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Auflistung nach Autor:in "Kempa, Martin"

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  • Zeitschriftenartikel
    Model Driven Architecture
    (Informatik-Spektrum: Vol. 28, No. 4, 2005) Kempa, Martin; Mann, Zoltán Adám
    Bei der Model Driven Architecture (MDA) bilden Modelle die zentralen Elemente des Softwareentwicklungsprozesses. Ziel ist es, plattformspezifische Modelle möglichst automatisiert aus plattformunabhängigen Modellen abzuleiten. Dadurch soll der Aufwand der Softwareentwicklung verringert und die Adaptierung an neue Technologien erleichtert werden.
  • Zeitschriftenartikel
    Multidimensional Expressions (MDX)
    (Datenbank-Spektrum: Vol. 11, No. 2, 2011) Kempa, Martin
  • Zeitschriftenartikel
    Sprachen und Werkzeuge zur Generierung von HTML- und XML-Dokumenten
    (Informatik-Spektrum: Vol. 25, No. 5, 2002) Linnemann, Volker; Kempa, Martin
    Inhalte von Webseiten werden heute zu einem großen Teil beispielsweise mit Hilfe des Inhalts von Datenbanken oder aus aktuellen Daten wie Aktienkursen oder Wetterdaten dynamisch generiert. Es gibt eine Fülle von Sprachen für die Realisierung solcher Webanwendungen.Summary. Nowadays, contents of web pages are very often generated dynamically, for example by integrating the results of data base queries or by using up to date stock exchange data or weather data. Numerous languages exist for implementing these web applications. In this paper, some languages are considered which, at least in part, are concerned with the generation of HTML- or XML-Documents. It is shown that, besides being rather complicated, these languages allow to ”prove” the validity of the generated structures only at runtime. A proposal which is currently being developed in Lübeck allows to check the validity of the generated HTML- and XML-documents at compile time.
  • Konferenzbeitrag
    Type checking in XOBE
    (BTW 2003 – Datenbanksysteme für Business, Technologie und Web, Tagungsband der 10. BTW Konferenz, 2003) Kempa, Martin; Linnemann, Volker
    XML is the upcoming standard for internet data. Java is the most important programming language for internet applications. Nevertheless, in today's languages and tools there is no smooth integration of Java and XML. The XML OBjEcts project (XOBE) at the University of Lübeck addresses this mismatch by defining XML objects by XML schemas and by making them to first-class data values. In XOBE, the distinction between XML documents and XML objects no longer exists. Instead, a running XOBE program works only with XML objects. XML documents in text form with explicit tags exist only for communicating with the outside world. This approach allows to check the validity of all XML objects within a program statically at compile time. This is accomplished by XML constructors. Previously generated XML objects are inserted in these constructors such that the validity can be checked at compile time. This paper concentrates on the type checking algorithm in XOBE which is used, among others, for checking the correctness of assignment statements involving XML objects. The type checking algorithm assures that all XML objects that can occur dynamically on the right hand side of an assignment statement are objects that can be assigned to the variable on the left hand side. This type checking is done statically without running the program. The algorithm is based upon regular hedge grammars and regular hedge expressions.
  • Konferenzbeitrag
    Type safe programming of XML-based applications
    (Informatik 2004, Informatik verbindet, Band 2, Beiträge der 34. Jahrestagung der Gesellschaft für Informatik e.V. (GI), 2004) Kempa, Martin; Linnemann, Volker
    There is an emerging amount of software for generating and manipulating XML documents. This paper addresses the problem of guaranteeing the validity of dynamically generated XML structures statically at compile time of an XML-based application. In the XOBE (XML OBJECTS) project we extend the object-oriented programming language Java by new language constructs. XML Schema is used for describing sets of valid XML documents. An XML schema provides a vehicle to define new classes, i.e. each element declaration in a schema defines a new class of objects (XML objects). Each object within a class represents an XML structure which is valid according to the underlying XML schema. XML objects are created by a new language construct called XML object constructor. XML object constructors are expressed in XML syntax. Previously generated XML objects can be inserted according to the declared XML schema. The main focus of the paper is the type system of XOBE. Among others, this type system provides the basis for checking the validity of assignments of XML objects to variables. The type system will be described and we present formally a type checking algorithm based on this type system.