Extension to UML Using Stereotypes

Transcription

1 Extension to UML Using Stereotypes Daniel Riesco Universidad Nacional de San Luis and Universidad Nacional de Río Cuarto, Argentina Marcela Daniele Daniel Romero Universidad Nacional de Río Cuarto, Argentina {marcela, German Montejano Universidad Nacional de San Luis Introduction The Unified Modeling Language UML, allows to visualize, to specify, to build and to document the devices of a system that it involves a great quantity of software. It provides a standard form of writing the models of a system, covering so much the conceptual aspects, such as processes of the business and functions of the system, as the concretes, such as the classes written in a specific programming language, schemas of databases and software components. In 1997 UML 1.1 it was approved by the OMG becoming the standard notation for the analysis and the design orient to objects. UML is the first language of modeled in publishing a metamodel in its own notation, it is a strict subset called Core. It is a metamodel self referential. It is a very expressive language that covers all the necessary views to develop and to deploy systems. UML is a language that provides three extension mechanisms [1], stereotypes, tag values and constrains. The stereotypes allow to create new types of elements of model based on the elements that form the metamodel UML extending the semantics of the same one, the tag values are an extension of the properties of an element of UML, allowing to add new information in the specification of the same one, and the constrains are an extension of the semantics of UML that you allow to add new rules or to modify the existent ones. The organization of this overview this given in the following way: first we present the stereotypes according to the standard of OMG, second we expose the analysis of works that extend UML using stereotypes in diverse real domains, third we make an analysis of the stereotypes of UML, and we finish giving a general conclusion in where we focus ourselves in the distinction of the works according to if they include the or the created stereotypes in the metamodel of UML. Stereotype according to standard of OMG A stereotype provides a form of classifying elements in such a way that they work in some aspects as if they were instances of a new constructor of the virtual metamodel. A stereotype could also be used to indicate a meaning or different use between two elements with identical structure. A stereotype can also specify a geometric icon to be used to present elements with the stereotype. BaseClass Icon Attributes This specifies the names of one or more elements from UML modeling to which the stereotype is applied, such as classes, associations. This is the geometric description for the icon that will be used to present an image of the element of the marked model with the stereotype. Using stereotypes in diverse real domains UML adapts to any technique, because it has extension mechanisms that don't need to redefine the nucleus UML, allowing to obtain a modeling one more appropriate to the different particular domains. All the

2 extensions should follow the standard proposed by the OMG [2]. Modeling of Business with UML UML was initially designed to describe aspects of a software system. For the modeling of business, UML needed to be extended to identify and to visualize, more clearly, resources, processes, objectives and rules, these are the primary concepts that define a business system, the calls Eriksson Penker Business Extensions [3] provide new stereotypes for their model. In a diagram of class of UML, they represent a process through a specific symbol that corresponds to an activity stereotyped in an activity diagram. The resources used by the process are modeled with a stereotyped dependence «supply» and the resources controlled by the process are modeled with a stereotyped dependence «control». Modeling of Aplicaciones Web with UML In [5], they propose a framework denominated W2000, for the design of applications web. They combine the use of UML and HDM (Hypermedia Model). The applications web requires the integration of two different, but interrelated, activities: the design hypermedia that is focused in the navigation way and the structure of the information, and the functional design that is focused in the operations. Between their main purposes it is the extension to the standard of UML of the dynamic diagrams. It uses «node type» like stereotype of UML to define a node type that allows to accede to different structures of information, defines the symbol "@" to indicate that a node stereotyped with «node type» it will be the node for defect where all the users begin to navigate. They propose a symbol called "index" that allows the users of a navigation to select one of the elements of a listing of indexes. The calls "collection links" define as the users can navigate between the center and the members of a collection, they add a symbol to represent graphically the patron "Index + Guided Tour". For the functional design they define the diagrams of scenarios, these are represented through extended sequence diagrams of UML, the extensions refer as much to objects as to the step of messages. The objects are organized in entities (components and nodes), semantic associations and collect. The "free navigation" is represented with dotted lines and the "constrained navigation" it is represented with a line with a diamond in the means. In [6], Jim Conallen, Principal Consultant of Conallen Inc., Object Oriented Application Development, en Conallen Inc, it presents in their paper an extension to UML, in a formal way, to model applications web. The extension is planned to be presented at several other conferences in 1999, including the next Rational Users Conference in Seattle (July 1999), and two Wrox Press ASP conferences in Washington, DC (September 1999) and in London, (November 1999). Various summaries and introductions to the extension have or will appear in the Communications of the ACM ([8]), and in the UML Resources web site at Rational Software. A full explanation of this work is currently being prepared for the book "Building Web Applications with UML" ([7]), published in the Object Technology Series of Addison Wesley Longman. This paper presents an extension of UML for web application designs. Part of the extension mechanism of UML is the ability to assign different icons to stereotyped classes. A list of prototype icons for the most common class stereotypes can be found as an appendix. It defines two new stereotypes to model the difference among the executed methods in the server and the executed functions in the client. In a page a method that executes on the server will be stereotyped as «server method» and functions that run on the client «client method». This solves the problem of distinguishing attributes and methods of a page object. It proposes the modeling of a page with two stereotyped classes, «server page» and «client page». They define several stereotypes to represent the associations, such as: «builds» that is modeled with an unidirectional association from the server page to client page, «redirects» to model the redirection to other «server page», «links» for defined associations between pages clients and other pages (client or server). Also, they define stereotypes to model components, «server component» and «client component», for Forms «form», for Framesets «frameset». Other defined stereotypes, «scriplet» for cached client page, and «xml» for a hierarchical data object that can be passed to and from a web server and client browser. In [9] defines an UML extension capable to refine the design of the client part of web application. Several

3 new diagrams are specified with provide for precise definition of the content of web pages and navigation between them. The composition diagram is a special case of class diagram. We use it to express structure of the web pages and identify their content: how they are connected together and what data is carried from one page to another. The main notion of the composition diagram is the page, defined as an autonomous block of screen. Each screen in the navigation diagram is mapped into several pages in the composition diagram. The tool may provide links from pages to screens and vice versa to show their relationship. A page is modeled in composition diagram as a class stereotyped «page». A page may play role of container for other pages. Nested pages are modeled as aggregated classes. The page has elements like buttons, links and input fields. They are modeled as attributes of the corresponding page. The «form» stereotype is a child of «page». It is used to model HTML forms. The navigable association between source and target pages is stereotyped «link». Each «link» has a tag context with expression as value. In [10] defines a set of stereotypes that are used in the construction of intuitive analysis and design models in the development of Web applications. These models are the navigation space model, the navigation structure model and the static presentation models. The basis of the navigation design is the conceptual model, and the outcome is a navigational model, which can be seen as a view over the conceptual model. The navigational model is defined in a two step process. In the first step the navigational space model is defined and in the second the navigational structure model is built. The navigation space model defines a view on the conceptual model showing which classes of the conceptual model can be visited through navigation in the Web application. The navigational structure model defines the navigation of the application. It is based on the navigation space model, but also additional model elements are included in the class diagram to perform the navigation between navigational objects: menus, indexes, guided tours, queries, external nodes and navigational contexts. The static presentational model is represented by UML composition diagrams that describe how the user interfaces are built. They define stereotypes to be able to build these diagrams. The set of defined stereotypes is: The «Navigational Class» represents a class whose instances are visited during navigation. «Direct Navigability»: Associations in the navigation model are interpreted as direct navigability from the source navigation class to the target navigation class. An «Index» is modeled by a composite object which contains an arbitrary number of index items. A «Guided Tour» is an object which provides sequential access to the instances of a navigational class. A «Query» is represented by an object which has a query string as an attribute. (This string may be given, for instance, by an OCL select operation). A «Menu» is a composite object which contains a fixed number of menu items. A «Presentational class» models the presentation of a navigational class or an access primitive, such as an index, a guided tour, query or menu. A «Frameset» is a top level element which is modeled by a composite that contains (lower level) presentational objects but may also contain an arbitrary number of nested framesets. An area of the frameset is assigned to each lower level element, so called «frame», the same stereotype is also used in [3]. A «window» is the area of the user interface where framesets or presentational objects are displayed. Also defined «text», «anchor», «button», «image», «audio», «video» and «form». A «collection» is a list of text elements that is introduced as a stereotype to provide a convenient representation of composites. An «anchored collection» a list of anchors. Real Time Systems Modeling with UML In [11], describe a set of constructs that facilitate the design of software architectures in the domain of real time software systems. The constructs, derived from field proven concepts originally defined in the ROOM methodology [12], are specified using the UML standard. In particular, show how these architectural constructs can be derived from more general UML modeling concepts by using the powerful extensibility mechanisms of UML. The following stereotypes are defined as UML extension: «protocol», «protocolrole», «port», «capsule» and «chainstate». A protocol role is modeled in UML by the «protocolrole» stereotype of Metamodel Class ClassifierRole. A protocol is modeled in UML by the «protocol» stereotype of Metamodel Class Collaboration with a composition relationship to each of its protocol roles representing the standard relationship that a collaboration has with its owned elements. A port object is modeled by the «port» stereotype, which is a stereotype of the UML Class concept. A capsule is represented by the «capsule» stereotype of Class. The capsule is in a composition relationships with its ports, sub capsules (except for plug in sub capsules), and internal connectors. A state whose only purpose is to chain further automatic (triggerless) transitions onto an input transition is modeling defined a stereotype

4 «chainstate» of the UML State concept. In [13], this paper show an extension UML with mechanisms for specifying temporal constrains and properties. Define schemes for the translation of UML specifications into semantically equivalent XTG based (extended Timed Graphs) specifications such that properties given on UML specification can be proved on the XTG specification. The realization of the approach uses the extensibility interface of the Rational Rose UML Tool [14]. Analysis of UML Stereotypes In [16], this paper takes up ideas from [17] where stereotypes have been introduced for relational database design. Have analyzed the expressibility of UML stereotypes and made some concrete suggestions for the improvement of the UML metamodel. Use OCL to define precise stereotypes. In [18] and [19], present a proposal of Evolutionary Stereotypes. These are incorporated into the modeling tool in such a way that they can extend the UML metamodel, including the new elements with their corresponding semantics. In this way, the environment of a tool can dynamically change its appearance and functionality to allow software engineers to use the stereotypes previously defined in the diagrams. The study in [15] proposes a new metamodelling facility (MMF) containing: Metamodelling Language (MML), Metamodelling Tools (MMT): a satisfaction checker does instance, X satisfy constraint C from model M?, check that a model satisfies its metamodel, check that a metamodel satisfies the MML rules, check that MML satisfies the MML rules. Conclusion UML is an universal language adopted for the modeling of applications in a wide range of domains. Is an open language, which it provides extension mechanisms ace one way to extend the metamodel. The UML extension mechanisms include: Tag values, Constrains and Stereotypes. In particular, the stereotypes should be carefully declared and used only when the message to be communicated cannot be expressed in any other UML terms. Necessary conditions in order to achieve a better use of stereotypes are that the UML metamodel should be adjusted and tool support should be provided for the complete part of the UML metamodel dealing with stereotypes. The papers analyzed in this work proposes a varied number of stereotypes to extend UML, with the purpose of using this language to model particular domains, such as: Web Applications, Real Time Systems, Business Modeling, XML, etc. Of the reading and the analysis carried out to these papers we detect that only in three of them ([11], [17], [19]), they define the stereotypes added as a complete extension of UML, through the incorporation of new elements to the metamodel with new semantic that assure the consistency of the metamodel UML. In the other analyzed papers, the stereotypes are presented using them in their specific context, but without extending the metamodel UML. This is presented like a clear deficiency in their definitions, since, when not including their stereotypes explicitly to the metamodel UML, they don't allow, or at least it is very difficult of making it, the maintenance of the metamodel UML in a consistent way. Also, to the non add the or the new created stereotypes to the metamodel, they won't be available to be used in generic solutions to problems belonging to the selected particular domain. References [1] [1] Booch, G., Rumbaugh. J., & Jacobson I. (1999). The Unified Modeling Language User Guide. Addison Wesley. [2] [2] OMG (2001). OMG Unified Modeling Language specification. On the World Wide Web: [3] [3] Eriksson, Hans Erik and Penker, Magnus. (1999). Business Modeling with UML: Business Patterns at Work, Wiley & Sons. [4] Rational Software and Miller Freeman, Inc, a United Newa & Media Company. (1999). Business Modeling with

5 UML. On the Word Wide Web: [5] [5] Baresi, L., Garzotto, F., Paoloni, P.(2001). Exending UML for Modeling Web Applicattions. [6] [6] Conallen, J. (1999). Modeling Web Applications with UML. [7] [7] Conallen, J. (2002). Building Web Applications with UML. Addison Wesley, Paperback, 2nd edition, Published October 2002, 468 pages, ISBN [8][8] ASPToday. [8] ASPToday. [9] [9] Gorshkova, E., Novikov, B. Exploiting (2001). UML Extensibility in the Design of Web Applications. [10] [10] Koch, N., Baumeister, H., Mandel, L. Extending UML to Model Navigation and Presentation in Web Applications. In Modeling Web Applications, Workshop of the UML Ed. Geri Winters and Jason Winters, York, England, Octubre, [11] [11] Selic, B., Rumbaugh, J. (1998) Using UML for Modeling Complex Real Time Systems. [12] [12] ROOM Metodology. [13] [13] Toetenel, H., Roubtsova, E., Katwijk, J.(2001). A Timed Automata Semantics for Real Time UML Specifications. Proceedings of the IEEE Symposia on Human Centric Computing Languages and Environments (HCC 01) /01 $ IEEE [14][14] Rational Rose 98i. Rose Extensibility Reference. Rational Software Corporation, Rational Rose 98i. Rose Extensibility Reference. Rational Software Corporation, [14] Rational Rose 98i. Rose Extensibility Reference. Rational Software Corporation, Rose 98i Documentation, [15] See for the document A Feasibility Study in Rearchitecting UML as a Family of Languages using a Precise OO Meta Modeling Approach, (Clark, Evans, Kent, Brodsky, Cook) and associated tools [16] [16] Gogolla, M., Henderson Sellers, B., Analysis of UML Stereotypes within the UML Metamodel. Proc. 5th Conf. Unified Modeling Language (UML'2002). J. M. Jezequel, H. Hussmann, S. Cook (Eds.), Springer, Berlin, LNCS. [17] [17] Gogolla, M. Using OCL for Defining Precise, Domain Specific UML Stereotypes. In Aybuke Aurum and Ross Jeery, editors, Proc. 6th Australian Workshop on Requirements Engineering (AWRE'2001), pages 51{60. Centre for Advanced Software Engineering Research (CAESER), University of New South Wales, Sydney, [18] [18] Riesco, D., Martellottto, P., Montejano, G., Extension to UML Using Stereotypes. Cap. XIV del libro Uml and the Unified Process, Liliana Favre, ISBN: Publisher: Irm Pr.,Publication date: April 1, 2003, Pages: 40. [19] [19] Riesco, D., Grumelli, A., Macció, A., Martellotto, P. (2002). Extensions to UML metamodel: Evolutionary stereotypes. 3rd ACIS International Conference on Software Engineering, Artificial Intelligence, Networking and Parallel / Distributed Computing. Madrid, Spain. Terms and definitions Extension mechanisms: Specifies how model elements are customized and extended with new semantics. Stereotype: It allows to create new types of elements of modeling, based on the elements that form the goal pattern UML, extending the semantics of the same one. Metamodel: Is an abstraction which defines the structure for a UML model. An model is an instance of a metamodel. Defines a language to describe an information domain. OMG: Has been "Setting The Standards For Distributed Computing " through its mission to promote the theory and practice of object technology for the development of distributed computing systems. The goal is to provide a common architectural framework for object oriented applications based on widely available interface specifications. [2]. Real domains: Particular or specific: they are the different application areas that can require to be modeled with UML. For example: Web Applications, Real Time System, XML, Business Modeling, Frameworks, Communication Protocols, Workflows, Geographical Information Systems, etc. Class Diagram: Class diagrams show the classes of the system, their interrelationships, and the collaborations

6 between those classes. OCL: The Object Constraint Language (OCL) is a notational language for analysis and design of software systems. It is a subset of the industry standard UML that allows software developers to write constraints and queries over object models.