Meta-Programming as a Model Creation Technique

Model-Driven Programming and Meta-Programming together with Semantic Web and End-User Programming techniques are vital ingredients of the User Driven Programming/Modelling approach used in this thesis. Dmitriev (2006) explains the problem to be solved in order to improve model production as “limitations of programming which force the programmer to think like the computer rather than having the computer think more like the programmer.” Meta-programming (Dmitriev, 2006) is a useful way of allowing for language independent software development, and can aid in providing a high level front-end to programming languages. “Meta-programming is the writing of programs that write or manipulate other programs (or themselves) as their data” (Wikipedia, 2008).

The idea behind use of meta-programming in this thesis is that instead of writing programs to do a task a domain expert needs the program for, the meta program developer creates an environment which all domain experts, in this and similar fields can use to create their own solutions. The developer then only needs to maintain and improve this programming environment, and can concentrate on this task; the domain expert can concentrate on solving the problem at hand without having to ask the developer to create the code on his or her behalf. Dmitriev (2006) advocates reducing dependency on languages and environments by enabling programmers to develop their own specific languages for solving each domain problem:

"If we are going to make creating languages easy, we need to separate the representation and storage of the program from the program itself. We should store programs directly as a structured graph, since this allows us to make any extensions we like to the language. Sometimes, we wouldn't even need to consider text storage at all. A good example of this today is an Excel spreadsheet. Ninety-nine percent of people don't need to deal with the stored format at all, and there are always import and export features when the issue comes up. The only real reason we use text today is because we don't have any better editors than text editors. But we can change this... Text editors... don't know how to work with the underlying graph structure of programs. But with the right tools, the editor could work directly with the graph structure, and give us freedom to use any visual representation we like in the editor. We could render the program as text, tables, diagrams, trees, or anything else. We could even use different representations for different purposes, e.g. a graphical representation for viewing, and a textual representation for editing. We could use domain specific representations for different parts of the code, e.g. graphical math symbols for math formulas, graphic charts for charts, rows and columns for spreadsheets, etc. We could use the most appropriate representation for the problem domain, which might be text, but is not limited to text. The best representation depends on how we think about the problem domain. This flexibility of representation would also enable us to make our editors more powerful than ever, since different representations could have specialized ways to edit them."

This provides a way to create programs that create programs so enabling the 3 step translation process used in this thesis, and this enables translations between people, between systems, and between languages. This could enable those who are not currently programmers to create models at their domain level using domain specific systems created for them by programmers. The mechanisms for this are recursive translation of the tree/graph code representation to multiple models and languages, where necessary aided by user/modeller choices.

References

Dmitriev, S., 2007. Language Oriented Programming: The Next Programming Paradigm - http://www.onboard.jetbrains.com/is1/articles/04/10/lop/.

Fischer, G., 2007. 'Meta-Design: A Conceptual Framework for End-User Software Engineering' http://drops.dagstuhl.de/opus/frontdoor.php?source_opus=1087 - Dagstuhl Seminar Proceedings.

Wikipedia (2008) Metaprogramming - http://en.wikipedia.org/wiki/Metaprogramming.

More information is available at - http://www.cems.uwe.ac.uk/amrc/seeds/softwareengineering.htm#MetaProgramming.

Meta-Languages and their usefulness for User Driven Programming

Meta-languages describe the structure of information to enable this information to be searched more easily by software systems. XML (eXtensible Markup Language) has emerged as the most important of these Meta-languages and is the base for many languages. XML standards are important for the Semantic Web, many computer based reasoning systems, and for communication between different software applications. Alternative representations of information should not be used in any system being developed now unless the author has examined XML based standards and found them insufficient. Such a situation is highly unlikely. Any software system that does not use these standards will have difficulty communicating with other software systems. Use of a generic standard keeps open the possibility of communication with the widest possible range of other software systems. Use of a domain specific standard targets the communication to a particular domain.

Extensible Markup Language XML is an important standard in the development of ontologies. This language allows for the construction of text documents in which the relationship between concepts is represented. Because it is an accepted standard it is possible to use XML on any type of computer. Further developments such as Resource Description Framework RDF add a layer of standardisation of semantics, above the standardised syntax of XML. It is also possible to represent diagrammatic, and graphical information using a variety of XML called Scalable Vector Graphics (SVG).

These open standard languages can be used for developing the program code of models. It is proposed that software and information represented by the software, be separated but represented in the same open standard searchable way. Software and the information it manipulates are just information that has different uses, there is no reason why software must be represented differently represented differently from other information. So XML can be used both as the information input and output by the application, and for the definition of the model itself. The model can read or write information it represents, and the information can read from or write to the model. This recursion makes 'meta-programming' possible. Meta programming is writing of programs by other programs. The purpose of this is to provide a cascading series of layers that translate a relatively easy to use visual representation of a problem to be modelled, into code that can be run by present day compilers and interpreters. This is to make it easier for computer literate non-programmers to specify instructions to a computer, without learning and writing code in computer languages. To achieve this, any layer of software or information must be able to read the code or the information represented in any other. Code and information are only separated out as a matter of design choice to aid human comprehension, they can be represented in the same way using the same kinds of open standard languages.

Meta Language Links

Dmitriev, S. (2004). Language Oriented Programming: The Next Programming Paradigm, http://www.onboard.jetbrains.com/is1/articles/04/10/lop/.

Mens, K., Michiels, I., Wuyts, R. (2002). Supporting Software Development through Declaratively Codified Programming Patterns, Expert Systems with Applications, 23: 405-413.

I am a Researcher in the final year of my PhD. I specialise in applying Semantic Web techniques. My current research is on a technique of 'User Driven Modelling/Programming'. My intention is to enable non-programmers to create software from a user interface that allows them to model a particular problem or scenario. This involves a user entering information visually in the form of a tree diagram. I am attempting to develop ways of automatically translating this information into program code in a variety of computer languages. This is very important and useful for many employees that have insufficient time to learn programming languages. I am looking to research visualisation, and visualisation techniques to create a human computer interface that allows non experts to create software.

I am a member of the Institute for End User Computing - http://www.ieuc.org/home.html.

My Home Page is http://www.cems.uwe.ac.uk/~phale/.

A web page for this article is at http://www.cems.uwe.ac.uk/amrc/seeds/PeterHale/EndUserHistory.htm.