diff --git a/include/wsrep/buffer.hpp b/include/wsrep/buffer.hpp
index 014b113..8d306a4 100644
--- a/include/wsrep/buffer.hpp
+++ b/include/wsrep/buffer.hpp
@@ -5,27 +5,52 @@
 #ifndef WSREP_BUFFER_HPP
 #define WSREP_BUFFER_HPP
 
+#include <vector>
+
 namespace wsrep
 {
-    class buffer
+    class const_buffer
     {
     public:
-        buffer()
+        const_buffer()
             : ptr_()
             , size_()
         { }
-        buffer(const void* ptr, size_t size)
+
+        const_buffer(const void* ptr, size_t size)
             : ptr_(ptr)
             , size_(size)
         { }
 
         const void* ptr() const { return ptr_; }
+        const void* data() const { return ptr_; }
         size_t size() const { return size_; }
 
     private:
+        // const_buffer(const const_buffer&);
+        // const_buffer& operator=(const const_buffer&);
         const void* ptr_;
         size_t size_;
     };
+
+
+    class mutable_buffer
+    {
+    public:
+        mutable_buffer()
+            : buffer_()
+        { }
+
+        void push_back(const char* begin, const char* end)
+        {
+            buffer_.insert(buffer_.end(), begin, end);
+        }
+        const char* data() const { return &buffer_[0]; }
+        size_t size() const { return buffer_.size(); }
+    private:
+        std::vector<char> buffer_;
+    };
+
 }
 
 #endif // WSREP_BUFFER_HPP
diff --git a/include/wsrep/client_context.hpp b/include/wsrep/client_context.hpp
index 6354bcb..0997a46 100644
--- a/include/wsrep/client_context.hpp
+++ b/include/wsrep/client_context.hpp
@@ -44,7 +44,7 @@
 #include "client_id.hpp"
 #include "mutex.hpp"
 #include "lock.hpp"
-#include "data.hpp"
+#include "buffer.hpp"
 #include "thread.hpp"
 
 
@@ -242,7 +242,7 @@ namespace wsrep
             return transaction_.append_key(key);
         }
 
-        int append_data(const wsrep::data& data)
+        int append_data(const wsrep::const_buffer& data)
         {
             assert(state_ == s_exec);
             return transaction_.append_data(data);
@@ -400,7 +400,7 @@ namespace wsrep
         friend int server_context::on_apply(client_context&,
                                             const wsrep::ws_handle&,
                                             const wsrep::ws_meta&,
-                                            const wsrep::data&);
+                                            const wsrep::const_buffer&);
         friend class client_context_switch;
         friend class client_applier_mode;
         friend class client_toi_mode;
@@ -425,18 +425,17 @@ namespace wsrep
         /*!
          * Append SR fragment to the transaction.
          */
-        virtual int append_fragment(wsrep::transaction_context&,
-                                    int, const wsrep::data&)
-        { return 0; }
-
+        virtual int append_fragment(const wsrep::transaction_context&,
+                                    int, const wsrep::const_buffer&) = 0;
 
+        virtual void remove_fragments(const wsrep::transaction_context&) = 0;
         /*!
          * This method applies a write set give in data buffer.
          * This must be implemented by the DBMS integration.
          *
          * \return Zero on success, non-zero on applying failure.
          */
-        virtual int apply(const wsrep::data& data) = 0;
+        virtual int apply(const wsrep::const_buffer& data) = 0;
 
         /*!
          * Virtual method which will be called
@@ -474,8 +473,10 @@ namespace wsrep
         virtual void wait_for_replayers(wsrep::unique_lock<wsrep::mutex>&) = 0;
 
         virtual int prepare_data_for_replication(
-            const wsrep::transaction_context&, wsrep::data& data) = 0;
+            const wsrep::transaction_context&) = 0;
 
+        virtual int prepare_fragment_for_replication(
+            const wsrep::transaction_context&, wsrep::mutable_buffer&) = 0;
         /*!
          * Return true if the current client operation was killed.
          */
diff --git a/include/wsrep/data.hpp b/include/wsrep/data.hpp
deleted file mode 100644
index 3718b28..0000000
--- a/include/wsrep/data.hpp
+++ /dev/null
@@ -1,27 +0,0 @@
-//
-// Copyright (C) 2018 Codership Oy <info@codership.com>
-//
-
-#ifndef WSREP_DATA_HPP
-#define WSREP_DATA_HPP
-
-namespace wsrep
-{
-    class data
-    {
-    public:
-        data()
-            : buf_()
-        {
-        }
-        data(const void* ptr, size_t len)
-            : buf_(ptr, len)
-        {
-        }
-        const wsrep::buffer& get() const { return buf_; }
-    private:
-        wsrep::buffer buf_;
-    };
-}
-
-#endif // WSREP_DATA_HPP
diff --git a/include/wsrep/key.hpp b/include/wsrep/key.hpp
index 04673ed..c230e74 100644
--- a/include/wsrep/key.hpp
+++ b/include/wsrep/key.hpp
@@ -33,7 +33,7 @@ namespace wsrep
             {
                 throw wsrep::runtime_error("key parts exceed maximum of 3");
             }
-            key_parts_[key_parts_len_] = wsrep::buffer(ptr, len);
+            key_parts_[key_parts_len_] = wsrep::const_buffer(ptr, len);
             ++key_parts_len_;
         }
 
@@ -47,14 +47,14 @@ namespace wsrep
             return key_parts_len_;
         }
 
-        const wsrep::buffer* key_parts() const
+        const wsrep::const_buffer* key_parts() const
         {
             return key_parts_;
         }
     private:
 
         enum type type_;
-        wsrep::buffer key_parts_[3];
+        wsrep::const_buffer key_parts_[3];
         size_t key_parts_len_;
     };
 }
diff --git a/include/wsrep/provider.hpp b/include/wsrep/provider.hpp
index 3e736cc..89a253b 100644
--- a/include/wsrep/provider.hpp
+++ b/include/wsrep/provider.hpp
@@ -7,7 +7,7 @@
 
 #include "gtid.hpp"
 #include "key.hpp"
-#include "data.hpp"
+#include "buffer.hpp"
 #include "client_id.hpp"
 #include "transaction_id.hpp"
 
@@ -213,7 +213,7 @@ namespace wsrep
         // TODO: Rename to assing_read_view()
         virtual int start_transaction(wsrep::ws_handle&) = 0;
         virtual int append_key(wsrep::ws_handle&, const wsrep::key&) = 0;
-        virtual int append_data(wsrep::ws_handle&, const wsrep::data&) = 0;
+        virtual int append_data(wsrep::ws_handle&, const wsrep::const_buffer&) = 0;
         virtual enum status
         certify(wsrep::client_id, wsrep::ws_handle&,
                 int,
diff --git a/include/wsrep/server_context.hpp b/include/wsrep/server_context.hpp
index 0438b4d..ffc0a4c 100644
--- a/include/wsrep/server_context.hpp
+++ b/include/wsrep/server_context.hpp
@@ -77,7 +77,7 @@ namespace wsrep
     class transaction_context;
     class gtid;
     class view;
-    class data;
+    class const_buffer;
 
     /*! \class Server Context
      *
@@ -342,7 +342,7 @@ namespace wsrep
         int on_apply(wsrep::client_context& client_context,
                      const wsrep::ws_handle& ws_handle,
                      const wsrep::ws_meta& ws_meta,
-                     const wsrep::data& data);
+                     const wsrep::const_buffer& data);
 
         /*!
          * This virtual method should be implemented by the DBMS
diff --git a/include/wsrep/transaction_context.hpp b/include/wsrep/transaction_context.hpp
index 38f3f67..6edba09 100644
--- a/include/wsrep/transaction_context.hpp
+++ b/include/wsrep/transaction_context.hpp
@@ -17,7 +17,7 @@ namespace wsrep
 {
     class client_context;
     class key;
-    class data;
+    class const_buffer;
 
 
     class transaction_context
@@ -67,10 +67,13 @@ namespace wsrep
         bool ordered() const
         { return (ws_meta_.seqno().nil() == false); }
 
+        /*!
+         * Return true if any fragments have been succesfully certified
+         * for the transaction.
+         */
         bool is_streaming() const
         {
-            // Streaming support not yet implemented
-            return false;
+            return (streaming_context_.fragments_certified() > 0);
         }
 
         bool pa_unsafe() const { return pa_unsafe_; }
@@ -91,7 +94,7 @@ namespace wsrep
 
         int append_key(const wsrep::key&);
 
-        int append_data(const wsrep::data&);
+        int append_data(const wsrep::const_buffer&);
 
         int after_row();
 
@@ -132,7 +135,6 @@ namespace wsrep
         void flags(int flags) { flags_ = flags; }
         int certify_fragment(wsrep::unique_lock<wsrep::mutex>&);
         int certify_commit(wsrep::unique_lock<wsrep::mutex>&);
-        void remove_fragments();
         void clear_fragments();
         void cleanup();
         void debug_log_state(const char*) const;
@@ -215,6 +217,14 @@ namespace wsrep
 
             size_t unit_counter() const { return unit_counter_; }
             void increment_unit_counter() { ++unit_counter_; }
+
+            void cleanup()
+            {
+                fragments_.clear();
+                rollback_replicated_for_ = wsrep::transaction_id::invalid();
+                bytes_certified_ = 0;
+                unit_counter_ = 0;
+            }
         private:
             std::vector<wsrep::seqno> fragments_;
             wsrep::transaction_id rollback_replicated_for_;
diff --git a/src/dbms_simulator.cpp b/src/dbms_simulator.cpp
index dd6d814..a1f0d74 100644
--- a/src/dbms_simulator.cpp
+++ b/src/dbms_simulator.cpp
@@ -13,7 +13,6 @@
 #include "wsrep/client_context.hpp"
 #include "wsrep/transaction_context.hpp"
 #include "wsrep/key.hpp"
-#include "wsrep/data.hpp"
 #include "wsrep/provider.hpp"
 #include "wsrep/condition_variable.hpp"
 #include "wsrep/view.hpp"
@@ -274,7 +273,7 @@ public:
     dbms_storage_engine& storage_engine() { return storage_engine_; }
 
     int apply_to_storage_engine(const wsrep::transaction_context& txc,
-                                const wsrep::data&)
+                                const wsrep::const_buffer&)
     {
         storage_engine_.bf_abort_some(txc);
         return 0;
@@ -346,7 +345,15 @@ public:
 private:
     bool is_autocommit() const override { return false; }
     bool do_2pc() const override { return false; }
-    int apply(const wsrep::data& data) override
+    int append_fragment(const wsrep::transaction_context&,
+                        int, const wsrep::const_buffer&) override
+    {
+        return 0;
+    }
+    void remove_fragments(const wsrep::transaction_context&) override
+    {
+    }
+    int apply(const wsrep::const_buffer& data) override
     {
         return server_.apply_to_storage_engine(transaction(), data);
     }
@@ -381,12 +388,12 @@ private:
     }
     void wait_for_replayers(wsrep::unique_lock<wsrep::mutex>&) override
     { }
-    int prepare_data_for_replication(const wsrep::transaction_context&,
-                                     wsrep::data&)
+    int prepare_data_for_replication(const wsrep::transaction_context&)
         override
-    {
-        return 0;
-    }
+    { return 0; }
+    int prepare_fragment_for_replication(const wsrep::transaction_context&,
+                                          wsrep::mutable_buffer&) override
+    { return 0; }
     bool killed() const override { return false; }
     void abort() override { ::abort(); }
 public:
@@ -454,8 +461,9 @@ private:
                 key.append_key_part(&client_key, sizeof(client_key));
                 key.append_key_part(&data, sizeof(data));
                 err = append_key(key);
-                err = err || append_data(wsrep::data(os.str().c_str(),
-                                                     os.str().size()));
+                err = err || append_data(
+                    wsrep::const_buffer(os.str().c_str(),
+                                        os.str().size()));
                 return err;
             });
         err = err || client_command(
diff --git a/src/mock_client_context.cpp b/src/mock_client_context.cpp
index 861a8c5..4c5a01e 100644
--- a/src/mock_client_context.cpp
+++ b/src/mock_client_context.cpp
@@ -7,7 +7,7 @@
 
 
 int wsrep::mock_client_context::apply(
-    const wsrep::data& data __attribute__((unused)))
+    const wsrep::const_buffer& data __attribute__((unused)))
 
 {
     assert(transaction_.state() == wsrep::transaction_context::s_executing);
diff --git a/src/mock_client_context.hpp b/src/mock_client_context.hpp
index 39c5462..f9a009e 100644
--- a/src/mock_client_context.hpp
+++ b/src/mock_client_context.hpp
@@ -42,11 +42,16 @@ namespace wsrep
                 (void)rollback();
             }
         }
-        int apply(const wsrep::data&);
+        int apply(const wsrep::const_buffer&);
         int commit();
         int rollback();
         bool is_autocommit() const { return is_autocommit_; }
         bool do_2pc() const { return do_2pc_; }
+        int append_fragment(const wsrep::transaction_context&,
+                            int, const wsrep::const_buffer&) WSREP_OVERRIDE
+        { return 0; }
+        void remove_fragments(const wsrep::transaction_context& )
+            WSREP_OVERRIDE { }
         void will_replay(wsrep::transaction_context&) WSREP_OVERRIDE { }
         int replay(wsrep::transaction_context& tc) WSREP_OVERRIDE
         {
@@ -68,17 +73,31 @@ namespace wsrep
             lock.lock();
         }
         int prepare_data_for_replication(
-            const wsrep::transaction_context&, wsrep::data& data) WSREP_OVERRIDE
+            const wsrep::transaction_context&) WSREP_OVERRIDE
         {
             if (error_during_prepare_data_)
             {
                 return 1;
             }
             static const char buf[1] = { 1 };
-            data = wsrep::data(buf, 1);
-            return 0;
-
+            wsrep::const_buffer data = wsrep::const_buffer(buf, 1);
+            return transaction_.append_data(data);
         }
+
+        int prepare_fragment_for_replication(const wsrep::transaction_context&,
+                                             wsrep::mutable_buffer& buffer)
+            WSREP_OVERRIDE
+        {
+            if (error_during_prepare_data_)
+            {
+                return 1;
+            }
+            static const char buf[1] = { 1 };
+            buffer.push_back(&buf[0], &buf[1]);
+            wsrep::const_buffer data(buffer.data(), buffer.size());
+            return transaction_.append_data(data);
+        }
+
         bool killed() const WSREP_OVERRIDE { return killed_before_certify_; }
         void abort() WSREP_OVERRIDE { ++aborts_; }
         void store_globals() WSREP_OVERRIDE { }
@@ -94,7 +113,7 @@ namespace wsrep
         }
         void debug_suicide(const char*) WSREP_OVERRIDE
         {
-            ::abort();
+            // Not going to do this while unit testing
         }
         void on_error(enum wsrep::client_error) { }
 
diff --git a/src/mock_provider.hpp b/src/mock_provider.hpp
index b32bb20..10656bc 100644
--- a/src/mock_provider.hpp
+++ b/src/mock_provider.hpp
@@ -7,6 +7,7 @@
 
 #include "wsrep/provider.hpp"
 #include "wsrep/logger.hpp"
+#include "wsrep/buffer.hpp"
 
 #include <cstring>
 #include <map>
@@ -50,7 +51,10 @@ namespace wsrep
         {
             wsrep::log_info() << "provider certify: "
                               << "client: " << client_id.get()
-                              << " flags: " << std::hex << flags;
+                              << " flags: " << std::hex << flags
+                              << std::dec
+                              << "next_error: " << next_error_;
+
             if (next_error_)
             {
                 return next_error_;
@@ -108,9 +112,9 @@ namespace wsrep
         }
 
         int append_key(wsrep::ws_handle&, const wsrep::key&)
-        { return next_error_; }
-        int append_data(wsrep::ws_handle&, const wsrep::data&)
-        { return next_error_; }
+        { return 0; }
+        int append_data(wsrep::ws_handle&, const wsrep::const_buffer&)
+        { return 0; }
         int rollback(const wsrep::transaction_id)
         { return next_error_; }
         enum wsrep::provider::status
diff --git a/src/server_context.cpp b/src/server_context.cpp
index 58bb699..7cbe0aa 100644
--- a/src/server_context.cpp
+++ b/src/server_context.cpp
@@ -114,7 +114,7 @@ int wsrep::server_context::on_apply(
     wsrep::client_context& client_context,
     const wsrep::ws_handle& ws_handle,
     const wsrep::ws_meta& ws_meta,
-    const wsrep::data& data)
+    const wsrep::const_buffer& data)
 {
     int ret(0);
     const wsrep::transaction_context& txc(client_context.transaction());
diff --git a/src/server_context_test.cpp b/src/server_context_test.cpp
index 7cf2bdf..2d2cdd4 100644
--- a/src/server_context_test.cpp
+++ b/src/server_context_test.cpp
@@ -39,7 +39,7 @@ BOOST_FIXTURE_TEST_CASE(server_context_applying_1pc,
 {
     char buf[1] = { 1 };
     BOOST_REQUIRE(sc.on_apply(cc, ws_handle, ws_meta,
-                              wsrep::data(buf, 1)) == 0);
+                              wsrep::const_buffer(buf, 1)) == 0);
     const wsrep::transaction_context& txc(cc.transaction());
     // ::abort();
     BOOST_REQUIRE_MESSAGE(
@@ -53,7 +53,7 @@ BOOST_FIXTURE_TEST_CASE(server_context_applying_2pc,
 {
     char buf[1] = { 1 };
     BOOST_REQUIRE(sc.on_apply(cc, ws_handle, ws_meta,
-                              wsrep::data(buf, 1)) == 0);
+                              wsrep::const_buffer(buf, 1)) == 0);
     const wsrep::transaction_context& txc(cc.transaction());
     BOOST_REQUIRE(txc.state() == wsrep::transaction_context::s_committed);
 }
@@ -66,7 +66,7 @@ BOOST_FIXTURE_TEST_CASE(server_context_applying_1pc_rollback,
     cc.fail_next_applying_ = true;
     char buf[1] = { 1 };
     BOOST_REQUIRE(sc.on_apply(cc, ws_handle, ws_meta,
-                              wsrep::data(buf, 1)) == 1);
+                              wsrep::const_buffer(buf, 1)) == 1);
     const wsrep::transaction_context& txc(cc.transaction());
     BOOST_REQUIRE(txc.state() == wsrep::transaction_context::s_aborted);
 }
@@ -79,7 +79,7 @@ BOOST_FIXTURE_TEST_CASE(server_context_applying_2pc_rollback,
     cc.fail_next_applying_ = true;
     char buf[1] = { 1 };
     BOOST_REQUIRE(sc.on_apply(cc, ws_handle, ws_meta,
-                              wsrep::data(buf, 1)) == 1);
+                              wsrep::const_buffer(buf, 1)) == 1);
     const wsrep::transaction_context& txc(cc.transaction());
     BOOST_REQUIRE(txc.state() == wsrep::transaction_context::s_aborted);
 }
diff --git a/src/transaction_context.cpp b/src/transaction_context.cpp
index 3ea780c..3579a9a 100644
--- a/src/transaction_context.cpp
+++ b/src/transaction_context.cpp
@@ -6,7 +6,6 @@
 #include "wsrep/client_context.hpp"
 #include "wsrep/server_context.hpp"
 #include "wsrep/key.hpp"
-#include "wsrep/data.hpp"
 #include "wsrep/logger.hpp"
 #include "wsrep/compiler.hpp"
 
@@ -87,7 +86,7 @@ int wsrep::transaction_context::append_key(const wsrep::key& key)
     return provider_.append_key(ws_handle_, key);
 }
 
-int wsrep::transaction_context::append_data(const wsrep::data& data)
+int wsrep::transaction_context::append_data(const wsrep::const_buffer& data)
 {
 
     return provider_.append_data(ws_handle_, data);
@@ -149,7 +148,7 @@ int wsrep::transaction_context::before_prepare()
             }
             else
             {
-                remove_fragments();
+                client_context_.remove_fragments(*this);
             }
             lock.lock();
             client_context_.debug_suicide(
@@ -658,8 +657,8 @@ int wsrep::transaction_context::certify_fragment(
         flags_ |= wsrep::provider::flag::start_transaction;
     }
 
-    wsrep::data data;
-    if (client_context_.prepare_data_for_replication(*this, data))
+    wsrep::mutable_buffer data;
+    if (client_context_.prepare_fragment_for_replication(*this, data))
     {
         lock.lock();
         state(lock, s_must_abort);
@@ -681,7 +680,8 @@ int wsrep::transaction_context::certify_fragment(
     sr_transaction_context.state(sr_lock, s_certifying);
     sr_lock.unlock();
     if (sr_client_context->append_fragment(
-            sr_transaction_context, flags_, data))
+            sr_transaction_context, flags_,
+            wsrep::const_buffer(data.data(), data.size())))
     {
         lock.lock();
         state(lock, s_must_abort);
@@ -750,8 +750,7 @@ int wsrep::transaction_context::certify_commit(
     flags(flags() | wsrep::provider::flag::commit);
     lock.unlock();
 
-    wsrep::data data;
-    if (client_context_.prepare_data_for_replication(*this, data))
+    if (client_context_.prepare_data_for_replication(*this))
     {
         // Note: Error must be set by prepare_data_for_replication()
         lock.lock();
@@ -870,14 +869,9 @@ int wsrep::transaction_context::certify_commit(
     return ret;
 }
 
-void wsrep::transaction_context::remove_fragments()
-{
-    throw wsrep::not_implemented_error();
-}
-
 void wsrep::transaction_context::clear_fragments()
 {
-    throw wsrep::not_implemented_error();
+    streaming_context_.cleanup();
 }
 
 void wsrep::transaction_context::cleanup()
diff --git a/src/transaction_context_test.cpp b/src/transaction_context_test.cpp
index 97b1215..33b37e4 100644
--- a/src/transaction_context_test.cpp
+++ b/src/transaction_context_test.cpp
@@ -140,7 +140,7 @@ BOOST_FIXTURE_TEST_CASE(transaction_context_append_key_data,
         key.append_key_part(&vals[i], sizeof(vals[i]));
     }
     BOOST_REQUIRE(cc.append_key(key) == 0);
-    wsrep::data data(&vals[2], sizeof(vals[2]));
+    wsrep::const_buffer data(&vals[2], sizeof(vals[2]));
     BOOST_REQUIRE(cc.append_data(data) == 0);
     BOOST_REQUIRE(cc.before_commit() == 0);
     BOOST_REQUIRE(cc.ordered_commit() == 0);
@@ -1204,3 +1204,21 @@ BOOST_FIXTURE_TEST_CASE(transaction_context_streaming_1pc_commit,
     BOOST_REQUIRE(sc.provider().commit_fragments() == 1);
 
 }
+
+BOOST_FIXTURE_TEST_CASE(transaction_context_streaming_2pc_commit,
+                        streaming_client_fixture_row)
+{
+    BOOST_REQUIRE(cc.start_transaction(1) == 0);
+    BOOST_REQUIRE(cc.after_row() == 0);
+    BOOST_REQUIRE(tc.streaming_context_.fragments_certified() == 1);
+    BOOST_REQUIRE(cc.before_prepare() == 0);
+    BOOST_REQUIRE(cc.after_prepare() == 0);
+    BOOST_REQUIRE(cc.before_commit() == 0);
+    BOOST_REQUIRE(cc.ordered_commit() == 0);
+    BOOST_REQUIRE(cc.after_commit() == 0);
+    BOOST_REQUIRE(cc.after_statement() == wsrep::client_context::asr_success);
+    BOOST_REQUIRE(sc.provider().fragments() == 2);
+    BOOST_REQUIRE(sc.provider().start_fragments() == 1);
+    BOOST_REQUIRE(sc.provider().commit_fragments() == 1);
+
+}
diff --git a/src/wsrep_provider_v26.cpp b/src/wsrep_provider_v26.cpp
index 52b2dc7..0b76c57 100644
--- a/src/wsrep_provider_v26.cpp
+++ b/src/wsrep_provider_v26.cpp
@@ -314,7 +314,7 @@ namespace
         assert(client_context);
         assert(client_context->mode() == wsrep::client_context::m_applier);
 
-        wsrep::data data(buf->ptr, buf->len);
+        wsrep::const_buffer data(buf->ptr, buf->len);
         wsrep::ws_handle ws_handle(wsh->trx_id, wsh->opaque);
         wsrep::ws_meta ws_meta(
             wsrep::gtid(wsrep::id(meta->gtid.uuid.data,
@@ -484,9 +484,9 @@ int wsrep::wsrep_provider_v26::append_key(wsrep::ws_handle& ws_handle,
 }
 
 int wsrep::wsrep_provider_v26::append_data(wsrep::ws_handle& ws_handle,
-                                           const wsrep::data& data)
+                                           const wsrep::const_buffer& data)
 {
-    const wsrep_buf_t wsrep_buf = {data.get().ptr(), data.get().size()};
+    const wsrep_buf_t wsrep_buf = {data.data(), data.size()};
     mutable_ws_handle mwsh(ws_handle);
     return (wsrep_->append_data(wsrep_, mwsh.native(), &wsrep_buf,
                                 1, WSREP_DATA_ORDERED, true)
diff --git a/src/wsrep_provider_v26.hpp b/src/wsrep_provider_v26.hpp
index b89298f..db650db 100644
--- a/src/wsrep_provider_v26.hpp
+++ b/src/wsrep_provider_v26.hpp
@@ -25,7 +25,7 @@ namespace wsrep
         enum wsrep::provider::status run_applier(void*);
         int start_transaction(wsrep::ws_handle&) { return 0; }
         int append_key(wsrep::ws_handle&, const wsrep::key&);
-        int append_data(wsrep::ws_handle&, const wsrep::data&);
+        int append_data(wsrep::ws_handle&, const wsrep::const_buffer&);
         enum wsrep::provider::status
         certify(wsrep::client_id, wsrep::ws_handle&,
                 int,