Once I thought all calls across COM apartments (not inside apartment) are all synchronous call, now after study re-entrancy problem, I think I am wrong, at least STA to MTA call is asynchronous.
(Link to re-entrancy problem, http://www.codeproject.com/KB/COM/sta_issues.aspx)
After some study, I can not find a conclusion whether the 4 types of calls are synchronous or asynchronous. Here is my study result, please feel free to correct me if I am wrong?
1. STA --> STA, I think asynchronous;
2. STA --> MTA, I think asynchronous;
3. MTA --> STA, I think synchronous;
4. MTA --> MTA, I think synchronous.
thanks in advance,