Model-Document-Renderer is an evolution of Passive-View design pattern, suggested by Martin Fowler [1]. The difference is mainly in the terminology and in the suggested way of decomposing the application. (Continued)
The goal of this case-study is to make a short overview of the development tools for developing web-based business applications. The tools must (should) satisfy the following criteria:
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ObjectTeams/Java (OT/J) is an extension to Java programming language that facilitates roles and collaborations as the first class language constructs. This article is an exercise on using (OT/J) for implementing collaborations.
This exercise considers two bank operations – money transfer and fund cashing. The course of events for these two operations is very similar in basic and differs in details. Considering this, it is implemented as an abstract withdraw routine leaving detail differences to concrete implementations.
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Graphs, networks and trees are commonly used to model application domains. In some cases these structures are highly dynamic and can not be defined at design time. Yet there are also cases when they are rather static and do not change during the application life cycle. An example of such static structure is a finite state automaton – defined as a part of design, it remains unchanged at the run-time.
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Where to keep SQL statements? This question arises almost for any more-less sophisticated Java application that accesses DBMS. Two most common approaches are: (1) as string constants in Java and (2) as text in external files. Both these approaches have significant drawbacks. Java strings get complicated when a string is too long to fit in one line, leading to a difficult to read and hard to maintain SQL code. SQL in external files are not easy to lookup and require some mapping technique to associate statement in the external file with a place in Java where it is needed. Also, as development goes, the text file adheres with more and more orphan SQL statements and there is no easy way to clean them up. This article suggests an approach that combines two mentioned above and inherits their strong sides.
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