[xlang] Cross language Python support (#6709)

java/test/src/main/resources/test_cross_language_invocation.py

@@ -12,6 +12,25 @@ def py_func(value):
     return b"Response from Python: " + value
 
 
+@ray.remote
+def py_func_call_java_function(value):
+    assert isinstance(value, bytes)
+    f = ray.java_function("org.ray.api.test.CrossLanguageInvocationTest",
+                          "bytesEcho")
+    r = f.remote(value)
+    return b"[Python]py_func -> " + ray.get(r)
+
+
+@ray.remote
+def py_func_call_java_actor(value):
+    assert isinstance(value, bytes)
+    c = ray.java_actor_class(
+        "org.ray.api.test.CrossLanguageInvocationTest$TestActor")
+    java_actor = c.remote(b"Counter")
+    r = java_actor.concat.remote(value)
+    return ray.get(r)
+
+
 @ray.remote
 class Counter(object):
     def __init__(self, value):