Advanced MFC Programming

Chapter 16. Context Sensitive Help
……
}
)
{
hszTopic == m_hszTopicName &&
hszItem == hszPokeItem &&
wFormat == CF_TEXT
if(hData != NULL)
{
Printf("Poke executed!\r\n");
}
else Printf("Poke failed!\r\n");
}
UnobtainHsz(hszPokeItem);
There is no change on the server side.
All types of transactions can be implemented by either synchronous or asynchronous mode.
15.7 Program Manager: A DDE Server
By now, we have introduced some of the most useful DDE transactions. We can use these data transfer
protocols to design and build applications that can share data and information. Besides this, we can also
write client application to communicate with standard DDE servers contained in the system.
Program Manager
Under Windows, all types of applications are managed into groups. By clicking on Start | Programs
command on the task bar, we will see many groups, such as “Accessories”, “Startup”. Within each group,
there may exist some items that are linked directly to executable files, or there may exist some sub-groups.
Sometimes we may want to modify this structure by adding a new item or deleting an existing item.
Actually this structure is managed by Program Manager, which is a DDE server. We can interact with
this server to create group, delete group, add items to the group, delete items from a group through
initiating Execute transactions.
The client sample from the previous section is modified so that it can be used to communicate only to
Program Manager. Here, the service name of the Program Manager is “Progman”. As we can see, the
DDE initialization for this client is exactly the same as we did before.
The five commands we will ask the server to execute are: creating group; bringing up an existing
group; deleting a group; creating an item; deleting an item. All the DDE commands must start and end with
square braces (‘[’ and ‘]’). The following table lists the formats of five commands:
Function
Command format
Create a group "[CreateGroup(group name)]"
Pop up a group "[ShowGroup(group name, 1)]"
Delete a group "[DeleteGroup(group name)]"
Create an item "[AddItem(File name, item name)]"
Delete an item "[DeleteItem(Item name)]"
A combo box for storing the command types is added to sample’s dialog box. Besides this, the dialog
box also contains an edit box and a button labeled “Command”. The edit box will be used to let the user
input parameters for the command. For example, if we want to create a group with name “Test”, we can
select “Create group” from the combo box and input “Test” into the edit box then click “Command” button.
The application will initiate an execute transaction to the Program Manager and send
“[CreateGroup(Test)]” command to it.
We can use this program to create groups and add items to a group. We can also delete unwanted
groups or remove items from a group.
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