START KEYSTROKE INTERCEPT (50)

3270 Host Connection Program 2.1 and 1.3.3 for AIX: Guide and Reference

START KEYSTROKE INTERCEPT (50)

Purpose

Enables an HLLAPI application to filter any keystrokes sent to a session by a user.

Prerequisite Calls

This function requires no prerequisite calls to other functions.

Syntax

hllc (func, apistring, len, ret)
int *func;
char *apistring;
int *len;
int *ret;

Supplied Parameters

Supply the following parameters to invoke the START KEYSTROKE INTERCEPT function:

func

Specifies the number of the function called; must be 50 for the START KEYSTROKE INTERCEPT function.

len

Does not apply for this function.

ret

Does not apply for this function.

apistring

Specifies the attributes of the data string; the calling 6 character data string contains:

Byte	Definition
Position 1	One of the following: The one-character letter short session ID of the PS A blank or null indicating a function call against the currently connected host PS
Position 2	A code character: D for AID keystrokes only L for all keystrokes
Positions 3-6	The data in these positions is ignored by HLLAPI. However, no error occurs if a migrating program has data in these positions. This data is accepted by HLLAPI to provide compatibility with migrating applications.

Returned Parameters

ret

The following codes are valid:

0	Specifies that the START KEYSTROKE INTERCEPT function was successful.
1	Specifies that the PS was invalid.
2	Specifies that an invalid option was specified.
4	Specifies that resource was unavailable; the requested presentation was in use by another application.
9	Specifies that a system error occurred.

Remarks

The START KEYSTROKE INTERCEPT function allows an HLLAPI application to filter any keystrokes sent to a session by a user. The intercepted keystrokes can be:

Received through the GET KEY (51) function and then sent to the same or another session with the SEND KEY (3) function. Setting the NORESET option with the SET SESSION PARAMETERS (9) function increases the performance of the SEND KEY (3) function.
Accepted and rejected through the POST INTERCEPT STATUS (52) function.
Replaced by other keystrokes with the SEND KEY (3) function.
Used to trigger some other process.

If the data string parameter contains the D option code, HLLAPI returns only attention identifier (AID) keys to the application program. HLLAPI sends non-AID keys to their intended presentation space (PS).

The START KEYSTROKE INTERCEPT function does not share the PS to which it is connected with other functions. Only one application at a time can trap keystrokes.

Since the CONNECT PRESENTATION SPACE (1) function and START KEYSTROKE INTERCEPT functions share common subsystem functions, successful requests by an application to share either of these functions (1 or 50) can affect the requesting of these functions by other applications.

Related Information

GET KEY (51) function, POST INTERCEPT STATUS (52) function,SEND KEY (3) function and SET SESSION PARAMETERS (9) function.

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