- Try to fix Python memory errors: change XML Parse, upgrade to Python 2.5... 
- Implement Data conversion
- Automatic Sub-Item Properties
- Browsing: Implement MaxElementsReturned/ContinuationPoint
            and BrowseFilter/ElementNameFilter/VendorFilter
            if possible in the server
- Implement a sample XML-File Server that reads items from a XML-File
- Check for missing Success/Error Codes of all OPC functions
- Implement microseconds/Timezones in the ZSI
- Implement "ValueTypeQualifier"
- Implement "Decimal" data type in ZSI
- Check "base64Binary" - what exactly is it, how could it be implemented
- Implement lists in lists
- HasChanged should also work for lists
- Implement RequestDeadline
- Implement deadband for datetime/time etc.
- Add Caching stragegies for subscription-sampling reads
- Try to prevent multiple sampling-reads on one item by blocking multiple
  reads and by creating an "intelligent" MaxSamplingRate
- Implement a optional periodic function purge_cache that deletes
  obsoleted entries from the ReadCache (e.g. older than 24 hours)

######## Ideas ##########
- Create a sample OPC-Browser with a Web-Interface based on Twisted
- Implement a Web Interface for the OPC Server with the following features:
  - Server-specific configuration (shutdown etc.)
  - Adding/Removing OPC Servers in the hierarchy
  - Configuring global and specific options of the server
- Add a ssh-interface with similar options as above 
  (Maybe there are some ideas in twisted?)
  - Add a manhole to this ssh-access
- Add SSL (Client/Server)
- Add User Management, Authorization etc. 
