Microsoft Sync Framework

Sync Services for ADO.NET Architecture

Microsoft Sync Services for ADO.NET is the synchronization provider for synchronizing across databases using ADO.NET. ADO.NET Datasets are synchronized between the source and the destination, which are then persisted to a database server. It can also support data sources other than a relational database, like an XML database or web service as long as a proxy is provided to abstract the data source and a data provider is available for the proxy.

The Sync Services for ADO.NET provider is intended for use in offline applications, where data from the central database is cached locally. The application works against the cached data, and the changes are uploaded in a batch. In addition, the provider can also be used for collaborative applications, where each application will work against its local dataset, which will be synchronized periodically in a peer-to-peer manner with the other participants. Locally, the datasets can be stored either by using the SQL Server Compact database or any other database server supporting ADO.NET. Sync Services for ADO.NET allows incremental change tracking, which allows only the changes to be replicated rather than replicating the entire copy.

The Sync Services for File Systems provider is used to synchronize two file system locations, which can either be local folders or network shares. In addition to mirroring new files, changes to existing files are also synchronized. Changes to files are detected by using timestamps, or optionally, by hashing the file contents. Conflicting changes to the same file are detected and can be set to be automatically resolved. For conflicting updates to a same file, the newer edit will be kept. If a file is deleted in one replica but updated in another, the update will take precedence over the delete. If two files with different content are created with the same name across two replicas, during the sync operation, the one created later will be persisted. If a rename operation caused the files to get the same name, both are retained by renaming one of them. Any deletes can be configured to move the file to the Recycle Bin, so that it can be recovered if necessary. The Sync Services for File Systems provider also provides a preview mode which enumerates the actions that will be taken for a sync operation, without actually performing the operations, with a view to letting the users review the changes that will be made. The synchronization is performed in a peer-to-peer manner. Neither Sync Framework or the Sync Services for File Systems provider perform any authentication before accessing the files; so any authentication is the job of the application using the Sync Framework API. The files are transferred without encryption. To use encryption in transit, custom providers that uses an encrypted TCP connection needs to be used. The Sync Services for File Systems provider also supports static filters to exclude files based on wildcards or attributes. In the first CTP release, however, the Sync Services for File Systems provider does not sync either NTFS security descriptors or Alternate Data Streams.

The Sync Services for FeedSync provider can be used to help synchronize replicas by creating a FeedSync enabled feed, either in RSS or ATOM formats, which can then be subscribed to by interested parties. The provider can also be used to extract items from a FeedSync feed and merge the changes back to the data store. Sync Services for FeedSync uses another provider to connect to the data store.

Sync Services for FeedSync provides services that can be used to help synchronize the data of a replica with RSS and Atom feeds. (A replica is a particular repository of information to be synchronized.) By using the FeedSync producer service, a synchronization application can work with a synchronization provider to create a list of items from a replica and put them in an RSS or Atom XML stream. These items can then be published to interested subscribers. Similarly, the FeedSync consumer service helps a synchronization application take an input RSS or Atom XML stream, extract items from it, and then use a synchronization provider to apply only the appropriate changes to a replica. Because Sync Framework underlies the exchange of feed items, two feeds can be cross-subscribed and easily synchronized with one another as peers in a synchronization community. (A synchronization community is a set of replicas that keep their data synchronized with each other.)

Microsoft Sync Framework is free on Windows and Windows Mobile devices. Support for other platforms is available through commercial licensing and porting kits.[2]