DDServer Control for Visual Basic 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 Services, each of which has a collection of Topics, each of which in turn has a collection of Data Items. The System Topic of each Service is created and maintained semi-automatically. The server application creates other Topics and may remove any Topic including the System Topic. The Data Item objects allow the application to treat the data as a string or any binary format

The User Control

Properties
FailedReturnString	User definable error return string
idInst	The DDEML instance handle
LogFile	The class managing the log file
ServerConvs	The class managing the ServerConv collection
Services	The class managing the Service collection
StateDescription	The status enumeration as a string
SZDDE_ITEM_ITEMLIST	The Item name of the Item list of a non-System Topic
SZDDESYS_ITEM_FORMATS	The System Topic Item name of the format list
SZDDESYS_ITEM_HELP	The System Topic Item name of the help text
SZDDESYS_ITEM_RTNMSG	The System Topic Item name of the return message
SZDDESYS_ITEM_STATUS	The System Topic Item name of the server status
SZDDESYS_ITEM_SYSITEMS	The System Topic Item name of list System Topic Items
SZDDESYS_ITEM_TOPICS	The System Topic Item name of list Topics
SZDDESYS_TOPIC	The standard name of the System Topic
Version	The DDServer version string
Methods
CDMLERR	Converts a DDEML error code to an enumerated value
ConvKey	Converts a DDEML hConv to a key
Disconnect	Destroys a DDE conversation
Enumerate	Lists all the conversations, Topics and Items
GetLastError	Returns the last DDEML error
Initialise	Initialises the DDEML library
QueryString	Returns the string for a string handle
ShowAboutBox	Shows the "About" dialog
Uninitialise	Cleans up all Services and the DDEML library
Events
DDEAdviseRequest	A client has started an advise or request loop
DDEAdviseStop	A client has stopped an advise or request loop
DDEConnect	A client has established a conversation
DDEDisconnect	The server or client has disconnected a conversation
DDEExecute	A client has issued an Execute command
DDENewAdviseRequest	A client wants an advise on a Data Item not currently available
DDENewDataRequested	A client has requested a Data Item not currently available
DDEPoke	A client has poked some data
DDERegister	A server has registered its Service name
DDEUnregister	A server has unregistered its Service name
LogFileError	An error has occurred in the log file
Objects
ServerConv	A single DDE conversation
Service	Encapsulates a DDE Service
Topic	Encapsulates a Topic provided by a Service
DDSVData	DDE data in string and binary format
LogFile	Handles logging output
Types, constants and enumerated values
ConvContext	A property of a conversation
QualityOfService	A property of a conversation
LogFileOptionsEnum	Logging output options
ExecuteResult	The possible results of an Execute command
DMLERREnum	DDEML error codes
Constants	Various enumerated values

The Service object

The Service class encapsulates a DDE Service. The name of the Service is sometimes referred to as the Application, because many applications use their name as their only DDE Service name. DDServer supports any number of Services. The Service class manages the Topic collection. The Topics in the collection can be iterated with a 'For Each' loop.

Properties
hszService	The string handle of the Service name
ServiceName	The Service name used by clients to connect
TopicCount	The number of Topics in the collection
TopicNames	A list of the Topics in the collection
Methods
CreateSystemTopic	Creates the System Topic or updates it.
CreateTopic	Creates a Topic and adds it to the collection
RemoveTopic	Removes a Topic from the collection
Topic	Returns a Topic from the collection

The Topic object

Each instance of the Service class maintains a collection of Topic objects. Each Topic maintains a collection of DDSVData Data Item objects available on that Topic. The programmer can enumerate the Items available in each Topic by a 'For Each' statement.

Properties
ItemCount	The number of Data Items in the collection
ItemNames	A list of the Data Items available in this Topic
TopicName	The Topic name
UserData	For the use of the server application
Methods
CreateItem	Creates a Data Item and adds it to the collection
Item	Returns a Data Item from the collection
RemoveItem	Removes a Data Item from the collection

The Server Data object

DDSVData is the class which manages data made available by the server or poked by the client. The data may be stored and retrieved either as a binary data block, or as a string, or byte by byte.

A server can provide on the same Topic many Items which have the same Item name if they have different formats. A data object is identified by the combination of its TopicName, ItemName and Format.

Properties
DataArray	The data viewed as an array of Byte values
DataString	The data as a string
Format	The Clipboard format of the data
ItemName	The Item name
NotifyAllowed	Whether or not advise/notify loops are allowed
NotifyRequests	The number of advise or notify loops for the Item
PokeAllowed	Whether or not a client is allowed to poke data
Size	The length of the data in bytes
TopicName	The Topic name
UserData	For the use of the server application
Methods
CopyByAddress	Copies the data to a given address
CopyByteArray	Copies the data to a Byte array
CopyIntegerArray	Copies the data to an Integer array
CopyLongArray	Copies the data to a Long array
NotifyClients	Notifies all clients that new data is available
StoreByAddress	Stores data in the object by address
StoreByteArray	Stores a Byte array in the data object
StoreIntegerArray	Stores an Integer array in the data object
StoreLongArray	Stores a Long array in the data object

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