[RPC] Implement RPC call to register a Driver with the backend.

rpc/protos/erdos_scheduler.proto

@@ -13,15 +13,20 @@ service SchedulerService {
     // itself with the backend scheduler, and is intended as an EHLO.
     rpc RegisterFramework(RegisterFrameworkRequest) returns (RegisterFrameworkResponse) {}
 
+    /// Deregisters the framework with the backend scheduler.
+    /// This is meant for the framework to signal its intent to shut down.
+    rpc DeregisterFramework(DeregisterFrameworkRequest) returns (DeregisterFrameworkResponse) {}
+
+    /// Registers the driver with the backend scheduler.
+    /// Drivers are long running entities that are allocated resources indefinitely
+    /// by the backend.
+    rpc RegisterDriver(RegisterDriverRequest) returns (RegisterDriverResponse) {}
+
     // Registers a new application with the backend scheduler.
     // This is the entry point for a new taskgraph (application) to register
     // itself with the backend scheduler, and is intended as an EHLO.
     rpc RegisterTaskGraph(RegisterTaskGraphRequest) returns (RegisterTaskGraphResponse) {}
 
-    /// Deregisters the framework with the backend scheduler.
-    /// This is meant for the framework to signal its intent to shut down.
-    rpc DeregisterFramework(DeregisterFrameworkRequest) returns (DeregisterFrameworkResponse) {}
-
     /// Registers a new Worker with the backend scheduler.
     /// This is invoked whenever a new Worker joins the framework.
     rpc RegisterWorker(RegisterWorkerRequest) returns (RegisterWorkerResponse) {}
@@ -54,6 +59,22 @@ message DeregisterFrameworkResponse {
     string message = 2;
 }
 
+/// Driver related RPC structures.
+/// The following structures represent the data that a driver must pass to the
+/// scheduling backend. This may involve things like the name of the driver, the
+/// URI, the number of resources required by the driver, and other general
+/// information.
+message RegisterDriverRequest {
+    string uri = 2;
+    int32 cores = 3;
+    int32 memory = 4;
+}
+
+message RegisterDriverResponse {
+    bool success = 1;
+    string message = 2;
+}
+
 /// Application related RPC structures.
 /// The following structures represent the data that an application (TaskGraph)
 /// must pass to the scheduling backend.
@@ -82,4 +103,4 @@ message RegisterWorkerRequest {
 message RegisterWorkerResponse {
     bool success = 1;
     string message = 2;
-}
+}