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MAKING DUMB TERMINALS SMART

Several vendors, including IBM, offer HTML gateways that give users of 3270 and 5250 terminals easy access to the Web and corporate intranets. The gateway converts 3270 or 5250 datastreams into hypertext transfer protocol to call up Internet or intranet hosts.

SNA Integration

With HTML and other Web protocol support, 3270 and 5250 users will be able to participate in the Java environment as well. In essence, Java makes dumb terminals smart.

IBM estimates that more than 50% of its Systems Network Architecture (SNA) users will need Internet or intranet access. But with more than $20 trillion invested in SNA applications and about 40,000 SNA networks worldwide, users are not quite ready to throw away their SNA networks just yet.

Equipping 3270 and 5250 terminals to handle HTML and Java allows users to choose between Web browsers or terminal emulators when accessing host data. Browsers are appropriate for accessing host programs and data over the corporate intranet. Web browsers give users a structured, graphical view of data that facilitates intuitive point-and-click navigation through large data bases.

In many cases, terminal emulation offers faster response time for data retrieval than graphically-oriented Web browsers. For some applications, terminal emulators may be the preferred tools because familiar function keys provide a fast way to navigate files and initiate processes. Furthermore, certain types of legacy data are easier to import into desktop applications than Web-formatted data.

With access to Transmission Control Protocol and Internet Protocol (TCP/IP) and SNA networks, the huge investment in terminals and legacy applications can be extended while giving users access to the Web and Java-enabled applications.

SUMMARY

The early success of the C++ programming language owes a great deal to its ability to access legacy code written in C. Likewise, Java preserves much of C++ and offers a number of compelling benefits: it is portable, high-level, secure, and easy to master. Together these and other benefits of Java have the potential to free companies from the dependence of long applications development cycles and let them adapt to changing business needs faster.

Once written, Java applications can be run unchanged on any operating system to which the Java interpreter has been ported. The code for an application written for Solaris-based SPARCstations, for example, can be copied to a Windows ’95 Pentium workstation and will run with no recompilation. In contrast, programming in C with various cross-platform tools promises portability, but generally there is still some code to rework before the application can work on another platform.

Java does have some shortcomings. IS departments that are planning to deploy critical production systems built with Java must weigh its benefits against its shortcomings. For example:

  There are differences in the way Java applications are displayed in different GUIs. For example, a scroll bar works on UNIX but not on Windows NT. These are the kind of problems that can be expected in the first release of an applications development tool and that will be ironed out in future releases of Java.
  Security is still evolving. Java’s security does not let a downloaded Java application read or write to the local hard disk. This prevents a virus written in Java from being able to infect the computer’s data and programs. The Netscape browser further restricts the application so that it can only communicate back to the server from which the data came, so a downloaded Java application cannot raid other servers. Yet these protections also limit what the application and end user can do. For example, spreadsheet users would not be able to update a local image of their spreadsheet from a central source because of the security restrictions in Java. Ultimately, Java will need to permit users to configure trusted applications.
  Heavy-duty processing is limited. Although Java’s performance is adequate for the kinds of applications it is being used for now—interactive client applications—it must become faster at the server where heavy application processing is done. Java’s code uses an interpreter as the application is being executed, so performance is slower than compiled third-generation code, such as C. The introduction of just-in-time (JIT) compilers for the Java clients and machine-code compilers for Java servers will make Java comparable in performance to raw C code.


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