public virtual void Pause(DdemlConversation conversation)
{
if (IsDisposed)
{
throw new ObjectDisposedException(this.GetType().ToString());
}
if (!IsRegistered)
{
throw new InvalidOperationException(DDE.NotRegisteredMessage);
}
if (conversation == null)
{
throw new ArgumentNullException("conversation");
}
if (conversation.IsPaused)
{
throw new InvalidOperationException(DDE.AlreadyPausedMessage);
}
// Disable the DDEML callback for the specified conversation only.
bool result = Ddeml.DdeEnableCallback(_InstanceId, conversation.Handle, Ddeml.EC_DISABLE);
// Check the result to see if the DDEML callback was disabled.
if (!result)
{
int error = Ddeml.DdeGetLastError(_InstanceId);
throw new DdemlException(DDE.ServerPauseFailedMessage, error);
}
// Increment the conversation's waiting count.
conversation.IncrementWaiting();
}
internal bool ProcessCallback(DdemlTransaction transaction)
{
// This is here to alias the transaction object with a shorter variable name.
DdemlTransaction t = transaction;
switch (t.uType)
{
case Ddeml.XTYP_ADVREQ:
{
StringBuilder psz;
int length;
// Get the topic name from the hsz1 string handle.
psz = new StringBuilder(Ddeml.MAX_STRING_SIZE);
length = Ddeml.DdeQueryString(_InstanceId, t.hsz1, psz, psz.Capacity, Ddeml.CP_WINANSI);
string topic = psz.ToString();
// Get the item name from the hsz2 string handle.
psz = new StringBuilder(Ddeml.MAX_STRING_SIZE);
length = Ddeml.DdeQueryString(_InstanceId, t.hsz2, psz, psz.Capacity, Ddeml.CP_WINANSI);
string item = psz.ToString();
// Create the advise request cache key.
string key = topic + "!" + item + ":" + t.uFmt.ToString();
// Get the data being advised if the cache does not contain it already.
if (!_AdviseRequestCache.ContainsKey(key))
{
// Get the data from the subclass.
byte[] data = OnAdvise(topic, item, t.uFmt);
// Add the data to the cache because it will be needed later.
_AdviseRequestCache.Add(key, data);
}
// Get the data from the advise request cache.
byte[] cached = _AdviseRequestCache[key];
// Get the number of remaining transactions of this type for the same topic name, item name, and format tuple.
int remaining = t.dwData1.ToInt32();
// If this is the last transaction then free the data handle.
if (remaining == 0)
{
// Remove the data from the cache because it is no longer needed.
_AdviseRequestCache.Remove(key);
}
// Create and return the data handle representing the data being advised.
if (cached != null && cached.Length > 0)
{
t.dwRet = Ddeml.DdeCreateDataHandle(_InstanceId, cached, cached.Length, 0, t.hsz2, t.uFmt, 0);
return true;
}
// This transaction could not be processed here.
return false;
}
case Ddeml.XTYP_ADVSTART:
{
// Get the item name from the hsz2 string handle.
StringBuilder psz = new StringBuilder(Ddeml.MAX_STRING_SIZE);
int length = Ddeml.DdeQueryString(_InstanceId, t.hsz2, psz, psz.Capacity, Ddeml.CP_WINANSI);
string item = psz.ToString();
// Get the Conversation from the conversation table.
DdemlConversation conversation = _ConversationTable[t.hConv];
// Get a value indicating whether an advise loop should be initiated from the subclass.
t.dwRet = OnStartAdvise(conversation, item, t.uFmt) ? new IntPtr(1) : IntPtr.Zero;
return true;
}
case Ddeml.XTYP_ADVSTOP:
{
// Get the item name from the hsz2 string handle.
StringBuilder psz = new StringBuilder(Ddeml.MAX_STRING_SIZE);
int length = Ddeml.DdeQueryString(_InstanceId, t.hsz2, psz, psz.Capacity, Ddeml.CP_WINANSI);
string item = psz.ToString();
// Get the Conversation from the conversation table.
DdemlConversation conversation = _ConversationTable[t.hConv];
// Inform the subclass that the advise loop has been terminated.
OnStopAdvise(conversation, item);
// Return zero to indicate that there are no problems.
t.dwRet = IntPtr.Zero;
return true;
}
case Ddeml.XTYP_CONNECT:
{
// Get the topic name from the hsz1 string handle.
StringBuilder psz = new StringBuilder(Ddeml.MAX_STRING_SIZE);
int length = Ddeml.DdeQueryString(_InstanceId, t.hsz1, psz, psz.Capacity, Ddeml.CP_WINANSI);
string topic = psz.ToString();
// Get a value from the subclass indicating whether the connection should be allowed.
t.dwRet = OnBeforeConnect(topic) ? new IntPtr(1) : IntPtr.Zero;
return true;
}
case Ddeml.XTYP_CONNECT_CONFIRM:
{
// Get the topic name from the hsz1 string handle.
StringBuilder psz = new StringBuilder(Ddeml.MAX_STRING_SIZE);
int length = Ddeml.DdeQueryString(_InstanceId, t.hsz1, psz, psz.Capacity, Ddeml.CP_WINANSI);
string topic = psz.ToString();
// Create a Conversation object and add it to the conversation table.
_ConversationTable.Add(t.hConv, new DdemlConversation(t.hConv, _Service, topic));
// Inform the subclass that a conversation has been established.
OnAfterConnect(_ConversationTable[t.hConv]);
// Return zero to indicate that there are no problems.
t.dwRet = IntPtr.Zero;
return true;
}
case Ddeml.XTYP_DISCONNECT:
{
// Get the Conversation from the conversation table.
DdemlConversation conversation = _ConversationTable[t.hConv];
// Remove the Conversation from the conversation table.
_ConversationTable.Remove(t.hConv);
// Inform the subclass that the conversation has been disconnected.
OnDisconnect(conversation);
// Return zero to indicate that there are no problems.
t.dwRet = IntPtr.Zero;
return true;
}
case Ddeml.XTYP_EXECUTE:
{
// Get the command from the data handle.
int length = Ddeml.DdeGetData(t.hData, null, 0, 0);
byte[] data = new byte[length];
length = Ddeml.DdeGetData(t.hData, data, data.Length, 0);
string command = _Context.Encoding.GetString(data, 0, data.Length);
if (command[command.Length - 1] == '\0')
{
command = command.Substring(0, command.Length - 1);
}
// Get the Conversation from the conversation table.
DdemlConversation conversation = _ConversationTable[t.hConv];
// Send the command to the subclass and get the result.
ExecuteResult result = OnExecute(conversation, command);
// Return DDE_FACK if the subclass processed the command successfully.
if (result == ExecuteResult.Processed)
{
t.dwRet = new IntPtr(Ddeml.DDE_FACK);
return true;
}
// Return CBR_BLOCK if the subclass needs time to process the command.
if (result == ExecuteResult.PauseConversation)
{
// Increment the conversation's waiting count.
conversation.IncrementWaiting();
t.dwRet = new IntPtr(Ddeml.CBR_BLOCK);
return true;
}
// Return DDE_FBUSY if the subclass is too busy.
if (result == ExecuteResult.TooBusy)
{
t.dwRet = new IntPtr(Ddeml.DDE_FBUSY);
return true;
}
// Return DDE_FNOTPROCESSED if the subclass did not process the command.
t.dwRet = new IntPtr(Ddeml.DDE_FNOTPROCESSED);
return true;
}
case Ddeml.XTYP_POKE:
{
// Get the item name from the hsz2 string handle.
StringBuilder psz = new StringBuilder(Ddeml.MAX_STRING_SIZE);
int length = Ddeml.DdeQueryString(_InstanceId, t.hsz2, psz, psz.Capacity, Ddeml.CP_WINANSI);
string item = psz.ToString();
// Get the data from the data handle.
length = Ddeml.DdeGetData(t.hData, null, 0, 0);
byte[] data = new byte[length];
length = Ddeml.DdeGetData(t.hData, data, data.Length, 0);
// Get the Conversation from the conversation table.
DdemlConversation conversation = _ConversationTable[t.hConv];
// Send the data to the subclass and get the result.
PokeResult result = OnPoke(conversation, item, data, t.uFmt);
// Return DDE_FACK if the subclass processed the data successfully.
if (result == PokeResult.Processed)
{
t.dwRet = new IntPtr(Ddeml.DDE_FACK);
return true;
}
// Return CBR_BLOCK if the subclass needs time to process the data.
if (result == PokeResult.PauseConversation)
{
// Increment the conversation's waiting count.
conversation.IncrementWaiting();
t.dwRet = new IntPtr(Ddeml.CBR_BLOCK);
return true;
}
// Return DDE_FBUSY if the subclass is too busy.
if (result == PokeResult.TooBusy)
{
t.dwRet = new IntPtr(Ddeml.DDE_FBUSY);
return true;
}
// Return DDE_FNOTPROCESSED if the subclass did not process the data.
t.dwRet = new IntPtr(Ddeml.DDE_FNOTPROCESSED);
return true;
}
case Ddeml.XTYP_REQUEST:
{
// Get the item name from the hsz2 string handle.
StringBuilder psz = new StringBuilder(Ddeml.MAX_STRING_SIZE);
int length = Ddeml.DdeQueryString(_InstanceId, t.hsz2, psz, psz.Capacity, Ddeml.CP_WINANSI);
string item = psz.ToString();
// Get the Conversation from the conversation table.
DdemlConversation conversation = _ConversationTable[t.hConv];
// Send the request to the subclass and get the result.
RequestResult result = OnRequest(conversation, item, t.uFmt);
// Return a data handle if the subclass processed the request successfully.
if (result == RequestResult.Processed)
{
// Create and return the data handle for the data being requested.
if (result.Data != null)
{
t.dwRet = Ddeml.DdeCreateDataHandle(_InstanceId, result.Data, result.Data.Length, 0, t.hsz2, t.uFmt, 0);
}
return true;
}
// Return CBR_BLOCK if the subclass needs time to process the request.
if (result == RequestResult.PauseConversation)
{
conversation.IncrementWaiting();
t.dwRet = new IntPtr(Ddeml.CBR_BLOCK);
return true;
}
// Return DDE_FNOTPROCESSED if the subclass did not process the command.
t.dwRet = new IntPtr(Ddeml.DDE_FNOTPROCESSED);
return true;
}
}
// This transaction could not be processed here.
return false;
}