NHibernate
NHibernate is a widely used ORM and it is supported by MassTransit for saga storage. The example below shows the code-first approach to using NHibernate for saga persistence.
public class OrderState : SagaStateMachineInstance{ public Guid CorrelationId { get; set; } public string CurrentState { get; set; } public DateTime? OrderDate { get; set; } // If using Optimistic concurrency, this property is required public int Version { get; set; }}The instance properties are configured using a SagaClassMapping.
The
SagaClassMapping has a default mapping for the CorrelationId as the primary key. If you create your own mapping, you must follow the same convention, or at least make it a Clustered Index + Unique, otherwise you will likely experience deadlock exceptions and/or performance issues in high throughput scenarios.public class OrderStateMap : SagaClassMapping<OrderState>{ public OrderStateMap() { Property(x => x.CurrentState, x => x.Length(64)); Property(x => x.OrderDate); Property(x => x.Version); // If using Optimistic concurrency }}Configuration
To configure NHibernate as the saga repository for a saga, use the code shown below using the AddMassTransit container extension. This will configure NHibernate to connect to the local NHibernate instance on the default port using Optimistic concurrency.
// the session factory should be registered as a single instancecontainer.RegisterSingleInstance<ISessionFactory>(...);container.AddMassTransit(cfg =>{ cfg.AddSagaStateMachine<OrderStateMachine, OrderState>() .NHibernateRepository();});Concurrency
NHibernate natively supports multiple concurrency handling mechanisms. The easiest is probably adding a Version property of type int to the saga instance class and map it to the column with the same name
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