WindX™ and JAVX
The Thin Client Environment  
   
Overview From a systems perspective, both WindX and JavX appear like intelligent graphical terminals that respond to a wide variety of command sequences. The command sequences are generated automatically by the system in response to your application logic and directives.
   
Mnemonic Processing Both WindX and JavX respond directly to the internal form of all mnemonics. Therefore, unlike conventional terminals, no translation table is required. Mnemonics, such as 'CS', are transmitted as $1B$ + "CS" and screen position commands, such as @(1,2), are sent as $1B$ + "@2" + CHR(1) + CHR(2). Long-form mnemonics, such as 'WINDOW' and 'DROP', are sent in their native form as well.

WindX and Javx are highly optimized intelligent terminal emulators designed primarily for use with ProvideX. A lot of the functionality normally done by the host when dealing with 'Dumb' terminals is done by WindX or JavX locally. This means that less data needs to be sent to a workstation to handle functions such as window manipulation. On a normal terminal when a window is created, the characters that make up the window border are transmitted from the Host to the terminal. Additionally, when a Window is removed, then all of the data that was hidden behind the window must be redrawn.

These two functions are processed locally by JavX and WindX, which reduces network traffic and improves system performance.

These products also provide enhanced graphical terminal emulation that allows graphical applications to run remotely. All graphical mnemonics such as drawing fonted text, rectangles, circles, etc, are supported.
* Note * Because the 'PICTURE' mnemonic needs to access image files for the purposes of rendering, special consideration needs to be given to this mnemonic.

On WindX:

If using the 'PICTURE' mnemonic with ProvideX, the file name specified must exist (or at least be accessible) from the WindX PC. Make sure that the pathname of the bitmap is correct for the PC.

When using the 'PICTURE' mnemonic with PxPlus, you can enable the auto-download capabilities, which will send images from the host to the workstation automatically. Please refer to the Auto-download capability for more information.

On JavX:

With JavX, the 'PICTURE' mnemonic takes either a URL or path on the local machine (e.g., www.pvx.com/some.jpg or c:\ some.jpg ). If JavX is running in a web browser as an applet, it cannot access local files. All image sources (button, picture etc.) must be URLs. If not, JavX will add the source of the page on which it is embedded to the beginning of the path (e.g., "some.jpg" would become "www.thesource/some.jpg").
Input handling All input entered on the workstation keyboard is sent directly to the host. Function keys and CTL events generated by graphical controls are included in the data stream as well.
   
Graphical Directives The host ProvideX/PxPlus tokenizes all graphical directives and references and then forwards them to JavX or WindX for processing.

WindX or JavX process these tokenized commands locally. Access to the new control properties (e.g., BackColour$, Height, Enabled) are also tokenized and forwarded to the client for processing.
   
Remote File Access WindX provides the additional functionality of allowing files to be opened and accessed remotely. Whenever a file open is executed on the host with a pathname prefix of "[WDX]" (or "[LCL]" for PxPlus), the file open request is forwarded to the workstation for processing locally. The host will then tokenize and forward all subsequent requests against that file to the workstation to be processed locally.

This feature allows host application to read and write files on the workstation with a minimum of effort.

The following File IO directives and functions are supported for remove files:

Directives:

  • OPEN, CLOSE, READ, EXTRACT, WRITE, REMOVE
  • REFILE, PURGE, LOCK, UNLOCK
  • KEYED, SERIAL, PROGRAM, INDEXED, ERASE

Functions:

  • KEY, KEF, KEP, KEC, KEL, RNO, IND, FIB, FIN, FID

Example:

open lock (1) "[wdx]a:\Payroll.dat"
read record (1,end=end_data) r$
…
end_data: close (1)

In the above example, the remote file access facility is being used to allow the host application to read a file from a diskette (a:\Payroll.dat) on the client workstation.

For more information on this subject, refer to the section of Special File Command Tags on [LCL] Access to users Local Machine and [WDX] Direct Action to Client machine.

At present the DIR= option is not supported on remote files by WindX.
* Note * To simplify access to files on a workstation we generally recommend on ProvideX that you set a Global variable (%WDX$) to either "" or "[WDX]" depending on whether you are running on a thin client. This can be determined by test TCB(88) which will have a non-zero value for Windx/JavX.

PxPlus makes this easier by providing a "[LCL]" prefix that indicates the file is on the local workstation and will be ignored if non-thin client and consider as "[WDX]" if using a thin client.
Remote Command Processing WindX also supports the ability to remote process the INVOKE and EXECUTE directives on the WindX PC. If the string parameter passed to either of these directives starts with the sequence "[WDX]" (or "[LCL]" in PxPlus), the rest of the command is passed to WindX to be executed locally.

Examples:

invoke "[wdx]notepad.exe c:\autoexec.bat"
execute "[lcl]set_param 'cd' "

The most common uses for issuing remote EXECUTE directives include:

  • Changing local directory
  • Changing system parameters
  • Changing the Prefix
* Note * Be aware that when using the EXECUTE directive remotely, it is possible that the local PC could be running a ProvideX with a different set of syntax tables, resulting in the directives not being correct.
Remote Procedure Call One of the more powerful features of WindX is its ability to execute ProvideX subprograms remotely. Since WindX itself is a ProvideX program, it is capable of calling and passing parameters to a local sub-program.

Like the OPEN directive, the file name passed to a CALL directive can be prefixed with [WDX] or [LCL]. This indicates that the specified sub-program is to be run on the local PC, not the host system. The sub-program must exist on, or be accessible from, the client PC.

Any arguments specified in the CALL are sent to the WindX PC and any changes are passed back as per normal CALL processing.

There is a limit of twenty (20) arguments that can be specified in a remote CALL.

PxPlus provides a built-in mechanism for downloading called programs to the workstation. Check out the section on the Auto-download capability for more information.
* Note * Remember that the called program is actually running on the client workstation, not on the host system that initiated the CALL. Only the variables that have been passed specifically on the CALL argument list are accessible. Global variables and files are not accessible to called programs.
Workstation requirements Most character-based or graphical applications can run without modification with WindX however, there are a few things to consider.

File Requirements on the Local PC

  • Many commands are tokenized and sent to the local PC for processing. Some of these, such as the 'PICTURE'( ) mnemonic and MULTI_MEDIA commands, may include file name references. Since these commands will be executed locally on the workstation, all files referenced by them must exist or be accessible by the local WindX PC. In the case of the 'PICTURE' mnemonic, when using PxPlus the Auto-download capability can be used to send a copy of the image to the workstation.
  • DLL's, OCXs, COM modules and VBXs must be resident/installed on the client PC.
  • Open requests to ODBC, DDE, *WINPRT*, or *WINDEV* files should be routed to the WindX PC by prefixing the pathname with "[WDX]" or "[LCL]".
  • Fonts used in 'FONT'( ) commands must exist on the client PC.
  • If using the Windows print drivers for Graphical printing, then a UNIX spooler queue could be used if set up as a Shared Printer and connected to print server software, such as VisionFS or SAMBA.
   
WindX Advantages Apart from the obvious advantages of being able to run graphical applications remote, using WindX has the following additional advantages over standard terminal emulators or running the application locally.

Remote Processing

The Remote Processing capability of WindX enables you to take full advantage of the potentials of both the Host and Client operating systems.

Faster Screen I/O

Simple screen transmissions and updates are often faster with WindX, since it can process all ProvideX mnemonics locally and eliminate screen redisplays. The reduced transmission requirements provides for faster communications since screen redrawing is done without retransmission of the data from the host.

Data Reliability

Using WindX to connect to a Windows based network to run your application eliminates the movement of application data and programs to the PC during processing. This minimizes the risk of corruption of the data or program logic. It provides your application with the data security and system integrity of UNIX while providing the look and feel of Windows.