S/Web Objects

S/Web Objects

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Properties
Methods

LH Object

This object handles information relating to Linear Hash files

Properties:

Property	Get/Set	Description
CACHEHANDLES	Get/Set	Sets or retrieves flag indicating whether LH Table handles are cached.
LOCKTYPE	Get/Set	Sets or retrieves flag indicating the LH lock type. 0 for optimistic, 1 for pessimistic (web only) and 2 for pessimistic (real time - web and local)
LOCKTIME	Get/Set	Sets or retrieves the time that indicates when a held lock times out.
UNLOCKQTIMEOUT	Get/Set	Sets or retrieves the amount of time to wait for another server to unlock the attempted record.
XVERSION	Get	Contains the current S/Web version

Methods:

call www_Exec_Method( "LH", method, param1, param2, param3, param4, param5 )

Method	Description
CREATE	Instantiate the current LH object, the constructor method.
DELETE	Used to delete a row or record from an LH table or file.
DESTROY	This method has not yet been implemented.
GET	Used to get properties of the current LH object
LOCK	Used to lock an LH row or record
OPEN	Used to open an LH table or file.
PURGE	Clears out all the locking data from the WWW_LH table and the current object.
READ	Used to read a row or record from an LH Table or file
READCACHE	Used to read a record that exists in the cache. This is similar to the R/BASIC or Basic+ READO statement.
SET	Used to set properties of the current LH object
UNLOCK	Used to unlock an LH row or record
UNLOCKQ	Called by the server to released expired lock records. This is only used with shared Pessimistic locking
WRITE	Used to write a row or record to an LH table or file

CREATE method

This method should not be called by the end user!

Argument	Description
param1	Not used.
param2	Not used.
param3	Not used.
param4	Not used.
param5	Not used.

DELETE method

This method deletes a row or record from an LH table or file.

Argument	Description
param1	A listing of literal table or file names. This value can be @RM delimited to hold multiple tables or files.
param2	A listing of row or record keys. This value can be @RM delimited to hold multiple rows or records.
param3	Polymorphic flag whose meaning depends on the type of locking in use. If the locktype is OPTIMISTIC then this value is Not used If the lock type is PESSIMISTIC then a TRUE$ will force a delete even if the client doesn't have the lock.
param4	Not used.
param5	Not used.

Example:

declare function www_Exec_Method, www_Get_Status, www_Set_Status
$insert www_Status_Equates
$insert logical

TableNames   =   "SWEB_TEST_TABLE1"
TableNames   :=  @RM : "SWEB_TEST_TABLE1"

RowIDs       =   "DELETEME1"
RowIDs       :=  "DELETEME2"

if www_Exec_Method( "LH", "DELETE", TableNames, RowIDS, "", "", "", errorText ) then
   * The specified information has been deleted
End Else
   * There has been an error
   GoSub ErrorHandlingSubroutine
End

DESTROY method

This method has not yet been implemented

Argument	Description
param1	Not Used
param2	Not used.
param3	Not used.
param4	Not used.
param5	Not used.

GET method

This method retrieves properties for the LH object.

Argument	Description
param1	The name of the property we wish to retrieve. This value can be @RM delimited to hold multiple properties
param2	Returns value of requested properties. This value will be @RM delimited to match param1
param3	Not used.
param4	Not used.
param5	Not used.

Example:

declare function www_Exec_Method, www_Get_Status, www_Set_Status
$insert www_Status_Equates
$insert logical

Properties   =   "LOCKTYPE"

if www_Exec_Method( "LH", "GET", Properties, ReturnValues, "", "", "", errorText ) then
   * The specified information has been retrieved
End Else
   * There has been an error
   GoSub ErrorHandlingSubroutine
End

LOCK method

This method locks a row(s) or record from an LH table or file.

Argument	Description
param1	A listing of literal table or file names. This value can be @RM delimited to hold multiple tables or files.
param2	A listing of row or record keys. This value can be @RM delimited to hold multiple rows or records.
param3	Returns true$ if locks successful.
param4	Not used.
param5	Not used.

Example:

declare function www_Exec_Method, www_Get_Status, www_Set_Status
$insert www_Status_Equates
$insert logical

TableNames   =   "SWEB_TEST_TABLE1"
TableNames   :=  @RM : "SWEB_TEST_TABLE1"

RowIDs       =   "LOCKME1"
RowIDs       :=  "LOCKME2"

if www_Exec_Method( "LH", "LOCK", TableNames, RowIDS, Result, "", "", errorText ) then
   * The specified information has been locked
End Else
   * There has been an error
   GoSub ErrorHandlingSubroutine
End

OPEN method

This method opens an LH table or file to a file variable.

Argument	Description
param1	A listing of literal table or file names. This value can be @RM delimited to hold multiple tables or files.
param2	File variables returned.
param3	TRUE$ if file handle should be cached to speed up subsequent access.
param4	Not used.
param5	Not used.

Example:

declare function www_Exec_Method, www_Get_Status, www_Set_Status
$insert www_Status_Equates
$insert logical

TableNames = "SWEB_TEST_TABLE1"
TableNames := @RM : "SWEB_TEST_TABLE2"

CacheState = False$

if www_Exec_Method( "LH", "OPEN", TableNames, hTableNames, CacheState, "", "", errorText ) then
   * The specified tables have been opened
End Else
   * There has been an error
   GoSub ErrorHandlingSubroutine
End

PURGE method

This method deletes a row or record from an LH table or file.

Argument	Description
param1	True$ if the locking table is to be purged, false if only the in memory locking flags are to be purged.
param2	Not used.
param3	Not used.
param4	Not used.
param5	Not used.

Example:

declare function www_Exec_Method, www_Get_Status, www_Set_Status
$insert www_Status_Equates
$insert logical

ClearTableFlag = True$

if www_Exec_Method( "LH", "PURGE", ClearTableFlag, "", "", "", "", errorText ) then
   * All lock information has been removed
End Else
   * There has been an error
   GoSub ErrorHandlingSubroutine
End

READ method

This method deletes a row or record from an LH table or file.

Argument	Description
param1	A listing of literal table or file names. This value can be @RM delimited to hold multiple tables or files.
param2	A listing of row or record keys. This value can be @RM delimited to hold multiple rows or records.
param3	Rows read returned in an @Rm delimited list. If Param4 is blank then complete rows will be returned.
param4	List of columns to read per row. An @Fm delimited list per @Rm delimited table. If null then all of the row(s) are returned.
param5	Not used.

Example:

declare function www_Exec_Method, www_Get_Status, www_Set_Status
$insert www_Status_Equates
$insert logical

TableNames   =   "PARENT_TABLE"
TableNames   :=  @RM : "CHILD_TABLE"

RowIDs       =   "ROW1"
RowIDs       :=  @Rm : "ROW2"

Columns      =   ""
Columns      :=  @Rm : 1 : @Fm : 2 : @Fm : "FULLNAME"

if www_Exec_Method( "LH", "READ", TableNames, RowIDS, Rows, Columns, "", errorText ) then
   * The specified information has been deleted
End Else
   * There has been an error
   GoSub ErrorHandlingSubroutine
End

READCACHE method

See READ method. Only difference is that READCACHE reads from the cache file - meaning the record as the current user read from disk on the initial read. Allows developer to ascertain whether row has changed since originally read from disk by issuing a read then a readcache.

SET method

This method sets a property of the LH object.

Argument	Description
param1	The name of the property we wish to retrieve. This value can be @RM delimited to hold multiple properties
param2	New values of requested properties. This value will be @RM delimited to match param1
param3	Returns old values of requested properties.
param4	Not used.
param5	Not used.

Example:

declare function www_Exec_Method, www_Get_Status, www_Set_Status
$insert www_Status_Equates
$insert logical

Properties   =   "LOCKTYPE"

Values    =   1

if www_Exec_Method( "LH", "SET", Properties, Values, ReturnValues,"", "", errorText ) then
   * The specified information has been retrieved
End Else
   * There has been an error
   GoSub ErrorHandlingSubroutine
End

UNLOCK method

This method unlocks a row or record from an LH table or file.

Argument	Description
param1	A listing of literal table or file names. This value can be @RM delimited to hold multiple tables or files.
param2	A listing of row or record keys. This value can be @RM delimited to hold multiple rows or records.
param3	Not used
param4	Not used.
param5	Not used.

Example:

declare function www_Exec_Method, www_Get_Status, www_Set_Status
$insert www_Status_Equates
$insert logical

TableNames   =   "SWEB_TEST_TABLE1"
TableNames   :=  @RM : "SWEB_TEST_TABLE1"

RowIDs       =   "DELETEME1"
RowIDs       :=  "DELETEME2"

if www_Exec_Method( "LH", "UNLOCK", TableNames, RowIDS, "", "", "", errorText ) then
   * The specified information has been unlocked
End Else
   * There has been an error
   GoSub ErrorHandlingSubroutine
End

UNLOCKQ method

This method unlocks all pessimistic locks held by the server. It should normally only be called by the server object.

Argument	Description
param1	Not used.
param2	Not used.
param3	Not used.
param4	Not used.
param5	Not used.

Example:

declare function www_Exec_Method, www_Get_Status, www_Set_Status
$insert www_Status_Equates
$insert logical

if www_Exec_Method( "LH", "UNLOCKQ", "", "","", "", "", errorText ) then
   * All locks have been removed
End Else
   * There has been an error
   GoSub ErrorHandlingSubroutine
End

WRITE method

This method deletes a row or record from an LH table or file.

Argument	Description
param1	A listing of literal table or file names. This value can be @RM delimited to hold multiple tables or files.
param2	A listing of row or record keys. This value can be @RM delimited to hold multiple rows or records.
param3	Rows to write in an @Rm delimited list. Must conform to column spec of read.
param4	Polymorphic flag. If locking is optimistic then clear the record from the cache after a write (used if the client no longer has the lock) if set to True$. If locking is pessimistic then write regardless of whether client has lock.
param5	Not used.

Example:

declare function www_Exec_Method, www_Get_Status, www_Set_Status
$insert www_Status_Equates
$insert logical

TableNames   =   "SWEB_TEST_TABLE1"
TableNames   :=  @RM : "SWEB_TEST_TABLE1"

RowIDs       =   "DELETEME1"
RowIDs       :=  @Rm : "DELETEME2"

* Rows built earlier in program

if www_Exec_Method( "LH", "WRITE", TableNames, RowIDS, Rows, False$, "", errorText ) then
   * The specified information has been written
End Else
   * There has been an error
   GoSub ErrorHandlingSubroutine
End

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