Applying the Use Case Methodology to Smart Cities Anwendung der Use Case Methodik an Smart Citites

Transcription

1 Applying the Use Case Methodology to Smart Cities Anwendung der Use Case Methodik an Smart Citites Marion Gottschalk, André Göring, Dr Mathias Uslar OFFIS ev, Oldenburg, Germany, {gottschalk, goering, Abstract The increasing integration of cities by information and communication technologies and the common interest in smart cities pose new challenges for standardization Due to the complexity of smart cities, new approaches and techniques are needed to create new standards which include all aspects of the domain and are accepted by all participants Hence, this paper represents the use case methodology and how it can be applied to the domain smart city The methodology is supported by a web-based tool which allows the cross-domain creation and analysis of use cases Aim of the methodology is to provide information for closing gaps in standardization Kurzfassung Die Vernetzung von Städten wird durch den vermehrten Einsatz von Informations- und Kommunikationstechnologien vorangetrieben, welche in Smart Cities der Abstimmung der beteiligten Parteien bedarf Um diesen Prozess steuern zu können, ist die Entwicklung neuer Standards nötig Aufgrund der Komplexität von Smart Cities müssen neue Ansätze und Techniken verwendet werden, um Standards für die gesamte Domäne zu entwickeln, welche außerdem von allen Beteiligten akzeptiert werden Daher wird in diesem Beitrag die Use Case Methodik vorgestellt und wie diese auf die Domäne Smart City angewandt werden kann Zur Unterstützung der Methodik wurde ein Werkzeug entwickelt, welches die domänenübergreife Erfassung und Auswertung von Use Cases erlaubt Die Methodik hat das Ziel, Lücken in der Standardisierung aufzudecken und relevante Informationen für das Schließen dieser Lücken bereitzustellen 1 Motivation The domain smart city describes the combination, connection, and integration of systems and infrastructures in cities which improve the human quality of life [1] Smart cities should comprise smart grid, smart living, smart building, electro vehicles, etc to enable a complete integration of systems and infrastructures inside a city All these domains improve the quality of human life in different sectors, eg smart grids facilitate the integration of distributed energy resources and smart living supports people in daily activities, such as airing and switch on the light Currently, these domains or systems are under development just as the domain smart city Due to the increasing number of components of these systems, new technologies are needed to realize them Also, more and more vendors in different countries develop devices, such as sensors, smart white goods, and cars, to fit already existing or planned systems This process should be organized to guarantee the interoperability between components and systems for smart cities Interoperability between components and systems is essential for planning and creating smart cities [2] and can be reached by creating and using standards To create new acceptable standards, the standardization has to consider these complex and cross-industry systems in more detail The known vertical approach to define standards cannot be applied in this case, because of the high number of actors and components which are involved in these systems and the ambiguous ideas of smart cities Hence, a horizontal approach should be used which describes systems functionalities in detail The description of systems functionalities in a use case contains a number of scenarios which depicts the interaction of actors and components in detailed steps In agile software development, user stories are the well known equivalent to use cases Standardization processes of interacting products, components, and systems in one use case level have to be coordinated [3, 4] Use cases allow a complete consideration and analysis of the domain within the standardization work International projects in the energy domain have shown that the use case methodology can be applied in the standardization for smart grids (SG) [5] SG functionalities are described in a detail manner and requirements can be deduced which creates an overview on needed products, components, and systems With this overview of interacting parts, the standardisation processes are simplified Now, the use case methodology will be verified for the domain ambient assisted living (AAL) by OFFIS in a further German project Also, a part of the group SG 5 AAL of the DKE deals with this approach which is described in Die deutsche Normungs-Roadmap AAL Version 2 [6] AAL provides a system at home which supports people for an independent life, eg elderly people are supported in cooking by checking the oven settings In this case, AAL assists challenges of the demographic change [7] Hence, it is an important topic in the future which must be supported by

2 standardization to get a consistent development of AAL Standardization in SG is supported by the use case methodology, and now, it should be adopted for AAL A convergence between these two domains regarding the system level exists For example, the SG needs an ICT connection to households and their distributed energy resources to create the billing for their energy consumption; if an AAL system is installed at this household, a similar ICT connection will be needed for AAL operators to check the human condition by sent devices information To avoid the development of two independent ICT infrastructures for different domains, the use case methodology is applied and extended Thus, it should be also possible to apply this methodology to the smart city concept as a whole The " German Standardization Roadmap Smart City" recommends to test the methodology for a number of examples and adapt it to the special needs of smart cities where necessary [8] The paper is structured as follows: Firstly, the use case approach for SG by the IEC/PAS and its extension for AAL are explained in Section 2 Secondly, in Section 3 the management of use cases and a tooling for it are demonstrated The importance of the use case management for standardisation is shown in Section 4 Finally, Section 5 concludes this paper with an outlook 2 Use Case Approach Use cases are a popular technique in software engineering to describe the functionality and boundaries of systems and their relationships to actors Actors can be further systems or individuals [9] A use case is a sequence of scenarios which a system performs On the basis of system s functional requirements, these sequences are identified In agile software development, user stories are brief explanations of an intent which software needs to do for the user [10] To understand sequences of scenarios, they are often described as stories for the user [9] These stories help to detect further functional requirements They also help different users, such as the management, technical experts, domain experts, and externals, to get a consistent overview of systems However, a uniform definition, how a use case should look like, does not exist Hence, several approaches and templates exist; one of these is UML which is used in software engineering [11] The idea to transfer the approach for software engineering to other domains was first mentioned for the standardization in the energy domain [12] This idea was further developed and denoted in the German roadmap for standardization [13] and the use cases are defined for standardization [14] For the domain SG, the standardized template IEC/PAS exists which is briefly presented in the next section Thereafter, adaptations for the domain AAL are explained 21 Smart Grid For the SG domain, a template and a development method are provided by the IEC/PAS [15] The use case template consists of many parts and relations to explain systems or domains functionalities in detail The short version of the template contains general information, a description, and involved actors In a more detailed version, use cases also contain technical details (eg conditions and references), step-by-step analysis (a sequence of scenarios and their steps), and summarize information (eg requirements, information objects) [15] This template is filled out in a five phase methodology to develop use cases incrementally by different experts; finally, a technical specification of SG use cases exists [15] The five phase methodology starts with the collection of business use cases which are created by the executives Domain experts create formal use cases which map to the business use cases Thereafter, project engineers describe a more detailed version of use cases IT and domain experts develop and assess the use cases regarding existing standards, technologies, and best practices Lastly, design engineers develop a technical specification Due to the high number of use cases in the SG domain, it is necessary that all users share the same template and format to exchange these and to facilitate their joint work The use case methodology supports experts with different backgrounds to collect use cases and requirements The joint work can be supported by a web-based tool which based on the use case template IEC/PAS [15] The IEC/PAS offers a standard to gather, administrate, maintain, and evaluate use cases Due to the web-based tool, a use case management repository (UCMR) is available (cf Section 3) This allows a consistent form of communication between different experts So, experts from different backgrounds can change existing use cases and add new ones to complete requirements lists For example, domain experts provide general ideas and functional requirements, and system experts concretize these to specify interfaces, dedicated functionalities, etc The first version of the UCMR improves the exchange and editing of SG use cases This tool was implemented by OFFIS [5], and it can be used by all experts who are necessary for creating use cases In the next steps, this approach is also verified and implemented for AAL, and later on, it could be verified for further domains and smart city, as recommended [8] Thus, the current approach for AAL is introduced 22 Ambient Assisted Living The domain AAL also needs a standardized template to describe their high number of use cases and to facilitate the work between different experts The domain complexity is similar to SG, and also, many interactions between different systems and components exist To deal with this complexity, the existing template in the SG domain is applied on AAL Thus, the template is extended by further information about used standards, actors and components, and their exchanged messages This extension is realized by integration profiles which are described in the AAL Joint Programme [16] Integration profiles are used to get a more detailed description of the products and components which are required in the AAL domain This information does not attempt to replace communication standards, but integration profiles try to close the gap between individual

3 Table 1 Template for AAL Integration Profiles with example data on the Integration Profile Behaviour Monitoring Integration Profile: Description: Behaviour Monitoring Monitoring of location and at-home-activities of the user Actor Transaction Optionality Body area sensor BAN parameter sent Required (a) Integration Profile template and example data Transaction: Description: Information Producer Body area sensor BAN parameter sent Body Area Sensor uses the transaction to send values to the BAN Gateway Producers Role Information Receiver Measures vital parameter and sends them BAN gateway Recieves sensor data Receivers Role Triggering Event Message Semantics Newly generated measurement Bluetooth Health Device Profile (b) Transaction remplate and example data communication standards and use cases Integration profiles describe the use case from user s perspective, and they identify system components which are needed to implement This information is required to extend and to maintain AAL systems over a long period of time and to get an overview on existing interfaces between the system and its components That supports modularity and interoperability of systems and their components, and helps vendors and customers to plan their AAL system The integration profile is used similar structured to the scenario part in the use case template IEC/PAS A part of the integration profile with example data of an AAL integration profile according to Behaviour Monitoring is shown in Table 1 It shows two tables to collect information about actors or components and whose transactions within one use case which are summarized in one integration profile The first table (cf Table 1a) contains an overview on one integration profile It includes a name, a description, and a list of involved actors, whose transactions, and the optionality of transactions For each actor, all ingoing and outgoing transactions are considered In the example case, the ability to send sensor parameters of the body area network (BAN) is required In the second table (cf Table 1b), each transaction is described in more detail Therefore, information producer and the information receiver with their role for this transaction are given Also, the triggering event and the message semantics for the transaction are specified which also includes a list of standards In the example case, the previously mentioned sensor measures vital parameters and sends them via a bluetooth profile to a gateway every time, a new measurement is generated These two tables extend the use case template to map the current AAL concept Furthermore, integration profiles are supported by diagrams, such as data-flow and sequence diagrams which are also included in the UCMR These diagram types are taken to visualize the communication and the exchanged data between actors [16] The including of integration profiles enables the creation of a more detailed description of exchanged information within use cases 3 Use Case Management Repository (UCMR) The web-based UCMR shall support the management of use cases of complex and / or cross-industry domains The management contains the creation, editing, exchange, analysis, and persistent storage of use cases The web-based solution supports different users to read, write, and exchange use cases without the need of installing software beside a web browser Additionally, it allows the collaborative editing of use cases by different experts The webbased representation of use cases bases on the IEC/PAS use case template [5] and the extension for AAL which is described in Section 2 and the UCMR will assist the use of other use case tools via import/export according to the developing exchange format IEC/PAS Additionally, the area management of the UCMR is presented to demonstrate how different domains can be linked Further aspects are the visualisation and the user rights in the UCMR which are also described in this section 31 Use Case Template Figure 1 visualizes the first version of the new developed UCMR demonstrator which is realized in the German project "Use Cases als Basis zur interdisziplinären Konvergenz in Smart Grid und AAL UC4AAL" Due to the adaptation of the AAL domain, a new development of the UCMR has occurred The view of the UCMR is shown in Figure 1 and is divided in three blocks The block on the left side includes an overview on the content of the UCMR by listing all areas:

4 Figure 1 Overview of the Use Case Management Repository (UCMR) Personal Space, Smart Grid, AAL, and Smart City The Personal Space is generated for each user of the UCMR in which users can create or modify use cases This modifications are not visible for other users If an area is selected, its content will be shown in several folders: Use Cases, Actors, Functions, Information Models, and Requirements These folders contain use cases and elements which are needed to simplify the creation of use cases If elements are missing for new use cases, users shall be enabled to create new elements which are added to the corresponding list Thereby, it should be guaranteed that each user chooses actors, functions, information models, and requirements from these lists to get a consistent denotation within all use cases The consistent denotation is one of the most important aspects for the standardization to compare use cases, their actors, interfaces, and the resulting standards In Figure 1, the use case Cut Power of Photovoltaic is selected The use case can include further use cases (Proof: Power is down) and scenarios (Switch switch and Cut cable) The interleaving of use cases and the use case folder are flexible and can be selected by the user Scenarios have also steps (Get SwitchController Access and Toggle Switch) which are shown in the tree The content of the selected use case is shown in the middle block The content is depicted in the structured form of the use case template IEC/PAS On the right side, additional information to the selected use case are given There, the use case relations and actors are shown The use case relation block displays all use cases in which the selected use case is involved in any way (includes, associates, and extends) The actor section shows all actors which are a part of the selected use case and its role in this use case As it is shown in Figure 1, actors and functions are also interleaved Users can extend and edit this interleaving Additionally, the UCMR provides an import for existing use cases and element libraries (actors, functions, etc) from the SG and AAL domain However, the existing use cases must be based on the template An additional functionality of the UCMR could be the possibility of analyses, eg depiction of all use cases in which one actor appears After creation and editing of use cases, user shall also be enabled to export use cases to use them for internal documentation or external tools, such as the three dimensional SGAM visualization for SG [17] Further support for the user of the UCMR is given by a glossary, help and search function, and the possibility to reduce the shown parts of the template, eg the management does not need a detailed view of the technical aspects of a use case Therefore, the defined short and complete view of the use case template can be used [15] All these functionalities enables users from different fields with different know-how the creation and editing of use cases for one or more domains in cooperation In the standardization work, those structured use cases and the analyses by the UCMR can be used to create new standards or to complete and to verify existing standards 32 Visualization As mentioned above, external tools can be used to visualize use cases For SG, the three dimensional smart grid architecture model (SGAM) exists The SGAM is developed by the EU mandate M490 reference architecture working group The SGAM visualization represents one use case on different layers (business, function, information, communication, and component) to show the use case in different levels of detail [5] This approach can also be trans-

5 Figure 2 Relations between Areas ferred to further domains For the domain smart building, the SHAM (Smart Home Architecture Model) visualization is used [18] For smart cities it is recommended to transfer the SGAM to a Smart City Infrastructure Architecture Model (SCIAM) [8] Further visualizations, such as the use case relations and the area management, are generated with the JavaViz API [19] A further interesting part of the developed UCMR is the area management The area management enables the management of use cases from different areas in one UCMR to facilitate the cooperated work between them, ie use cases from one area can be transferred to another area An example for the area structure in the UCMR is shown in Figure 2 33 Area Management The structure is demonstrated as a graph in which each node has any number of parents and children, excepted the first node Repository The Repository node is the starting point for all areas The graph shows exemplarily which dependencies between areas could exist The edges show which areas have common use cases and elements, eg use cases which are described in SG and AAL are also relevant for the smart building area Also, described use cases in smart building and electrical vehicles are relevant in smart city The smart city area can be extended by further use cases to close the gap between smart building and electrical vehicles (in this example) This technique supports the development of new complex and cross-industry systems, such as smart city New areas can be created by the user, and also, the dependencies between areas can be changed by the user to include new domains and relate them to existing domains 34 User Rights The UCMR is used by different experts, and to facilitate the management of the high number of use cases, user rights are added In this case, the rights read, submit, write, and manage are considered For each area, rights for all UCMR users are set, ie if a new area is created, the originator gets the manage right and has to decide which users get which rights The manage right includes the user management in this area and the checking of submitted use cases to this area The read right allows users to see the new area, its use cases, and its elements If users have the right to submit, they are able to ask the area manager whether their use case or element can be added to the area, but they do not have write permission on the area The write right of an area allows users to change and to create use cases If users do not have any rights for an area, the area will be invisible for them The hierarchical structure of the user rights facilitates the management of the use cases by limiting the number of users which can change data (write right) without proofing it by the manager 4 Importance for Standardization The domains AAL, SG, and smart city are evolving, so a complete overview about their functionality does not exist Use cases help to describe these domains by scenarios and steps to detect further important functional and non-functional requirements (eg security, privacy) or new products which are needed to realize the described functionality Use cases are the basis of a common understanding of a domain, their tasks and actors Due to the stepby-step description of a use case; actors, systems, interfaces, etc can be identified for a domain This depicts a communication basis between several organizations Standardization processes of these interacting products, components, and systems have to be coordinated to identify common interfaces which should be standardized to ensure a smooth connection [3, 4] These common interfaces would allow cross-system interaction, and hence, a better integration of different domains With the described UCMR approach, the cross-system and cross-domain interactions can be planned Also, generic use cases can be identified to create uniform specifications for products, such as sensors and assistance systems Due to the UCMR, the communication and knowledge transfer is improved Standardization organisations and experts can use the UCMR to exchange and to extend use cases So, the description of a domain by use cases by different experts supports the detection of standardization gaps and the creation of interoperability tests This process supports the development of smart domains 5 Outlook This paper provides an overview on the current development of the Use Case Management Repository (UCMR) to manage use cases and whose elements from different do-

6 mains in one repository by applying the IEC/PAS use case template In the next step, the implementation of the UCMR is completed, and the UCMR is configured with data from the domains SG and AAL For both domains, a similar template with the extension of integration profiles is used [6], so that the template and the functionality of the UCMR can be used for both domains without any changes Hereupon, the template should be adopted to further domains, such as electro vehicles, smart buildings, etc The application of the approach in the electro mobility domain is under progress [20] If the template is applicable to further domains, a combination of all these domains (SG, AAL, electro vehicles, smart building, etc) in the UCMR will support the standardization of products, systems, and interfaces for smart cities For the semantical integration with other standards, an existing Ontology for the IntelliGrid Template [21] the IntelliGrid template is the basis of IEC/PAS template can be used Due to the usage of one UCMR for all domains, further use cases for cross-system domains, such as smart cities, can be created and analyzed to close gaps between these domains These use cases supports the standardization organisation, different experts, and vendors to identify new standards, as described above Also, it makes the current planning for new component by vendors easier, when standards are defined which are important for the future 6 Acknowledgment The research leading to these results has received funding from the German Federal Ministry for Economic Affairs and Energy under Grant Agreement no 01FS13028, UC4AAL 7 References [1] T Nam and T A Pardo Smart City as urban innovation: Focusing on management, policy, and context In ACM, Tallinn, Estonia, 2011 [2] acatech Smart Cities Technical report, acatech, Munich, 2011 [3] M Uslar, S Rohjans, J M González, M Specht, and J Trefke Das Standardisierungsumfeld im Smart Grid - Roadmap und Outlook e & i Elektrotechnik und Informationstechnik, 128(4): , 2011 [4] R Santodomingo, M Uslar, A Göring, M Gottschalk, L Nordstrom, A Saleem, and M Chenine SGAM-based methodology to analyse Smart Grid solutions in DISCERN european research project In Energy Conference (ENERGYCON), 2014 IEEE International, pages , May 2014 [5] M Uslar, M Specht, C Dänekas, J Trefke, S Rohjans, J Gonzalez, C Rosinger, and R Bleiker Standardization in Smart Grids Springer, Germany, 2013 [6] DKE Die deutsche Normungs-Roadmap AAL Version 2 Technical report, DKE, Frankfurt, 2014 [7] DKE The German AAL Standardization Roadmap Technical report, DKE, Frankfurt, 2012 [8] DKE The German Standardization Roadmap Smart City Technical report, DKE, Frankfurt, 2014 [9] I Jacobson, I Spence, and K Bittner Use Case 20 the guide to succeeding with use cases Technical report, Ivar Jacobson International, Sweden, 2011 [10] Dean Leffingwell Agile software requirements Lean Requirements Practices for Teams, Programs, and the Enterprise Pearson Education, 2011 [11] OMG OMG Unified Modeling Language superstructure Technical report, OMG, 2011 [12] M Uslar, S Rohjans, T Schmedes, J Gonzalez, P Beenken, T Weidelt, M Specht, C Mayer, A Niesse, J Kamenik, C Busemann, K Schwarz, and F Hein Untersuchung des Normungsumfeldes zum BMWi-Förderschwerpunkt e-energy IKTbasiertes Energiesystem der Zukunft Bundesministerium für Wirtschaft und Technologie, 2009 [13] Becks, Bitterer, Brandstetter, Buchholz, Englert, Glaunsinger, Hagen, Kahmann, Horenkamp, Kerber, Kiessling, Krause, Malina, Meierhofer, Nickel, Rehtanz, Sporer, Stein, Steusloff, Thies, Uslar, and von Sengbusch Die deutsche Normungsroadmap E- Energy/Smart Grid DKE, 2010 [14] P Kellendonk, A Kiessling, M Uslar, J Trefke, J Gonzalez, and J Stein Definition von Use Cases in der Normung - Basis für eine aktive Beteiligung privater Haushalte im Smart Grid In Internationaler ETG-Kongress 2011 in Würzburg, 2011 [15] IEC/PAS 62559: IntelliGrid methodology for developing requirements for energy systems, 2008 [16] M Eichelberg, L Rölker-Denker, and A Helmer Action aimed at promoting standards and interoperability in the field of AAL - AAL Use Cases and Integration Profiles Technical report, AAL Joint Programme, 2014 [17] J Bruinenberg, C Colton, E Darmois, J Dorn, O Elloumi, H Englert, R Forbes, J Heiles, P Hermans, F Kuhnert, F Rumph, M Uslar, and P Wetterwald Smart Grid Coordination Group Reference Architecture for the Smart Grid version 10 (draft) Technical report, CEN, CENELEC, ETSI, 2012 [18] DKE Die deutsche Normungs-Roadmap Smart Home + Building Technical report, DKE, 2013 [19] S Kruse and P Gringel Generische Visualisierung strukturierter Daten In Smart Cities Intelligente Lösungen für das Leben in der Zukunft VDE, 2014 [20] C Mayer, T Suding, M Uslar, and T Weidelt IKT- Integration von Elektromobilität in ein zukünftiges Smart Grid In VDE-Kongress E-Mobility: Technologien - Infrastruktur - Märkte in Leipzig VDE Verlag, Berlin, 2010 [21] Mathias Uslar Ontologiebasierte Integration heterogener Standards in der Energiewirtschaft PhD thesis, Universität Oldenburg, 2009