at, Auto Trader 1 and Rightmove2 save customers’ searches and notifythem via emails when a new result to their query is available. Personalised web services attract more customers(if done properly!) and provide better tailored services [5].1 http://www.autotrader.co.uk2 http://www.rightmove.co.uk2.3 Leveraging Metcalfe’s LawFinally, an important task for any killer app is to develop a user community, a large number of users each ofwhom adds value to the network.Communities of Practice: A killer app should have the potential to create a community of users and aidthis community to grow and develop. Metcalfe’s Law states that the utility of a network is proportional to thesquare of its user base [1], and so a tenfold increase in the number of users, for instance, makes the networkone hundred times more valuable. This law is often used to explain the success of many of today’s killer apps[2][6][5], and the value of networked applications such as the Internet, email, and instant messaging software.One email account is useless as there will be no one to email! But as the number of email accounts increases,so will the value of this application.Take Yahoo messenger for example. They made it very easy for existing members to invite others to down-load and use the tool. They also provide a number of games and chat rooms where members can meet toencourage the creation of more interconnections between their members, thus boosting their network value.Open Systems: When a system opens to direct interactions with other existing systems, its value increasesby acquiring additional value from those systems [6]. By being open source and extendable, Prote´ge´ allowedmany existing systems and tools to be linked or integrated with it, thus increasing Prote´ge´’s use and value. Forthis reason, and for being available for free, Prote´ge´ is quickly becoming the default ontology editing tool.Active User Community: User community of Protege increased dramatically once it became open sourceand freely available [7]. This has benefited the tool greatly by widening its user base, thus increasing its networkvalue by many folds.Prote´ge´ supported its large community through emailing lists, short courses, and conferences, providing itwith an excellent technical support which has so far been up to scale, another quality of Prote´ge´, missing frommost of its competitors.By going open source, and adopting an extendable architecture, Prote´ge´ managed to move part of thedevelopment effort to third parties. User were able to build their own personal extensions to Prote´ge´, and manythird party plugins have become available to the community. The continuous emergence of plugins is one ofthe most attractive features of Prote´ge´, which made it stand out amongst other similar tools.2.4 A range of requirements for the Semantic WebAll of these considerations leads us to think of how the SW in general, and the tasks associated with ontologymanagement in particular, will ideally drive development of Prote´ge´. Essential aspects of the new SW environ-ment with which Prote´ge´ may have to grapple include the range of SW languages that have been appearing andwill continue to appear, the potential size of the SW, and issues related to the publishing of and access to onlineknowledge services.Language Support: Prote´ge´ has been quick to endorse new SW schema representation languages, suchas RDF and OWL, thus staying up to date with W3C’s latest standardisations. With respect to RDFS, Prote´ge´extended the language to enable it to express certain things, such as cardinality, multiple slot range, etc. [8].Even though those extra representations did not conform to the RDFS standard, but they were necessary formore detailed domain representations. Those extensions are specific to Prote´ge´, and hence can not be read byother RDFS tools.Scalability: Not a long time ago, much effort was given for building very large ontologies (e.g. CyC 3,Gene Ontology4, SUMO5). As the SW is developing, particularly under the stimulus of the annual SemanticWeb Challenge, we are beginning to see knowledge bases containing small to medium size ontologies, but withvery large number of instantiations [9]. The winner of the 2003 challenge, CS AKTive Space[10], contained25m RDF triples stored in 3Store6, while the winner in 2004, Flink7, had 35m stored in a Sesame8 KB. KBs ofthis order require a great deal of management.3 http://www.cyc.com/4 http://www.geneontology.org/GO.biblio.shtml5 http://ontology.teknowledge.com/6 http://www.aktors.org/technologies/3store/7 http://prauw.cs.vu.nl:8080/flink/8 http://www.openrdf.org/Prote´ge´’s main design goals where interoperability, and ease of use [11]. Scalability was not at the heartof Prote´ge´’s design, as is the case with some triple stores, such as 3Store 9, Sesame10, and Kowari11. Thisneeds to be addressed if Prote´ge´ is to be used as a platform for launching SW applications. Prote´ge´ certainlyoffers much more than the triple stores mentioned above, in terms of editing capabilities, data visualisation,ontology merging tools, versioning, etc. If Prote´ge´ is to deploy services over large KBs, then it has to scaleaccordingly. RDF and OWL database backends for Prote´ge´ are available for dealing with large KBs. TheRDF(s)-DB backend plugin that connects Prote´ge´ to a Sesame repository is a good effort [12], assuming thatProte´ge´’s user interface can also scale to high limits.Publishing and Access: Providing online knowledge services is a crucial part of launching the SW. Thetriple stores mentioned earlier are designed for this purpose, with online querying facilities using queryinglanguages such as RDQL and SPARQL. Both of these languages are W3C standards for querying RDF stores.Prote´ge´ currently does not have a strong and current support for such languages.3 ConclusionsWe have looked at some important factors in the development of the Semantic Web. Ontology development andmanagement will be an essential task, and tools will be required for this. But for an application to become akiller app for the SW it has to meet certain requirements and possess certain qualities.We discussed those features and qualities in the scope of Prote´ge´, which managed to become a killer appfor ontology editing and management for a large number of SW enthusiasts. By looking at analyses of thecharacteristics of killer apps in general, and the requirements of the SW in particular (even requirements thatstrictly go beyond what Prote´ge´ is capable of providing), we can get some sense of how Prote´ge´ should developfurther in the SW context.AcknowledgmentsThis work is supported under the Advanced Knowledge Technologies (AKT) Interdisciplinary Research Collaboration(IRC), which is sponsored by the UK Engineering and Physical Sciences Research Council under grant number GR/N15764/01.The AKT IRC comprises the Universities of Aberdeen, Edinburgh, Sheffield, Southampton and the Open University. Theviews and conclusions contained herein are those of the authors and should not be interpreted as necessarily representingofficial policies or endorsements, either express or implied, of the EPSRC or any other member of the AKT IRC.References1. Gilder, G.: Metcalfe’s law and legacy. Forbes ASAP, 13 September (1993)2. Downes, L., Mui, C.: Unleashing the Killer App. MIT Press, Harvard Business School Press (2000)3. Christensen, C.M.: The Innovator’s Dilemma. Harvard Business School Press (1997)4. Go´mez-Pe´rez, A., Ferna´ndez-Lo´pez, M., Corcho, O.: Ontological Engineering. Springer-Verlag (2004)5. Evans, P., Wurster, T.: Blown to Bits. Harvard Business School Press (2000)6. Kelly, K.: New Rules for the New Economy: 10 Radical Strategies for a Connected World. Penguin Books (1998)7. Gennari, J.H., Musen, M.A., W.Fergerson, R., Grosso, W.E., Crube´zy, M., Eriksson, H., Noy, N.F., Tu, S.W.: Theevolution of protege: An environment for knowledge-based systems development. International Journal of Human-Computer Studies 58 (2003) 90–1238. Noy, N.F., Sintek, M., Decker, S., Crubezy, M., Fergerson, R.W., Musen, M.A.: Creating semantic web contents withprotege-2000. IEEE Intelligent Systems (2001) 60–719. Klein, M., Visse, U.: Semantic web clahhenge 2003. IEEE Intelligent Systems 19 (2004) 31–3310. Shadbolt, N., monica schraefel, Gibbins, N., Harris, S.: Cs aktive space: or how we stopped worrying and learned tolove the semantic web. In: Proc. 2nd Int. Semantic Web Conf, Florida (2003)11. Noy, N.F., Fergerson, R.W., Musen, M.A.: The knowledge model of protege-2000: Combining interoperability andflexibility. In: Proc. 2nd Int. Conf. Knowledge Engineering and Knowledge Management (EKAW’2000), Juan-les-Pins, France (2000)12. Askar, K., Siril, Y., Dougherty, M.: Passerelle - a plug-in that connects prote´ge´ to sesame. In: Proc. 8th Int. Prote´ge´Conference, Madrid (2005)9 http://www.aktors.org/technologies/3store/10 http://www.openrdf.org/11 http://www.kowari.org/

Common features of killer apps: A comparison with Protégé

Southampton (e-Prints Soton)

Common Features of Killer Apps: A Comparison with Prot´ eg´ eHarith Alani, Kieron O’Hara, Nigel ShadboltIntelligence, Agents, Multimedia GroupSchool of Electronics and Computer ScienceUniversity of Southampton, UKha@ecs.soton.ac.ukAbstract. Killer apps are highly transformative technologies that create new markets and widespread pat-terns of behaviour. IT generally, and the Web in particular, has beneﬁted from killer apps creating newnetworks of users. The Semantic Web community on the other hand, is still unsure whether any of theirapplications could become a killer app. This paper sheds some light on the main aspects of killer apps ingeneral, and compares them with the features of Prot´ eg´ e as a killer app for ontology curation and manage-ment.1 IntroductionFor a technology to develop a large user base, it is helpful to exist applications in which (a) the technologyis essential, and (b) many users can ﬁnd proﬁt or utility. Such an application is often called a ‘killer app’.Killer apps appear in the intersection between technology, society and business. In the ﬁrst place, killer appsare technological, that is, artiﬁcial solutions to perceived problems or opportunities. They need not be hi-tech,they could be simple gadgets or even non-physical systems (such as double-entry book-keeping).The effect ofa killer app in a domain is to increase network effects so that a large community of users develops and reachescritical mass. This community will have enough members to attract new users, not by the underlying technolo-gies, but by the opportunities (whether commercial, scientiﬁc or just fashionable) created by the existence ofthe community itself.The development of the Web was greatly boosted by a number of killer apps that increased the usability,desirability and utility of the Web, thereby attracting users beyondthe academic community.Applications suchas eBayallowednewformsofbehaviourthatusersﬁndattractive;Amazonextendedtheexperienceofshoppingfor books; Google made navigation through the web less hit-and-miss.It has often been observed that the Semantic Web (SW) needs to gain similar momentum to the Web;Metcalfe’s Law [1], which states that the utility of a community is proportional to the square of the number ofmembers, implies that a large network needs to be in place before the utility of the SW will become visible. Inthat case, SW research may well be aided by informed guesses about what a SW killer app would look like.Research in this area is not just an example of academics trying misguidedly to think like entrepreneurs;rather,the success of the SW as a technology depends to some extent on where the killer apps lie.However, mere innovation is not enough. A killer app must meet a need, or open up some opportunity,for enough people to create a critical mass of users; hence its use must integrate into people’s work or otherbehaviour patterns. And, as well as the social aspects of the user base, there must be sufﬁcient economicadvantage for some businesses to take the risk of development and marketing.In this paper, we discuss the notion of killer apps in the SW, in the context of Prot´ eg´ e. The idea of a killerapp sounds verybroad, but there is quite a literature on the ways that killer apps transformbusiness contexts. Inthe next section we will discuss potential features that killer apps are thought to require, and features thoughtto be desirable, and link these into the current state, and potential, of Prot´ eg´ e, in relation to the SW, and itsinevitable needs for ontology management.2 Killer Apps on the Semantic WebSpotting a killer app is in reality as much art as science. However, there have been a number of academic andbusiness studies of the concept, e.g. [2][3], which tend to discuss and categorise killer apps by some of thefeatures they exhibit in relation to their environment;of course, contextis very importantto judgingkiller apps,an application that appears at the wrong time or in the wrong context is as good as useless.In the remainder of this section, we will think about killer apps in the context of both the SW as an envi-ronment, and Prot´ eg´ e as a technology applied in that environment. We will discuss some of the features thatwould be useful for the SW, and map these features onto general features that we might expect to see in a killerapp, and onto the current structure of, or potential for development for, Prot´ eg´ e.Prot´ eg´ e has evolved over many years to become one of the most popular tools in ontology editing andmanagement, with more than 26K registered users at the time of writing. Prot´ eg´ e has certainly become a killerapp in its niche domain. For Prot´ eg´ e to reach this level of popularity it must have shown some superiorityover other similar tools, such as OntoEdit, Ontolingua,WebOnto, OilEd, and KAON, which all co-existed withProt´ eg´ e at some point in time. A comparisonof earlier versions of these tools is detailed in [4]. Results showedthat Prot´ eg´ e has many superior features to most of its competitors at the time, such as open source, freelyavailable, extendible design, friendly user interface, range of plugins offering additional features, excellenttechnicalsupport,etc. A quicklookat the qualities that boostedProtege’s popularitymayteach us some lessonsabout developing killer apps in general, and SW killer apps in particular.2.1 IndispensabilityThere is nothing better than being indispensable to make one wanted. This is as true of killer apps as it is inany other area of life. Such an app must grow into an essential part of an existing market (e.g. eBay, Amazon)or even create a new market of its own (e.g. Napster). Being ﬁrst in a new market is a distinct advantage [2][3],but late entrants can also succeed if they outperform existing services [5].Support for Ontology Development: There is no doubt that ontologies will be one of the SW supportingpillars. The simplicity of Prot´ eg´ e’s user interface made ontology development and management a much lesscostly and challenging task. Manually writing ontologies directly in RDF or OWL is out of the question, andhence a graphical tool to shield the complexity of SW languages is certainly very beneﬁcial.In additionto editingan ontologyschema, ontologydevelopersoftenneed to queryit, compareit with otherontologies, extend it with further schemas, populate it with instances, etc. Prot´ eg´ e addressed such needs andexpandedits use to not only the edition of schemas, but also of building and managingentire Knowledge Bases(KB).2.2 Hitting the markOne important feature that a killer app must have is the ability to meet a range of requirements for a particulartask. The technologymust also outstrip its opponents,usually in terms of costs, but also by doing the job better,or by providing extra services interleaved with the fundamental taskCost: Killer apps are often cheaper than similar, or alternative, market products [3]. The more affordablean application is to obtain and operate, the more users will be able to embrace it. Giving an application or asystem for free is probably the best cost-effective approach to make them ubiquitous [6].Superiority: A killer app has to provide higher service quality than other existing technologies to justifyits use and attract the masses (e.g. email vs post mail, broadband vs dial-up connection).Ease of Use: Easy to use, non-complex applications certainly increase the likelihood of their adoption andusage. Imagine where the Web would be now if everyonehad to learn HTML before they could even browse it!Personalisation: Customers tend to become more loyal to services they can customise to their liking [2].Many of today’s killer apps have some level of personalisation. Amazon for example makes recommendationsbasedonwhat the customerbuysor looksat, AutoTrader1 andRightmove2 save customers’searchesandnotifythem via emails when a new result to their query is available. Personalised web services attract more customers(if done properly!) and provide better tailored services [5].1 http://www.autotrader.co.uk2 http://www.rightmove.co.uk2.3 Leveraging Metcalfe’s LawFinally, an important task for any killer app is to develop a user community, a large number of users each ofwhom adds value to the network.Communities of Practice: A killer app should have the potential to create a community of users and aidthis community to grow and develop. Metcalfe’s Law states that the utility of a network is proportional to thesquare of its user base [1], and so a tenfold increase in the number of users, for instance, makes the networkone hundred times more valuable. This law is often used to explain the success of many of today’s killer apps[2][6][5], and the value of networked applications such as the Internet, email, and instant messaging software.One email account is useless as there will be no one to email! But as the number of email accounts increases,so will the value of this application.Take Yahoo messenger for example. They made it very easy for existing members to invite others to down-load and use the tool. They also provide a number of games and chat rooms where members can meet toencourage the creation of more interconnections between their members, thus boosting their network value.Open Systems: When a system opens to direct interactions with other existing systems, its value increasesby acquiring additional value from those systems [6]. By being open source and extendable, Prot´ eg´ e allowedmany existing systems and tools to be linked or integrated with it, thus increasing Prot´ eg´ e’s use and value. Forthis reason, and for being available for free, Prot´ eg´ e is quickly becoming the default ontology editing tool.Active User Community: User community of Protege increased dramatically once it became open sourceandfreelyavailable[7].Thishas beneﬁtedthetoolgreatlybywideningits userbase,thus increasingits networkvalue by many folds.Prot´ eg´ e supported its large community through emailing lists, short courses, and conferences, providing itwith an excellent technical support which has so far been up to scale, another quality of Prot´ eg´ e, missing frommost of its competitors.By going open source, and adopting an extendable architecture, Prot´ eg´ e managed to move part of thedevelopmenteffort to third parties. User were able to build their own personal extensions to Prot´ eg´ e, and manythird party plugins have become available to the community. The continuous emergence of plugins is one ofthe most attractive features of Prot´ eg´ e, which made it stand out amongst other similar tools.2.4 A range of requirements for the Semantic WebAll of these considerations leads us to think of how the SW in general, and the tasks associated with ontologymanagement in particular, will ideally drive development of Prot´ eg´ e. Essential aspects of the new SW environ-ment with which Prot´ eg´ e may have to grapple include the range of SW languages that have been appearing andwill continue to appear,the potential size of the SW, and issues related to the publishingof and access to onlineknowledge services.Language Support: Prot´ eg´ e has been quick to endorse new SW schema representation languages, suchas RDF and OWL, thus staying up to date with W3C’s latest standardisations. With respect to RDFS, Prot´ eg´ eextended the language to enable it to express certain things, such as cardinality, multiple slot range, etc. [8].Even though those extra representations did not conform to the RDFS standard, but they were necessary formore detailed domain representations. Those extensions are speciﬁc to Prot´ eg´ e, and hence can not be read byother RDFS tools.Scalability: Not a long time ago, much effort was given for building very large ontologies (e.g. CyC 3,Gene Ontology4, SUMO5). As the SW is developing, particularly under the stimulus of the annual SemanticWeb Challenge, we are beginningto see knowledgebases containingsmall to medium size ontologies,but withvery large number of instantiations [9]. The winner of the 2003 challenge, CS AKTive Space[10], contained25m RDF triples stored in 3Store6, while the winner in 2004, Flink7, had 35m stored in a Sesame8 KB. KBs ofthis order require a great deal of management.3 http://www.cyc.com/4 http://www.geneontology.org/GO.biblio.shtml5 http://ontology.teknowledge.com/6 http://www.aktors.org/technologies/3store/7 http://prauw.cs.vu.nl:8080/ﬂink/8 http://www.openrdf.org/Prot´ eg´ e’s main design goals where interoperability, and ease of use [11]. Scalability was not at the heartof Prot´ eg´ e’s design, as is the case with some triple stores, such as 3Store9, Sesame10, and Kowari11. Thisneeds to be addressed if Prot´ eg´ e is to be used as a platform for launching SW applications. Prot´ eg´ e certainlyoffers much more than the triple stores mentioned above, in terms of editing capabilities, data visualisation,ontology merging tools, versioning, etc. If Prot´ eg´ e is to deploy services over large KBs, then it has to scaleaccordingly. RDF and OWL database backends for Prot´ eg´ e are available for dealing with large KBs. TheRDF(s)-DB backend plugin that connects Prot´ eg´ e to a Sesame repository is a good effort [12], assuming thatProt´ eg´ e’s user interface can also scale to high limits.Publishing and Access: Providing online knowledge services is a crucial part of launching the SW. Thetriple stores mentioned earlier are designed for this purpose, with online querying facilities using queryinglanguages such as RDQL and SPARQL. Both of these languages are W3C standards for querying RDF stores.Prot´ eg´ e currently does not have a strong and current support for such languages.3 ConclusionsWe have lookedat some importantfactors in the developmentof the Semantic Web. Ontologydevelopmentandmanagement will be an essential task, and tools will be required for this. But for an application to become akiller app for the SW it has to meet certain requirements and possess certain qualities.We discussed those features and qualities in the scope of Prot´ eg´ e, which managed to become a killer appfor ontology editing and management for a large number of SW enthusiasts. By looking at analyses of thecharacteristics of killer apps in general, and the requirements of the SW in particular (even requirements thatstrictly go beyondwhat Prot´ eg´ e is capableof providing),we can get some sense of how Prot´ eg´ e should developfurther in the SW context.AcknowledgmentsThis work is supported under the Advanced Knowledge Technologies (AKT) Interdisciplinary Research Collaboration(IRC),which issponsored by the UKEngineering and PhysicalSciences Research Council under grant number GR/N15764/01.The AKT IRC comprises the Universities of Aberdeen, Edinburgh, Shefﬁeld, Southampton and the Open University. Theviews and conclusions contained herein are those of the authors and should not be interpreted as necessarily representingofﬁcial policies or endorsements, either express or implied, of the EPSRC or any other member of the AKT IRC.References1. Gilder, G.: Metcalfe’s law and legacy. Forbes ASAP, 13 September (1993)2. Downes, L., Mui, C.: Unleashing the Killer App. MIT Press, Harvard Business School Press (2000)3. Christensen, C.M.: The Innovator’s Dilemma. Harvard Business School Press (1997)4. G´ omez-P´ erez, A., Fern´ andez-L´ opez, M., Corcho, O.: Ontological Engineering. Springer-Verlag (2004)5. Evans, P., Wurster, T.: Blown to Bits. Harvard Business School Press (2000)6. Kelly, K.: New Rules for the New Economy: 10 Radical Strategies for a Connected World. Penguin Books (1998)7. Gennari, J.H., Musen, M.A., W.Fergerson, R., Grosso, W.E., Crub´ ezy, M., Eriksson, H., Noy, N.F., Tu, S.W.: Theevolution of protege: An environment for knowledge-based systems development. 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Metcalfe’s law and legacy.

New Rules for the New Economy: 10 Radical Strategies for a Connected World.

Ontological Engineering.

Passerelle - a plug-in that connects prot´ eg´ e to sesame. In:

S.W.: The evolution of protege: An environment for knowledge-based systems development.

Semantic web clahhenge

The Innovator’s Dilemma.

The knowledge model of protege-2000: Combining interoperability and ﬂexibility. In:

Unleashing the Killer App.

Common features of killer apps: a comparison with Protégé

http://oro.open.ac.uk/21193/1/protege05-Alani.pdf

Common features of killer apps: A comparison with Protégé

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