diff --git a/composer.json b/composer.json
index d6ea39c..3a8bd63 100644
--- a/composer.json
+++ b/composer.json
@@ -37,7 +37,8 @@
         "webmozart/glob": "^4.1",
         "sabre/uri": "^2.0",
         "JetBrains/phpstorm-stubs": "dev-master",
-        "composer/composer": "^1.3"
+        "composer/composer": "^1.3",
+        "reactivex/rxphp": "^1.5"
     },
     "repositories": [
         {
diff --git a/src/LanguageServer.php b/src/LanguageServer.php
index 7e856b1..9d069d6 100644
--- a/src/LanguageServer.php
+++ b/src/LanguageServer.php
@@ -122,40 +122,66 @@ class LanguageServer extends AdvancedJsonRpc\Dispatcher
             $this->shutdown();
             $this->exit();
         });
-        $this->protocolReader->on('message', function (Message $msg) {
-            coroutine(function () use ($msg) {
-                // Ignore responses, this is the handler for requests and notifications
-                if (AdvancedJsonRpc\Response::isResponse($msg->body)) {
+        // Map from request ID to subscription
+        $subscriptions = [];
+        $this->protocolReader->on('message', function (Message $msg) use ($subscriptions) {
+            // Ignore responses, this is the handler for requests and notifications
+            if (AdvancedJsonRpc\Response::isResponse($msg->body)) {
+                return;
+            }
+            if ($msg->body->method === '$/cancelRequest') {
+                if (!isset($subscriptions[$msg->body->id])) {
                     return;
                 }
-                $result = null;
-                $error = null;
-                try {
-                    // Invoke the method handler to get a result
-                    $result = yield $this->dispatch($msg->body);
-                } catch (AdvancedJsonRpc\Error $e) {
-                    // If a ResponseError is thrown, send it back in the Response
-                    $error = $e;
-                } catch (Throwable $e) {
-                    // If an unexpected error occured, send back an INTERNAL_ERROR error response
-                    $error = new AdvancedJsonRpc\Error(
-                        (string)$e,
-                        AdvancedJsonRpc\ErrorCode::INTERNAL_ERROR,
-                        null,
-                        $e
+                // Express that we are not interested anymore in the observable
+                $subscriptions[$msg->body->id]->dispose();
+                return;
+            }
+            // The result object that is built through JSON patches
+            $result = null;
+            $error = null;
+            try {
+                // Invoke the method handler to get a result
+                $obs = $this->dispatch($msg->body);
+            } catch (\Throwable $e) {
+                $obs = Observable::error($e);
+            }
+            // Notifications dont need further acting
+            if (AdvancedJsonRpc\Notification::isNotification($msg->body)) {
+                return;
+            }
+            if (!($obs instanceof ObservableInterface)) {
+                $obs = Observable::just($obs);
+            }
+            $subscriptions[$msg->body->id] = $obs->subscribe(new CallbackObserver(
+                function (JSONPatch $patch) use (&$result) {
+                    $this->protocolWriter->write(
+                        new Message(
+                            new AdvancedJsonRpc\Notification(
+                                '$/partialResult', ['id' => $msg->body->id, 'patch' => $patch]
+                            )
+                        )
                     );
-                }
-                // Only send a Response for a Request
-                // Notifications do not send Responses
-                if (AdvancedJsonRpc\Request::isRequest($msg->body)) {
-                    if ($error !== null) {
-                        $responseBody = new AdvancedJsonRpc\ErrorResponse($msg->body->id, $error);
-                    } else {
-                        $responseBody = new AdvancedJsonRpc\SuccessResponse($msg->body->id, $result);
+                    // Apply path to result object for BC
+                    $patch->apply($result);
+                },
+                function (\Exception $error) use ($msg) {
+                    if (!($error instanceof AdvancedJsonRpc\Error)) {
+                        $error = new AdvancedJsonRpc\Error(
+                            (string)$error,
+                            AdvancedJsonRpc\ErrorCode::INTERNAL_ERROR,
+                            null,
+                            $error
+                        );
                     }
-                    $this->protocolWriter->write(new Message($responseBody));
+                    // If an unexpected error occured, send back an INTERNAL_ERROR error response
+                    $this->protocolWriter->write(new Message(new AdvancedJsonRpc\ErrorResponse($msg->body->id, $error)));
+                },
+                function () use ($msg, &$result) {
+                    // Return the built result object for BC
+                    $this->protocolWriter->write(new Message(new AdvancedJsonRpc\SuccessResponse($msg->body->id, $result)));
                 }
-            })->otherwise('\\LanguageServer\\crash');
+            ));
         });
         $this->protocolWriter = $writer;
         $this->client = new LanguageClient($reader, $writer);
diff --git a/src/Server/Workspace.php b/src/Server/Workspace.php
index 5aae7cf..b1e4f3d 100644
--- a/src/Server/Workspace.php
+++ b/src/Server/Workspace.php
@@ -62,10 +62,31 @@ class Workspace
      * The workspace symbol request is sent from the client to the server to list project-wide symbols matching the query string.
      *
      * @param string $query
-     * @return Promise <SymbolInformation[]>
+     * @return Observable <SymbolInformation[]>
      */
-    public function symbol(string $query): Promise
+    public function symbol(string $query): Observable
     {
+        (
+            $this->index->isStaticComplete()
+            ? observableFromEvent($this->index->once('static-complete', function () {
+
+            })
+            : Observable::empty()
+        )
+        return Observable::create(function (ObserverInterface $observer) {
+            // Wait until indexing for definitions finished
+            if (!$this->index->isStaticComplete()) {
+                $this->index->once('static-complete', function () {
+
+                });
+            }
+            $observer->onNext(42);
+            $observer->onCompleted();
+
+            return new CallbackDisposable(function () {
+
+            });
+        });
         return coroutine(function () use ($query) {
             // Wait until indexing for definitions finished
             if (!$this->index->isStaticComplete()) {
diff --git a/src/utils.php b/src/utils.php
index 8ab7beb..e4655d9 100644
--- a/src/utils.php
+++ b/src/utils.php
@@ -93,6 +93,20 @@ function waitForEvent(EmitterInterface $emitter, string $event): Promise
     return $p;
 }
 
+/**
+ * Returns a promise that is fulfilled once the passed event was triggered on the passed EventEmitter
+ *
+ * @param EmitterInterface $emitter
+ * @param string           $event
+ * @return Promise
+ */
+function observableFromEvent(EmitterInterface $emitter, string $event): Promise
+{
+    Observable::create()
+    $emitter->once($event, [$p, 'fulfill']);
+    return $p;
+}
+
 /**
  * Returns the closest node of a specific type
  *