/// <summary> Poll the ZIS for messages pending in the agent's queue.
///
/// This method is typically called by a ProtocolHandler thread to perform a
/// periodic pull when the agent is running in pull mode. It may also be
/// called by the framework to force a pull if the framework requires an
/// immediate response to a message it has sent to the ZIS, such as a
/// request for SIF_ZoneStatus.
///
///
/// If a message is retrieved from the ZIS, it is dispatched through the
/// Adk's usual message routing mechanism just as pushed messages are. Thus,
/// there is no difference between push and pull mode once a message has
/// been obtained from the ZIS. Because message routing is asynchronous (i.e.
/// the MessageDispatcher will forward the message to the appropriate
/// framework or agent code), this method does not return a value. If an
/// error is returned in the SIF_Ack, the agent's FaultListener will be
/// notified if one is registered. If an exception occurs, it is thrown to
/// the caller.
///
///
/// Each time this method is invoked it repeatedly sends SIF_GetMessage to
/// the ZIS until no more messages are available, effectively emptying out
/// the agent's queue.
///
/// </summary>
/// <returns> zero if no messages were waiting in the agent's queue; 1 if a
/// message was pulled from the agent's queue; -1 if the zone is sleeping
/// </returns>
public virtual int Pull()
{
// Wait for fPullCanStart to be set to true by the ZoneImpl class once
// the zone is connected
if (fPullCanStart != null)
{
lock (fPullCanStart)
{
try
{
Monitor.Wait(fPullCanStart);
}
catch
{
// Do Nothing
}
}
}
while (true)
{
if ((Adk.Debug & AdkDebugFlags.Messaging_Pull) != 0)
{
fZone.Log.Debug("Polling for next message...");
}
// Send a SIF_GetMessage, get a SIF_Ack
SIF_SystemControl sys = new SIF_SystemControl();
SIF_SystemControlData cmd = new SIF_SystemControlData();
cmd.AddChild(new SIF_GetMessage());
sys.SIF_SystemControlData = cmd;
SIF_Ack ack = null;
try
{
ack = send(sys, true);
}
catch (PullMessageParseException pmpe)
{
// Unable to parse the pulled message. Try sending the proper
// Error SIF_Ack to remove the message from the queue
if (pmpe.fSourceMessage != null)
{
fZone.Log.Debug("Handling exception by creating a SIF_Error", pmpe.fParseException);
// Try parsing out the SIF_OriginalMsgId so that we can remove the message
// from the queue.
// Ack either the SIF_Ack or the internal, embedded message, based on our setting
int startIndex = fAckAckOnPull ? 0 : 10;
int messageStart = pmpe.fSourceMessage.IndexOf("<SIF_Message", startIndex);
SifException sourceException = null;
if (pmpe.fParseException is SifException)
{
sourceException = (SifException)pmpe.fParseException;
}
else
{
sourceException = new SifException(
SifErrorCategoryCode.Xml,
SifErrorCodes.XML_GENERIC_ERROR_1,
"Unable to parse pulled SIF_Message",
pmpe.fParseException.Message,
fZone, pmpe.fParseException );
}
SIF_Ack errorAck = SIFPrimitives.ackError(pmpe.fSourceMessage.Substring(messageStart), sourceException, fZone);
errorAck.SifVersion = sys.SifVersion;
send( errorAck );
continue;
}
}
//
// Process the response. If status code 9 (no message), no
// action is taken. If status code 0 (success), the content of
// the SIF_Status / SIF_Data element is parsed and dispatched.
// If an error is reported in the ack, the agent's fault
// handler is called with a SifException describing the error
// if a fault handler has been registered.
//
if (ack.HasStatusCode(SifStatusCodes.NO_MESSAGES_9))
{
if ((Adk.Debug & AdkDebugFlags.Messaging_Pull ) != 0)
fZone.Log.Debug( "No messages waiting in agent queue" );
return 0;
}
if(ack.HasError())
{
SifException se = new SifException(ack, fZone);
fZone.Log.Debug("Unable to pull the next message from the queue: " + se.ToString());
AdkUtils._throw(se, fZone.Log);
}
if (ack.HasStatusCode(SifStatusCodes.SUCCESS_0))
{
AdkException parseEx = null;
SifMessagePayload payload = getPullMessagePayload(ack);
if ((Adk.Debug & ( AdkDebugFlags.Messaging | AdkDebugFlags.Messaging_Pull ) ) != 0)
{
fZone.Log.Debug("Pulled a " + payload.ElementDef.Tag(payload.SifVersion) + " message (SIF " + payload.SifVersion + ")");
}
#region Notify MessagingListeners...
bool cancelled = false;
ICollection<IMessagingListener> msgList = GetMessagingListeners(fZone);
if (msgList.Count > 0)
{
StringWriter tmp = new StringWriter();
SifWriter sifwriter = new SifWriter(tmp);
sifwriter.Write(payload);
sifwriter.Flush();
tmp.Flush();
StringBuilder xml = new StringBuilder();
xml.Append(tmp.ToString());
// Determine message type before parsing
foreach (IMessagingListener listener in msgList)
{
try
{
SifMessageType pload =
(SifMessageType)
Adk.Dtd.GetElementType(payload.ElementDef.Name);
MessagingReturnCode code = listener.OnMessageReceived(pload, xml);
switch (code)
{
case MessagingReturnCode.Discard:
cancelled = true;
break;
case MessagingReturnCode.Reparse:
{
try
{
// Reparse the XML into a new message
payload =
(SifMessagePayload)
fParser.Parse(xml.ToString(), fZone);
}
catch (IOException ioe)
{
parseEx =
new AdkException
(
"Failed to reparse message that was modified by MessagingListener: " +
ioe, fZone);
}
}
break;
}
}
catch (AdkException adke)
{
parseEx = adke;
}
}
}
#endregion
if (fQueue != null)
{
// TODO: put message on agent local queue
}
else
{
if (parseEx != null)
{
throw parseEx;
}
int ackStatus = SifStatusCodes.IMMEDIATE_ACK_1;
SifException err = null;
bool acknowledge = true;
try
{
// Dispatch the message
if (!cancelled)
{
ackStatus = dispatch(payload);
}
}
catch (LifecycleException)
{
throw;
}
catch (SifException se)
{
err = se;
}
catch (AdkException adke)
{
// TODO: This needs to generate proper category/code based on payload
if (adke.HasSifExceptions())
{
// Return the first exception
err = adke.SIFExceptions[0];
}
else
{
// Build a SifException to describe this AdkException
err =
new SifException
(SifErrorCategoryCode.Generic,
SifErrorCodes.GENERIC_GENERIC_ERROR_1, adke.Message, fZone);
}
}
catch (Exception thr)
{
// Uncaught exception (probably an Adk internal error)
string txt =
"An unexpected error occurred while processing a pulled message: " +
thr;
fZone.Log.Debug(txt);
// Build a SifException to describe this Throwable
err =
new SifException
(SifErrorCategoryCode.System, SifErrorCodes.SYS_GENERIC_ERROR_1,
thr.Message, thr.ToString(), fZone, thr);
fZone.Log.Debug(err);
}
if (acknowledge)
{
sendPushAck(ack, payload, ackStatus, err);
}
else
return 1;
}
}
else
{
// We only get to here if there is no error and no success code
if (ack.HasStatusCode(SifStatusCodes.SLEEPING_8))
{
// Zone is sleeping
return -1;
}
else
{
// Unknown condition
AdkUtils._throw(new SifException(ack, fZone), fZone.Log );
}
}
}
}
private SIF_Ack SifSystemControl(SifElement command, ZoneImpl zone)
{
SIF_SystemControl msg = new SIF_SystemControl(zone.HighestEffectiveZISVersion);
SIF_SystemControlData cmd = new SIF_SystemControlData();
cmd.AddChild(command);
msg.SIF_SystemControlData = cmd;
return zone.Dispatcher.send(msg);
}
