KDE PIM/Akonadi Next/Terminology

Glossary of Akonadi-Next Terms

akonadi1: The current akonadi implementation that uses a central server and an SQL database
akonadi-next: This is the codename for the project. In the long run this is supposed to be folded into regular akonadi, so we will never release a product called akonadi-next.
client: any application which accesses data using akonadi
entity: The atomic unit for a given type of data. An email is an entity; an email folder is an entity; a calendar event is an entity; a contact is an entity; etc. Different kinds of entities may have their own data structure, but conceptually they are equivalent in most other ways.
revision: A version of an entity. One entity may have multiple revisions in a store, representing (for instance) the local state and the synchronized state of the entity.
source: The canonical data set, which may be a remote IMAP server, a local iCal file, a local maildir, etc.
store: The local, persistent (e.g. on disk) record of entities belonging to a source. This may be a full mirror of the data or simply metadata, a detail left up to the resource. The format of the data in the store is defined by the resource that owns it.
resource: A plugin which provides a client command processor, data facade and synchronization service for a given type of store. The resource also manages the configuration for a given source including server settings, local paths, etc.
synchronizer: The operating system process responsible for overseeing the process of modifying and synchronizing a store. To accomplish this, a synchronizer loads the correct resource plugin, manages pipelines and handles client communication. One synchronizer is created for each source that is accessed by clients; these processes are shared by all clients.
filter: A component that takes an entity and performs some modification of it (e.g. changes the folder an email is in) or processes it in some way (e.g. indexes it)
pipeline: A run-time definable set of filters which are applied to an entity after a resource has performed a specific kind of function on it (add, update, remove)
query: A declarative method for requesting entities from one or more sources that match a given set of constraints
command: Clients request modifications, additions and deletions to the store by sending commands to a synchronizer for processing
command queue: a queue of commands kept by the synchronizer to ensure durability and, when necessary, replayability
notification: a message sent from a synchronizer to inform the client of a change in the store