Institute for Informatics
Georg-August-Universität Göttingen

Databases and Information Systems

dbis
Uni Göttingen

Semistructured Data and XML
Summer 2021

Prof. Dr. Wolfgang May
Lars Runge, M.Sc., Sebastian Schrage, M.Sc.

Date and Time:

  • Monday 14-16 ct, IFI SR 2.101
  • Wednesday 10-12 ct, IFI SR 2.101
  • Virtual Meetings: We will use BigBlueButton provided by GWDG; the rooms/meetings can be entered via StudIP. There also the recordings can be found (they cannot be exported or edited at all)
    Please also read the general and technical information about DBIS virtual teaching.

Lecture and Exercises mixed (see announcements on this page). There will be non-mandatory exercise sheets whose solutions will be discussed as parts of the lecture.

Module M.Inf.1141, 4 SWS, 6 ECTS.
The module's home is the MSc studies in Applied CS. It can also be credited in the BSc studies in Applied CS (as "Vertiefung Softwaresysteme und Daten"),
and in several other studies:
BSc/MSc Wirtschaftsinformatik, Mathematik (BSc/MSc), Teaching/2-Fach-Bachelor, PhD GAUSS, ...

Course Description

One of the most important facts that lead to the overall success of XML is that the "XML world" combines a lot of already known concepts in an optimal way for coping with a broad spectrum of requirements. The course will first review some of these preceding (partially even historic) concepts (network database model, relational databases, object-oriented databases) and the integration of data and metadata (SchemaSQL). Then, the idea of "semistructured data" is introduced by showing early representatives that helped to shape the XML world (F-Logic, OEM).

In the main part, XML is presented as a data model and a markup-meta-language, and the current languages of the concepts of the XML world are systematically investigated and applied: DTD, XPath, XQuery, XSLT, XLink, XML Schema, and SQL/XML.

The lecture uses the geographical sample database "Mondial" in its XML version for illustrations.

For practical exercises, the XML software is installed in the IFI CIP Pool. The software playground page can be found here; the XPath/XQuery/XSLT Web interface is available here.
The sample code fragments can be found in the CIP pool under /afs/informatik.uni-goettingen.de/course/xml-lecture/ .

Dates & Topics

  • Mon 12.4. No lecture. There is the institute's MSc welcome meeting in the afternoon.
  • Wed 14.4. and Mon 19.4.: No SSD/XML meetings
  • As stated on information about DBIS virtual teaching, this year, DBIS will use mainly non-live teaching by pre-recordings; there will be a small number of live meetings.
  • For newcomers, we will link a recording on the technical/online teaching issues here (cleaned recording from last year)
  • Wed 21.4.: live meeting via StudIP->Meetings->SSD-2021-04-21
    Administrativa, Overview, ...

    The lecture is intended to have three dimensions:

    • A typical technology course (XML and its languages) with much practical contents. Perfect for self-learning and experimenting.
    • XML is a perfect example of many computer science concepts (practically: around data, data exchange and interoperability, theoretical: trees, language design)
      By now, most of you have already practical experience with many of them: ant, maven (XML), JSON (a form of a much newer "lightweight" reduction of XML).
      Learning: Always be aware and analytical of the underlying concepts and structures.
    • "History": how did (do, and will do) computer science and IT concepts evolve?
      The "XML world" (and many other things, like most basic Web technologies) were developed as a response to new requirements in the mid/late 1990s. A very interesting time, where many already existing ideas and experiments were improved and combined.
      Learning: see how to analyze and question requirements and existing things/software.

    Just a quick and dirty introduction to XML as document and data format and querying it with our Web Interface:
    document and data trees [ss16]
    Recording: Document (XHTML, like this (self!) document) and data trees (with an introduction to Mondial in XML))

Part I: History, evolution, and comparison of data models until 1995 and requirements for XML

  • 26.4.-15.5.: No pre-scheduled live meetings.
    Materials for self-studying (videos taken from summer term 2020 as the dates in the filenames indicate):
  • 26.4./28.4.
  • 3.5.: Data Models: about structuring data and the development of query languages.
    Slides: the Relational Model
    Recording: General concepts of data models, the relational model (with its querying concepts) as an example data model.
  • 5./10.5.: The Requirements for "semistructured data" in the mid 90s, history of data models: appropriateness of the data model for modeling data and other requirements of the time.
    Slides: data models
    Recording: the network database model (1960s, pre-declarative querying) and the object-oriented database model (late 1980s)
    Recording: the object-oriented database model (late 1980s, OQL, OIF, Corba)
  • Some references to read about database history (optional):
  • 12./17.5.: "History" continued - requirements and academic prototypes of the early 1990s:
    SchemaSQL (an extremely powerful, yet syntactically minimal "opening" of SQL to metadata) and early semistructured data models (Tsimmis/OEM and F-Logic):
    Slides: early semistructured data models
    Recording: SchemaSQL
    Recording:Tsimmis/OEM (part 1)
    Recording: Tsimmis (part 2), F-Logic and the situation pre-XML
  • Monday, May 17th 14:15: Live online meeting
    to get some feedback (maybe some ad-hoc polls), answer questions, and to discuss/give a roadmap for the rest of the lecture.
    From then on, the course gets "productive" and continues with XML and the languages of the XML world.

Part II: XML concepts and technology - aspects of XML as a data structure in Computer Science

  • According to the poll in the meeting, the exam has now been scheduled. The plan is to have a written exam (if there is only a very small number of participants, we could switch to oral exams) on Tuesday, August 17th, somewhere between 9-13h.
    Depending on the Corona situation, either as at-home exam (Ilias or download-upload), or in the E-Learning room (then it will be Ilias-based) or in any other computer pool. The plan is that you can choose to use your own laptop (Ilias in the browser) or the E-Learning/Pool computer (for those who do not have a laptop).
    The exam ist project-like, i.e., a project description for which XML and DTD have to be created/completed, an then XPath/XQuery/XSLT are applied, and some text-style questions on the materials of the lecture.
    We will link earlier exams for training on this web page (you can already find them on the Web pages of the before years, but they do not yet belong "here".)
  • (Exercise: if you have knowledge about JSON, compare JSON with the concepts discussed in Part I, and with the following aspects of XML)

  • 19.5.: XML: data model, language, DTDs etc.
    Slides: XML basics
    Recording: XML basics
  • 24.5.: according to the schedule, this is a holiday
  • 26.5.: XML: DTDs etc. (cont'd)
    Recording: DTD, the xmllint tool
    notes
  • 31.5.: XML parsing ...
    Recording: XML parsing, XHTML (and parsing)
    Exercise Sheet 1
    (XML basics, parsing, grammar aspects)

Part III: Languages of the XML world: XPath, XQuery, XSLT ...

Exams

The exam will (most probably) be a written exam. Depending on the situation, classically in presence (paper-based or Ilias-based), or online-at home (with ILIAS or download-upload).
Current plan: Tuesday, August 17th, somewhere between 9-13h