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DataServer Class

Provide the base class from which all X# data servers are subclassed.
Inheritance Hierarchy
Object
  DataServer
    DbServer
    SQLSelect

Namespace:  VO
Assembly:  VOSystemClasses (in VOSystemClasses.dll) Version: 2.7
Syntax
 CLASS DataServer
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The DataServer type exposes the following members.

Constructors
  NameDescription
Public methodDataServer
**Missing documentation **
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Properties
  NameDescription
Public propertyBoF
A logical value indicating whether this data server is positioned at the beginning of the file, on the first record (TRUE if yes, FALSE if no).
Public propertyClients
**Missing documentation **
Public propertyConcurrencyControl
A constant, identifying the mode of automatic concurrency control for this data server, determining when and how records are locked and released:
Public propertyDBStruct
An array containing the structure of this data server.
Public propertyEoF
A logical value indicating whether this data server is positioned at the end of the file, on the last record after an attempt to move beyond the last record (TRUE if yes, FALSE if no).
Public propertyFCount
The number of fields in this data server.
Public propertyHLStatus
**Missing documentation **
Public propertyCode exampleHyperLabel
The hyperlabel connected to this data server.  From the hyperlabel, you can retrieve additional information about the data server
Public propertyName
A string representing the name of this data server.
Public propertyNameSym
A symbol representing the name of this data server.
Public propertyRecCount
A numeric value representing the number of records in this data server.
Public propertyRecNo
A numeric value representing the current record number, identifying the position of the record pointer in this data server.
Public propertyCode exampleStatus
A hyperlabel identifying the status of this data server after the last operation.
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Methods
  NameDescription
Public methodAppend
Append a blank record to the end of this data server (the new record becomes the current position and is ready for assignment of data values).
Public methodAsString
Return the descriptive label defined for this data server.
Public methodClose
Close down the server in a manner specific to the database used.
Public methodCommit
Force all pending updates to this data server to be permanently written to disk.
Public methodDataField
Retrieve the DataField object at a specified field position.
Public methodDelete
Delete the current record in this data server.
Public methodFIELDGET
Return the contents of a specified field in this data server.
Public methodFieldGetFormatted
Return the contents of a specified field in this data server, according to the formatting specifications of its FieldSpec.
Public methodFieldHyperLabel
Return the hyperlabel defined for a field in this data server.
Public methodFieldName
Return the name of a field in this data server.
Public methodFieldPos
Return the position of a field in this data server.
Public methodFIELDPUT
Assign a value to a field in this data server.
Public methodFieldSpec
Return the FieldSpec object for a field in this data server.
Public methodFieldStatus
Determine the status of a field in this data server after the last operation.
Public methodFieldSym
Return the symbolic name of a field in this data server.
Public methodFieldValidate
Perform all the validations defined to the FieldSpec of a field in this data server (for example, required, maximum and minimum digits, maximum and minimum value, validation rule) and return the result of the test.
Public methodFLOCK
Lock this entire data server for exclusive access.
Public methodGoBottom
Position this data server at the last record.
Public methodGoTo
Position this data server on a specified record number.
Public methodGoTop
Position this data server at the first record.
Public methodNoIVarGet
Provide a general error interception that is automatically called (in any class) whenever an access reference is made to a non-existent exported instance variable.  In the DataServer class, it is used to implement the virtual field variable.
Important!  NoIVarGet() should not be called directly; it is called by the system for handling invalid references.
Public methodNoIVarPut
Provide a general error interception that is automatically called (in any class) whenever an assignment reference is made to a non-existent exported instance variable.  In the DataServer class, it is used to implement the virtual field variable.
Important!  NoIVarPut() should not be called directly; it is called by the system for handling invalid references.
Public methodNotify
An event handler that responds to events that have occurred in methods of this server, or in other servers that are linked to this server in some way.  The standard implementation notifies all the server's clients of the event. Description
Important!  This method is automatically called by the various action methods of the data server, and should normally not be called by application code.
Public methodPostInit
Implement customized initialization code for the window.
Public methodPreInit
Implement customized initialization code for the server.
Public methodRegisterClient
Register an object as a client of this data server, so that it receives notification messages from the server about certain actions.
Public methodResetNotification
Resume the broadcasting of Notify messages to the server's attached clients (after DataServer:SuspendNotification() has been called).
Public methodRLOCK
Lock a specific record in this data server for exclusive write access; other users can still make read-only reference to the record.
Public methodRLockVerify
Determine if the current record in this data server has any pending updates and lock it for exclusive write access if there are none.
Public methodRollback
Undo the changes made to this data server within the current transaction.
Public methodSeek
Move to the next record having a specified key value in the controlling order.
Public methodSetDataField
Assign a DataField object to a specified field in this data server.
Public methodSkip
Move the record pointer forward or backward in this data server a specified number of records.
Public methodSuspendNotification
Suspend the broadcasting of Notify messages to the server's attached clients.
Public methodUnLock
Remove all locks held on this data server.
Public methodUnRegisterClient
Remove the registration of an object as a client of this data server, so that it no longer receives notification messages from the server about certain actions.
Public methodUpdate
Update this server with data from another server or table.
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Remarks

Important!  DataServer is an abstract class and should not be used directly — instead, use one of its subclasses, which include DBServer and SQLSelect.  The documentation in this class is provided for the purposes of creating a DataServer subclass and details the data server entities that should be implemented for a consistent interface to other X# components (for example, a data window). This abstract class defines the common protocol — properties and behavior — used by the various X# data servers.  These data servers provide an object-oriented interface to databases in many contexts, but they are particularly useful as drivers for the DataWindow class.  For example, any class that derives from DataServer can be connected as a server to a data window or data browser.
See Also

Reference