Opens a session for querying symbols.
If successful, returns S_OK; otherwise, returns an error code. The following table shows the possible return values for this method.
The IDiaDataSource object has not previously been initialized with a source of symbols.
Invalid ppSession parameter.
Insufficient memory to open the session.
This method opens an IDiaSession object for a data source.
IDiaSession objects implement queries into the data source. A session manages one address space for each set of debug symbols. If the .exe or .dll file described by the data source symbols is active in multiple address ranges (for example, because multiple processes have it loaded), then one session for each address range should be used.