This document covers the following topics:
NGUSVWAT
Lets the server wait for data supplied with a message from some client. DDE-VIEW.MESSAGE will hold one of the values described below. You must then ensure that your event handler code acts on the value of DDE-VIEW.MESSAGE
The possible values of DDE-VIEW.MESSAGE are:
| CONNECT | On request by a client, a conversation has been established with the topic DDE-VIEW.TOPIC and the service DDE-VIEW.SERVICE. Topic and service must have been registered by the server. The value in DDE-VIEW.CONV-ID uniquely identifies this conversation. |
|---|---|
| DISCONNECT | On request by a client, the conversation identified by DDE-VIEW.CONV-ID has been closed. |
| REQUEST | The client of the conversation specified in DDE-VIEW.CONV-ID has requested data as specified in DDE-VIEW.ITEM. |
| ADVISE | The client of the conversation specified in DDE-VIEW.CONV-ID has requested a data link for the data specified in DDE-VIEW.ITEM. The DDE-server event handler must then use the NGU-SERVER-DATA subprogram whenever new data become available during the conversation. |
| UNADVISE | The client of the conversation specified in DDE-VIEW.CONV-ID has requested to close a data link for the data specified in DDE-VIEW.ITEM. (This data link was previously opened using "Advise".) |
| POKE | The client of the conversation specified in DDE-VIEW.CONV-ID has sent data as specified in DDE-VIEW.ITEM and DDE-VIEW.DATA. These data have the length of DDE-VIEW.DATALEN. DDE-VIEW.DATA should be chosen as appropriate for the expected conversations. |
| EXECUTE | The client of the conversation specified in DDE-VIEW.CONV-ID has requested the execution of the command specified in DDE-VIEW.DATA and DDE-VIEW.ITEM. The length of this command is held in DDE-VIEW.DATALEN. |
| TIMEOUT | A timeout has occurred. No client message has been received during a specified time interval. |
When DDE-VIEW.MESSAGE has the value DISCONNECT, DATA, or NOTIFY, the fields DDE-VIEW.SERVICE and DDE-VIEW.TOPIC are also set appropriately.
The value in DDE-VIEW.TIMEOUT specifies the maximum number of milliseconds the server wants to wait for a message:
If set to "-1", the server will wait indefinitely.
If set to "0", a message will be returned immediately, if there is one pending, or "Timeout" will be returned.
If set to any other value, the exact time that elapses before a message is returned can only be guaranteed to be no less than DDE-VIEW.TIMEOUT.
| Name/Data Type | Explanation |
|---|---|
| 1 DDE-VIEW | Input/Output PDA for DDE subprograms. |
| 2 SERVICE (A20) | Service name. |
| 2 TOPIC (A20) | Topic name. |
| 2 CONV-ID (I4) | Conversation ID. |
| 2 MESSAGE (A20) | Message information. |
| 2 ITEM (A20) | Item of current conversation. |
| 2 FORMAT (A20) | Format of data to be sent. |
| 2 TIMEOUT (I4) | Time interval before the conversation is interrupted because there is no server message. |
| 2 DATALEN (I2) | Length of data. |
| 2 DATA-ARRAY (A1/1:V) | |
| 1 Max-Index (I2) | Input Highest index of DATA-ARRAY; can be set to any I2 value. |
| 1 Response (I4) | Output Natural error (if applicable). |