Sync Framework Glossary

This glossary lists and defines Microsoft Sync Framework concepts and terminology.

Terminology

• batching
  The process of sending changes in small groups instead of in a one-shot transfer of the data in its entirety.

• change unit
  The minimal unit of change tracking in a store. Change units are contained in an item, such as name and address fields in a contact item. In change propagation, only the change units that are changed must be sent. In conflict detection, only changes to the same change unit are considered a conflict.

• client
  A service, application, or device that wants to integrate into the Sync Framework architecture.

• clock vector
  A replica key/tick count pair that represents updates to a replica. Any change that occurs between 0 and the tick count is contained in the vector.

• conflict resolution method
  The method that is used to determine which change is written to the store if there is a conflict. Typical conflict resolution methods are as follows: last writer wins, source wins, destination wins, custom, or deferred. For custom resolution, the resolving application reads the conflict from the conflict log and selects a resolution. For deferred resolution, the conflict is logged together with the conflicting change data and the made-with knowledge of the change.

• consistency unit
  The minimal unit of consistency. Because all changes that have the same consistency unit are sent together, synchronization can never be interrupted when only part of a consistency unit is applied.

• flexible identifier
  An identifier that is assigned to various synchronization entities, such as replicas. The identifier can be of fixed or variable length.

• global identifier
  A unique identifier that is assigned to a data item. The identifier must be unique across all clients. A global identifier is a flexible identifier and so can be any format. However, the format is typically a GUID and an 8-byte prefix.

• item
  A unit of data or metadata that is being synchronized. A typical item of data might be a file or record, whereas a typical item of metadata might be a knowledge item.

• made-with knowledge
  The current knowledge of a source replica, to be used in conflict detection. Made-with knowledge answers the question: What did you know when you made these changes?

• learned knowledge
  The current knowledge of a source replica about a specific set of changes, and the logged conflicts of that replica. Learned knowledge answers the question: What will I learn when I apply this batch of changes?

• knowledge
  The metadata that is maintained by each participant that describes all the changes it has seen. In its simplest form, known as a watermark, a knowledge item is a clock vector that consists of pairs of replica keys and replica tick counts.

• participant
  A provider and its associated replica.

• range
  A set of continuous item identifiers to which the same clock vector applies. A range is represented by a starting point, an ending point, and a clock vector that applies to all IDs that are in between.

• replica
  A particular repository of information to be synchronized.

• replica ID
  A value that uniquely identifies a replica.

• replica key
  A 4-byte value that maps to a replica ID in a replica key map.

• scope
  The set of data that is being synchronized.

• synchronization application
  A software component, such as a personal information manager or music database, that hosts a synchronization session and invokes synchronization providers to synchronize different data stores.

• synchronization community
  A set of replicas that keep their data synchronized with one another.

• synchronization provider
  A software component that represents a replica for synchronization. When acting as a source, it enumerates changes from its replica. When acting as a destination, it applies changes to its replica. For data format mismatch, it performs any necessary schema transformation.

• synchronization session
  A unidirectional synchronization in which the source provider enumerates its changes and sends them to the destination provider, which applies them to its store.

• tick count
  A monotonically increasing number that is specific to a replica and combined with a replica key to make a version.

• tombstone
  A marker that is used to represent an item that has been deleted. A tombstone is used to track deleted items and prevent their reintroduction into the synchronization community.

• version
  Metadata that identifies a revision to an item. It consists of the replica key and the replica tick count for the item.

See Also

Other Resources

Microsoft Sync Framework