ProvideX V8.20 > Language Reference > 9. Special Command Tags

799

Use such a global variable in a statement like OPEN (30)%WDX$+"*WINPRT*" to

bypass an Error #12: File does not exist (or already exists) when

WindX isn't running.

How ProvideX Detects WindX

ProvideX uses terminal type to detect a WindX session. In UNIX, ProvideX

recognizes two terminal types as potential WindX stations (TERM="winterm" for

the WindX client PC and TERM="ansi"). Since most UNIX systems and applications

can't recognize or use the winterm type, the ProvideX ansi device driver sends a

special escape sequence to a terminal to test for a WindX client. If the terminal is a

WindX PC, a special response is generated. If no response is generated before a

time-out occurs, ProvideX assumes the device is ansi.

GUI Requests

Once the ProvideX session on the server recognizes the terminal as a WindX station,

it changes the internal settings to allow graphical requests to be routed correctly.

(Then, graphical requests are automatically tokenized and forwarded to WindX for

processing. That is, you do not need the [WDX] tag.)

For instance, a server command to print a picture in a UNIX environment would

automatically be sent to WindX for the client. ProvideX transmits standard

mnemonics to WindX as an escape ($1B$) followed by the mnemonic in native form.

Traffic from the host/server is minimized because the WindX client's ProvideX

interpreter handles a lot of the functionality locally (on the client) for screen

refreshing and graphical requests.

In WindX, your instruction to print is sent to the client, bundled as is. When you use

mnemonics and/or graphics like .bmp's, they must exist on the client or be accessible to

the client. The following example uses a 'PICTURE' that is defined and shared on a

common Windows server instead of being stored on each individual client machine:

print 'picture'(10,10,10,10),"\\serv_name\driveshare\your_bmps\that.bmp"

See Also

ProvideX Client-Server Reference

Formats 1 & 2: Initiate Remote Command

EXECUTE "[WDX]statement"

INVOKE "[WDX]statement"

Use the EXECUTE and INVOKE formats with the [WDX] tag to process commands on

the WindX PC (remote client). Common applications of the EXECUTE format would

be: changing the client's local directory, setting system parameters, or altering the

prefix and in file creation.

Warning: When you use the EXECUTE and INVOKE directives from your server to initiate

action remotely on a client, the client PC might be running a ProvideX activation with a

different set of syntax tables. As a result, your MNEMONICs might be invalid.