As multiple servers start writing out the objects to the user workstation, the input must be managed in a temporally intelligent manner and coordinated so that buffers of appropriate streams are managed separately and synchronized for rendering. A composition process manager is essential for this purpose. This problem becomes more complex if some objects must overlap other objects and remain visible. The sequence in which these objects are received and buffered becomes crucial for correct operation.
Another synchronization issue occurs when multiple authors must edit a set of objects sharing common areas on a timeline in a predefined sequence in real time. The objects must be played out to the different users in the proper order. Editing these objects can result in timeline shifts that must be adjusted dynamically.
Finally in a complex composition system, the user may need some specialized capabilities for customizing their environment. A programmable system is highly desirable for such system authoring requirements.