A group may be characterized as either persistent or transient. A persistent group and its shared state exist even when the group has no members. A client joining a persistent group will receive the state of the group's shared data. A transient group ceases to exist when it has no members, and its shared state is lost. Persistency is achieved by logging the group state to the disk and it is an important feature in the context of asynchronous collaboration .
Corona also provides support for state log reduction.
Since the communication service is general-purpose, the interpretation of the semantics of shared data is the responsibility of collaborating processess. Therefore, the client application is responsible for providing the checkpointed state of the group for reducing the state log. Currently, a single server implementation of Corona is used as production version. There exists also a replicated server implementation, but it is not complete and it does not ensure the whole functionality of the single server version. The ChatBox allows participants to exchange textual messages.