Fig. 1. Ring of double linked fields.

Fig. 2. Architecture overview.

Fig. 3. Architecture of the database based collaborative editor.

Fig. 4. Data representation in the editor and database.

Fig. 5. Architecture of the editor.

Fig. 6. Class diagram of the system package.

Fig. 7. Class diagram of the Collaborative editor-plug-in.

Fig. 8. Class diagram of the core classes of Caché.

Fig. 9. Message propagating service.

Fig. 12. Insert characters.

Fig. 10. Open a document.

Fig. 11. Close a document.

Fig. 13. Delete characters.

Fig. 14. Remote write protocol.

Fig. 15. Time for message propagating.

Fig. 16. Synchronous approach with direct update.

Fig. 17. Synchronous approach with update using the database update process.

Fig. 18. Asynchronous approach.

Fig. 19. Classification of the discussed approaches.

Fig. 20. Insert at the same position.

Fig. 21. Delete at the same position.

Fig. 22. Insert and delete at the same position.

Fig. 23. Deleting and insert at the same position.

Fig. 24. Pessimistic approach with exclusive lock.

Fig. 25. Update process in detail.

Fig. 26. Insert character, scenario 1.

Fig. 27. Insert character, scenario 2.

Fig. 28. Insert at the same position.

Fig. 29. Insert and delete at the same position.

Fig. 30. Insert transaction.

Fig. 31. Define elementary process.

Fig. 32. Flow of elementary processes.

Fig. 33. Measurements.

Fig. 34. Insert time per character.

Fig. 35. Insert time depending on the DB-size.

Fig. 36. Simultaneous editing simulation.

Fig. 37. Possible number of concurrent users.

Fig. 38. Network traffic of the server (382 users, at 180 keystrokes a minute).

Fig. 39. DB-size per stored characters.