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<h3>dp_RPC</h3>
<p><b>Syntax</b></p>
<pre>dp_RPC <em>rpcChan</em> ?-timeout <em>amount</em> ?-timeoutReturn <em>script</em>?? ?-events <em>evtList</em>? <em>rpcCmd</em> ?args ...?</pre>
<p><b>Comments</b></p>
<p>dp_RPC allows one to send a Tcl expression to a remote Tcl
interpreter to be evaluated by it. <em>rpcChan</em> is a channel
opened with dp_connect and registered for RPCs with dp_admin.
Unlike dp_RDO, this command waits for a return code, although
because of the asynchronous nature of events and I/O, RPC return
codes are not guaranteed in any specific order. If one does not
need a return code, it is highly recommended that dp_RDO be
used instead; it is much faster and far less complex.</p>
<p>The timeout <em>amount</em> specifies how long
dp_RPC will block before returning an error and is in
milliseconds. <em>script</em> is the script to evaluate if the
RPC times out. Specifying a timeout script without a timeout
value is invalid. The prototype for the timeoutReturn script is
as follows:</p>
<pre>proc errorHandler {channelName} {}</pre>
<p><em>evtList</em> is a normal Tcl event list that tells
DP which events to respond to while waiting for the
RPC to return. See the Tcl documentation on events for valid
parameters.</p>
<p>dp_RPC returns the return value of the <i>rpcCmd</i>.</p>
<hr>
<p>If you are using RPCs with just tclsh, an RPC will not execute
asynchronously due to the fact that Tcl relies on
Tcl_DoOneEvent() to process events. It is recommended that you
use wish or add a vwait command in your script to force Tcl into
an event loop. As an example, if you send an RPC to puts
"foobar", the receiving intrepreter will not print
"foobar" until update is called.</p>
<hr>
<p><b>Examples</b></p>
<pre>dp_RPC $myChan puts stdout hello
dp_RPC $myChan -timeout 100 puts stdout foo
dp_RPC $myChan -timeout 100 -timeoutReturn "set a 1" -events all puts stdout hello</pre>
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