Horizontal Scalability and Multi-Server Mode
This section is fully dedicated to the Workflow Engine and Workflow Server scalability and deployment.
- By default, Workflow Engine and Workflow Server operate in the single-server mode, when it is highly recommended that a single Workflow Engine or Workflow Server instance is connected to a single database.Therefore, this mode is not suitable for horizontal scaling. The multi-server mode is the solution.
- In the multi-server mode, any number of Workflow Engine or Workflow Server instances can be connected to a single database. All these instances are independent; the only thing that unites them in a cluster is the common database (or schema). The servers can be disconnected and connected to the database at any time; for the cluster to keep on working, one server is enough.
- If a server or all of the servers fail during the operation, all of them or part of them stop, then the data of the active processes launched during the shutdown must be restored. The recovery procedure that can be customized is used for that. But, even without customization, one working server is enough to get everything back nice and smoothly. If you are using the single server, just restart it to recover.
- Moreover, out-of-the-box Workflow Engine and Workflow Server support multi-tenant applications.