feat(tdg): add example how to work with services

tarantool-client/src/test/java/io/tarantool/client/integration/tdg/TDGClientTest.java

@@ -233,4 +233,50 @@ void testTDGThrowError() {
     Assertions.assertEquals(
         "Type \"NoSpace\" not found", tarantoolSlashErrorsException.getReason().getErr());
   }
+
+  @Test
+  void testServiceWithArgs() {
+
+    // service name from config file!
+    final String serviceName = "get_by_id";
+
+    final TarantoolDataGridSpace space = client.space("User");
+    final Map<String, Object> user =
+        new HashMap<String, Object>() {
+          {
+            put("age", 1);
+            put("name", "nick");
+          }
+        };
+
+    final Map<?, ?> insertedUser = space.put(user).join();
+    Assertions.assertEquals(user, insertedUser);
+
+    final Map<String, Object> serviceArgs = new HashMap<>();
+    serviceArgs.put("model_type", "User");
+    serviceArgs.put("id", 1);
+
+    final List<?> callResult =
+        client.call("call_service", Arrays.asList(serviceName, serviceArgs)).join().get();
+    // 0 - response, 1 - error
+    Assertions.assertEquals(2, callResult.size());
+    Assertions.assertInstanceOf(Map.class, callResult.get(0));
+    Assertions.assertEquals(user, callResult.get(0));
+  }
+
+  @Test
+  void testServiceWithoutArgs() {
+
+    // service name from config file!
+    final String serviceName = "hello";
+
+    final String expectedString = "hello!";
+    final List<?> callResult =
+        client.call("call_service", Collections.singletonList(serviceName)).join().get();
+
+    // 0 - response, 1 - error
+    Assertions.assertEquals(2, callResult.size());
+    Assertions.assertInstanceOf(String.class, callResult.get(0));
+    Assertions.assertEquals(expectedString, callResult.get(0));
+  }
 }

tarantool-shared-resources/tdg/test-cluster-configuration/config.yml

@@ -1,3 +1,16 @@
 ---
 types:
   __file: model.avsc
+
+services:
+  get_by_id:
+    doc: "Return User data by id"
+    function: services.users.get_by_id
+    args:
+      model_type: string
+      id: int
+    return_type: User
+  hello:
+    doc: "Return 'hello!' string"
+    function: services.users.say_hello
+    return_type: string

tarantool-shared-resources/tdg/test-cluster-configuration/src/services/users.lua

@@ -0,0 +1,10 @@
+return {
+  -- Args must be the table!
+  get_by_id = function(args)
+    local repository = require("repository")
+    return repository.get(args.model_type, args.id);
+  end,
+  say_hello = function()
+    return 'hello!';
+  end
+}