Basant Nanda and Prasad Bodeupdi have written what is probably my favorite book on Object Oriented programming. PowerBuilder is now up to version 8, and this book was written based on version 5 - but interestingly enough, the concepts are sound, the writing is witty and well illustrated and the ideas are sound and on-topic. This is an excellent introduction to PowerBuilder, and for those who have never involved themselves in it...Object Oriented programming (OO).
PowerBuilder is a visual GUI tool marketed by the Sybase Corporation. It is the leader in Rapid Application Development and during the hay-day of the Client-Server revolution - it was the premier development tool on the market. It accommodates very fast application creation, utilizing a technology called the DataWindow. This is a tool that allows a programmer to create a window object and connect it to a database through either native drivers or ODBC and bring data into it quickly.
WROX publishing has a series of books for Beginners, one for Professionals, one that contains Instant information - they title them as such. This is a modestly priced book at $39.95 and shorter at less than 300 pages.
Chapters
1 - An Introduction to PowerBuilder and OOP
The introductory chapter describes the fundamentals of Object Oriented programming - which essentially means a discussion of classes, objects, abstraction, methods, inheritance, encapsulation, polymorphism, and overloading. These are all computing industry buzzwords, but truly they are completely functional within a programming text. The concepts of Object Oriented programming at the heart are about sharing software, so that there are libraries. It is also about a neutral approach to software, data or other code; not allowing you to call it anything but an object.
2 - Working with Objects
This chapter is all about Events and Messages. Within the programming world, an Event is a moment used to describe when a user does something, or a planned occurrence. A mouse click is an event to a programmer. When you click on your mouse; I have to make the software do something. When you hit your escape key, that is an event; and it sends a message back to the computer; telling it to perform an act based on the event.
3, 4 - User Objects & C++ Objects
These are chapters that discuss what an object is, and how to use it. They go into the definition of visual and non-visual objects from the PowerBuilder perspective. They also cover how to get from C++ objects to your PowerBuilder code. The chapters also cover proper object design, and transaction objects. These transaction objects are very important in PowerBuilder as they cover the means of getting data moved back and forth. They amount to the transportation of connectivity. These chapters also discuss the use of Tab Objects, Rich Text, Type Ahead buffers,
This is also where we are led into a discussion of DLLs (Dynamic Link Libraries), which is a good place to encapsulate or refer to code. You can use DLLs in PB to create an easy link to a number of different places in the software where you can look at code. It is an excellent way to save memory. There are also some references to C++ data types.
5 - Object-Oriented Menus
This chapter covers pop up menus, and how to most conservatively hide your code, and make sure that you do not take up as much memory space. He also talks about the differences between static menus and dynamic menus. A Dynamic menu is one that is only executed at run time, it is hidden until you need to code, and then it appears. This is a very OO Coding technique.
6, 7 Ole and Ole Automation
Ole is the acronym for Object Linking and Embedding. This is a means of linking to other software or embedding it into yours. You can take a window, and link or embed to a Word document or a piece of Excel. This can be a very slow process, and almost not worth the trouble sometimes.
This is not the most efficient way of doing your business. However, if you have some users who are married to their spreadsheets, and will not get their information moved into a decent Database, then you may need to link your application to their Microsoft product. PowerBuilder can handle this and these two chapters discuss techniques for doing this, at length.
8 - Component-Based Design Using Design Patterns
Design patterns are a more specific way to establish design and to ensure a certain level of consistency among programmers in a shop or environment. These patterns are based somewhat on the nature of the activity of an object, how it acts and reacts.
They talk about Decorators, Global Utility Objects, Object Managers and Model/View/Component methods of design. These are all strong, viable methods and the authors are fairly objective in their assessment of how to use them for your PowerBuilder.
9 - Object Oriented Analysis and Design
This is really another model entirely for designing your classes and components. This is getting into some much more advanced programming techniques, but it is loosely based on the URL model. The authors are strongly moved by code re-use, and make good discussion of it in this chapter. This chapter provides a most excellent example of how to maintain the relationships in an OO model of design. This has excellent examples.
10 - Designing Frameworks and Object Libraries
A framework is an entire group of pre-designed software that is inter-related and gives you an overall feel of code re-use. Frameworks consist of the basic pieces of an entire system, and require a lot of preplanning.
11 - PowerBuilder Foundation Class Library
A lovely chapter on the PowerBuilder Foundation Class Library (PFC), which is the pre-packaged software from Sybase that comes with every version of PowerBuilder from V5 and above. The PFC has its own objects for screens, menus, and a security module. It is an incredible time saver, can give you a consistent look and feel to your software and makes the coding easy to maintain. It can be a little harder to debug, as you have to pass through more than one layer of software to get down to what is broken. This is one of the new premier features of PowerBuilder.
12 - Distributed Computing
A primer on the basics of distributed objects, and how to split your code onto multiple servers for protection, performance and code reuse. Distributed computing is all about putting your software onto multiple places, multiple computers, so that it will not all rest in one spot. You can put a set of your formal business rules in a single place, and you can have the code that your users directly interact with on another, then your database on yet another. There can at times be performance issues, as there are more software handoffs, but it can be a stable means of getting the job done. One of the objects necessary for a distributed PowerBuilder application is a Proxy object, where you create an object on one server that refers to another, looks and feels like the one it is looking at, but is really only standing in its place.
Conclusion
I have used this book as my introduction to Object Oriented programming. As it related to PowerBuilder, it was a joy to me, as I was already a PB programmer. This book is a must own.
