This is an implementation of a data backplane for NServiceBus endpoints. It allows the endpoints to exhange out-of-band information between each other. An example of such information might be list of messages that can be handled by a given endpoint. Based on that information each endpoint can build a complete routing table for all messages without requiring any configuration.

Data backplane API has three basic operations.

Task<IDataBackplaneSubscription> GetAllAndSubscribeToChanges(string type, Func<Entry, Task> onChanged, Func<Entry, Task> onRemoved);

Task Publish(string type, string data);

Task Revoke(string type);

which allow for querying (and continuously monitor changes) for data, publishing new data and removal of publications.

busConfig.EnableDataBackplane<FileSystemBackplane>();

The file system implementation is designed for development environments only. It uses a local directory (defaults to a temp folder) as a container for backplane publications.

busConfig.EnableDataBackplane<SqlServerBackplane>("Data Source=(local);Initial Catalog=Backplane1;Integrated Security=True");

The SQL Server based implementation is designed for production. It uses a table in SQL Server database as a container for the backplane publications. Because the problems in connectivity with backplane can potentially cause endpoint to malfunction, it is essential to use the same database as used to store application data. In case endpoints use different databases, SQL Server merge replication can be used to synchronized backplane tables.

busConfig.EnableDataBackplane<ConsulBackplane>("http://127.0.0.1:8500");

The Consul based implementation is suitable for enviroments that are already running a highly available Consul cluster to do service discovery and management. It registers endpoint instanes and all the messages types they handle in the Consul service registry so other endpoints can route messages based on this information.

In order to see the backplane-based routing in action, please run both Sender and Publisher projects.

The data backplane can be used for auto-configuring other features, e.g. SQL Server multi-database feature.