diff --git a/dbsim/db_client.cpp b/dbsim/db_client.cpp
index d0436b8..c0ab683 100644
--- a/dbsim/db_client.cpp
+++ b/dbsim/db_client.cpp
@@ -16,8 +16,8 @@ db::client::client(db::server& server,
     , params_(params)
     , server_(server)
     , server_state_(server.server_state())
-    , client_state_(mutex_, cond_, this, server_state_, client_service_, client_id, mode)
-    , client_service_(client_state_)
+    , client_state_(mutex_, cond_, server_state_, client_service_, client_id, mode)
+    , client_service_(*this)
     , se_trx_(server.storage_engine())
     , stats_()
 { }
@@ -114,7 +114,7 @@ void db::client::run_one_transaction()
         {
             // wsrep::log_debug() << "Commit";
             assert(err == 0);
-            if (client_state_.do_2pc())
+            if (do_2pc())
             {
                 err = err || client_state_.before_prepare();
                 err = err || client_state_.after_prepare();
diff --git a/dbsim/db_client.hpp b/dbsim/db_client.hpp
index 2057d9c..6046af4 100644
--- a/dbsim/db_client.hpp
+++ b/dbsim/db_client.hpp
@@ -44,6 +44,7 @@ namespace db
         { }
         void start();
         wsrep::client_state& client_state() { return client_state_; }
+        bool do_2pc() const { return false; }
     private:
         friend class db::server_state;
         friend class db::client_service;
diff --git a/dbsim/db_client_service.cpp b/dbsim/db_client_service.cpp
index 965a372..b3289a8 100644
--- a/dbsim/db_client_service.cpp
+++ b/dbsim/db_client_service.cpp
@@ -6,24 +6,22 @@
 #include "db_high_priority_service.hpp"
 #include "db_client.hpp"
 
+db::client_service::client_service(db::client& client)
+    : wsrep::client_service()
+    , client_(client)
+    , client_state_(client_.client_state())
+{ }
 
-int db::client_service::commit(const wsrep::ws_handle&,
-                               const wsrep::ws_meta&)
+bool db::client_service::do_2pc() const
 {
-    db::client* client(client_state_.client());
-    int ret(client_state_.before_commit());
-    if (ret == 0) client->se_trx_.commit();
-    ret = ret || client_state_.ordered_commit();
-    ret = ret || client_state_.after_commit();
-    return ret;
+    return client_.do_2pc();
 }
 
 int db::client_service::bf_rollback()
 {
-    db::client* client(client_state_.client());
     int ret(client_state_.before_rollback());
     assert(ret == 0);
-    client->se_trx_.rollback();
+    client_.se_trx_.rollback();
     ret = client_state_.after_rollback();
     assert(ret == 0);
     return ret;
@@ -34,13 +32,13 @@ db::client_service::replay()
 {
     wsrep::high_priority_context high_priority_context(client_state_);
     db::high_priority_service high_priority_service(
-        client_state_.client()->server_, client_state_.client());
+        client_.server_, client_);
     auto ret(client_state_.provider().replay(
                  client_state_.transaction().ws_handle(),
                  &high_priority_service));
     if (ret == wsrep::provider::success)
     {
-        ++client_state_.client()->stats_.replays;
+        ++client_.stats_.replays;
     }
     return ret;
 }
diff --git a/dbsim/db_client_service.hpp b/dbsim/db_client_service.hpp
index d0b3cfa..59e6f2d 100644
--- a/dbsim/db_client_service.hpp
+++ b/dbsim/db_client_service.hpp
@@ -8,37 +8,26 @@
 #include "wsrep/client_service.hpp"
 #include "wsrep/transaction.hpp"
 
-#include "db_client_state.hpp"
-
 namespace db
 {
+    class client;
+    class client_state;
+
     class client_service : public wsrep::client_service
     {
     public:
-        client_service(db::client_state& client_state)
-            : wsrep::client_service()
-            , client_state_(client_state)
-        { }
+        client_service(db::client& client);
 
-        bool do_2pc() const override
-        {
-            return client_state_.do_2pc();
-        }
+        bool do_2pc() const override;
 
         bool interrupted() const override
         {
             return false;
         }
 
-        void reset_globals() override
-        {
-            client_state_.reset_globals();
-        }
+        void reset_globals() override { }
 
-        void store_globals() override
-        {
-            client_state_.store_globals();
-        }
+        void store_globals() override { }
 
         int prepare_data_for_replication() override
         {
@@ -56,6 +45,7 @@ namespace db
         {
             return true;
         }
+
         int prepare_fragment_for_replication(wsrep::mutable_buffer&) override
         {
             return 0;
@@ -64,12 +54,6 @@ namespace db
         void remove_fragments() override
         { }
 
-        // int apply_write_set(const wsrep::const_buffer&) override;
-
-        // int apply_toi(const wsrep::const_buffer&) override;
-
-        int commit(const wsrep::ws_handle&, const wsrep::ws_meta&) override;
-
         int bf_rollback() override;
 
         void will_replay() override
@@ -79,17 +63,12 @@ namespace db
         enum wsrep::provider::status replay()
             override;
 
-        int append_fragment(const wsrep::transaction&, int,
-                            const wsrep::const_buffer&) override
-        {
-            return 0;
-        }
-
         void emergency_shutdown() { ::abort(); }
         void debug_sync(const char*) override { }
         void debug_crash(const char*) override { }
     private:
-        db::client_state& client_state_;
+        db::client& client_;
+        wsrep::client_state& client_state_;
     };
 }
 
diff --git a/dbsim/db_client_state.hpp b/dbsim/db_client_state.hpp
index cb4a180..8d9a91f 100644
--- a/dbsim/db_client_state.hpp
+++ b/dbsim/db_client_state.hpp
@@ -16,7 +16,6 @@ namespace db
     public:
         client_state(wsrep::mutex& mutex,
                      wsrep::condition_variable& cond,
-                     db::client* client,
                      db::server_state& server_state,
                      wsrep::client_service& client_service,
                      const wsrep::client_id& client_id,
@@ -27,22 +26,11 @@ namespace db
                                   client_service,
                                   client_id,
                                   mode)
-            , client_(client)
-            , is_autocommit_(false)
-            , do_2pc_(false)
         { }
-        db::client* client() { return client_; }
-        void reset_globals() { }
-        void store_globals() { wsrep::client_state::store_globals(); }
-        bool is_autocommit() const { return is_autocommit_; }
-        bool do_2pc() const { return do_2pc_; }
 
     private:
         client_state(const client_state&);
         client_state& operator=(const client_state&);
-        db::client* client_;
-        bool is_autocommit_;
-        bool do_2pc_;
     };
 }
 
diff --git a/dbsim/db_high_priority_service.cpp b/dbsim/db_high_priority_service.cpp
index 5861526..7ed59dc 100644
--- a/dbsim/db_high_priority_service.cpp
+++ b/dbsim/db_high_priority_service.cpp
@@ -7,7 +7,7 @@
 #include "db_client.hpp"
 
 db::high_priority_service::high_priority_service(
-    db::server& server, db::client* client)
+    db::server& server, db::client& client)
     : wsrep::high_priority_service(server_.server_state())
     , server_(server)
     , client_(client)
@@ -17,7 +17,7 @@ int db::high_priority_service::start_transaction(
     const wsrep::ws_handle& ws_handle,
     const wsrep::ws_meta& ws_meta)
 {
-    return client_->client_state().start_transaction(ws_handle, ws_meta);
+    return client_.client_state().start_transaction(ws_handle, ws_meta);
 }
 
 void db::high_priority_service::adopt_transaction(const wsrep::transaction&)
@@ -27,8 +27,8 @@ void db::high_priority_service::adopt_transaction(const wsrep::transaction&)
 
 int db::high_priority_service::apply_write_set(const wsrep::const_buffer&)
 {
-    client_->se_trx_.start(client_);
-    client_->se_trx_.apply(client_->client_state().transaction());
+    client_.se_trx_.start(&client_);
+    client_.se_trx_.apply(client_.client_state().transaction());
     return 0;
 }
 
@@ -41,29 +41,29 @@ int db::high_priority_service::apply_toi(
 
 int db::high_priority_service::commit()
 {
-    int ret(client_->client_state_.before_commit());
-    if (ret == 0) client_->se_trx_.commit();
-    ret = ret || client_->client_state_.ordered_commit();
-    ret = ret || client_->client_state_.after_commit();
+    int ret(client_.client_state_.before_commit());
+    if (ret == 0) client_.se_trx_.commit();
+    ret = ret || client_.client_state_.ordered_commit();
+    ret = ret || client_.client_state_.after_commit();
     return ret;
 }
 
 int db::high_priority_service::rollback()
 {
-    int ret(client_->client_state_.before_rollback());
+    int ret(client_.client_state_.before_rollback());
     assert(ret == 0);
-    client_->se_trx_.rollback();
-    ret = client_->client_state_.after_rollback();
+    client_.se_trx_.rollback();
+    ret = client_.client_state_.after_rollback();
     assert(ret == 0);
     return ret;
 }
 
 void db::high_priority_service::after_apply()
 {
-    client_->client_state_.after_statement();
+    client_.client_state_.after_statement();
 }
 
 bool db::high_priority_service::is_replaying() const
 {
-    return (client_->client_state_.transaction().state() == wsrep::transaction::s_replaying);
+    return (client_.client_state_.transaction().state() == wsrep::transaction::s_replaying);
 }
diff --git a/dbsim/db_high_priority_service.hpp b/dbsim/db_high_priority_service.hpp
index d18653a..02eefd3 100644
--- a/dbsim/db_high_priority_service.hpp
+++ b/dbsim/db_high_priority_service.hpp
@@ -14,11 +14,14 @@ namespace db
     class high_priority_service : public wsrep::high_priority_service
     {
     public:
-        high_priority_service(db::server& server, db::client* client);
+        high_priority_service(db::server& server, db::client& client);
         int start_transaction(const wsrep::ws_handle&,
                               const wsrep::ws_meta&) override;
         void adopt_transaction(const wsrep::transaction&) override;
         int apply_write_set(const wsrep::const_buffer&) override;
+        int append_fragment(const wsrep::ws_meta&, const wsrep::const_buffer&)
+            override
+        { return 0; }
         int commit() override;
         int rollback() override;
         int apply_toi(const wsrep::ws_meta&, const wsrep::const_buffer&) override;
@@ -33,7 +36,7 @@ namespace db
         high_priority_service(const high_priority_service&);
         high_priority_service& operator=(const high_priority_service&);
         db::server& server_;
-        db::client* client_;
+        db::client& client_;
     };
 }
 
diff --git a/dbsim/db_server.cpp b/dbsim/db_server.cpp
index 15c677c..1bc212f 100644
--- a/dbsim/db_server.cpp
+++ b/dbsim/db_server.cpp
@@ -36,7 +36,7 @@ void db::server::applier_thread()
                        simulator_.params());
     wsrep::client_state* cc(static_cast<wsrep::client_state*>(
                                 &applier.client_state()));
-    db::high_priority_service hps(*this, &applier);
+    db::high_priority_service hps(*this, applier);
     cc->open(cc->id());
     cc->before_command();
     enum wsrep::provider::status ret(
@@ -110,21 +110,6 @@ void db::server::donate_sst(const std::string& req,
     simulator_.sst(*this, req, gtid, bypass);
 }
 
-wsrep::client_state* db::server::local_client_state()
-{
-    std::ostringstream id_os;
-    size_t client_id(++last_client_id_);
-    db::client* client(new db::client(*this, client_id,
-                                      wsrep::client_state::m_local,
-                                      simulator_.params()));
-    return &client->client_state();
-}
-void db::server::release_client_state(wsrep::client_state* client_state)
-{
-    db::client_state* db_client_state(
-        dynamic_cast<db::client_state*>(client_state));
-    delete db_client_state->client();
-}
 
 wsrep::high_priority_service* db::server::streaming_applier_service()
 {
diff --git a/dbsim/db_server_service.cpp b/dbsim/db_server_service.cpp
index 605fcab..bf53d65 100644
--- a/dbsim/db_server_service.cpp
+++ b/dbsim/db_server_service.cpp
@@ -4,6 +4,7 @@
 
 #include "db_server_service.hpp"
 #include "db_server.hpp"
+#include "db_storage_service.hpp"
 
 #include "wsrep/logger.hpp"
 #include "wsrep/high_priority_service.hpp"
@@ -12,15 +13,16 @@ db::server_service::server_service(db::server& server)
     : server_(server)
 { }
 
-wsrep::client_state* db::server_service::local_client_state()
+wsrep::storage_service* db::server_service::storage_service(
+    wsrep::client_service&)
 {
-    return server_.local_client_state();
+    return new db::storage_service();
 }
 
-void db::server_service::release_client_state(
-    wsrep::client_state* client_state)
+void db::server_service::release_storage_service(
+    wsrep::storage_service* storage_service)
 {
-    server_.release_client_state(client_state);
+    delete storage_service;
 }
 
 wsrep::high_priority_service* db::server_service::streaming_applier_service()
@@ -41,7 +43,12 @@ bool db::server_service::sst_before_init() const
 
 std::string db::server_service::sst_request()
 {
-    return server_.server_state().id();
+    std::ostringstream os;
+    os << server_.server_state().id();
+    wsrep::log_info() << "SST request: "
+                      << server_.server_state().id();
+
+    return os.str();
 }
 
 int db::server_service::start_sst(
diff --git a/dbsim/db_server_service.hpp b/dbsim/db_server_service.hpp
index c34fe4b..77590cc 100644
--- a/dbsim/db_server_service.hpp
+++ b/dbsim/db_server_service.hpp
@@ -15,8 +15,8 @@ namespace db
     {
     public:
         server_service(db::server& server);
-        wsrep::client_state* local_client_state() override;
-        void release_client_state(wsrep::client_state*) override;
+        wsrep::storage_service* storage_service(wsrep::client_service&) override;
+        void release_storage_service(wsrep::storage_service*) override;
         wsrep::high_priority_service* streaming_applier_service() override;
         void release_high_priority_service(wsrep::high_priority_service*) override;
 
diff --git a/dbsim/db_simulator.cpp b/dbsim/db_simulator.cpp
index 4b67095..d9b5089 100644
--- a/dbsim/db_simulator.cpp
+++ b/dbsim/db_simulator.cpp
@@ -23,11 +23,12 @@ void db::simulator::sst(db::server& server,
                         const wsrep::gtid& gtid,
                         bool bypass)
 {
-    size_t id;
+    wsrep::id id;
     std::istringstream is(request);
     is >> id;
     wsrep::unique_lock<wsrep::mutex> lock(mutex_);
     auto i(servers_.find(id));
+    wsrep::log_info() << "SST request";
     if (i == servers_.end())
     {
         throw wsrep::runtime_error("Server " + request + " not found");
@@ -86,9 +87,10 @@ void db::simulator::start()
         id_os << (i + 1);
         std::ostringstream address_os;
         address_os << "127.0.0.1:" << server_port(i);
+        wsrep::id server_id(id_os.str());
         auto it(servers_.insert(
                     std::make_pair(
-                        (i + 1),
+                        server_id,
                         std::make_unique<db::server>(
                             *this,
                             name_os.str(),
diff --git a/dbsim/db_simulator.hpp b/dbsim/db_simulator.hpp
index d386354..b8f9ba6 100644
--- a/dbsim/db_simulator.hpp
+++ b/dbsim/db_simulator.hpp
@@ -46,7 +46,7 @@ namespace db
 
         wsrep::default_mutex mutex_;
         const db::params& params_;
-        std::map<size_t, std::unique_ptr<db::server>> servers_;
+        std::map<wsrep::id, std::unique_ptr<db::server>> servers_;
         std::chrono::time_point<std::chrono::steady_clock> clients_start_;
         std::chrono::time_point<std::chrono::steady_clock> clients_stop_;
     public:
diff --git a/dbsim/db_storage_service.hpp b/dbsim/db_storage_service.hpp
new file mode 100644
index 0000000..8974f9e
--- /dev/null
+++ b/dbsim/db_storage_service.hpp
@@ -0,0 +1,33 @@
+//
+// Copyright (C) 2018 Codership Oy <info@codership.com>
+//
+
+#ifndef WSREP_DB_STORAGE_SERVICE_HPP
+#define WSREP_DB_STORAGE_SERVICE_HPP
+
+#include "wsrep/storage_service.hpp"
+#include "wsrep/exception.hpp"
+
+namespace db
+{
+    class storage_service : public wsrep::storage_service
+    {
+        int start_transaction() override
+        { throw wsrep::not_implemented_error(); }
+        int append_fragment(const wsrep::id&, wsrep::client_id,
+                            int,
+                            const wsrep::const_buffer&) override
+        { throw wsrep::not_implemented_error(); }
+        int update_fragment_meta(const wsrep::ws_meta&) override
+        { throw wsrep::not_implemented_error(); }
+        int commit(const wsrep::ws_handle&, const wsrep::ws_meta&) override
+        { throw wsrep::not_implemented_error(); }
+        int rollback(const wsrep::ws_handle&, const wsrep::ws_meta&)
+            override
+        { throw wsrep::not_implemented_error(); }
+        void store_globals() override { }
+        void reset_globals() override { }
+    };
+}
+
+#endif // WSREP_DB_STORAGE_SERVICE_HPP
diff --git a/include/wsrep/client_service.hpp b/include/wsrep/client_service.hpp
index 8a3878b..a463977 100644
--- a/include/wsrep/client_service.hpp
+++ b/include/wsrep/client_service.hpp
@@ -69,9 +69,13 @@ namespace wsrep
         virtual bool statement_allowed_for_streaming() const = 0;
         virtual size_t bytes_generated() const = 0;
         virtual int prepare_fragment_for_replication(wsrep::mutable_buffer&) = 0;
+        /**
+         * Remove fragments from the storage within current transaction.
+         * Fragment removal will be committed once the current transaction
+         * commits.
+         */
         virtual void remove_fragments() = 0;
 
-        virtual int commit(const wsrep::ws_handle&, const wsrep::ws_meta&) = 0;
         //
         // Rollback
         //
@@ -128,12 +132,6 @@ namespace wsrep
          */
         virtual void wait_for_replayers(wsrep::unique_lock<wsrep::mutex>&) = 0;
 
-        // Streaming replication
-        /**
-         * Append a write set fragment into fragment storage.
-         */
-        virtual int append_fragment(const wsrep::transaction&, int flag, const wsrep::const_buffer&) = 0;
-
         //
         // Debug interface
         //
diff --git a/include/wsrep/client_state.hpp b/include/wsrep/client_state.hpp
index 0792770..916ce19 100644
--- a/include/wsrep/client_state.hpp
+++ b/include/wsrep/client_state.hpp
@@ -306,6 +306,23 @@ namespace wsrep
             enum wsrep::streaming_context::fragment_unit
             fragment_unit,
             size_t fragment_size);
+
+        /**
+         * Prepare write set meta data for fragment storage ordering.
+         * This method should be called from storage service commit
+         * or rollback before performing the operation.
+         */
+        int prepare_for_fragment_ordering(const wsrep::ws_handle& ws_handle,
+                                          const wsrep::ws_meta& ws_meta,
+                                          bool is_commit)
+        {
+            assert(mode_ == m_high_priority);
+            assert(state_ == s_exec);
+            return transaction_.prepare_for_fragment_ordering(
+                ws_handle, ws_meta, is_commit);
+        }
+        /** @} */
+
         /** @name Applying interface */
         /** @{ */
         int start_transaction(const wsrep::ws_handle& wsh,
@@ -734,26 +751,6 @@ namespace wsrep
         return to_c_string(mode);
     }
 
-    class client_state_switch
-    {
-    public:
-        client_state_switch(wsrep::client_state& orig_context,
-                              wsrep::client_state& current_context)
-            : orig_context_(orig_context)
-            , current_context_(current_context)
-        {
-            current_context_.client_service_.store_globals();
-        }
-        ~client_state_switch()
-        {
-            orig_context_.client_service_.store_globals();
-        }
-    private:
-        client_state& orig_context_;
-        client_state& current_context_;
-    };
-
-
     /**
      * Utility class to switch the client state to high priority
      * mode. The client is switched back to the original mode
@@ -804,44 +801,6 @@ namespace wsrep
         enum wsrep::client_state::mode orig_mode_;
     };
 
-    class client_deleter
-    {
-    public:
-        client_deleter(wsrep::server_service& server_service)
-            : server_service_(server_service)
-        { }
-        void operator()(wsrep::client_state* client_state)
-        {
-            server_service_.release_client_state(client_state);
-        }
-    private:
-        wsrep::server_service& server_service_;
-    };
-
-    template <class D>
-    class scoped_client_state
-    {
-    public:
-        scoped_client_state(wsrep::client_state* client_state, D deleter)
-            : client_state_(client_state)
-            , deleter_(deleter)
-        {
-            if (client_state_ == 0)
-            {
-                throw wsrep::runtime_error("Null client_state provided");
-            }
-        }
-        wsrep::client_state& client_state() { return *client_state_; }
-        ~scoped_client_state()
-        {
-            deleter_(client_state_);
-        }
-    private:
-        scoped_client_state(const scoped_client_state&);
-        scoped_client_state& operator=(const scoped_client_state&);
-        wsrep::client_state* client_state_;
-        D deleter_;
-    };
 }
 
 #endif // WSREP_CLIENT_STATE_HPP
diff --git a/include/wsrep/high_priority_service.hpp b/include/wsrep/high_priority_service.hpp
index 3af7dba..e702544 100644
--- a/include/wsrep/high_priority_service.hpp
+++ b/include/wsrep/high_priority_service.hpp
@@ -40,6 +40,7 @@ namespace wsrep
          * Adopt a transaction.
          */
         virtual void adopt_transaction(const wsrep::transaction&) = 0;
+
         /**
          * Apply a write set.
          *
@@ -50,6 +51,11 @@ namespace wsrep
          */
         virtual int apply_write_set(const wsrep::const_buffer&) = 0;
 
+        /**
+         *
+         */
+        virtual int append_fragment(const wsrep::ws_meta&,
+                                    const wsrep::const_buffer& data) = 0;
         /**
          * Commit a transaction.
          */
diff --git a/include/wsrep/id.hpp b/include/wsrep/id.hpp
index 25a35fe..91b1f5c 100644
--- a/include/wsrep/id.hpp
+++ b/include/wsrep/id.hpp
@@ -83,6 +83,7 @@ namespace wsrep
     };
 
     std::ostream& operator<<(std::ostream&, const wsrep::id& id);
+    std::istream& operator>>(std::istream&, wsrep::id& id);
 }
 
 #endif // WSREP_ID_HPP
diff --git a/include/wsrep/server_service.hpp b/include/wsrep/server_service.hpp
index 155ff45..81a13f1 100644
--- a/include/wsrep/server_service.hpp
+++ b/include/wsrep/server_service.hpp
@@ -20,7 +20,8 @@
 
 namespace wsrep
 {
-    class client_state;
+    class client_service;
+    class storage_service;
     class high_priority_service;
     class ws_meta;
     class gtid;
@@ -28,17 +29,11 @@ namespace wsrep
     class server_service
     {
     public:
-        /**
-         * Create client state instance which acts only locally, i.e. does
-         * not participate in replication. However, local client
-         * state may execute transactions which require ordering,
-         * as when modifying local SR fragment storage requires
-         * strict commit ordering.
-         *
-         * @return Pointer to Client State.
-         */
-        virtual wsrep::client_state* local_client_state() = 0;
-        virtual void release_client_state(wsrep::client_state*) = 0;
+
+        virtual wsrep::storage_service* storage_service(
+            wsrep::client_service&) = 0;
+
+        virtual void release_storage_service(wsrep::storage_service*) = 0;
         /**
          * Create an applier state for streaming transaction applying.
          *
diff --git a/include/wsrep/server_state.hpp b/include/wsrep/server_state.hpp
index 26be715..6d7277c 100644
--- a/include/wsrep/server_state.hpp
+++ b/include/wsrep/server_state.hpp
@@ -87,6 +87,7 @@ namespace wsrep
     class transaction;
     class const_buffer;
     class server_service;
+
     /** @class Server Context
      *
      *
@@ -172,11 +173,11 @@ namespace wsrep
         const std::string& name() const { return name_; }
 
         /**
-         * Return Server identifier string.
+         * Return Server identifier.
          *
-         * @return Server indetifier string.
+         * @return Server identifier.
          */
-        const std::string& id() const { return id_; }
+        const wsrep::id& id() const { return id_; }
 
         const std::string& incoming_address() const
         { return incoming_address_; }
@@ -575,7 +576,7 @@ namespace wsrep
         streaming_appliers_map streaming_appliers_;
         wsrep::provider* provider_;
         std::string name_;
-        std::string id_;
+        wsrep::id id_;
         std::string incoming_address_;
         std::string address_;
         std::string working_dir_;
diff --git a/include/wsrep/storage_service.hpp b/include/wsrep/storage_service.hpp
new file mode 100644
index 0000000..43d20df
--- /dev/null
+++ b/include/wsrep/storage_service.hpp
@@ -0,0 +1,75 @@
+//
+// Copyright (C) 2018 Codership Oy <info@codership.com>
+//
+
+/** @file storage_service.hpp
+ *
+ * Abstract interface which defines required access to DBMS storage
+ * service. The service is used for storing streaming replication
+ * write set fragments into stable storage. The interface is used
+ * from locally processing transaction context only. Corresponding
+ * operations for high priority processing can be found from
+ * wsrep::high_priority_service interface.
+ */
+#ifndef WSREP_STORAGE_SERVICE_HPP
+#define WSREP_STORAGE_SERVICE_HPP
+
+#include "client_id.hpp"
+#include "id.hpp"
+#include "buffer.hpp"
+
+namespace wsrep
+{
+    // Forward declarations
+    class ws_handle;
+    class ws_meta;
+
+
+    /**
+     * Storage service abstract interface.
+     */
+    class storage_service
+    {
+    public:
+        virtual ~storage_service() { }
+        /**
+         * Start a new transaction for storage access.
+         *
+         * @param ws_hande Write set handle
+         * @param ws_meta Write set meta data
+         *
+         * @return Zero in case of success, non-zero on error.
+         */
+        virtual int start_transaction() = 0;
+
+        /**
+         * Append fragment into stable storage.
+         */
+        virtual int append_fragment(const wsrep::id& server_id,
+                                    wsrep::client_id client_id,
+                                    int flags,
+                                    const wsrep::const_buffer& data) = 0;
+
+        /**
+         * Update fragment meta data after certification process.
+         */
+        virtual int update_fragment_meta(const wsrep::ws_meta&) = 0;
+
+        /**
+         * Commit the transaction.
+         */
+        virtual int commit(const wsrep::ws_handle&, const wsrep::ws_meta&) = 0;
+
+        /**
+         * Roll back the transaction.
+         */
+        virtual int rollback(const wsrep::ws_handle&,
+                             const wsrep::ws_meta&) = 0;
+
+
+        virtual void store_globals() = 0;
+        virtual void reset_globals() = 0;
+    };
+}
+
+#endif // WSREP_STORAGE_SERVICE_HPP
diff --git a/include/wsrep/transaction.hpp b/include/wsrep/transaction.hpp
index 59bd203..8eaeca5 100644
--- a/include/wsrep/transaction.hpp
+++ b/include/wsrep/transaction.hpp
@@ -87,6 +87,10 @@ namespace wsrep
         int start_transaction(const wsrep::ws_handle& ws_handle,
                               const wsrep::ws_meta& ws_meta);
 
+        int prepare_for_fragment_ordering(const wsrep::ws_handle& ws_handle,
+                                          const wsrep::ws_meta& ws_meta,
+                                          bool is_commit);
+
         int start_replaying(const wsrep::ws_meta&);
 
         int append_key(const wsrep::key&);
diff --git a/src/id.cpp b/src/id.cpp
index 3ff5c7e..64b0aab 100644
--- a/src/id.cpp
+++ b/src/id.cpp
@@ -52,3 +52,11 @@ std::ostream& wsrep::operator<<(std::ostream& os, const wsrep::id& id)
         return (os << uuid_str);
     }
 }
+
+std::istream& wsrep::operator>>(std::istream& is, wsrep::id& id)
+{
+    std::string id_str;
+    std::getline(is, id_str);
+    id = wsrep::id(id_str);
+    return is;
+}
diff --git a/src/server_state.cpp b/src/server_state.cpp
index 625fe0f..9b0efc0 100644
--- a/src/server_state.cpp
+++ b/src/server_state.cpp
@@ -576,6 +576,10 @@ void wsrep::server_state::on_sync()
         case s_joiner:
             state(lock, s_initializing);
             break;
+        case s_donor:
+            state(lock, s_joined);
+            state(lock, s_synced);
+            break;
         case s_initialized:
             state(lock, s_joined);
             // fall through
diff --git a/src/transaction.cpp b/src/transaction.cpp
index 7e1d341..6ae493d 100644
--- a/src/transaction.cpp
+++ b/src/transaction.cpp
@@ -5,6 +5,7 @@
 #include "wsrep/transaction.hpp"
 #include "wsrep/client_state.hpp"
 #include "wsrep/server_state.hpp"
+#include "wsrep/storage_service.hpp"
 #include "wsrep/high_priority_service.hpp"
 #include "wsrep/key.hpp"
 #include "wsrep/logger.hpp"
@@ -20,6 +21,65 @@
         else wsrep::log_debug() << msg;                 \
     } while (0)
 
+
+namespace
+{
+    class storage_service_deleter
+    {
+    public:
+        storage_service_deleter(wsrep::server_service& server_service)
+            : server_service_(server_service)
+        { }
+        void operator()(wsrep::storage_service* storage_service)
+        {
+            server_service_.release_storage_service(storage_service);
+        }
+    private:
+        wsrep::server_service& server_service_;
+    };
+
+    template <class D>
+    class scoped_storage_service
+    {
+    public:
+        scoped_storage_service(wsrep::client_service& client_service,
+                               wsrep::storage_service* storage_service,
+                               D deleter)
+            : client_service_(client_service)
+            , storage_service_(storage_service)
+            , deleter_(deleter)
+        {
+            if (storage_service_ == 0)
+            {
+                throw wsrep::runtime_error("Null client_state provided");
+            }
+            client_service_.reset_globals();
+            storage_service_->store_globals();
+        }
+
+        wsrep::storage_service& storage_service()
+        {
+            return *storage_service_;
+        }
+
+        ~scoped_storage_service()
+        {
+            storage_service_->reset_globals();
+            client_service_.store_globals();
+            deleter_(storage_service_);
+        }
+    private:
+        scoped_storage_service(const scoped_storage_service&);
+        scoped_storage_service& operator=(const scoped_storage_service&);
+        wsrep::client_service& client_service_;
+        wsrep::storage_service* storage_service_;
+        D deleter_;
+    };
+
+
+
+}
+
 // Public
 
 wsrep::transaction::transaction(
@@ -94,6 +154,20 @@ int wsrep::transaction::start_transaction(
     return 0;
 }
 
+int wsrep::transaction::prepare_for_fragment_ordering(
+    const wsrep::ws_handle& ws_handle,
+    const wsrep::ws_meta& ws_meta,
+    bool is_commit)
+{
+    assert(active());
+
+    ws_handle_ = ws_handle;
+    ws_meta_ = ws_meta;
+    certified_ = is_commit;
+
+    return 0;
+}
+
 int wsrep::transaction::start_replaying(const wsrep::ws_meta& ws_meta)
 {
     ws_meta_ = ws_meta;
@@ -745,25 +819,32 @@ int wsrep::transaction::certify_fragment(
         return 1;
     }
 
-    // Client context to store fragment in separate transaction
-    // Switch temporarily to sr_transaction, switch back
-    // to original when this goes out of scope
-    wsrep::scoped_client_state<wsrep::client_deleter> sr_client_state_scope(
-        server_service_.local_client_state(),
-        wsrep::client_deleter(server_service_));
-    wsrep::client_state& sr_client_state(
-        sr_client_state_scope.client_state());
-    wsrep::client_state_switch client_state_switch(
-        client_state_,
-        sr_client_state);
+    // The rest of this method will be executed in storage service
+    // scope.
+    scoped_storage_service<storage_service_deleter>
+        sr_scope(
+            client_service_,
+            server_service_.storage_service(client_service_),
+            storage_service_deleter(server_service_));
+    wsrep::storage_service& storage_service(
+        sr_scope.storage_service());
 
-    wsrep::unique_lock<wsrep::mutex> sr_lock(sr_client_state.mutex());
-    wsrep::transaction& sr_transaction(
-        sr_client_state.transaction_);
-    sr_transaction.state(sr_lock, s_certifying);
-    sr_lock.unlock();
-    if (sr_client_state.client_service().append_fragment(
-            sr_transaction, flags_,
+    // First the fragment is appended to the stable storage.
+    // This is done to ensure that there is enough capacity
+    // available to store the fragment. The fragment meta data
+    // is updated after certification.
+    if (storage_service.start_transaction())
+    {
+        lock.lock();
+        state(lock, s_must_abort);
+        client_state_.override_error(wsrep::e_append_fragment_error);
+        return 1;
+    }
+
+    if (storage_service.append_fragment(
+            client_state_.server_state().id(),
+            client_state_.id(),
+            flags_,
             wsrep::const_buffer(data.data(), data.size())))
     {
         lock.lock();
@@ -774,30 +855,22 @@ int wsrep::transaction::certify_fragment(
 
     enum wsrep::provider::status
         cert_ret(provider().certify(client_state_.id().get(),
-                                   sr_transaction.ws_handle_,
-                                   flags_,
-                                   sr_transaction.ws_meta_));
+                                    ws_handle_,
+                                    flags_,
+                                    ws_meta_));
 
     int ret(0);
     switch (cert_ret)
     {
     case wsrep::provider::success:
-        streaming_context_.certified(sr_transaction.ws_meta().seqno());
-        sr_lock.lock();
-        sr_transaction.certified_ = true;
-        sr_transaction.state(sr_lock, s_committing);
-        sr_lock.unlock();
-        if (sr_client_state.client_service().commit(
-                sr_transaction.ws_handle(), sr_transaction.ws_meta()))
+        streaming_context_.certified(ws_meta_.seqno());
+        if (storage_service.commit(ws_handle_, ws_meta_))
         {
             ret = 1;
         }
         break;
     default:
-        sr_lock.lock();
-        sr_transaction.state(sr_lock, s_must_abort);
-        sr_lock.unlock();
-        sr_client_state.client_service().bf_rollback();
+        storage_service.rollback(ws_handle_, ws_meta_);
         ret = 1;
         break;
     }
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index d34d19f..9b8d83b 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -3,8 +3,9 @@
 #
 
 add_executable(wsrep-lib_test
-  mock_high_priority_service.cpp
   mock_client_state.cpp
+  mock_high_priority_service.cpp
+  mock_storage_service.cpp
   test_utils.cpp
   id_test.cpp
   server_context_test.cpp
diff --git a/test/mock_client_state.cpp b/test/mock_client_state.cpp
index 58016a2..a3a61f2 100644
--- a/test/mock_client_state.cpp
+++ b/test/mock_client_state.cpp
@@ -6,31 +6,6 @@
 #include "mock_client_state.hpp"
 #include "mock_high_priority_service.hpp"
 
-int wsrep::mock_client_service::commit(
-    const wsrep::ws_handle&, const wsrep::ws_meta&)
-{
-    int ret(0);
-    if (do_2pc())
-    {
-        if (client_state_.before_prepare())
-        {
-            ret = 1;
-        }
-        else if (client_state_.after_prepare())
-        {
-            ret = 1;
-        }
-    }
-    if (ret == 0 &&
-        (client_state_.before_commit() ||
-         client_state_.ordered_commit() ||
-         client_state_.after_commit()))
-    {
-        ret = 1;
-    }
-    return ret;
-}
-
 int wsrep::mock_client_service::bf_rollback()
 {
     int ret(0);
diff --git a/test/mock_client_state.hpp b/test/mock_client_state.hpp
index 5515dbf..c256ac1 100644
--- a/test/mock_client_state.hpp
+++ b/test/mock_client_state.hpp
@@ -63,21 +63,15 @@ namespace wsrep
 
         int apply_toi(const wsrep::const_buffer&) WSREP_OVERRIDE;
 
-        int commit(const wsrep::ws_handle&, const wsrep::ws_meta&)
-            WSREP_OVERRIDE;
-
         int bf_rollback() WSREP_OVERRIDE;
 
-        bool is_autocommit() const WSREP_OVERRIDE
-        { return is_autocommit_; }
-
         bool do_2pc() const WSREP_OVERRIDE
         { return do_2pc_; }
 
         bool interrupted() const WSREP_OVERRIDE
         { return killed_before_certify_; }
 
-        void reset_globals() WSREP_OVERRIDE { }
+
         void emergency_shutdown() WSREP_OVERRIDE { ++aborts_; }
 
         int append_fragment(const wsrep::transaction&,
@@ -135,6 +129,7 @@ namespace wsrep
         }
 
         void store_globals() WSREP_OVERRIDE { }
+        void reset_globals() WSREP_OVERRIDE { }
 
         void debug_sync(const char* sync_point) WSREP_OVERRIDE
         {
@@ -181,7 +176,6 @@ namespace wsrep
         //
         size_t replays() const { return replays_; }
         size_t aborts() const { return aborts_; }
-
     private:
         wsrep::mock_client_state& client_state_;
         size_t replays_;
diff --git a/test/mock_high_priority_service.hpp b/test/mock_high_priority_service.hpp
index e1e7467..c228c70 100644
--- a/test/mock_high_priority_service.hpp
+++ b/test/mock_high_priority_service.hpp
@@ -33,6 +33,9 @@ namespace wsrep
 
         void adopt_transaction(const wsrep::transaction&) WSREP_OVERRIDE;
         int apply_write_set(const wsrep::const_buffer&) WSREP_OVERRIDE;
+        int append_fragment(const wsrep::ws_meta&,
+                            const wsrep::const_buffer& data) WSREP_OVERRIDE
+        { return 0; }
         int commit() WSREP_OVERRIDE;
         int rollback() WSREP_OVERRIDE;
         int apply_toi(const wsrep::ws_meta&,
diff --git a/test/mock_server_state.hpp b/test/mock_server_state.hpp
index 0d69f01..536c281 100644
--- a/test/mock_server_state.hpp
+++ b/test/mock_server_state.hpp
@@ -9,6 +9,7 @@
 #include "wsrep/server_service.hpp"
 #include "mock_client_state.hpp"
 #include "mock_high_priority_service.hpp"
+#include "mock_storage_service.hpp"
 #include "mock_provider.hpp"
 
 #include "wsrep/compiler.hpp"
@@ -32,9 +33,22 @@ namespace wsrep
             , cond_()
             , provider_(*this)
             , last_client_id_(0)
+            , last_transaction_id_(0)
         { }
+
         wsrep::mock_provider& provider() const
         { return provider_; }
+
+        wsrep::storage_service* storage_service(wsrep::client_service&)
+        {
+            return new wsrep::mock_storage_service(*this, ++last_client_id_);
+        }
+
+        void release_storage_service(wsrep::storage_service* storage_service)
+        {
+            delete storage_service;
+        }
+
         wsrep::client_state* local_client_state()
         {
             wsrep::client_state* ret(new wsrep::mock_client(
@@ -43,6 +57,7 @@ namespace wsrep
             ret->open(ret->id());
             return ret;
         }
+
         void release_client_state(wsrep::client_state* client_state)
         {
             delete client_state;
@@ -103,6 +118,11 @@ namespace wsrep
 
         int wait_committing_transactions(int) WSREP_OVERRIDE { return 0; }
 
+        wsrep::transaction_id next_transaction_id()
+        {
+            return wsrep::transaction_id(++last_transaction_id_);
+        }
+
         void debug_sync(const char* sync_point) WSREP_OVERRIDE
         {
             if (sync_point_enabled_ == sync_point)
@@ -128,6 +148,7 @@ namespace wsrep
         wsrep::default_condition_variable cond_;
         mutable wsrep::mock_provider provider_;
         unsigned long long last_client_id_;
+        unsigned long long last_transaction_id_;
     };
 }
 
diff --git a/test/mock_storage_service.cpp b/test/mock_storage_service.cpp
new file mode 100644
index 0000000..9ae0899
--- /dev/null
+++ b/test/mock_storage_service.cpp
@@ -0,0 +1,56 @@
+//
+// Copyright (C) 2018 Codership Oy <info@codership.com>
+//
+
+#include "mock_storage_service.hpp"
+#include "mock_server_state.hpp"
+
+#include "wsrep/client_state.hpp"
+
+wsrep::mock_storage_service::mock_storage_service(
+    wsrep::mock_server_state& server_state,
+    wsrep::client_id client_id)
+    : server_state_(server_state)
+    , client_service_(client_state_)
+    , client_state_(server_state, client_service_, client_id,
+                    wsrep::client_state::m_high_priority)
+{
+    client_state_.open(client_id);
+    client_state_.before_command();
+}
+
+
+wsrep::mock_storage_service::~mock_storage_service()
+{
+    client_state_.after_command_before_result();
+    client_state_.after_command_after_result();
+    client_state_.close();
+    client_state_.cleanup();
+}
+
+int wsrep::mock_storage_service::start_transaction()
+{
+    return client_state_.start_transaction(
+        server_state_.next_transaction_id());
+}
+
+int wsrep::mock_storage_service::commit(const wsrep::ws_handle& ws_handle,
+                                        const wsrep::ws_meta& ws_meta)
+{
+    return client_state_.prepare_for_fragment_ordering(
+        ws_handle, ws_meta, true) ||
+        client_state_.before_commit() ||
+        client_state_.ordered_commit() ||
+        client_state_.after_commit() ||
+        client_state_.after_statement();
+}
+
+int wsrep::mock_storage_service::rollback(const wsrep::ws_handle& ws_handle,
+                                          const wsrep::ws_meta& ws_meta)
+{
+    return client_state_.prepare_for_fragment_ordering(
+        ws_handle, ws_meta, false) ||
+        client_state_.before_rollback() ||
+        client_state_.after_rollback() ||
+        client_state_.after_statement();
+}
diff --git a/test/mock_storage_service.hpp b/test/mock_storage_service.hpp
new file mode 100644
index 0000000..6aaa1be
--- /dev/null
+++ b/test/mock_storage_service.hpp
@@ -0,0 +1,48 @@
+//
+// Copyright (C) 2018 Codership Oy <info@codership.com>
+//
+
+#ifndef WSREP_MOCK_STORAGE_SERVICE_HPP
+#define WSREP_MOCK_STORAGE_SERVICE_HPP
+
+#include "wsrep/storage_service.hpp"
+#include "mock_client_state.hpp"
+
+namespace wsrep
+{
+class mock_server_state;
+    class mock_storage_service : public wsrep::storage_service
+    {
+    public:
+        mock_storage_service(wsrep::mock_server_state&,
+                                 wsrep::client_id);
+        ~mock_storage_service();
+
+        int start_transaction() WSREP_OVERRIDE;
+
+        int append_fragment(const wsrep::id&,
+                            wsrep::client_id,
+                            int,
+                            const wsrep::const_buffer&)
+            WSREP_OVERRIDE
+        { return 0; }
+
+        int update_fragment_meta(const wsrep::ws_meta&) WSREP_OVERRIDE
+        { return 0; }
+
+        int commit(const wsrep::ws_handle&, const wsrep::ws_meta&)
+            WSREP_OVERRIDE;
+
+        int rollback(const wsrep::ws_handle&, const wsrep::ws_meta&)
+            WSREP_OVERRIDE;
+
+        void store_globals() WSREP_OVERRIDE { }
+        void reset_globals() WSREP_OVERRIDE { }
+    private:
+        wsrep::mock_server_state& server_state_;
+        wsrep::mock_client_service client_service_;
+        wsrep::mock_client_state client_state_;
+    };
+}
+
+#endif // WSREP_MOCK_STORAGE_SERVICE_HPP