Deletes an instance of a persistent procedure. The persistent procedure can be local or
remote.
Syntax
DELETE PROCEDURE proc-handle[ NO-ERROR ]
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proc-handle
- The handle of a local or remote persistent procedure. This is a variable, field, or
expression of type HANDLE that contains a valid persistent procedure handle.
For a
proxy procedure handle, this statement deletes the handle immediately unless there is
an outstanding asynchronous request on this handle
(handle:ASYNC-REQUEST-COUNT is greater than zero (0)). If
handle:ASYNC-REQUEST-COUNT is greater than zero (0), this
statement raises the ERROR condition. Otherwise, the statement also sends a request to
the AppServer to delete the corresponding remote persistent procedure on the
AppServer. If the AppServer is executing any asynchronous requests ahead of it, the
AVM queues the delete request (as with any asynchronous remote request) until the
AppServer is available to handle it.
Note: This same behavior occurs if
the remote procedure deletes itself (using DELETE...THIS-PROCEDURE) on the
AppServer.
For more information on remote persistent procedures, see
OpenEdge Application Server: Developing AppServer
Applications.
- NO-ERROR
- Suppresses ABL errors or error messages that would otherwise occur and diverts them to
the ERROR-STATUS system handle. If an error occurs, the action of
the statement is not done and execution continues with the next statement. If the
statement fails, any persistent side-effects of the statement are backed out. If the
statement includes an expression that contains other executable elements, like methods,
the work performed by these elements may or may not be done, depending on the order the
AVM resolves the expression elements and the occurrence of the error.
To check for
errors after a statement that uses the NO-ERROR option:
- Check the ERROR-STATUS:ERROR attribute to see if the AVM raised the ERROR
condition.
- Check if the ERROR-STATUS:NUM-MESSAGES attribute is greater than zero to see if
the AVM generated error messages. ABL handle methods used in a block without
a CATCH end block treat errors as warnings and do not raise ERROR, do not set the
ERROR-STATUS:ERROR attribute, but do add messages to the ERROR-STATUS system handle.
Therefore, this test is the better test for code using handle methods without CATCH
end blocks. ABL handle methods used in a block with a CATCH end block raise
ERROR and add messages to the error object generated by the AVM. In this case, the
AVM does not update the ERROR-STATUS system handle.
- Use ERROR-STATUS:GET-MESSAGE( message-num ) to retrieve a
particular message, where message-num is 1 for the first
message.
If the statement does not include the NO-ERROR option, you can use a CATCH end
block to handle errors raised by the statement.
Some other important usage notes
on the NO-ERROR option:
- NO-ERROR does not suppress errors that raise the STOP or QUIT condition.
- A CATCH statement, which introduces a CATCH end block, is analogous to a NO-ERROR
option in that it also suppresses errors, but it does so for an entire block of
code. It is different in that the error messages are contained in a class-based
error object (generated by the AVM or explicitly thrown), as opposed to the
ERROR-STATUS system handle. Also, if errors raised in the block are not handled by a
compatible CATCH block, ON ERROR phrase, or UNDO statement, then the error is not
suppressed, but handled with the default error processing for that block type.
- When a statement contains the NO-ERROR option and resides in a block with a CATCH
end block, the NO-ERROR option takes precedence over the CATCH block. That is, an
error raised on the statement with the NO-ERROR option will not be handled by a
compatible CATCH end block. The error is redirected to the ERROR-STATUS system
handle as normal.
- If an error object is thrown to a statement that includes the NO-ERROR option,
then the information and messages in the error object will be used to set the
ERROR-STATUS system handle. This interoperability feature is important for those
integrating code that uses the traditional NO-ERROR technique with the newer,
structured error handling that features error objects and CATCH end blocks.
Example
When you run the following procedure non-persistently, the procedure creates a persistent
instance of itself in addition to the non-persistent instance, creating two query windows
for the Customer table. Choosing the Cancel button in either window causes the instance that
owns that window to terminate. If the instance you terminate is persistent, the Cancel
button runs an internal procedure that executes the DELETE PROCEDURE statement for that
instance as specified by the THIS-PROCEDURE system handle.
r-delprc.p
DEFINE QUERY custq FOR Customer.
DEFINE BROWSE custb QUERY custq
DISPLAY name balance phone WITH 10 DOWN.
DEFINE BUTTON bName LABEL "Query on Name".
DEFINE BUTTON bBalance LABEL "Query on Balance".
DEFINE BUTTON bCancel LABEL "Cancel".
DEFINE FRAME CustFrame custb SKIP bName bBalance bCancel.
DEFINE VARIABLE custwin AS HANDLE.
ON CHOOSE OF bName IN FRAME CustFrame DO:
custwin:TITLE = "Customers by Name".
OPEN QUERY custq FOR EACH Customer BY Customer.Name.
END.
ON CHOOSE OF bBalance IN FRAME CustFrame DO:
custwin:TITLE = "Customers by Balance".
OPEN QUERY custq FOR EACH Customer BY Customer.Balance DESCENDING.
END.
IF THIS-PROCEDURE:PERSISTENT THEN DO:
THIS-PROCEDURE:PRIVATE-DATA = "Customer Browse".
CREATE WIDGET-POOL.
END.
CREATE WINDOW custwin ASSIGN
TITLE = IF THIS-PROCEDURE:PERSISTENT THEN
"Persistent Customer Browser" ELSE "Customer Browser"
SCROLL-BARS = FALSE
MAX-HEIGHT-CHARS = FRAME CustFrame:HEIGHT-CHARS
MAX-WIDTH-CHARS = FRAME CustFrame:WIDTH-CHARS.
THIS-PROCEDURE:CURRENT-WINDOW = custwin.
ENABLE ALL WITH FRAME CustFrame.
IF THIS-PROCEDURE:PERSISTENT THEN DO:
ON CHOOSE OF bCancel IN FRAME CustFrame DO:
RUN destroy-query.
END.
END.
ELSE DO:
RUN r-delprc.p PERSISTENT.
WAIT-FOR CHOOSE OF bCancel IN FRAME CustFrame.
DELETE WIDGET custwin.
END.
PROCEDURE destroy-query:
DELETE PROCEDURE THIS-PROCEDURE.
DELETE WIDGET-POOL.
END PROCEDURE.
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Notes
- To be valid for deletion, proc-handle must reference an active
persistent procedure. You can use the VALID-HANDLE function and PERSISTENT procedure
attribute to check the validity of proc-handle. Thus, both
VALID-HANDLE(proc-handle) and
proc-handle:PERSISTENT must be TRUE to delete the specified procedure.
If either of these expressions is FALSE, the DELETE PROCEDURE statement raises the ERROR
condition.
- When you delete a persistent procedure instance, its context goes out of scope and all
allocated resources are returned to the system. In addition, it is removed from the chain
of persistent procedures referenced by the FIRST-PROCEDURE and LAST-PROCEDURE attributes
of the SESSION system handle.
- If you delete a persistent procedure instance while executing statements within that
procedure, the DELETE PROCEDURE statement pends until the largest executing block in the
persistent procedure terminates. Thus, if the DELETE PROCEDURE occurs while the main
procedure block is executing (when the persistent procedure is called), the procedure is
deleted when the procedure returns (as if it were non-persistent). If the DELETE PROCEDURE
occurs during execution of a trigger or execution of an internal procedure that is called
from another external procedure, the procedure is deleted after the trigger block or
internal procedure returns. Note that while the delete is pending, the persistent
procedure remains valid in the persistent procedure chain.
- The DELETE PROCEDURE statement will only delete the proxy handle on the client of a
procedure run as single-run or singleton. This is because the AVM automatically deletes a
single-run procedure after execution, and a singleton procedure may be running on multiple
AppServer agents.
- The DELETE PROCEDURE statement disconnects any local buffers established by the
procedure. In addition, any buffers passed as parameters to a persistent procedure are
treated as local buffers. While all cursor positioning established on these buffers by the
persistent procedure is lost, there is no affect on the original buffers passed as
parameters from the caller. Note that all buffers are validated before being disconnected
(which might cause database write triggers to execute). If the validation fails, the
DELETE PROCEDURE statement raises the ERROR condition and pends the deletion until the
validation succeeds and all database write triggers have completed.
- For more information on working with asynchronous remote procedures and event
procedures, see OpenEdge Application Server: Developing AppServer
Applications.