diff --git a/proto/caosdb/entity/v1alpha1/main.proto b/proto/caosdb/entity/v1alpha1/main.proto
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+++ b/proto/caosdb/entity/v1alpha1/main.proto
@@ -0,0 +1,53 @@
+//
+// This file is a part of the CaosDB Project.
+//
+// Copyright (C) 2021 Timm Fitschen <t.fitschen@indiscale.com>
+// Copyright (C) 2021 IndiScale GmbH <info@indiscale.com>
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as
+// published by the Free Software Foundation, either version 3 of the
+// License, or (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program. If not, see <https://www.gnu.org/licenses/>.
+//
+
+// This is the main file of the caosdb.entity.v1alpha1 package.
+syntax                      = "proto3";
+option  java_multiple_files = true;
+option  java_package        = "org.caosdb.api.entity.v1alpha1";
+package caosdb.entity.v1alpha1;
+
+// Entity message
+message Entity {
+  // Entity ID
+  string eid = 1;
+  // Entity Name
+  string name = 2;
+  // Entity Description
+  string description = 3;
+}
+
+// RetrieveRequest message
+message RetrieveRequest {
+  // requested entity
+  Entity entity = 1;
+}
+
+// RetrieveResponse message
+message RetrieveResponse {
+  // payload of the retrieval
+  Entity entity = 1;
+}
+
+// Entity Transaction Service
+service EntityTransactionService {
+  // Retrieve a single entity
+  rpc Retrieve(RetrieveRequest) returns (RetrieveResponse);
+}