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.