HTrack (Function)

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HFSQL Client/Server functions

HAddScheduledOptimization

HCS.FrameSize (Variable)

HCS.Timeout (Variable)

HDeleteScheduledBackup

HDeleteScheduledOptimization

HExecuteScheduledBackup

HExecuteScheduling

HInfoBackup

HInfoDatabaseProperty

HInfoDatabaseRights (Example)

HInfoDatabaseRights

HInfoFileProperty

HInfoFileRights (Example)

HInfoServerRights (Example)

HListScheduledOptimization

HModifyDatabaseProperty

HModifyDatabaseRights

HModifyFileProperty

HModifyFileRights

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HModifyScheduledBackup

HModifyScheduledOptimization

HModifyScheduling

HModifyServerProperty

HNotifAddEmailRecipient

HNotifConfigure

HNotifDeleteCCRecipient

HNotifDeleteEmailRecipient

HNotifListCCRecipient

HNotifListEmailRecipient

HRestoreBackup (Example)

WLanguage procedure
Special cases

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HTrack (Function)

In french: HSurveille

Available only with this kind of connection

Starts tracking write actions (addition, modification or deletion) performed on a file found in an HFSQL server. In case of modification, a specific procedure can be triggered.

This track can be stopped by HTrackStop.

Versions 26 and later

This function is now available in iOS widget mode.

This function is now available for Android applications.

This function is now available in Android widget mode.

This function is now available for Java applications.

New in version 26

This function is now available in iOS widget mode.

This function is now available for Android applications.

This function is now available in Android widget mode.

This function is now available for Java applications.

This function is now available in iOS widget mode.

This function is now available for Android applications.

This function is now available in Android widget mode.

This function is now available for Java applications.

Example

// Starts tracking the Order data file
// The ProcessOrder procedure is called whenever a record is added to the data file
HTrack(Order, ProcessOrder, hRecNumAll, hsAdd)

Syntax

<Result> = HTrack(<Data file> , <WLanguage procedure> [, <Record number> [, <Action to track>]])

<Result>: Boolean

True if the tracking is enabled,
False otherwise. To get more details on the error, use ErrorInfo.

<Data file>: Optional character string

Name of HFSQL data file to use. The data file is associated with a connection and with a server.
If this parameter is an empty string (""), HTrack manipulates the last data file used by the last HFSQL function (function starting with "H").

<WLanguage procedure>: Procedure name

Name of the WLanguage procedure ("callback") called when a change is made in the specified data file.
For more details on this procedure, see Parameters of the procedure used by HTrack.

<Record number>: Optional integer

Number of the record to track.
hRecNumAll constant to track all the records found in the data file (which means the entire data file).

<Action to track>: Optional constant (or combination of constants)

Actions to track for which the procedure will be started:
hsAdd Monitors the operations for adding records.
hsCross Monitors the operations for crossing records.
hsDeletion Monitors the operations for deleting records.
hsModification Monitors the operations for modifying records.

Remarks

WLanguage procedure

The WLanguage procedure is called in the main thread of the application, with the HFSQL context corresponding to the procedure:

If the procedure is a local procedure of a window that uses an independent context, the window's context will be used.
If the procedure belongs to a component that uses an independent context, the context used will be the one of the component.

Caution:
The procedure associated with HTrack can be called at any time in the application.
If the procedure performs HFSQL browses or moves in the data files, this will impact the application (like the timers).
It may therefore be necessary to use:

HSavePosition and HRestorePosition to save the contexts of the files used.
Versions 27 and later
a variable of type Alias to perform operations on alias files.
New in version 27
a variable of type Alias to perform operations on alias files.
a variable of type Alias to perform operations on alias files.

Multitask must not be used in the procedure code.

For more details on this procedure, see Parameters of the procedure used by HTrack

Special cases

The track is defined for a data file and a connection:

If the physical name or the connection associated with the logical file name changes, the file tracked by the server remains the one specified during the call to HTrack.
If the connection is closed, the track is automatically stopped.
The tracking continues if the connection is lost then restored by automatic reconnection.

To stop tracking the data file, use HTrackStop.

Versions 24 and later
HTrack and HTrackStop can be used in a Windows service.

New in version 24
HTrack and HTrackStop can be used in a Windows service.

HTrack and HTrackStop can be used in a Windows service.

Business / UI classification: Business Logic

Component: wd270hf.dll