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1.4 The Complexity Crisis

One reason to invest in software language engineering is that over the past decades, the nature of not only software languages but also software development has changed. In fact, it is the nature of the software applications that has changed and with it, software development.

Software applications are becoming more and more complex. As Grady Booch once mentioned in a presentation on UML 1.1, computer scientists today do not create the type of application from the 1960s or 1970s in less time and with less effort. Instead, they create far more complex applications.

The number of languages, frameworks, and so on, that an ordinary programmer nowadays needs to deal with is exceedingly large. For example, in the development of an average Web application based on Java, one needs to have knowledge of the Java language and some of its APIs, XML, XSD, XSLT, JSP, Struts or JSF, Enterprise JavaBeans or Hibernate/Spring, SQL, UML, Web Services, and, lately, Ajax. All these bring with them their own complexity, not to mention the complexity that arises from the combination. The time when printing "Hello, World" on a screen was a simple exercise for novices is long gone. Nowadays, you need to know how the graphical user interface (GUI) library works, because this text needs to be shown in a separate window with fitting fonts and colors. Furthermore, user demands are such that the sentence must be personalized into "Hello Mrs. Kleppe," for which data must be retrieved from the database. Even better would be to print the text "Goodmorning, Mrs. Kleppe," for which you have to find out what time of day it is at the user's site. In short, building software is becoming more and more challenging for all of us, not only for novices.

Unfortunately, all this means that the problem, which was called the software crisis by Bauer in 1968 and Dijkstra in 1972 [Dijkstra 1972], has grown worse: Many software projects take more time and budget than planned. However, this is not because of the fact that there has been no progress in computer science. Rather, there has been so much progress that we are able to take up increasingly complex assignments. This means that time and again, we are facing a new, unknown, and uncertain task, which in its turn leads to an inability to take full control over the development process.

An interesting and worrying consequence of the increasing size and complexity of software applications is that it is no longer possible to know an application inside out. Much expert knowledge from various areas is needed to create an application. In many projects, experts on one topic—say, XML—are creating parts of the application without intimate knowledge of what other experts—for instance, on user interface design—produce. It is no longer humanly possible to know all the things that need to be known about an application.

A common way to tackle the complexity is to revert to using frameworks and patterns. And although in the short term this approach does help, in the long term we need our software languages to be at a higher level of abstraction if we want to be able to keep understanding what it is that we are producing. A higher level of abstraction means that we keep manual control over the parts of the development process in which new problems are tackled (variability), while relying on automation for the simpler parts (standardization). The stuff that we have created time and again and thus know thoroughly can be created automatically by mapping the higher-level mogram to a lower-level target language. This is the essence of model-driven development.

Furthermore, we are faced with an increase of interest in creating domain-specific languages. When these are not well designed, the applications created with these languages will not be of good quality.

The challenge for language engineers is that the software languages that we need to create must be at a higher level of abstraction, a level we are not yet familiar with. They must be well designed, and software developers must be able to intermix the use of multiple languages. Here too, we are facing a new, unknown, and uncertain task.

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