Book Review of: |
| As use of the Internet increases at a geometric pace, access speed
decreases by a proportional amount. More trunk lines, and wider bandwidth
are only partial solutions. I believe more efficient data transfers will
come from JAVA, ActiveX, and applications created by them. Active Visual
J++ uses actual source code along with detailed information about programming
in JAVA using Visual J++.
If you are looking for a book that is a primer, or a simple ABC to learning JAVA, keep looking. Not that this book is poorly written, just the opposite. It is however, well beyond the beginner or one with a casual interest. The author, Mr. Ladd, does a good job of explaining terminology, and in giving a background on JAVA, but you need to know something about C or C++, or even JAVA itself. He uses actual JAVA code for the reader to assemble and run, and as he explains, he "likes to teach programming by showing programs". Why JAVA? WIN/TEL, MaC, UNIX, mainframes, Internet Explorer, and Netscape are some of the reasons. When you are dealing with so many incompatible machines and platforms, a common denominator is necessary. HTML (HyperText Markup Language) takes care of documents and images, but something else is needed for interactivity. A browser is basically a virtual document display that reads an HTML document and tailors it to a specific computer. The designers of JAVA (Sun Microsystems) defined an abstract computer known as the JAVA Virtual Machine (JVM). Programmers need only write code for a virtual machine, and any computer or platform that has a compatible emulator (browser) will run it. "The JAVA Application Programming Interface (API) is a set of functional packages implemented inside the virtual machine. If your JAVA program uses the standard I/O and file packages, your compiled code won't contain copies of those functions-instead, your applet will have links to equivalent features in the virtual machine. The concept is similar to the od Dynamic-Link Libraries (dlls), in which compiled code is put into modules that are called by many programs. But whereas DLL code is system-specific, the JAVA API is built into every virtual machine. The design of the API makes JAVA eminently efficient, since only the unique applet code will travel over the Internet. If the API were linked into the applets, as library functions are in C++, people would be downloading the standard packages over and over. The API functions belong in the virtual machine, where they can efficiently implement system-specific functions through a generic interface." Now that you know something about JAVA, remember the title-- "Active Visual J++". The author uses Visual J++, an application by Microsoft for creating J++ apps, to create and compile the examples in the book and on the included cd. Mr. Ladd also goes into some depth explaining ActiveX and COM (Component Object Model). ActiveX technology has received some bad publicity due so called "rogue applets". ActiveX is optimized for the transfer of components and allows you to download a control and it's associated data asynchronously. "An ActiveX control is a piece of native code, which means that it has access to any part of your system-including files, I/O ports, and other sensitive facilities. The JVM has no way of controlling the actions of any ActiveX control, even if it is linked by script to an applet." This allows the operation outside the virtual machine, which can create security problems. Some people in Germany were reportedly able to electronically transfer other people's funds using ActiveX technology. JAVA operates inside the virtual machine which helps prevent such mischief. Microsoft is aware of this problem, and has a security system in Visual J++ called Authenticode. The book is loaded with such information, and also places very useful notes in strategic locations. More information about JAVA can be found in the April '97 issue of the Alamode. Check out articles by Miguel Hidalgo, Ed Rios, and Ray Lopez. The book includes a cd inside with Microsoft's JAVA SDK (software developer's kit) version 2.0, as well as several applets. As I mentioned earlier, this is not a see spot run book, but if you are interested in JAVA and it's various forms, this book deserves a look. The book is available locally at the larger bookstores, and sells at or near its manufacturer's suggested retail proce, which is $39.99. Active Visual J++ by Scott Robert Ladd
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