• In Firefly, temporal composition is expressed in terms of relations between instants (beginning and ending of objects and user interactions).

• This is the first work in the constraint-based area that has considered the unpredictable nature of some multimedia objects (like user interactions) (issue 5).

Working:

•  In order to provide a static formatting process handling this kind of objects, the Firefly scheduler partitions the temporal scenario at compile-time by grouping connected components (i. e. instants related by a temporal relation or a predictable duration).

• Figure 10 shows the Firefly description of the Mascot scenario: there are two sets of connected components and two unpredictable objects (Button and Message) which appear with a dotted line.

• The simplex algorithm is used to independently find the optimal solution of each partition. An event-driven scheduler dynamically handles the integration of the partitions.

Disadvantages:

• Unfortunately, the time performances of this batch process is not good-enough in a interactive and incremental context (issue 12). This is the most important drawback of the Firefly approach.

• Another weak point of Firefly is that it does not provide the user with any abstraction capabilities (issue 13).