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DDClient DDE component interface details

Properties, methods, events, types and constants

You can read the full details by downloading the control and reading the help file, from which the diagram is taken. The boxes are all hyperlinks in the help file. The diagram shows the main components of the control from a functional point of view. Use the object browser in the Visual Basic development environment for a syntactic view.

  • The control has a collection of conversations and a collection of channels (available services and topics)

  • Each conversation has a collection of advise loops (hot links), a collection of request loops (warm links) and a collection of outstanding transactions
  • The DDEData object allows the application to treat the data as a string or any binary format


FailedReturnStringUser definable error return string
HandleEarlyAdvises Enables the handling of data sent before an advise loop is fully established
idInstThe DDEML instance handle
VersionThe DDClient version string


HandleEarlyAdvises When true, data sent before an advise look is established is saved
InitialiseInitialises the DDEML library
UninitialiseUnitialises the DDEML library
ReInitialiseReinitialises the DDEML library
ConnectCreates a DDE conversation
DisconnectDestroys a DDE conversation
ReconnectReconnects a conversation disconnected by the server
FindChannels Finds service/topic pairs using DDE Wildconnect and adds them to the channels collection
ClearChannelsRemoves channels found by FindChannels
Enumerate Lists all the conversations, advise loops, request loops and channels
ProcessEarlyAdvises Processes data sent early, before an advise loop is fully established
CreateConvContextCreates a ConvContext object used in Connect
CreateQualityOfServiceCreate a Quality of Service object used in Connect
TransTypeNameDescribes a transaction type
ConvKeyConverts a DDEML hConv to a key to the conversations collection
ItemKeyConverts a DDEML string handle to a key for an Advise Loop collection or a Request Loop collection
GetLastErrorReturns the last DDEML error
QueryStringReturns the string for a DDEML string handle
TransKeyConverts DDEML transaction handle to a key to the transactions collection
ShowAboutBoxShows the "About" dialog


TransactionAdviseLoopStartedAn advise loop start has completed
DDEAdviseAdvise loop data arrival
TransactionAdviseLoopStoppedAn advise loop has stopped
TransactionRequestLoopStartedA request loop start has completed
DDENotifyRequest loop notification
TransactionRequestLoopStoppedA request loop has stopped
TransactionPokeCompletedA poke transaction has completed
TransactionRequestCompletedA data request has completed
TransactionExecuteCompleted An execute transaction has been acknowledged by the server
TransactionFailedA transaction has failed
DDEDisconnectThe server has disconnected a conversation
DDERegisterA server has registered its service name. The service is added to the Channels collection
DDEUnregisterA server has unregistered its service name. The name is removed from the collection
LogFileErrorAn error has occurred in the log file


Conversations Collection A Conversation Object collection. Each instance of the control has one of these collections
AdviseLoops CollectionAn AdviseLoop Object collection, each conversation has one such collection
RequestLoops CollectionA RequestLoop Object collection, each conversation has one such collection
Transactions CollectionA Transaction Object collection, each conversation has one such collection
Channels CollectionA Channel Object collection


Conversation ObjectEncapsulates a single DDE conversation
AdviseLoop ObjectEncapsulates an advise loop
RequestLoop ObjectEncapsulates a request loop
Transaction ObjectAn outstanding DDE transaction
Channel ObjectA registered server recorded at a DDERegister event or channel found by the FindChannels method
DDEData ObjectDDE data in string and binary format
LogFile ObjectHandles logging output

Types, constants and enumerated values

ConvContext An optional structure used in creating a conversation
QualityOfServiceAn optional structure used in creating a conversation
TransactionsEnumThe various transaction types
LogFileOptionsEnumLogging output options
DMLEEREnumDDEML error codes
ConstantsOther enumerated values

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