diff --git a/CMakeLists.txt b/CMakeLists.txt
index f19cc2946637dea895b30bc22a2df922ac12088b..288c5461e6c05aca02057c7c3b1abfed83823418 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -21,6 +21,10 @@
 cmake_minimum_required(VERSION 3.14)
 
 set(libcaosdb_VERSION 0.0.5)
+set(libcaosdb_COMPATIBLE_SERVER_VERSION_MAJOR 0)
+set(libcaosdb_COMPATIBLE_SERVER_VERSION_MINOR 5)
+set(libcaosdb_COMPATIBLE_SERVER_VERSION_PATCH 0)
+set(libcaosdb_COMPATIBLE_SERVER_VERSION_PRE_RELEASE "GRPC${libcaosdb_VERSION}")
 
 project(libcaosdb
     VERSION ${libcaosdb_VERSION}
diff --git a/doc/CMakeLists.txt b/doc/CMakeLists.txt
index 5ea0ae59c1110413bc35461d47e068b572641c09..090df1c53c4c7cfc99ee9943d68c97b22b854eae 100644
--- a/doc/CMakeLists.txt
+++ b/doc/CMakeLists.txt
@@ -21,9 +21,11 @@
 find_package(Doxygen)
 
 if (DOXYGEN_FOUND)
-    string(REPLACE ";" " " DOXYGEN_INPUT "${libcaosdb_INCL}")
+    string(REPLACE ";" " " DOXYGEN_INPUT "${PROJECT_INCLUDE_DIR} ${CMAKE_BINARY_DIR}/include")
+    string(REPLACE ";" " " DOXYGEN_STRIP_FROM_PATH "${PROJECT_INCLUDE_DIR} ${CMAKE_BINARY_DIR}/include")
     configure_file(Doxyfile.in Doxyfile)
 
+
     # Note: do not put "ALL" - this builds docs together with application EVERY TIME!
     add_custom_target(doc-doxygen
         COMMAND ${DOXYGEN_EXECUTABLE} Doxyfile
@@ -35,7 +37,9 @@ if (DOXYGEN_FOUND)
     if (SPHINX_CMD)
         configure_file(conf.py.in conf.py)
         configure_file(index.rst.in index.rst)
-        configure_file(api/index.rst.in api/index.rst)
+
+        # create C++ docs
+        configure_file(cppapi/index.rst.in cppapi/index.rst)
 
         # create rst pages for every header file
         list(LENGTH libcaosdb_INCL len_header_files)
@@ -43,20 +47,28 @@ if (DOXYGEN_FOUND)
         foreach (i RANGE "${len_header_files}")
             list(GET libcaosdb_INCL ${i} HEADER_FILE)
             string(REPLACE
-                "${PROJECT_INCLUDE_DIR}/caosdb/"
+                "${PROJECT_INCLUDE_DIR}/"
                 ""
                 HEADER_FILE_NAME
                 ${HEADER_FILE})
             string(REPLACE
-                "${CMAKE_BINARY_DIR}/include/caosdb/"
+                "${CMAKE_BINARY_DIR}/include/"
                 ""
                 HEADER_FILE_NAME
                 ${HEADER_FILE_NAME})
             configure_file(
-                api/header_file.rst.in
-                api/_${HEADER_FILE_NAME}.rst)
+                header_file.rst.in
+                cppapi/_${HEADER_FILE_NAME}.rst)
         endforeach ()
 
+        # create (plain) C docs
+        configure_file(capi/index.rst.in capi/index.rst)
+        set(HEADER_FILE_NAME ccaosdb.h)
+        set(HEADER_FILE ccaosdb.h)
+        configure_file(
+            header_file.rst.in
+            capi/_ccaosdb.rst)
+
         add_custom_target(doc-sphinx
             COMMAND ${SPHINX_CMD}
                 -b html
diff --git a/doc/Doxyfile.in b/doc/Doxyfile.in
index d0f329b99f37f6baeb05424f73decdb96ccc4cef..798198a973a2996a22402e771d4712b9ec31eafa 100644
--- a/doc/Doxyfile.in
+++ b/doc/Doxyfile.in
@@ -68,7 +68,7 @@ OUTPUT_DIRECTORY       = doxygen_out
 # performance problems for the file system.
 # The default value is: NO.
 
-CREATE_SUBDIRS         = NO
+CREATE_SUBDIRS         = YES
 
 # If the ALLOW_UNICODE_NAMES tag is set to YES, doxygen will allow non-ASCII
 # characters to appear in the names of generated files. If set to NO, non-ASCII
@@ -170,7 +170,7 @@ FULL_PATH_NAMES        = YES
 # will be relative from the directory where doxygen is started.
 # This tag requires that the tag FULL_PATH_NAMES is set to YES.
 
-STRIP_FROM_PATH        =
+STRIP_FROM_PATH        = @DOXYGEN_STRIP_FROM_PATH@
 
 # The STRIP_FROM_INC_PATH tag can be used to strip a user-defined part of the
 # path mentioned in the documentation of a class, which tells the reader which
@@ -944,7 +944,7 @@ FILE_PATTERNS          = *.c \
 # be searched for input files as well.
 # The default value is: NO.
 
-RECURSIVE              = NO
+RECURSIVE              = YES
 
 # The EXCLUDE tag can be used to specify files and/or directories that should be
 # excluded from the INPUT source files. This way you can easily exclude a
diff --git a/doc/api/.gitignore b/doc/api/.gitignore
deleted file mode 100644
index a463abd406508c6ad4c99ff83aa59e4196947228..0000000000000000000000000000000000000000
--- a/doc/api/.gitignore
+++ /dev/null
@@ -1 +0,0 @@
-_*.rst
diff --git a/doc/api/index.rst.in b/doc/capi/index.rst.in
similarity index 97%
rename from doc/api/index.rst.in
rename to doc/capi/index.rst.in
index 8a34c64d35cc72179a07ca96d1ba5914b0d741f1..b4fe4a88bc38dc40cbf09023cc4a3140ea0dded8 100644
--- a/doc/api/index.rst.in
+++ b/doc/capi/index.rst.in
@@ -21,10 +21,11 @@
 
 .. _api_root:
 
-API
-===
+C API
+=====
 
 .. toctree::
     :glob:
 
-    *
+    _*
+    _*/*
diff --git a/doc/cppapi/index.rst.in b/doc/cppapi/index.rst.in
new file mode 100644
index 0000000000000000000000000000000000000000..f0639ce79c10e118c09b82eee75595756dfb62eb
--- /dev/null
+++ b/doc/cppapi/index.rst.in
@@ -0,0 +1,31 @@
+..
+    #
+    # 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/>.
+    #
+
+.. _api_root:
+
+C++ API
+=======
+
+.. toctree::
+    :glob:
+
+    _*
+    _*/*
diff --git a/doc/api/header_file.rst.in b/doc/header_file.rst.in
similarity index 100%
rename from doc/api/header_file.rst.in
rename to doc/header_file.rst.in
diff --git a/doc/index.rst.in b/doc/index.rst.in
index 086a2f4096ca7d54a57c1dc01db1898f46f1a230..a4061607a924db8080e9a3970b08d1bce28d8944 100644
--- a/doc/index.rst.in
+++ b/doc/index.rst.in
@@ -35,6 +35,7 @@ This is work in progress.
     :caption: Contents:
 
     Welcome <self>
-    api/index
+    cppapi/index
+    capi/index
 
 * :ref:`genindex`
diff --git a/include/caosdb/authentication.h b/include/caosdb/authentication.h
index 703fcf51bae519a1f1fe0112ba1e8f84246d16a9..6b26dd68f1e7465763f63f7b638be23fa78c0429 100644
--- a/include/caosdb/authentication.h
+++ b/include/caosdb/authentication.h
@@ -22,7 +22,7 @@
 #ifndef CAOSDB_AUTHENTICATION_H
 #define CAOSDB_AUTHENTICATION_H
 /**
- * @file authentication.h
+ * @file caosdb/authentication.h
  * @author Timm Fitschen
  * @date 2021-06-28
  * @brief Configuration and setup of the client authentication.
diff --git a/include/caosdb/connection.h b/include/caosdb/connection.h
index 7f45319a837e2e0131dc1337fab032638bd0ef0d..4e87702fa8289dce7157955f046838c2fdffce43 100644
--- a/include/caosdb/connection.h
+++ b/include/caosdb/connection.h
@@ -46,41 +46,40 @@ using caosdb::info::v1alpha1::GeneralInfoService;
 using caosdb::transaction::Transaction;
 using grpc::ChannelCredentials;
 
-class CACertificateProvider {
+class CertificateificateProvider {
 public:
-  [[nodiscard]] auto virtual GetCACertPem() const -> std::string = 0;
+  [[nodiscard]] auto virtual GetCertificatePem() const -> std::string = 0;
 };
 
-class PemFileCACertProvider : public CACertificateProvider {
+class PemFileCertificateProvider : public CertificateificateProvider {
 private:
   std::string cacert;
 
 public:
-  explicit PemFileCACertProvider(const std::string &path);
-  [[nodiscard]] auto GetCACertPem() const -> std::string override;
+  explicit PemFileCertificateProvider(const std::string &path);
+  [[nodiscard]] auto GetCertificatePem() const -> std::string override;
 };
 
-class PemCACertProvider : public CACertificateProvider {
+class PemCertificateProvider : public CertificateificateProvider {
 private:
   std::string cacert;
 
 public:
-  explicit PemCACertProvider(const std::string &cacert);
-  [[nodiscard]] auto GetCACertPem() const -> std::string override;
+  explicit PemCertificateProvider(const std::string &cacert);
+  [[nodiscard]] auto GetCertificatePem() const -> std::string override;
 };
 
 /**
  * @brief Configuration of the CaosDB connection.
  */
-class CaosDBConnectionConfig {
+class ConnectionConfig {
 private:
   std::string host;
   int port;
 
 public:
-  CaosDBConnectionConfig(const std::string &host, int port);
-  friend auto operator<<(std::ostream &out,
-                         const CaosDBConnectionConfig &config)
+  ConnectionConfig(const std::string &host, int port);
+  friend auto operator<<(std::ostream &out, const ConnectionConfig &config)
     -> std::ostream &;
 
   [[nodiscard]] auto virtual ToString() const -> std::string = 0;
@@ -90,31 +89,31 @@ public:
     -> std::shared_ptr<ChannelCredentials> = 0;
 };
 
-class InsecureCaosDBConnectionConfig : public CaosDBConnectionConfig {
+class InsecureConnectionConfig : public ConnectionConfig {
 private:
   std::shared_ptr<ChannelCredentials> credentials;
 
 public:
-  InsecureCaosDBConnectionConfig(const std::string &host, int port);
+  InsecureConnectionConfig(const std::string &host, int port);
   [[nodiscard]] auto GetChannelCredentials() const
     -> std::shared_ptr<ChannelCredentials> override;
   [[nodiscard]] auto ToString() const -> std::string override;
 };
 
-class SslCaosDBConnectionConfig : public CaosDBConnectionConfig {
+class TlsConnectionConfig : public ConnectionConfig {
 private:
   std::shared_ptr<ChannelCredentials> credentials;
   std::string cacert;
 
 public:
-  SslCaosDBConnectionConfig(const std::string &host, int port);
-  SslCaosDBConnectionConfig(const std::string &host, int port,
-                            const Authenticator &authenticator);
-  SslCaosDBConnectionConfig(const std::string &host, int port,
-                            const CACertificateProvider &cacert);
-  SslCaosDBConnectionConfig(const std::string &host, int port,
-                            const CACertificateProvider &cacert,
-                            const Authenticator &authenticator);
+  TlsConnectionConfig(const std::string &host, int port);
+  TlsConnectionConfig(const std::string &host, int port,
+                      const Authenticator &authenticator);
+  TlsConnectionConfig(const std::string &host, int port,
+                      const CertificateificateProvider &cacert);
+  TlsConnectionConfig(const std::string &host, int port,
+                      const CertificateificateProvider &cacert,
+                      const Authenticator &authenticator);
   [[nodiscard]] auto GetChannelCredentials() const
     -> std::shared_ptr<ChannelCredentials> override;
   [[nodiscard]] auto ToString() const -> std::string override;
@@ -123,14 +122,14 @@ public:
 /**
  * @brief A reusable connection to a CaosDBServer.
  */
-class CaosDBConnection {
+class Connection {
   std::shared_ptr<grpc::Channel> channel;
   std::unique_ptr<GeneralInfoService::Stub> general_info_service;
   std::shared_ptr<EntityTransactionService::Stub> entity_transaction_service;
 
 public:
-  explicit CaosDBConnection(const CaosDBConnectionConfig &config);
-  friend auto operator<<(std::ostream &out, const CaosDBConnection &connection)
+  explicit Connection(const ConnectionConfig &config);
+  friend auto operator<<(std::ostream &out, const Connection &connection)
     -> std::ostream &;
   [[nodiscard]] auto GetVersionInfo() const -> std::unique_ptr<VersionInfo>;
   [[nodiscard]] auto CreateTransaction() const -> std::unique_ptr<Transaction>;
diff --git a/include/caosdb/constants.h.in b/include/caosdb/constants.h.in
index 566cbb1c87e17f03a548c1e1386dc0ddb06decd4..b13176cc30414a2f90bd38c042e2b668cbb71776 100644
--- a/include/caosdb/constants.h.in
+++ b/include/caosdb/constants.h.in
@@ -29,6 +29,10 @@ namespace caosdb {
 const int LIBCAOSDB_VERSION_MAJOR = @libcaosdb_VERSION_MAJOR@;
 const int LIBCAOSDB_VERSION_MINOR = @libcaosdb_VERSION_MINOR@;
 const int LIBCAOSDB_VERSION_PATCH = @libcaosdb_VERSION_PATCH@;
+const int COMPATIBLE_SERVER_VERSION_MAJOR = @libcaosdb_COMPATIBLE_SERVER_VERSION_MAJOR@;
+const int COMPATIBLE_SERVER_VERSION_MINOR = @libcaosdb_COMPATIBLE_SERVER_VERSION_MINOR@;
+const int COMPATIBLE_SERVER_VERSION_PATCH = @libcaosdb_COMPATIBLE_SERVER_VERSION_PATCH@;
+const char* COMPATIBLE_SERVER_VERSION_PRE_RELEASE = "@libcaosdb_COMPATIBLE_SERVER_VERSION_PRE_RELEASE@";
 // clang-format on
 #ifdef __cplusplus
 } // namespace caosdb
diff --git a/include/ccaosdb.h b/include/ccaosdb.h
index 2c32888be20b47dd17be959cdf1204425e91ae31..24f478a2b53467db0f302cfd7c5c5b27c3a4d052 100644
--- a/include/ccaosdb.h
+++ b/include/ccaosdb.h
@@ -5,22 +5,51 @@ extern "C" {
 #endif
 
 /**
- * A wrapper of the C++ CaosDBConnection class.
+ * Return the constant caosdb::LIBCAOSDB_VERSION_MAJOR.
+ */
+const int caosdb_constants_LIBCAOSDB_VERSION_MAJOR();
+/**
+ * Return the constant caosdb::LIBCAOSDB_VERSION_MINOR
+ */
+const int caosdb_constants_LIBCAOSDB_VERSION_MINOR();
+/**
+ * Return the constant caosdb::LIBCAOSDB_VERSION_PATCH.
+ */
+const int caosdb_constants_LIBCAOSDB_VERSION_PATCH();
+/**
+ * Return the constant caosdb::COMPATIBLE_SERVER_VERSION_MAJOR.
+ */
+const int caosdb_constants_COMPATIBLE_SERVER_VERSION_MAJOR();
+/**
+ * Return the constant caosdb::COMPATIBLE_SERVER_VERSION_MINOR.
+ */
+const int caosdb_constants_COMPATIBLE_SERVER_VERSION_MINOR();
+/**
+ * Return the constant caosdb::COMPATIBLE_SERVER_VERSION_PATCH.
+ */
+const int caosdb_constants_COMPATIBLE_SERVER_VERSION_PATCH();
+/**
+ * Return the constant caosdb::COMPATIBLE_SERVER_VERSION_PRE_RELEASE.
+ */
+const char *caosdb_constants_COMPATIBLE_SERVER_VERSION_PRE_RELEASE();
+
+/**
+ * A wrapper of the C++ Connection class.
  *
  * We use a wrapper for future extensibility and in order to have a minimal
  * capability for type checking in C even though the C++ class
- * CaosDBConnection is opaque in C.
+ * Connection is opaque in C.
  */
 typedef struct {
   void *wrapped_connection;
 } caosdb_connection_connection;
 
 /**
- * A wrapper of the C++ CaosDBConnectionConfig class.
+ * A wrapper of the C++ ConnectionConfig class.
  *
  * We use a wrapper for future extensibility and in order to have a minimal
  * capability for type checking in C even though the C++ class
- * CaosDBConnection is opaque in C.
+ * Connection is opaque in C.
  */
 typedef struct {
   void *wrapped_connection_configuration;
@@ -31,7 +60,7 @@ typedef struct {
  *
  * We use a wrapper for future extensibility and in order to have a minimal
  * capability for type checking in C even though the C++ class
- * CaosDBConnection is opaque in C.
+ * Connection is opaque in C.
  */
 typedef struct {
   int major;
diff --git a/src/caosdb/connection.cpp b/src/caosdb/connection.cpp
index 09a219cb394b77a2da0b85770e5ae7d5dee49807..5f271a4a711ecfa040dd5aa710f436cd33946c62 100644
--- a/src/caosdb/connection.cpp
+++ b/src/caosdb/connection.cpp
@@ -52,102 +52,99 @@ using grpc::InsecureChannelCredentials;
 using grpc::SslCredentials;
 using grpc::SslCredentialsOptions;
 
-PemFileCACertProvider::PemFileCACertProvider(const std::string &path) {
+PemFileCertificateProvider::PemFileCertificateProvider(
+  const std::string &path) {
   this->cacert = load_string_file(path);
 }
 
-auto PemFileCACertProvider::GetCACertPem() const -> std::string {
+auto PemFileCertificateProvider::GetCertificatePem() const -> std::string {
   return this->cacert;
 }
 
-PemCACertProvider::PemCACertProvider(const std::string &cacert) {
+PemCertificateProvider::PemCertificateProvider(const std::string &cacert) {
   this->cacert = cacert;
 }
 
-auto PemCACertProvider::GetCACertPem() const -> std::string {
+auto PemCertificateProvider::GetCertificatePem() const -> std::string {
   return this->cacert;
 }
 
-CaosDBConnectionConfig::CaosDBConnectionConfig(const std::string &host,
-                                               int port) {
+ConnectionConfig::ConnectionConfig(const std::string &host, int port) {
   this->host = host;
   this->port = port;
 }
 
-auto CaosDBConnectionConfig::GetHost() const -> std::string {
-  return this->host;
-}
+auto ConnectionConfig::GetHost() const -> std::string { return this->host; }
 
-auto CaosDBConnectionConfig::GetPort() const -> int { return this->port; }
+auto ConnectionConfig::GetPort() const -> int { return this->port; }
 
-auto operator<<(std::ostream &out, const CaosDBConnectionConfig &config)
+auto operator<<(std::ostream &out, const ConnectionConfig &config)
   -> std::ostream & {
   out << config.ToString();
   return out;
 }
 
-InsecureCaosDBConnectionConfig::InsecureCaosDBConnectionConfig(
-  const std::string &host, int port)
-  : CaosDBConnectionConfig(host, port) {
+InsecureConnectionConfig::InsecureConnectionConfig(const std::string &host,
+                                                   int port)
+  : ConnectionConfig(host, port) {
   this->credentials = InsecureChannelCredentials();
 }
 
-auto InsecureCaosDBConnectionConfig::GetChannelCredentials() const
+auto InsecureConnectionConfig::GetChannelCredentials() const
   -> std::shared_ptr<ChannelCredentials> {
   return this->credentials;
 }
 
-auto InsecureCaosDBConnectionConfig::ToString() const -> std::string {
-  return "InsecureCaosDBConnectionConfig(" + this->GetHost() + "," +
+auto InsecureConnectionConfig::ToString() const -> std::string {
+  return "InsecureConnectionConfig(" + this->GetHost() + "," +
          std::to_string(this->GetPort()) + ")";
 }
 
-SslCaosDBConnectionConfig::SslCaosDBConnectionConfig(const std::string &host,
-                                                     int port)
-  : CaosDBConnectionConfig(host, port) {
+TlsConnectionConfig::TlsConnectionConfig(const std::string &host, int port)
+  : ConnectionConfig(host, port) {
   SslCredentialsOptions options;
   this->credentials = SslCredentials(options);
 }
 
-SslCaosDBConnectionConfig::SslCaosDBConnectionConfig(
-  const std::string &host, int port, const CACertificateProvider &cacert)
-  : CaosDBConnectionConfig(host, port) {
+TlsConnectionConfig::TlsConnectionConfig(
+  const std::string &host, int port, const CertificateificateProvider &cacert)
+  : ConnectionConfig(host, port) {
   SslCredentialsOptions options;
-  options.pem_root_certs = cacert.GetCACertPem();
+  options.pem_root_certs = cacert.GetCertificatePem();
   this->credentials = SslCredentials(options);
 }
 
-SslCaosDBConnectionConfig::SslCaosDBConnectionConfig(
-  const std::string &host, int port, const Authenticator &authenticator)
-  : CaosDBConnectionConfig(host, port) {
+TlsConnectionConfig::TlsConnectionConfig(const std::string &host, int port,
+                                         const Authenticator &authenticator)
+  : ConnectionConfig(host, port) {
 
   SslCredentialsOptions options;
   this->credentials = grpc::CompositeChannelCredentials(
     SslCredentials(options), authenticator.GetCallCredentials());
 }
 
-SslCaosDBConnectionConfig::SslCaosDBConnectionConfig(
-  const std::string &host, int port, const CACertificateProvider &cacert,
+TlsConnectionConfig::TlsConnectionConfig(
+  const std::string &host, int port, const CertificateificateProvider &cacert,
   const Authenticator &authenticator)
-  : CaosDBConnectionConfig(host, port) {
+  : ConnectionConfig(host, port) {
 
   SslCredentialsOptions options;
-  options.pem_root_certs = cacert.GetCACertPem();
+  options.pem_root_certs = cacert.GetCertificatePem();
   this->credentials = grpc::CompositeChannelCredentials(
     SslCredentials(options), authenticator.GetCallCredentials());
 }
 
-auto SslCaosDBConnectionConfig::GetChannelCredentials() const
+auto TlsConnectionConfig::GetChannelCredentials() const
   -> std::shared_ptr<ChannelCredentials> {
   return this->credentials;
 }
 
-auto SslCaosDBConnectionConfig::ToString() const -> std::string {
-  return "SslCaosDBConnectionConfig(" + this->GetHost() + "," +
+auto TlsConnectionConfig::ToString() const -> std::string {
+  return "TlsConnectionConfig(" + this->GetHost() + "," +
          std::to_string(this->GetPort()) + "," + this->cacert + ")";
 }
 
-CaosDBConnection::CaosDBConnection(const CaosDBConnectionConfig &config) {
+Connection::Connection(const ConnectionConfig &config) {
   const std::string target =
     config.GetHost() + ":" + std::to_string(config.GetPort());
   this->channel = grpc::CreateChannel(target, config.GetChannelCredentials());
@@ -156,13 +153,13 @@ CaosDBConnection::CaosDBConnection(const CaosDBConnectionConfig &config) {
     std::make_shared<EntityTransactionService::Stub>(this->channel);
 }
 
-auto operator<<(std::ostream &out, const CaosDBConnection & /*connection*/)
+auto operator<<(std::ostream &out, const Connection & /*connection*/)
   -> std::ostream & {
-  out << "CaosDBConnection()";
+  out << "Connection()";
   return out;
 }
 
-[[nodiscard]] auto CaosDBConnection::GetVersionInfo() const
+[[nodiscard]] auto Connection::GetVersionInfo() const
   -> std::unique_ptr<VersionInfo> {
   const GetVersionInfoRequest request;
   GetVersionInfoResponse response;
@@ -185,7 +182,7 @@ auto operator<<(std::ostream &out, const CaosDBConnection & /*connection*/)
   return std::make_unique<VersionInfo>(response.release_version_info());
 }
 
-[[nodiscard]] auto CaosDBConnection::CreateTransaction() const
+[[nodiscard]] auto Connection::CreateTransaction() const
   -> std::unique_ptr<Transaction> {
   auto service_stub = this->entity_transaction_service;
   return std::make_unique<Transaction>(service_stub);
diff --git a/src/ccaosdb.cpp b/src/ccaosdb.cpp
index 4465c78654f76548d64ad6b7fa012fdfea386591..412f37358a9dc8bee72ab691c679cb8a937d60a3 100644
--- a/src/ccaosdb.cpp
+++ b/src/ccaosdb.cpp
@@ -1,5 +1,6 @@
 #include <iostream>
 #include <stdio.h>
+#include "caosdb/constants.h"
 #include "caosdb/utility.h"
 #include "caosdb/constants.h"
 #include "caosdb/connection.h"
@@ -7,6 +8,34 @@
 
 extern "C" {
 
+const int caosdb_constants_LIBCAOSDB_VERSION_MAJOR() {
+  return caosdb::LIBCAOSDB_VERSION_MAJOR;
+}
+
+const int caosdb_constants_LIBCAOSDB_VERSION_MINOR() {
+  return caosdb::LIBCAOSDB_VERSION_MINOR;
+}
+
+const int caosdb_constants_LIBCAOSDB_VERSION_PATCH() {
+  return caosdb::LIBCAOSDB_VERSION_PATCH;
+}
+
+const int caosdb_constants_COMPATIBLE_SERVER_VERSION_MAJOR() {
+  return caosdb::COMPATIBLE_SERVER_VERSION_MAJOR;
+}
+
+const int caosdb_constants_COMPATIBLE_SERVER_VERSION_MINOR() {
+  return caosdb::COMPATIBLE_SERVER_VERSION_MINOR;
+}
+
+const int caosdb_constants_COMPATIBLE_SERVER_VERSION_PATCH() {
+  return caosdb::COMPATIBLE_SERVER_VERSION_PATCH;
+}
+
+const char *caosdb_constants_COMPATIBLE_SERVER_VERSION_PRE_RELEASE() {
+  return caosdb::COMPATIBLE_SERVER_VERSION_PRE_RELEASE;
+}
+
 const char *caosdb_utility_get_env_var(const char *name,
                                        const char *fall_back) {
   return caosdb::utility::get_env_var(name, fall_back);
@@ -15,13 +44,13 @@ const char *caosdb_utility_get_env_var(const char *name,
 int caosdb_connection_create_pem_file_certificate_provider(
   caosdb_connection_certificate_provider *out, const char *path) {
   out->wrapped_certificate_provider =
-    new caosdb::connection::PemFileCACertProvider(std::string(path));
+    new caosdb::connection::PemFileCertificateProvider(std::string(path));
   return 0;
 }
 
 int caosdb_connection_delete_certificate_provider(
   caosdb_connection_certificate_provider *provider) {
-  delete static_cast<caosdb::connection::CACertificateProvider *>(
+  delete static_cast<caosdb::connection::CertificateificateProvider *>(
     provider->wrapped_certificate_provider);
   return 0;
 }
@@ -50,31 +79,31 @@ int caosdb_connection_create_tls_connection_configuration(
   auto host_str = std::string(host);
   if (authenticator != nullptr && provider != nullptr) {
     auto wrapped_provider =
-      static_cast<caosdb::connection::CACertificateProvider *>(
+      static_cast<caosdb::connection::CertificateificateProvider *>(
         provider->wrapped_certificate_provider);
     auto wrapped_authenticator =
       static_cast<caosdb::authentication::Authenticator *>(
         authenticator->wrapped_authenticator);
     out->wrapped_connection_configuration =
-      new caosdb::connection::SslCaosDBConnectionConfig(
+      new caosdb::connection::TlsConnectionConfig(
         host_str, port, *wrapped_provider, *wrapped_authenticator);
   } else if (authenticator != nullptr) {
     auto wrapped_authenticator =
       static_cast<caosdb::authentication::Authenticator *>(
         authenticator->wrapped_authenticator);
     out->wrapped_connection_configuration =
-      new caosdb::connection::SslCaosDBConnectionConfig(host_str, port,
-                                                        *wrapped_authenticator);
+      new caosdb::connection::TlsConnectionConfig(host_str, port,
+                                                  *wrapped_authenticator);
   } else if (provider != nullptr) {
     auto wrapped_provider =
-      static_cast<caosdb::connection::CACertificateProvider *>(
+      static_cast<caosdb::connection::CertificateificateProvider *>(
         provider->wrapped_certificate_provider);
     out->wrapped_connection_configuration =
-      new caosdb::connection::SslCaosDBConnectionConfig(host_str, port,
-                                                        *wrapped_provider);
+      new caosdb::connection::TlsConnectionConfig(host_str, port,
+                                                  *wrapped_provider);
   } else {
     out->wrapped_connection_configuration =
-      new caosdb::connection::SslCaosDBConnectionConfig(host_str, port);
+      new caosdb::connection::TlsConnectionConfig(host_str, port);
   }
   return 0;
 }
@@ -83,13 +112,13 @@ int caosdb_connection_create_insecure_connection_configuration(
   caosdb_connection_connection_configuration *out, const char *host,
   const int port) {
   out->wrapped_connection_configuration =
-    new caosdb::connection::InsecureCaosDBConnectionConfig(host, port);
+    new caosdb::connection::InsecureConnectionConfig(host, port);
   return 0;
 }
 
 int caosdb_connection_delete_connection_configuration(
   caosdb_connection_connection_configuration *configuration) {
-  delete static_cast<caosdb::connection::CaosDBConnectionConfig *>(
+  delete static_cast<caosdb::connection::ConnectionConfig *>(
     configuration->wrapped_connection_configuration);
   return 0;
 }
@@ -97,16 +126,16 @@ int caosdb_connection_delete_connection_configuration(
 int caosdb_connection_create_connection(
   caosdb_connection_connection *out,
   const caosdb_connection_connection_configuration *configuration) {
-  caosdb::connection::CaosDBConnectionConfig *config =
-    static_cast<caosdb::connection::CaosDBConnectionConfig *>(
+  caosdb::connection::ConnectionConfig *config =
+    static_cast<caosdb::connection::ConnectionConfig *>(
       configuration->wrapped_connection_configuration);
-  out->wrapped_connection = new caosdb::connection::CaosDBConnection(*config);
+  out->wrapped_connection = new caosdb::connection::Connection(*config);
   return 0;
 }
 
 int caosdb_connection_delete_connection(
   caosdb_connection_connection *connection) {
-  delete static_cast<caosdb::connection::CaosDBConnection *>(
+  delete static_cast<caosdb::connection::Connection *>(
     connection->wrapped_connection);
   return 0;
 }
@@ -114,9 +143,8 @@ int caosdb_connection_delete_connection(
 int caosdb_connection_get_version_info(
   caosdb_info_version_info *out,
   const caosdb_connection_connection *connection) {
-  auto *wrapped_connection =
-    static_cast<caosdb::connection::CaosDBConnection *>(
-      connection->wrapped_connection);
+  auto *wrapped_connection = static_cast<caosdb::connection::Connection *>(
+    connection->wrapped_connection);
   auto version_info = wrapped_connection->GetVersionInfo();
 
   out->major = (int)version_info->GetMajor();
diff --git a/src/cxxcaosdbcli.cpp b/src/cxxcaosdbcli.cpp
index af83b403bc49ed68c8947f57e04a27959736908d..81fd99cece84e35239b5c4a9f7cf2e8717b95d3b 100644
--- a/src/cxxcaosdbcli.cpp
+++ b/src/cxxcaosdbcli.cpp
@@ -54,10 +54,10 @@ auto main() -> int {
   // setup the connection
   auto auth =
     caosdb::authentication::PlainPasswordAuthenticator(user, password);
-  auto cacert = caosdb::connection::PemFileCACertProvider(pem_file);
+  auto cacert = caosdb::connection::PemFileCertificateProvider(pem_file);
   auto config =
-    caosdb::connection::SslCaosDBConnectionConfig(host, port, cacert, auth);
-  caosdb::connection::CaosDBConnection connection(config);
+    caosdb::connection::TlsConnectionConfig(host, port, cacert, auth);
+  caosdb::connection::Connection connection(config);
 
   // get version info of the server
   const auto &v_info = connection.GetVersionInfo();
diff --git a/test/test_connection.cpp b/test/test_connection.cpp
index eb2cea11410f5959a899ee98b8d89521a9cd7591..4ea1a7c739b4bbbeaae73aa386baa7fdbb2715cd 100644
--- a/test/test_connection.cpp
+++ b/test/test_connection.cpp
@@ -23,13 +23,13 @@
 #include <gtest/gtest-message.h>   // for Message
 #include <gtest/gtest-test-part.h> // for TestPartResult, SuiteApiRes...
 #include <memory>                  // for allocator, operator!=, shar...
-#include "caosdb/connection.h"     // for PemCACertProvider, Insecure...
+#include "caosdb/connection.h"     // for PemCertificateProvider, Insecure...
 #include "gtest/gtest_pred_impl.h" // for Test, AssertionResult, EXPE...
 
 namespace caosdb::connection {
 
 TEST(test_connection, configure_insecure_localhost_8080) {
-  InsecureCaosDBConnectionConfig config("localhost", 8000);
+  InsecureConnectionConfig config("localhost", 8000);
 
   EXPECT_EQ("localhost", config.GetHost());
   EXPECT_EQ(8000, config.GetPort());
@@ -38,8 +38,8 @@ TEST(test_connection, configure_insecure_localhost_8080) {
 }
 
 TEST(test_connection, configure_ssl_localhost_8080) {
-  auto cacert = PemCACertProvider("ca chain");
-  SslCaosDBConnectionConfig config("localhost", 44300, cacert);
+  auto cacert = PemCertificateProvider("ca chain");
+  TlsConnectionConfig config("localhost", 44300, cacert);
 
   EXPECT_EQ("localhost", config.GetHost());
   EXPECT_EQ(44300, config.GetPort());
diff --git a/test/test_transaction.cpp b/test/test_transaction.cpp
index 7570e5c557165163dc1824bec954d72f488440df..ca4ab51f860c24a744a446533f1b49943cf4b0d9 100644
--- a/test/test_transaction.cpp
+++ b/test/test_transaction.cpp
@@ -21,7 +21,7 @@
  */
 
 #include <memory>                           // for allocator, make_shared
-#include "caosdb/connection.h"              // for InsecureCaosDBConnection...
+#include "caosdb/connection.h"              // for InsecureConnection...
 #include "caosdb/entity.h"                  // for Entity
 #include "caosdb/entity/v1alpha1/main.pb.h" // for Entity
 #include "caosdb/exceptions.h"              // for ConnectionError
@@ -32,16 +32,16 @@
 #include "gtest/gtest_pred_impl.h"          // for Test, TestInfo, TEST
 
 namespace caosdb::transaction {
-using caosdb::connection::CaosDBConnection;
-using caosdb::connection::InsecureCaosDBConnectionConfig;
+using caosdb::connection::Connection;
+using caosdb::connection::InsecureConnectionConfig;
 using caosdb::exceptions::ConnectionError;
 using caosdb::transaction::UniqueResult;
 using ProtoEntity = caosdb::entity::v1alpha1::Entity;
 
 TEST(test_transaction, create_transaction) {
   const auto *host = "localhost";
-  auto config = InsecureCaosDBConnectionConfig(host, 8000);
-  CaosDBConnection connection(config);
+  auto config = InsecureConnectionConfig(host, 8000);
+  Connection connection(config);
   auto transaction = connection.CreateTransaction();
 
   transaction->RetrieveById("100");