Creating a Cross-Process EventWaitHandle

Question

I have two windows application, one is a windows service which create EventWaitHandle and wait for it. Second application is a windows gui which open it by calling EventWait

Answer 1

You need to use the version of the EventWaitHandle constructor that takes an EventWaitHandleSecurity instance. For example, the following code should work (it's not tested, but hopefully will get you started):

// create a rule that allows anybody in the "Users" group to synchronise with us
var users = new SecurityIdentifier(WellKnownSidType.BuiltinUsersSid, null);
var rule = new EventWaitHandleAccessRule(users, EventWaitHandleRights.Synchronize | EventWaitHandleRights.Modify,
                          AccessControlType.Allow);
var security = new EventWaitHandleSecurity();
security.AddAccessRule(rule);

bool created;
var wh = new EventWaitHandle(false, EventResetMode.AutoReset, "MyEventName", out created, security);
...

Also, if you're running on Vista or later, you need to create the event in the global namespace (that is, prefix the name with "Global\"). You'd also have to do this on Windows XP if you use the "Fast User Switching" feature.