Re: Is it possible in RPG to display a window when user tab to a field?

Glenn:

Whether you use DDS, or DSM, or "raw" 5250 data streams (via UDDS keyword in DDS), you are working with the 5250 architecture; the 5250 family are "block-mode" devices. You send a whole screen of data out, to formatsthe screen, typically with a "fill-in-the-blanks" form, and the user is then free to type information into each of the input fields, pressing tab or using cursor movement keys to move from field to field, etc., all locally, with no interaction with the host.

Only when the user finally presses a function key, or Enter (or one of several other special "AID" keys), the 5250 device sends back the entire buffer of all data that was input. (This behavior is just like the 3270 family on IBM mainframes.)

This "block mode" architecture helped to "off-load" much processing that would otherwise have to be done "keystroke-by-keystroke" on many competing architectures, such as most minicomputers that were popular and that competed with IBM's midrange systems (S/3, S/34, S/36, S/38, AS/400, etc.). This architecture is what enabled even a low-powered (CPU-wise) System/36 or low-end AS/400 model to handle many 5250 terminals and service many interactive users "simultaneously" -- because as long as the device was sitting at a "READ" command, where the host was waiting to read data from the device, the CPU was free to work on other interactive or batch tasks, and only when the user presses Enter or a Function key, does the device return data to the host system, requiring the system to "pay attention" to that user once again.

Of course, much of the economic benefits of this approach has shifted in recent years, with the advent of powerful PCs and other intelligent devices as the "front end" for the user interface (e.g. browsers, tablets, smart phones, etc.) and the central processors are many orders of magnitude faster than just a few years ago. For example, I expect that the CPU inside an iPhone or iPad or similar devices is far more powerful than any of the early AS/400 CISC IMPI models, and they have way more memory, too.. (The early AS/400 CISC IMPI machines measured main storage sizes in Megabytes, where modern devices like an iPad or iPhone measure memory in Gigabytes.)

Hope that helps,

Mark S. Waterbury

> On 1/29/2014 2:34 PM, Glenn Gundermann wrote:

Would Dynamic Screen Manager APIs do the trick?

-----Original Message-----
From: Shaheen Ahmed <Syed.Ahmed@xxxxxxxxxxxxxxx>
Sender: rpg400-l-bounces@xxxxxxxxxxxx
Date: Wed, 29 Jan 2014 18:58:13
To: rpg400-l@xxxxxxxxxxxx<rpg400-l@xxxxxxxxxxxx>
Reply-To: "RPG programming on the IBM i \(AS/400 and iSeries\)" <rpg400-l@xxxxxxxxxxxx>
Subject: Is it possible in RPG to display a window when user tab to a field?

Is it possible in RPG to display a window when user tab to a field?