docs: add DR about dataplane selection improvements (#4149)

* docs: add DR about dataplane selection improvements

* PR remarks

docs/developer/decision-records/2024-05-24-dataplane-selection-improvements/README.md

@@ -0,0 +1,40 @@
+# Dataplane Selection Improvements
+
+## Decision
+
+In the scope of `Dataplane Signaling`, a new way to manage dataplane registration and de-registration will be implemented
+
+## Rationale
+
+Currently, the dataplane registration is done manually by the operator through the management-api, this way is not optimal
+because it could lead to errors, plus, there's no way for the control plane to ensure that the dataplane is still active
+and ready to accept new transfer requests.
+
+## Approach
+
+The dataplane needs to register itself to the control plane.
+To do that, it will need a way to be aware of its supported `source` types and `transferTypes`.
+
+In the first iteration, a new method needs to be added to the `DataSourceFactory` interface, that indicates the type that is handled by the
+factory:
+```java
+public interface DataSourceFactory {
+    String supportedType();
+}
+```
+
+Doing so, the `canHandle` method will become obsolete, and the factory will be bound to a specific type.
+
+The `transferTypes` instead will need:
+- for `PUSH` flows: the same method will be added to the `DataSinkFactory`, so collecting the types from the registered
+  factories will give the set of supported `PUSH` types
+- for `PULL` flows: the types are registered to the `PublicEndpointGeneratorService`
+
+
+With this knowledge, the dataplane will be able at startup to register itself to the controlplane via the `control-api`
+(and de-register itself at shutdown).
+
+The dataplane will need to have a UUID configured to handle idempotency.
+
+The controlplane will have the possibility to "heartbeat" the dataplane to verify its availability in order to be able
+to build the catalog in the correct way and being able to tell if a requested transfer can be started or not.

docs/developer/decision-records/README.md

@@ -53,5 +53,6 @@
 - [2023-11-20 Transfer_Type](./2023-11-20-transfer-type)
 - [2023-11-09 Protocol Services Refactor](./2023-11-27-refactor-protocol-services)
 - [2023-12-12 Data Plane Signaling and Access Control Architecture](./2023-12-12-dataplane-signaling)
-- [2023-12-12 Token Handling Refactor](./2023-12-19-token-handling-refactor)
-- [2024-01-12 Dynamic_Constraint_Functions](./2024-01-12-dynamic-constraint-functions)
+- [2023-12-19 Token Handling Refactor](./2023-12-19-token-handling-refactor)
+- [2024-01-12 Dynamic Constraint Functions](./2024-01-12-dynamic-constraint-functions)
+- [2024-05-24 Dataplane Selection Improvements](./2024-05-24-dataplane-selection-improvements)