************************************* * * * DB/C Newsletter * * September 2001 * * * ************************************* News and Comments I'd like to thank all of the many non-US customers of DB/C who have sent us messages of support concerning the recent bombings in the United States. Although they happened here, these terrorist acts were not just an attack on the United States. Citizens from more than 60 countries were killed in New York. This was an attack all people who cherish liberty. We continue to work on DB/C DX 12. We now hope to start beta testing it in early October. Several companies have already volunteered to be part of the testing, but we can always use more. If you're interested, send me an email. A reminder - the price for renewing lapsed support on all DB/C software products increases on October 1st. You can review the status of all of your licenses of DB/C DX, DB/C FS and DB/C JX using the Online Sales and Update System at www.dbcsoftware.com. Also note that, after December 31st, no credit will be given for owners of licenses of DB/C 8 who wish to upgrade to DB/C DX. In addition, the prices for upgrading from DB/C 9 to DB/C DX will increase on January 1st. This month's article provides some reasons for why we think Smart Client is such an important feature of DB/C DX. If you haven't looked into using Smart Client, you should! don.wills@dbcsoftware.com ****************************************************************************** Smart Client The Smart Client feature of DB/C DX 11 is one of the more important features that we've added to DB/C DX in several years. This feature allows for any TCP/IP-connected computer to act as the user interface for DB/C programs that are running on a server. There are several reasons why we built Smart Client - most have to do with the Internet. The initial reason was to improve performance for users running traditional KEYIN/DISPLAY programs who connected to a DB/C runtime using telnet via the Internet. DISPLAY performance is generally acceptable in this environment. However, performance of the KEYIN verb in this environment is highly variable - sometimes it is very poor. The problem is that, although the TCP/IP protocol guarantees that data will get through, sometimes the TCP/IP transmission delay (or latency) causes an unacceptable delay for echoing characters. KEYIN is a very powerful verb. Using KEYIN, a DB/C program has complete control over what characters are echoed in response to keystrokes, thus very sophisticated applications can be constructed. Unfortunately, when TCP/IP latency is greater than half a second, applications using KEYIN over telnet become almost unusable. The solution to this KEYIN problem is to have the client's computer echo characters in response to keystrokes. This requires that an entire KEYIN statement be sent to the client's computer, it then be executed by a program on that computer, and then the resulting variables and KEYIN ending key be sent back to the DB/C DX runtime that is running the user's program. That's exactly what Smart Client does. A second reason that we built Smart Client is to effectively allow existing DB/C programs to run in a web browser. The Smart Client Java applet feature provides this capability. You design a traditional HTML web page with a rectangle for the 25 by 80 window which will run the Smart Client applet. When the user loads that web page, the Smart Client applet runs - just like applets run the banner ads found on many web pages. But instead of just displaying an ad, the Smart Client applet makes a TCP/IP connection with the server machine running the DB/C DX runtime. The Smart Client applet handles the KEYIN and DISPLAY functions just like in other non-browser environments. It's a quick and easy way to web-enable your DB/C application software. We didn't want to limit Smart Client's utility to only KEYIN/DISPLAY programs. Smart Client supports the full suite of DB/C DX GUI functions, including all window handling, dialogs, image drawing, and user input (keyboard and mouse) functions. The really neat feature that came from this is that, using Smart Client, you can run your DB/C GUI applications on a UNIX/LINUX server machine. You get the best of both worlds - the user friendliness of a graphical interface along with the administrative and price/performance superiority of UNIX. And you can mix user GUI interfaces. The GUI Smart Client comes in two flavors - Windows and Java. Thus, you can run your DB/C GUI programs on Windows workstations as well as in many non-Windows graphical environments on various platforms including UNIX (LINUX, AIX, HPUX, Solaris, etc.), OS/2, MacOS, and others. The bottom line is that the flexibility that Smart Client provides you is unmatched by anything else available. The technical details of how all of this works are found in the chapter titled 'Compiling and Running Programs' in the DB/C DX 11 documentation. ****************************************************************************** DB/C Class Schedule Class: DB/C DX and JX Language Fundamentals Date: January, 2002 Location: Oak Brook, Illinois For information, send email to admin@dbcsoftware.com. ****************************************************************************** Subscribing to the DB/C Newsletter If you don't already have the DB/C Newsletter delivered to your email address and would like to have it emailed to you monthly, just send an email message to 'dbcnews-subscribe@dbcsoftware.com'. The newsletter will be delivered to the email address from which the message was sent.