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diff --git a/src/seastar/include/seastar/json/formatter.hh b/src/seastar/include/seastar/json/formatter.hh
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+++ b/src/seastar/include/seastar/json/formatter.hh
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+/*
+ * This file is open source software, licensed to you under the terms
+ * of the Apache License, Version 2.0 (the "License").  See the NOTICE file
+ * distributed with this work for additional information regarding copyright
+ * ownership.  You may not use this file except in compliance with the License.
+ *
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+/*
+ * Copyright 2015 Cloudius Systems
+ */
+
+#pragma once
+
+#include <string>
+#include <vector>
+#include <unordered_map>
+#include <map>
+#include <time.h>
+#include <sstream>
+#include <seastar/core/loop.hh>
+#include <seastar/core/sstring.hh>
+#include <seastar/core/iostream.hh>
+
+namespace seastar {
+
+namespace json {
+
+class jsonable;
+
+typedef struct tm date_time;
+
+/**
+ * The formatter prints json values in a json format
+ * it overload to_json method for each of the supported format
+ * all to_json parameters are passed as a pointer
+ */
+class formatter {
+    enum class state {
+        none, array, map
+    };
+    static sstring begin(state);
+    static sstring end(state);
+
+    template<typename K, typename V>
+    static sstring to_json(state s, const std::pair<K, V>& p) {
+        return s == state::array ?
+                        "{" + to_json(state::none, p) + "}" :
+                        to_json(p.first) + ":" + to_json(p.second);
+    }
+
+    template<typename Iter>
+    static sstring to_json(state s, Iter i, Iter e) {
+        std::stringstream res;
+        res << begin(s);
+        size_t n = 0;
+        while (i != e) {
+            if (n++ != 0) {
+                res << ",";
+            }
+            res << to_json(s, *i++);
+        }
+        res << end(s);
+        return res.str();
+    }
+
+    // fallback template
+    template<typename T>
+    static sstring to_json(state, const T& t) {
+        return to_json(t);
+    }
+
+    template<typename K, typename V>
+    static future<> write(output_stream<char>& stream, state s, const std::pair<K, V>& p) {
+        if (s == state::array) {
+            return stream.write("{").then([&stream, &p] {
+                return write(stream, state::none, p).then([&stream] {
+                   return stream.write("}");
+                });
+            });
+        } else {
+            return stream.write(to_json(p.first) + ":").then([&p, &stream] {
+                write(stream, p.second);
+            });
+        }
+    }
+
+    template<typename Iter>
+    static future<> write(output_stream<char>& stream, state s, Iter i, Iter e) {
+        return do_with(true, [&stream, s, i, e] (bool& first) {
+            return stream.write(begin(s)).then([&first, &stream, s, i, e] {
+                return do_for_each(i, e, [&first, &stream] (auto& m) {
+                    auto f = (first) ? make_ready_future<>() : stream.write(",");
+                    first = false;
+                    return f.then([&m, &stream] {
+                        return write(stream, m);
+                    });
+                }).then([&stream, s] {
+                    // FIXME: future is discarded
+                    (void)stream.write(end(s));
+                });
+            });
+        });
+    }
+
+    // fallback template
+    template<typename T>
+    static future<> write(output_stream<char>& stream, state, const T& t) {
+        return stream.write(to_json(t));
+    }
+
+public:
+
+    /**
+     * return a json formated string
+     * @param str the string to format
+     * @return the given string in a json format
+     */
+    static sstring to_json(const sstring& str);
+
+    /**
+     * return a json formated int
+     * @param n the int to format
+     * @return the given int in a json format
+     */
+    static sstring to_json(int n);
+
+    /**
+     * return a json formated unsigned
+     * @param n the unsigned to format
+     * @return the given unsigned in a json format
+     */
+    static sstring to_json(unsigned n);
+
+    /**
+     * return a json formated long
+     * @param n the long to format
+     * @return the given long in a json format
+     */
+    static sstring to_json(long n);
+
+    /**
+     * return a json formated float
+     * @param f the float to format
+     * @return the given float in a json format
+     */
+    static sstring to_json(float f);
+
+    /**
+     * return a json formated double
+     * @param d the double to format
+     * @return the given double in a json format
+     */
+    static sstring to_json(double d);
+
+    /**
+     * return a json formated char* (treated as string)
+     * @param str the char* to foramt
+     * @return the given char* in a json foramt
+     */
+    static sstring to_json(const char* str);
+
+    /**
+     * return a json formated bool
+     * @param d the bool to format
+     * @return the given bool in a json format
+     */
+    static sstring to_json(bool d);
+
+    /**
+     * return a json formated list of a given vector of params
+     * @param vec the vector to format
+     * @return the given vector in a json format
+     */
+    template<typename... Args>
+    static sstring to_json(const std::vector<Args...>& vec) {
+        return to_json(state::array, vec.begin(), vec.end());
+    }
+
+    template<typename... Args>
+    static sstring to_json(const std::map<Args...>& map) {
+        return to_json(state::map, map.begin(), map.end());
+    }
+
+    template<typename... Args>
+    static sstring to_json(const std::unordered_map<Args...>& map) {
+        return to_json(state::map, map.begin(), map.end());
+    }
+
+    /**
+     * return a json formated date_time
+     * @param d the date_time to format
+     * @return the given date_time in a json format
+     */
+    static sstring to_json(const date_time& d);
+
+    /**
+     * return a json formated json object
+     * @param obj the date_time to format
+     * @return the given json object in a json format
+     */
+    static sstring to_json(const jsonable& obj);
+
+    /**
+     * return a json formated unsigned long
+     * @param l unsigned long to format
+     * @return the given unsigned long in a json format
+     */
+    static sstring to_json(unsigned long l);
+
+
+
+    /**
+     * return a json formated string
+     * @param str the string to format
+     * @return the given string in a json format
+     */
+    static future<> write(output_stream<char>& s, const sstring& str) {
+        return s.write(to_json(str));
+    }
+
+    /**
+     * return a json formated int
+     * @param n the int to format
+     * @return the given int in a json format
+     */
+    static future<> write(output_stream<char>& s, int n) {
+        return s.write(to_json(n));
+    }
+
+    /**
+     * return a json formated long
+     * @param n the long to format
+     * @return the given long in a json format
+     */
+    static future<> write(output_stream<char>& s, long n) {
+        return s.write(to_json(n));
+    }
+
+    /**
+     * return a json formated float
+     * @param f the float to format
+     * @return the given float in a json format
+     */
+    static future<> write(output_stream<char>& s, float f) {
+        return s.write(to_json(f));
+    }
+
+    /**
+     * return a json formated double
+     * @param d the double to format
+     * @return the given double in a json format
+     */
+    static future<> write(output_stream<char>& s, double d) {
+        return s.write(to_json(d));
+    }
+
+    /**
+     * return a json formated char* (treated as string)
+     * @param str the char* to foramt
+     * @return the given char* in a json foramt
+     */
+    static future<> write(output_stream<char>& s, const char* str) {
+        return s.write(to_json(str));
+    }
+
+    /**
+     * return a json formated bool
+     * @param d the bool to format
+     * @return the given bool in a json format
+     */
+    static future<> write(output_stream<char>& s, bool d) {
+        return s.write(to_json(d));
+    }
+
+    /**
+     * return a json formated list of a given vector of params
+     * @param vec the vector to format
+     * @return the given vector in a json format
+     */
+    template<typename... Args>
+    static future<> write(output_stream<char>& s, const std::vector<Args...>& vec) {
+        return write(s, state::array, vec.begin(), vec.end());
+    }
+
+    template<typename... Args>
+    static future<> write(output_stream<char>& s, const std::map<Args...>& map) {
+        return write(s, state::map, map.begin(), map.end());
+    }
+
+    template<typename... Args>
+    static future<> write(output_stream<char>& s, const std::unordered_map<Args...>& map) {
+        return write(s, state::map, map.begin(), map.end());
+    }
+
+    /**
+     * return a json formated date_time
+     * @param d the date_time to format
+     * @return the given date_time in a json format
+     */
+    static future<> write(output_stream<char>& s, const date_time& d) {
+      return s.write(to_json(d));
+     }
+
+    /**
+     * return a json formated json object
+     * @param obj the date_time to format
+     * @return the given json object in a json format
+     */
+    static future<> write(output_stream<char>& s, const jsonable& obj) {
+      return s.write(to_json(obj));
+     }
+
+    /**
+     * return a json formated unsigned long
+     * @param l unsigned long to format
+     * @return the given unsigned long in a json format
+     */
+    static future<> write(output_stream<char>& s, unsigned long l) {
+      return s.write(to_json(l));
+     }
+};
+
+}
+
+}