LinkZoo: A collaborative resource management tool based on Linked Data
Editor(s): Name Surname, University, Country Solicited review(s): Name Surname, University, Country Open review(s): Name Surname, University, Country
Marios Meimarisa,b, Giorgos Alexioua,c and George Papastefanatosa aInstitute for the Management of Information Systems, Research Center “Athena”, Greece bDepartment of Computer Science and Biomedical Informatics, University of Thessaly, Greece cDepartment of Electrical and Computer Engineering, National Technical University of Athens, Greece
Abstract. In this paper, we present LinkZoo, a web-based, linked data enabled tool that supports collaborative management of information resources. LinkZoo addresses the modern needs of information-intensive collaboration environments to publish, manage and share heterogeneous resources within user-driven contexts. Users create and manage diverse types of resources into common spaces such as files, web documents, people, datasets and calendar events. They can interlink them, annotate them and share them with other users, thus enabling collaborative editing, as well as enrich them with links to external linked data resources. Resources are inherently modeled and published as RDF, and can be explicitly interlinked and dereferenced by external applications. LinkZoo supports creation of dynamic communities that enable web-based collaboration through resource sharing and annotating, exposing objects on the Linked Data Cloud under controlled vocabularies and permissions. We demonstrate the applicability of the tool on a popular collaboration use case scenario for sharing and organizing research resources.
Keywords: Linked Data, Semantic Web, Collaborative Environments, Resource Management, Personal Information Management
1. Introduction manage, connect, organize and explore these resources in various meaningful ways. Publication of Collaborative management of communal resources these resources as linked data enables further exposal is required in many contexts and scenarios, such as for external reference and processing. collaboration between and within professional Currently, the linked data (LD) initiative focuses organizations, research teams, ad-hoc social on either providing representations of singular groupings that fulfil various purposes and so on. entities, or publishing large datasets in flux, created Providing a common representation model for through loosely-defined, context-dependent different types of artefacts, such as files, documents, workflows. In this sense, publication of linked data locations, websites, people and events, enables them becomes a complicated, non-universal process, where to be managed and organized under shared principles often custom publishing tools and systems need to be that ultimately allow for the creation and association defined in order to deal with domain-dependent of intricate aggregations of different kinds of items complexities. W3C’s general guidelines for with dynamic processes, flows and contexts. publishing linked data, as reviewed in the Best With the re-use of ontologies, codelists and Practices for Publishing Linked Data Note1, are commonly used linked data URIs to annotate mostly concerned with good data modelling (i.e. artefacts we can provide a layer of semantics that is inherently shared between stakeholders, and helps 1 http://www.w3.org/TR/ld-bp/ using existing ontologies and vocabularies where collaboratively manage and annotate those using possible), following good URI design practices, and established or custom ontologies. LinkZoo enables providing machine access; in real world applications, users to create views that organize their resources most of these issues are primarily solved with ad-hoc under different perspectives and make them available design decisions. Except for the publishing needs, to others. Finally, it offers an intuitive way of most popular semantic tools and systems focus on the searching over private or public resources and storage, interlinking and presentation (e.g., browsing, exploring them via a faceted browsing functionality. visualization) aspects of whole linked datasets rather We have implemented a web-based front-end, than on the user-oriented manipulation of single available at http://www.linkzoo.gr, that provides a user interface covering all the aforementioned information resources. This creates a lack of functionality, and we expose the core functions of technical support and functionality when it comes to resource management to developers and applications applying linked data techniques on social and by making them programmatically available through collaborative environments, where data-driven user a REST API as well. interaction is intuitive and dynamic. Hence, existing This paper is organized as follows: in section 2 the semantic techniques and systems must be main features are presented, in section 3 the model complemented by tools that target the operational and architecture is described, section 4 deals with the layer, promoting user-oriented, dynamic interactions system’s implementation, section 5 presents the between resources at most granular levels. tool’s functionality through a detailed use case, For example, consider a scenario where a team of section 6 presents related tools and finally section 6 researchers get together and start working on a new concludes and discusses future directions. hypothesis. They start by collecting the literature for reviewing, which can be stored locally in the form of PDF or in remote websites. They annotate and 2. LinkZoo Features categorize papers based on several properties such as their authors, subjects, venues and journals they were In this section we present and discuss the main published in and enrich these properties by providing features of our tool. references to external web and linked data resources. Furthermore, they gather relevant dataset sources, 2.1. Resource publishing experimental data, and information concerning the conference \ journal they intend to submit their work. LinkZoo seamlessly integrates the processes of They share these resources with each other, show creating and publishing heterogeneous resources as part of them to a proof-reader, and collaboratively work and manage their on-going research along all RDF linked data, and offers a toolkit of common needed resources. In their individual accounts, each actions for their appropriate management, depending team member organizes the same resources on their type. Items created are published given differently, by creating distinct folder structures and dereferenceable URIs as well as internal identifiers workspaces that they find more intuitive. Finally, and are either public or visible to specific users. they make available the process or the results of their Moreover, their URIs are citable and can be used by work as linked data and they enable citation and external users for referencing resources without dereferencing for all resources they managed. having to link them to their account, similar to the In this paper, we present LinkZoo; a web-based notion of a shareable link in cloud storage systems platform for resource sharing and collaboration. such as Google Drive2 and Dropbox3. Their LinkZoo is a cloud-based tool that allows users to representation and metadata can be easily extracted upload, interlink and organize different types of as RDF in a variety of serializations (e.g., XML, resources, such as files, websites, people, datasets JSON, etc.). and calendar events, in collaborative workspaces. It enables sharing and annotation of resources, enrichment with properties and publishing as linked data for citing and consuming. LinkZoo is a Linked Data platform with social characteristics that enables users to form groups and communities by sharing 2 http://drive.google.com heterogeneous resources, and allows them to 3 http://www.dropbox.com 2.2. LinkZoo resource types and operations collaboratively edited, with changes being immediately visible to users, as a derivative of the Every item published in LinkZoo is called a internal model that will be presented in section 3. resource. In their simplest form, resources are represented using a common model that draws from existing vocabularies for non-functional descriptive lz:Resource properties, such as Dublin Core4 and FOAF5. This accommodates basic metadata assertion, but resources can be further classified into different resource types that help specialize the sets of actions that can be performed on them. lz:File lz:LinkedDataURI lz:Dataset lz:Person lz:Event LinkZoo handles a variety of resource types (Fig 1), with a common representation layer making it possible for heterogeneous resources to co-exist and lz:MP3 lz:WebURL lz:RDFDataset be combined to form meaningful aggregations and flows. Current resource types include files, web Figure 1. The LinkZoo taxonomy of resource types. documents (i.e., URLs), people, linked data Moreover, each user can organize and explore resources (URIs), full RDF datasets, and general their resources in their own ways. When sharing purpose folders. Folders are special types of folders, their contents are also shared. resources that organize into contexts sets of resources The created resources can be processed, annotated, and can be enriched and linked with knowledge in enriched and shared by their users, independently of the same way as other resources. their type. The roles of owner, editor and viewer Sub-types are also possible in order to extend have been implemented. Owners and editors resource actions in more specialized ways. For practically have the same rights; the distinction helps instance, the MP3 type extends the File type so that to keep track provenance. Furthermore, the notion of instead of merely enabling download, the user can discoverability is applied to all resources, where also playback audio, view retrieved music videos and resources can be private, i.e. they can only be seen by browse similar suggestions based on the MP3 file explicit sharing, or public, i.e. they can be openly and its metadata. Extending the list of resource types discovered and annotated by anyone on the web. is a trivial procedure, and can be used to tailor types Resources can be enriched by assigning new to the users’ specific needs. properties to them by any shared editor. Available user actions include creation of a new resource (file upload, URL import or other type- 2.4. Annotation and enrichment specific actions), creation of new folders, moving, renaming and deleting resources, sharing resources Users can assert new facts about resources either with other users and annotating/enriching resource manually by annotating them with new properties or properties, either manually or in an automatic way. automatically by enriching them with knowledge from external knowledge bases. Each resource exists 2.3. Resource sharing and collaboration in its creator’s account along with all the triples it is a subject of (as will be described in the next section). Resources can be shared among groups of users Most well-known ontologies have been imported in in ad-hoc manners. When shared, a resource becomes the platform for ease of access via an auto-complete visible to other users’ workspaces and can be mechanism, but users can use external ontologies and manipulated depending on the assigned role(s). A vocabularies by importing them in their LinkZoo notification mechanism ensures that all involved account. users are instantly notified about the addition of Moreover, users are able to define their own shared resources in their workspace. Shared properties on the fly under a user-specific namespace resources among a group of users can be viewed and and use these properties for enriching their resource with custom attributes. In our example, a researcher 4 http://dublincore.org/documents/dces/ wishes to annotate papers under review with 5 http://xmlns.com/foaf/spec/ information about their origin, keywords, fields of Property filtering is implemented in the form of application and authors, so that she will be able to facets over the list of available properties of the navigate through them easily based on their search results. More specifically, when the user properties. Some of these properties can be filled navigates to a folder, the system finds all distinct using existing ontologies, which they import. Others, properties of the resources within that folder, and however, may not exist, e.g., a property denoting that lists them by descending order of the count of their a paper is “under review” by a team member. In distinct objects. When a property is selected for LinkZoo, she can define the new property, named filtering, its distinct objects will be listed as virtual “underReview”, under the user-specific schema and folders, containing the resources that are linked to use it at their discretion. them via the selected property. For instance, the Furthermore, the user can annotate a single researchers can create dynamic facets (in the form of resource or a collection of resources, which do not virtual folders) and explore the collected papers by necessarily belong to the same type. Collections of authors, fields of application or any other property resources can be aggregated in a drop-zone and their resources are annotated with. assigned with properties in a bulk manner. The two methods, keyword search and property Enrichment with properties and interlinking with filtering, can be combined and applied in an other resources and external linked data can also be exploratory “find-as-you-go” manner and ongoing done automatically using external web services. This results can be stored in multiple views. version of LinkZoo utilizes the Alchemy API6 in order to automatically enrich incoming URIs based 2.6. Views on their content. For example, URL resources are fed to the Alchemy API before importing to LinkZoo. The descriptions of resources enable multiple Depending on their structure and content, they can be ways of organization due to the diverse properties annotated by Alchemy with relevant DBPedia and objects found in their triples. The default way of resources via the generic rdfs:seeAlso property. browsing resources is based on an intuitive directory- like manner; still our platform exploits the semantics of a user’s resources in order to offer multiple ways 2.5. Keyword search and exploration of organizing, exploring and searching. Users have the ability to organize resources, LinkZoo offers intuitive resource exploration by public or private, based on their characteristics and combining keyword search functionality over store the results as views. Views do not alter the resource descriptions with property based filtering. storage location of a resource; instead they provide Keyword search is implemented in a close-to-natural- different ways of organizing it. language way, based on the characteristics of a user’s Views can be static or dynamic. Static views are available resources. More specifically, keyword arbitrary collections of resources where the user is search is done in either a one-step or a two-step responsible for insertion and removal. They operate process. One-step searching is done by entering a very similarly to a virtual folder, where multiple keyword and matching it in all possible places of resources are collected and organized explicitly by triples, i.e. subjects, predicates and objects. Two-step the user. Static views are different ways to organize searching feeds live query suggestions to the user the same resources into folders. Users create static based on the keywords they type. When the user views and within them they define different folder selects one of the suggested queries, the system structures in order to manage and categorize their outputs the relevant results aggregated in a virtual resources in various ways. This way, a given folder. These can then be collaboratively edited, resource can exist in two or more views shared, deleted and so on. Text-based search is simultaneously. performed incrementally, by specializing the returned search results with the introduction of new keywords for search and further limiting the result set.
6 http://www.alchemyapi.com/ User 1 Graph
lz:resource_1 lz:resource_2 View 1 lz:resource_1 lz:resource_5 lz:resource_2 lz:resource_3 lz:resource_6 lz:resource_5
lz:resource_7 lz:resource_3 lz:resource_6 lz:resource_7
lz:resource_8
lz:resource_10 lz:resource_8 View 2 lz:resource_9 lz:resource_10
lz:resource_9
User 2 Graph User 4 Graph User 3 Graph
(a) (b) Figure 2 (a)The user graph for User 1. The resources that have their own subgraphs are owned by User 1 (colored with blue), while the resources that point to other external user graphs are shared with user 1 (not colored). (b) The same resources from User 1’s user graph are organized into two different views by the user. Resources 6 and 7 coexist in both views.
On the other hand, dynamic views are created first is concerned with resources along with their based on the results of a search query, thus enabling functional as well as non-functional metadata, such the user to refresh the contents of the view based on as resource types, titles, descriptions, comments, its query definition. For example, one of the users of identifiers, dates and related users. We have defined the research team can ask for “Files that are under a simple taxonomy of resource types that is review, are related with dbpedia:SemanticWeb and extensible to accommodate new resource types as are shared with me” and save the result of the query well as specializations of existing types. as a dynamic view. A top level lz:Resource class acts as the common Then, in any given moment this dynamic view can ancestor class for all types of resources. Non- be refreshed to contain the updated result of the functional metadata such as titles, descriptions, query, if for example another member of the team comments, identifiers and so on are modelled by uploads a Semantic Web paper and marks it to be default with the use of commonly used paradigms under review. The user has no explicit control over and schemata, namely RDFS, SKOS, FOAF and the contents of the container folder that corresponds Dublin Core. For instance, FOAF is used to model to the dynamic view. Containing resources are resources that represent people, while Dublin Core dynamically evaluated based on the query populating properties are used independently of the type. the view, which in turn may retrieve resources either Finally, users can import their own ontologies and from the user graph or other users’ graphs. In this recall them on demand, as well as create new custom way, views leverage semantic web by offering properties. These are created within a user-specific intuitive means to users for organizing, searching and namespace that is assigned to each user upon discovering new resources. registration. The second part of the model concerns resource administration and privileges over the user base. 3. Model and Architecture Specifically, information about ownership, discoverability and sharing is modelled with the use 3.1. LinkZoo Data Model of a set of a small ontology of properties and classes that we have defined. This captures notions such as Within LinkZoo resources are represented using a Private vs. Public for a resource, Owner vs Editor for data model that consists of three conceptual parts; the a user and so on. The third part contains the definitions of views have been abstracted in order to make the Storage and the participation of resources in them. Layer vendor-independent. The Storage Layer along Specifically, views provide the way to visually with the Data Access Layer (DAL) are the two main organize resources and can be of two types, namely components involved in data manipulation, storage static and dynamic, as mentioned in section 2. and retrieval. The internal data model of LinkZoo makes heavy use of named graphs for defining resources, views, 3.2.2. Core Functionality Layer user contexts and so on. In particular, we model the The Data Access Layer communicates directly space of each user as a user graph that holds with the backend’s core functionality component, information concerning all the resources owned by which is comprised of four main sub-components, that user. When resources are shared to other users, namely (i) the Profile Management module, (ii) the essentially what is shared is a pointer to the named Resource Action Management module, (iii) the View graph that holds the resource (among other things Management module, and (iv) the Search and such as privileges). The user graph contains all triples Exploration module. of resources owned by the user, even the ones The Profile Management module is used for contributed by shared users. It serves as a singular managing the profile data of each user, and is access point for its given resources, thus making it responsible for user administration (creation, deletion possible for other users and applications to gain of users), user graph assignment and management of access to a resource by knowing its URI and user a user’s associated assets, such as imported and graph, given appropriate privileges and/or custom ontologies. discoverability. The user graph is the linked data The Resource Action Management module publishing point that actually contains all RDF triples implements all actions applied on resources, as well related to a user’s owned and shared resources. as resource input/output, disk allocation for file Views are modelled as named graphs as well and upload, and sharing. Different actions are possible for they are classified as static or dynamic with the use different types of resources, for example files can be of appropriate classes of the LinkZoo ontology. A downloaded, URLs can be used to direct the browser, view is represented by a named graph URI and it MP3 files can be played online and so on. contains the query parameters in case of a dynamic Furthermore, the Resource Action Management view, information about a view’s base folder as well module is responsible for dereferencing URIs of as folder containment for each resource. This is done LinkZoo resources and serving content to external with the use of a simple transitive property that applications. This works as follows: the user has the denotes folder containment between a resource and a ability to create a dereferenceable URI for his/her given folder. resources, much like the “get shareable link” Figure 2 displays a user’s graph of resources and function of several commercial cloud storage their organization into views. systems. When this produced URI is dereferenced by a web-browser or a software client, the platform will 3.2. Architecture produce an HTML description of the resource, regardless of whether the client is logged in as a The main architectural components of the system LinkZoo user. Depending on the owner’s preference, are shown in Figure 3. All services that comprise the dereferenced description of the resource may also LinkZoo’s backend are accessible via a RESTful give out a link for external users to add the resource API, making it possible for different kinds of end- to their LinkZoo account, thus effectively becoming user applications or tools to take advantage of co-sharers of the resource. LinkZoo’s functionality. The View Manager is used for defining and updating static and dynamic views. It is the primary 3.2.1. Storage and Data Access Layers mechanism for defining folder hierarchy and LinkZoo’s Storage Layer is built on top of a handling metadata about views. persistent quad store that supports RDF triple The Search and Exploration Module provides storage, named graphs and SPARQL queries. This is keyword search and property filtering, as discussed particularly helpful in implementing the LinkZoo in section 2. model that utilizes named graphs. The implementation specifics of the Storage component User Interface
HTTP REST API
Security Module (Permissions, Access etc.)
LinkZoo Resource Search & Interlinking & Profile Mgmt View Mgmt Action Mgmt Exploration Enrichment backend Module Module Module Module Mgmt Module
Data Access Layer (DAL)
Quad Store
Figure 3 LinkZoo Architecture It is also responsible for the navigation of the user Depending on the evaluation result, the requests are between folders and/or views, as querying for passed on or rejected. specific hierarchical relations between resources and folders is easily handled by the search sub-module’s query engine. The module allows for on-the-go 4. Implementation incremental keyword search over a user’s resources, either belonging in her graph or in shared graphs. It is LinkZoo is implemented using open source also used to search resources over public graphs. technologies. Virtuoso 7.17 open source edition is Search is performed on the triples that describe a used as a quad store in the Storage Layer. The web user’s resources, thus semantics play an important GUI is deployed on an Apache web server, and the role in navigating via keyword search or discovering application layer (backend) is implemented with Java new items in the public graph. 1.7. The application layer is built using the Play Finally, the Interlinking and Enrichment module Framework8 for web-based RESTful APIs and uses external APIs in order to retrieve and enrich deployed on an Apache Tomcat server. resources with facts. Currently, Wikipedia, DBPedia Most of the functionality of the backend of and AlchemyAPI are used for knowledge LinkZoo is implemented in a RESTful fashion, in enrichment, and the FalconsAPI for searching order to isolate business logic from the usage and external ontologies. representation layers. Effectively, LinkZoo is implemented under the Model-View-Controller 3.2.3. HTTP API Layer design pattern. In the following section we describe the technical details of our tool. Incoming HTTP requests are routed in the HTTP API Layer. The requests are evaluated and depending 4.1. Resource URI minting and handling on the parameters, they invoke the appropriate set of controllers after given appropriate access permission Resources are given URIs upon creation based on by the Security Layer. a mechanism that combines the current timestamp with the user’s identifier. Aside from that, unique 3.2.4. Security Layer integer identifiers are assigned to every resource. Finally, permissions and user privileges are Upon registration, each user is given a dedicated managed separately in their dedicated Security Layer, named graph, which stores the resources created by as most actions require user authentication. User credentials and access tokens are transferred between 7https://github.com/openlink/virtuoso-opensource HTTP requests and evaluated in this layer. 8 https://www.playframework.com/ each user, along with their respective triples. In the where the variable ?g binds to any possible graph case of a URL, no additional URI is created, but URI found in the user’s graph. rather the source URL is kept. Therefore, when two users import the same URL in their accounts, it will 4.3. Views have the same URI (its URL) but different identifiers, and will reside in two different user graphs. Views are also implemented as named graphs containing references to resource URIs. Dynamic 4.2. Sharing and Aggregation of Resources views are associated with the search parameters (SPARQL query) of a search operation. These When a resource is shared there is no replication parameters are stored as triples with the view’s URI of its description, instead a pointer to the resource’s as subject. The user can refresh the view’s contents graph is given, thus allowing users to be able to by revaluating the query on the available public or collaborate on the same data object when private resources, in effect rerunning the query and manipulating a resource, and at the same time refreshing the contents of the view. inherently keeping provenance information. Hence, the sharing procedure creates two triples on the 4.4. Searching shared users’ graphs, one for their role (e.g. editor, viewer etc.) and one to declare the resource’s source Searching is implemented using auto-complete graph. Also, sharing of resources generate instant suggestions over resource types and property values, notifications to the involved users, such that they are in combination with a faceted property filtering aware of the resources that are added to their graph. mechanism. The resulting query strings are visualized as natural-language phrases (e.g. ‘find Table 1 A sample query for retrieving all resources and some basic URLs with rdfs:seeAlso dbpedia:Youtube and metadata from the Current View and the Current Folder. linkZoo:owner ‘John’). Search can be limited on a SELECT DISTINCT directory, a view or a user’s privately shared ?resource ?identifier ?label ?type ?mod resources, but can also be done in the publicly shared ?role – anonymous - graph. FROM
Figure 4 Folder-based exploration, with search on top, and properties filtering on the right sidebar. papers that have the property lz:assignedTo and the name of the team he wants to track. The second way is to use the property filtering option by selecting resources that are papers. All resources of that type will be listed in the result set and the property list will be refreshed to the available properties of the papers. Out of this list, the project manager will select the property lz:assignedTo and all the possible names will appear to the result set. As mentioned, each member of the team, in his Figure 5 Views and drop zone individual account, may organize completely Now that the majority of the data (literature and different the same resources that she shares with the datasets) has been collected, the next step for the other members of the team without affecting the way team is to make the task assignments for each that the other members organize them. Yet, some member. Therefore, they create a “Person” resource members, like the project manager, may want their type for each member of the team and the project resources to be organized with multiple ways. In manager assigns each person to one or more order to achieve that, they may use the LinkZoo’s resources. For example, the project manager could static or dynamic view feature. For instance, from the easily, using the keyword search and exploiting their previous example with the project manager and the semantics, categorize the papers for the literature assigned members, it is possible that the project review and assign one or more members of the team manager may wish to have all papers organized not to the respective categories / papers. In this way, the only according to her interests, but also based on project manager as well as the other members of the their assignments to members. Through LinkZoo she team could easily track and organize their resources could use the keyword search again (querying about based on the assignments. the papers and their assignments) with the “save as For instance, let us suppose that the project view” option, where she is prompt for providing a manager wants to find quickly what resources from new name and saving the search results in this new the literature have been assigned to a specific view. In Fig 5 the new view, named “assignments” member of his team. There are two ways to do that. along with the default one is shown. The first is to use the keyword search and search for
Figure 6 The properties pane for resource dbpedia:nonprofits_research . The top part contains forms that can be used to add more properties to the resource. By default, rdfs:seeAlso is used, but auto-complete draws from imported ontologies to provide suggestions
Figure 7 Searching for publications assigned for review to team member 1. The new view does not affect the way that she has resources marked as publications under review by organized her resources in the default way. user ‘team member 1’ can be seen in Fig 7. Moreover, if a new assignment or deletion is made in Finally, after they have finished all the process of the resources contained in this view, she can easily experiments and writing, the team could easily track it, just by refreshing the view. This action will switch the final version of their paper along with the automatically update the resources within the view in dataset and the experiments, from private to public order to match the query from which the view was and publish them as Linked Data. In this way, they created. enable citation and dereferencing for these resources. Continuing our scenario, two of the members of For the interested reader, the aforementioned use the team have finished a set of experiments and case along with a sample workspace is available at uploaded the spreadsheet with the results on their www.linkzoo.gr under the account swj-demo\swj- private space and annotate them properly. The demo (same as the owner column in Fig 7). annotation was made with two external ontologies that the researchers imported in the system. The first researcher has imported, from an RDF file, an 6. Related Tools ontology about scientific experiments and the second researcher has imported, from a public URI, an In this paper we build upon the work done in [19]. ontology about data provenance. These two members Due to the various functionalities of LinkZoo, we are the primary authors of the spreadsheet while a position our work in the intersection of Personal third member does not participate in the experimental Information Management, Collaborative Platforms, process, but is interested in reviewing their work. Social Networking, Linked Data and the Semantic They can share a subset of their resources with him, Web. To our knowledge there are no approaches that e.g. their draft along with a few spreadsheet files with tackle the same collection of issues, however a lot of experimental data, by giving him the role of viewer. work has been done on smaller combinations of the aforementioned fields. Moreover, they can annotate this subset with a Several tools address collaborative semantic specific property, e.g., “underReview”, which editing [2,6,12,13,14,15,16,17,18] however most of facilitates the reviewer to easily find and organize these are concerned with ontology editing within these shared resources in her own workspace. In case closed communities, and thus render themselves as this relevant property is not defined in either of the tools for conceptual modelling in communities of system ontologies, they can ad-hoc define and in the experts. same step use this new property for annotating these The idea of managing heterogeneous items in the resources. In Fig 6 the properties pane for the collection of a user’s personal information has been resource dbpedia:nonprofits_research is shown, addressed by Personal Information Management where the user can inspect existing or assign new (PIM) tools, and adding a semantic layer to this gave properties. Also, a sample search containing rise to the Semantic Desktop. In [3,4,5,7,8,9,10,11] systems, tools and frameworks are presented that apply a semantic layer on user desktops, and combine Information Management. LinkZoo is designed diverse things such as files and email. In [3] the core across these dimensions, while inherently it makes aim of the NEPOMUK project was to specify a use of linked data technologies in order to introduce standard for Semantic Desktop communication and interoperability and collaboration on the web. processing. Their work is based on Semantic Web In the future we intend to extend the coverage of standards and technologies, with RDF serving as a resource types and incorporate data from social common data representation format. In [4] X-COSIM networks, such as linkedIn, g+ and youtube in order is presented as a RDF-based semantic desktop that to build thorough social user profiles. We also intend supports information linkage and reuse for email and to study scalability and performance issues file management. The Gnowsis Semantic Desktop [5] concerning large user-bases and greedy annotations. provides the ability to connect files, contacts and Finally, we intend to use the platform as a test-bed other user assets and assigns URLs to them so that for automated integration of information resources on they can be annotated by third party applications. In [1] the authors present TripFS, a system that provides the Data Web. a Linked Data layer on files of existing file systems, by assigning URIs and making them dereferenceable on the web. 8. References Most of these approaches lack the social dimension and do not offer centralized, web-based 1. B. Schandl, N. Popitsch. "Lifting File Systems into the functionality or space for users to interact and share Linked Data Cloud with TripFS." In LDOW. 2010. resources, but rather operate under a more closed- 2. S. Auer, S. Dietzold, T. Riechert. “OntoWiki - A Tool for Social, Semantic Collaboration”. In ISWC 2006: 736-749 world assumption, with deployment taking place on 3. A. Bernardi, G.A. Grimnes, T. Groza, S. Scerri. “The the client side, and minimum support for external NEPOMUK Semantic Desktop”. Context and Semantics application development. LinkZoo provides a for Knowledge Management 2011: 255-273. centralized, web-accessible platform that is easy and 4. T. Franz, S. Staab, R. Arndt. "The X-COSIM integration intuitive to use, as well as accessible from third-party framework for a seamless semantic desktop." In K- users and applications. CAP2007. 5. L. Sauermann. "The Gnowsis Semantic Desktop for Information Integration." Wissensmanagement. 2005. 7. Conclusions and Future Work 6. D. Quan, D. Huynh, D. R. Karger. "Haystack: A platform for authoring end user semantic web applications." In We have presented LinkZoo, a web-based, ISWC 2003. 738-753. Linked Data tool that supports collaborative 7. 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