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| Allegro CL version 9.0 Unrevised from 8.2 to 9.0. 8.2 version

## send-request

Arguments: client-port item &key link timeout

Sends a DDE "Request" or "Advice" message to retrieve information from a DDE server for a particular item.

If link is :cold (which is the default), then the values returned by the DDE server application are synchronously returned from the call to send-request. If link is :warm or :hot, then send-request does not return an answer from the DDE server application, but instead starts an "advice" link with the server; whenever the server's value for the requested item has changed, the server asynchronously sends a message to Allegro CL, and the receive-advice method for this DDE port is then called with the values from the server. If link is :stop, then any advice link that was previously started for this item is stopped.

When unsuccessful, send-request returns `nil`. When successful, it returns a value from the DDE server for a :cold link, or t for a :warm, :hot, or :stop link. `nil` normally indicates that the DDE server does not support the particular request that was made.

The raw data buffer returned by the DDE server is first passed to the convert-returned-dde-buffer method for the port. That method should return a single value (perhaps constructing a list from multiple values that the server has encoded into the buffer), which is then either returned from send-request for a :cold link or passed to the port's receive-advice method for a :warm or :hot link. Refer to convert-returned-dde-buffer and convert-returned-dde-string for more information on converting the values from the server. If the request is unsuccessful, as when the server doesn't handle the requested item, then `nil` is returned.

Many applications that act as DDE servers implement a topic called system and an item called sysitems, and sometimes an item called topics, to which you can send a request to find out about additional topics.

See dde.htm for information about DDE support.

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This page was not revised from the 8.2 page.
Created 2012.5.30.

|  | ToC | DocOverview | CGDoc | RelNotes | FAQ | Index | PermutedIndex
| Allegro CL version 9.0 Unrevised from 8.2 to 9.0. 8.2 version