I understand that Restate and Temporal look similar from a superficial perspective but Restate is not only a durable execution engine but a durable runtime that also provides consistent state and reliable communication. These are the building blocks to build reliable agents and applications w/o having to fit them into a workflow-activity like model. If you want to learn more about how Temporal differs from Restate, check out https://restate.dev/vs/temporal.
The way it works is that Restate supports suspending workflows that sleep for months and later (once the sleep finishes) resumes them at exactly this point. Technically, this is the same process as resuming a crashed workflow.
While the workflow is actively doing work (like calling other services, accessing state or interacting with external services, for example) the server is connected to the workflow deployment via a low-latency bidirectional streaming connection to receive and acknowledge progress that the workflow makes. That way the workflow can finish as fast as possible.
A nice side effect of this model is that you can co-locate your workflow with expensive resources, such as a sandbox, which should be used by all durable actions that the workflow executes. The reason this works is because Restate can inline durable steps (what would be modeled in Temporal as activities, I believe).
Like Temporal, Restate supports workflows that sleep for months at a time and let's them reliably finish.
It actually does many more useful things. For example, you can have services that remember state across invocations and there is no need for continue-as-new.
Since Restate allows inlining durable steps into your workflow, it is very easy to co-locate your workflows with expensive resources such as sandboxes or other per-node resources. And the nice thing is that each durable step is really cheap and adds only minimal overhead.
Restate's spiritual father is Stateful Functions (https://nightlies.apache.org/flink/flink-statefun-docs-maste...) a library for event driven applications built on top of Apache Flink. If you want to learn more about why we started building Restate, I recommend this excellent blog post https://restate.dev/blog/why-we-built-restate.
I understand that Restate and Temporal look similar from a superficial perspective but Restate is not only a durable execution engine but a durable runtime that also provides consistent state and reliable communication. These are the building blocks to build reliable agents and applications w/o having to fit them into a workflow-activity like model. If you want to learn more about how Temporal differs from Restate, check out https://restate.dev/vs/temporal.