/// <summary>
/// Reads the guids from the enumerator.
/// </summary>
private List <Guid> ReadClasses(OpcRcw.Comn.IOPCEnumGUID enumerator)
{
List <Guid> guids = new List <Guid>();
int fetched = 0;
Guid[] buffer = new Guid[10];
do
{
try
{
IntPtr pGuids = Marshal.AllocCoTaskMem(Marshal.SizeOf(typeof(Guid)) * buffer.Length);
try
{
enumerator.Next(buffer.Length, pGuids, out fetched);
if (fetched > 0)
{
IntPtr pos = pGuids;
for (int ii = 0; ii < fetched; ii++)
{
buffer[ii] = (Guid)Marshal.PtrToStructure(pos, typeof(Guid));
pos = (IntPtr)(pos.ToInt64() + Marshal.SizeOf(typeof(Guid)));
guids.Add(buffer[ii]);
}
}
}
finally
{
Marshal.FreeCoTaskMem(pGuids);
}
}
catch
{
break;
}
}while (fetched > 0);
return(guids);
}
/// <summary>
/// Returns a list of servers that support the specified specification.
/// </summary>
public ServerDescription[] GetAvailableServers(params Guid[] catids)
{
// enumerate servers on specified machine.
try
{
// get list of servers in the specified specification.
OpcRcw.Comn.IOPCEnumGUID enumerator = null;
m_server.EnumClassesOfCategories(
catids.Length,
catids,
0,
null,
out enumerator);
// read clsids.
List <Guid> clsids = ReadClasses(enumerator);
// release enumerator object.
Utils.ReleaseServer(enumerator);
enumerator = null;
// fetch class descriptions.
ServerDescription[] servers = new ServerDescription[clsids.Count];
for (int ii = 0; ii < servers.Length; ii++)
{
servers[ii] = ReadServerDetails(clsids[ii]);
}
return(servers);
}
catch (Exception e)
{
throw Utils.CreateComException(e, ResultIds.E_FAIL, "Could not enumerate COM servers.");
}
}
