diff --git a/TODO.txt b/TODO.txt
index f82bd99..a6677de 100644
--- a/TODO.txt
+++ b/TODO.txt
@@ -1 +1,2 @@
-- implement connection pooling with  PgBouncer
+DONE - check the parameters and return types (should be const ref)
+DONE - implement connection pooling with  PgBouncer
diff --git a/concordia-server/concordia_server.cpp b/concordia-server/concordia_server.cpp
index e7da983..9426db1 100644
--- a/concordia-server/concordia_server.cpp
+++ b/concordia-server/concordia_server.cpp
@@ -4,17 +4,9 @@
 #include <string>
 
 #include "json_generator.hpp"
-
-#define OPERATION_PARAM "operation"
-#define PATTERN_PARAM "pattern"
-#define SOURCE_SENTENCE_PARAM "sourceSentence"
-#define TARGET_SENTENCE_PARAM "targetSentence"
-#define TM_ID_PARAM "tmId"
-
-#define ADD_SENTENCE_OP "addSentence"
-#define SIMPLE_SEARCH_OP "simpleSearch"
-#define CONCORDIA_SEARCH_OP "concordiaSearch"
-
+#include "config.hpp"
+#include "logger.hpp"
+#include "rapidjson/rapidjson.h"
 
 ConcordiaServer::ConcordiaServer(const std::string & configFilePath)
                                          throw(ConcordiaException) {
@@ -48,6 +40,23 @@ std::string ConcordiaServer::handleRequest(std::string & requestString) {
                 std::string targetSentence = d[TARGET_SENTENCE_PARAM].GetString();
                 int tmId = d[TM_ID_PARAM].GetInt();
                 _indexController->addSentence(jsonWriter, sourceSentence, targetSentence, tmId);
+            } else if (operation == ADD_SENTENCES_OP) {
+                std::vector<std::string> sourceSentences;
+                std::vector<std::string> targetSentences;
+                std::vector<int> tmIds;
+                // loading data from json
+                const rapidjson::Value & sentencesArray = d[SENTENCES_PARAM];
+                for (rapidjson::SizeType i = 0; i < sentencesArray.Size(); i++) {
+                    if (sentencesArray[i].Size() != 3) {
+                        JsonGenerator::signalError(jsonWriter, "sentence should be an array of 3 elements");
+                        break;
+                    } else {
+                        tmIds.push_back(sentencesArray[i][0].GetInt());
+                        sourceSentences.push_back(sentencesArray[i][1].GetString());
+                        targetSentences.push_back(sentencesArray[i][2].GetString());
+                    }
+                }
+                _indexController->addSentences(jsonWriter, sourceSentences, targetSentences, tmIds);
             } else if (operation == SIMPLE_SEARCH_OP) {
                 std::string pattern = d[PATTERN_PARAM].GetString();
                 _searcherController->simpleSearch(jsonWriter, pattern);
diff --git a/concordia-server/config.hpp b/concordia-server/config.hpp
index 58033a3..4b9119f 100644
--- a/concordia-server/config.hpp
+++ b/concordia-server/config.hpp
@@ -6,3 +6,17 @@
 #define DB_PASSWORD "concordia"
 #define DB_HOST "localhost"
 #define DB_PORT "6543"
+
+// json syntax
+#define OPERATION_PARAM "operation"
+#define PATTERN_PARAM "pattern"
+#define SOURCE_SENTENCE_PARAM "sourceSentence"
+#define TARGET_SENTENCE_PARAM "targetSentence"
+#define TM_ID_PARAM "tmId"
+#define SENTENCES_PARAM "sentences"
+
+#define ADD_SENTENCE_OP "addSentence"
+#define ADD_SENTENCES_OP "addSentences"
+#define SIMPLE_SEARCH_OP "simpleSearch"
+#define CONCORDIA_SEARCH_OP "concordiaSearch"
+
diff --git a/concordia-server/config.hpp.in b/concordia-server/config.hpp.in
index da7c021..300e892 100644
--- a/concordia-server/config.hpp.in
+++ b/concordia-server/config.hpp.in
@@ -6,3 +6,17 @@
 #define DB_PASSWORD "@DB_PASSWORD@"
 #define DB_HOST "@DB_HOST@"
 #define DB_PORT "@DB_PORT@"
+
+// json syntax
+#define OPERATION_PARAM "operation"
+#define PATTERN_PARAM "pattern"
+#define SOURCE_SENTENCE_PARAM "sourceSentence"
+#define TARGET_SENTENCE_PARAM "targetSentence"
+#define TM_ID_PARAM "tmId"
+#define SENTENCES_PARAM "sentences"
+
+#define ADD_SENTENCE_OP "addSentence"
+#define ADD_SENTENCES_OP "addSentences"
+#define SIMPLE_SEARCH_OP "simpleSearch"
+#define CONCORDIA_SEARCH_OP "concordiaSearch"
+
diff --git a/concordia-server/db_connection.cpp b/concordia-server/db_connection.cpp
index f184390..bced9c7 100644
--- a/concordia-server/db_connection.cpp
+++ b/concordia-server/db_connection.cpp
@@ -122,14 +122,26 @@ void DBconnection::clearResult(PGresult * result) {
     PQclear(result);
 }
 
-int DBconnection::getIntValue(PGresult * result, int row, int col) {
-    char * valueStr = PQgetvalue(result,row,col);
-    return strtol(valueStr, NULL, 10);
+int DBconnection::getIntValue(PGresult * result, int row, int col) throw (ConcordiaException) {
+    try {
+        char * valueStr = PQgetvalue(result,row,col);
+        return strtol(valueStr, NULL, 10);
+    } catch (std::exception & e) {
+        std::stringstream ss;
+        ss << "Error getting int value. Message: " << e.what();
+        throw ConcordiaException(ss.str());    
+    }
 }
 
-std::string DBconnection::getStringValue(PGresult * result, int row, int col) {
-    char * valueStr = PQgetvalue(result,row,col);
-    return std::string(valueStr);
+std::string DBconnection::getStringValue(PGresult * result, int row, int col)  throw (ConcordiaException) {
+    try {
+        char * valueStr = PQgetvalue(result,row,col);
+        return std::string(valueStr);
+    } catch (std::exception & e) {
+        std::stringstream ss;
+        ss << "Error getting string value. Message: " << e.what();
+        throw ConcordiaException(ss.str());
+    }
 }
 
 
diff --git a/concordia-server/db_connection.hpp b/concordia-server/db_connection.hpp
index dfb3344..666d704 100644
--- a/concordia-server/db_connection.hpp
+++ b/concordia-server/db_connection.hpp
@@ -29,9 +29,9 @@ public:
 
     void clearResult(PGresult * result);
     
-    int getIntValue(PGresult * result, int row, int col);
+    int getIntValue(PGresult * result, int row, int col)  throw (ConcordiaException);
     
-    std::string getStringValue(PGresult * result, int row, int col);
+    std::string getStringValue(PGresult * result, int row, int col) throw (ConcordiaException);
 
 private:
     void close();
diff --git a/concordia-server/index_controller.cpp b/concordia-server/index_controller.cpp
index 0506a05..d2d470b 100644
--- a/concordia-server/index_controller.cpp
+++ b/concordia-server/index_controller.cpp
@@ -1,5 +1,7 @@
 #include "index_controller.hpp"
 
+#include <concordia/common/config.hpp>
+
 #include "json_generator.hpp"
 
 IndexController::IndexController(boost::shared_ptr<Concordia> concordia)
@@ -13,12 +15,12 @@ IndexController::~IndexController() {
 
 void IndexController::addSentence(
                      rapidjson::Writer<rapidjson::StringBuffer> & jsonWriter,
-                     std::string & sourceSentence,
-                     std::string & targetSentence,
-                     int tmId) {
+                     const std::string & sourceSentence,
+                     const std::string & targetSentence,
+                     const int tmId) {
 
     try {
-        boost::shared_ptr<TokenizedSentence> tokenizedSentence = _concordia->tokenize(sourceSentence);
+        TokenizedSentence tokenizedSentence = _concordia->tokenize(sourceSentence);
         int sentenceId = _unitDAO.addSentence(tokenizedSentence, targetSentence, tmId);     
         _concordia->addTokenizedExample(tokenizedSentence, sentenceId);
         _concordia->refreshSAfromRAM();
@@ -34,3 +36,25 @@ void IndexController::addSentence(
     }
 }
 
+void IndexController::addSentences(
+                 rapidjson::Writer<rapidjson::StringBuffer> & jsonWriter,
+                 const std::vector<std::string> & sourceSentences,
+                 const std::vector<std::string> & targetSentences,
+                 const std::vector<int> & tmIds) {
+    try {
+        std::vector<TokenizedSentence> tokenizedSentences = _concordia->tokenizeAll(sourceSentences);
+        std::vector<SUFFIX_MARKER_TYPE> sentenceIds = _unitDAO.addSentences(tokenizedSentences, targetSentences, tmIds);     
+        _concordia->addAllTokenizedExamples(tokenizedSentences, sentenceIds);
+        _concordia->refreshSAfromRAM();
+
+        jsonWriter.StartObject();
+        jsonWriter.String("status");
+        jsonWriter.String("success");
+        jsonWriter.EndObject();
+    } catch (ConcordiaException & e) {
+        std::stringstream errorstream;
+        errorstream << "concordia error: " << e.what();
+        JsonGenerator::signalError(jsonWriter, errorstream.str());        
+    }
+}
+
diff --git a/concordia-server/index_controller.hpp b/concordia-server/index_controller.hpp
index 51a7692..33ce7c6 100644
--- a/concordia-server/index_controller.hpp
+++ b/concordia-server/index_controller.hpp
@@ -21,9 +21,14 @@ public:
     virtual ~IndexController();
 
     void addSentence(rapidjson::Writer<rapidjson::StringBuffer> & jsonWriter,
-                     std::string & sourceSentence,
-                     std::string & targetSentence,
-                     int tmId);
+                     const std::string & sourceSentence,
+                     const std::string & targetSentence,
+                     const int tmId);
+
+    void addSentences(rapidjson::Writer<rapidjson::StringBuffer> & jsonWriter,
+                     const std::vector<std::string> & sourceSentences,
+                     const std::vector<std::string> & targetSentences,
+                     const std::vector<int> & tmIds);
 
 private:
     boost::shared_ptr<Concordia> _concordia;
diff --git a/concordia-server/logger.cpp b/concordia-server/logger.cpp
index 77a0a48..aed26e2 100644
--- a/concordia-server/logger.cpp
+++ b/concordia-server/logger.cpp
@@ -1,31 +1,56 @@
 #include "logger.hpp"
 
-#include "log4cpp/Category.hh"
 #include "log4cpp/Appender.hh"
 #include "log4cpp/FileAppender.hh"
 #include "log4cpp/BasicLayout.hh"
 #include "log4cpp/Priority.hh"
 
+#include <sstream>
+
 Logger::Logger() {
 }
 
 Logger::~Logger() {
 }
 
-int Logger::initialized = 0;
+int Logger::_initialized = 0;
 
 void Logger::log(std::string message) {
     log4cpp::Category & root = log4cpp::Category::getRoot();
-    if (initialized == 0) {
-        log4cpp::Appender *appender = new log4cpp::FileAppender("default", "/tmp/concordia-server.log");
-	    appender->setLayout(new log4cpp::BasicLayout());
-
-	    root.setPriority(log4cpp::Priority::INFO);
-	    root.addAppender(appender);
-	    
-	    initialized = 1;
-	}
+    if (_initialized == 0) {
+        _initialize(root);
+ 	}
 	root.info(message);
 }
 
+void Logger::logInt(std::string name, int value) {
+    log4cpp::Category & root = log4cpp::Category::getRoot();
+    if (_initialized == 0) {
+        _initialize(root);
+ 	}
+ 	std::stringstream ss;
+ 	ss << "    " << name << ": " << value;
+	root.info(ss.str());
+}
+
+void Logger::logString(std::string name, std::string value) {
+    log4cpp::Category & root = log4cpp::Category::getRoot();
+    if (_initialized == 0) {
+        _initialize(root);
+ 	}
+ 	std::stringstream ss;
+ 	ss << "    " << name << ": " << value;
+	root.info(ss.str());
+}
+
+void Logger::_initialize(log4cpp::Category & root) {
+    log4cpp::Appender *appender = new log4cpp::FileAppender("default", "/tmp/concordia-server.log");
+    appender->setLayout(new log4cpp::BasicLayout());
+
+    root.setPriority(log4cpp::Priority::INFO);
+    root.addAppender(appender);
+    
+    _initialized = 1;
+}
+
 
diff --git a/concordia-server/logger.hpp b/concordia-server/logger.hpp
index 9653c19..ddbd089 100644
--- a/concordia-server/logger.hpp
+++ b/concordia-server/logger.hpp
@@ -4,6 +4,9 @@
 #include <string>
 #include <sstream>
 
+#include "log4cpp/Category.hh"
+
+
 class Logger {
 public:
     /*! Constructor.
@@ -14,8 +17,14 @@ public:
     virtual ~Logger();
     
     static void log(std::string message);
+
+    static void logInt(std::string name, int value);
+
+    static void logString(std::string name, std::string value);
 private:
-    static int initialized;
+    static void _initialize(log4cpp::Category & root);
+
+    static int _initialized;
 };
 
 #endif
diff --git a/concordia-server/unit_dao.cpp b/concordia-server/unit_dao.cpp
index fc6ca59..afb3a3c 100644
--- a/concordia-server/unit_dao.cpp
+++ b/concordia-server/unit_dao.cpp
@@ -1,6 +1,5 @@
 #include "unit_dao.hpp"
 
-#include "db_connection.hpp"
 #include "query_param.hpp"
 #include "string_param.hpp"
 #include "int_param.hpp"
@@ -18,46 +17,47 @@ UnitDAO::~UnitDAO() {
 }
 
 int UnitDAO::addSentence(
-     boost::shared_ptr<TokenizedSentence> sourceSentence,
-     std::string & targetSentence,
-     int tmId) {
+     const TokenizedSentence & sourceSentence,
+     const std::string & targetSentence,
+     const int tmId) {
     
     DBconnection connection;
     connection.startTransaction();
-    std::string query = "INSERT INTO unit(source_segment, target_segment, tm_id, source_tokens) values($1::text,$2::text,$3::integer,$4) RETURNING id";
-    std::vector<QueryParam*> params;
-    params.push_back(new StringParam(sourceSentence->getSentence()));
-    params.push_back(new StringParam(targetSentence));
-    params.push_back(new IntParam(tmId));
-    params.push_back(new IntArrayParam(_getTokenPositions(sourceSentence)));
-    
-    PGresult * result = connection.execute(query, params);
-    int newId = connection.getIntValue(result, 0, 0);
-    connection.clearResult(result);
+    int newId = _addSingleSentence(connection, sourceSentence, targetSentence, tmId);
     connection.endTransaction();
-    
-    BOOST_FOREACH (QueryParam * param, params) {
-        delete param;
-    }
-
     return newId;
-     
 }
 
-std::vector<SimpleSearchResult> UnitDAO::getSearchResults(std::vector<MatchedPatternFragment> concordiaResults) {
+std::vector<SUFFIX_MARKER_TYPE> UnitDAO::addSentences(
+             const std::vector<TokenizedSentence> & sourceSentences,
+             const std::vector<std::string> & targetSentences,
+             const std::vector<int> & tmIds) {
+    DBconnection connection;
+    std::vector<SUFFIX_MARKER_TYPE> newIds;
+    connection.startTransaction();
+    int index = 0;
+    BOOST_FOREACH(const TokenizedSentence & sourceSentence, sourceSentences) {    
+        newIds.push_back(_addSingleSentence(connection, sourceSentence, targetSentences.at(index), tmIds.at(index)));
+        index++;
+    }
+    connection.endTransaction();
+    return newIds;
+}
+
+
+std::vector<SimpleSearchResult> UnitDAO::getSearchResults(const std::vector<MatchedPatternFragment> & concordiaResults) {
     std::vector<SimpleSearchResult> results;
 
     DBconnection connection;
     connection.startTransaction();
 
-    BOOST_FOREACH(MatchedPatternFragment & fragment, concordiaResults) {
+    BOOST_FOREACH(const MatchedPatternFragment & fragment, concordiaResults) {
         std::string query = "SELECT id, source_segment, target_segment, source_tokens[$1::integer], source_tokens[$2::integer] FROM unit WHERE id = $3::integer;";
         std::vector<QueryParam*> params;
         params.push_back(new IntParam(2*fragment.getExampleOffset()+1));
         params.push_back(new IntParam(2*(fragment.getExampleOffset()+fragment.getMatchedLength())));
         params.push_back(new IntParam(fragment.getExampleId()));
         PGresult * result = connection.execute(query, params);
-        
         results.push_back(SimpleSearchResult(connection.getIntValue(result,0,0),
                                              connection.getIntValue(result,0,3),
                                              connection.getIntValue(result,0,4),
@@ -70,14 +70,37 @@ std::vector<SimpleSearchResult> UnitDAO::getSearchResults(std::vector<MatchedPat
 }
 
 
-std::vector<int> UnitDAO::_getTokenPositions(boost::shared_ptr<TokenizedSentence> ts) {
+std::vector<int> UnitDAO::_getTokenPositions(const TokenizedSentence & ts) {
     std::vector<int> result;
-    BOOST_FOREACH(const TokenAnnotation & token, ts->getTokens()) {
+    BOOST_FOREACH(const TokenAnnotation & token, ts.getTokens()) {
         result.push_back(token.getStart());
         result.push_back(token.getEnd());
     }
     return result;
 }
 
+int UnitDAO::_addSingleSentence(
+         DBconnection & connection,
+         const TokenizedSentence & sourceSentence,
+         const std::string & targetSentence,
+         const int tmId) {
+    std::string query = "INSERT INTO unit(source_segment, target_segment, tm_id, source_tokens) values($1::text,$2::text,$3::integer,$4) RETURNING id";
+    std::vector<QueryParam*> params;
+    params.push_back(new StringParam(sourceSentence.getSentence()));
+    params.push_back(new StringParam(targetSentence));
+    params.push_back(new IntParam(tmId));
+    params.push_back(new IntArrayParam(_getTokenPositions(sourceSentence)));
+    
+    PGresult * result = connection.execute(query, params);
+    int newId = connection.getIntValue(result, 0, 0);
+    connection.clearResult(result);
+    BOOST_FOREACH (QueryParam * param, params) {
+        delete param;
+    }
+    
+    return newId;
+}
+
+
 
 
diff --git a/concordia-server/unit_dao.hpp b/concordia-server/unit_dao.hpp
index 8b5f44e..dbe6062 100644
--- a/concordia-server/unit_dao.hpp
+++ b/concordia-server/unit_dao.hpp
@@ -4,12 +4,14 @@
 #include <string>
 #include <vector>
 
+#include <concordia/common/config.hpp>
 #include <concordia/tokenized_sentence.hpp>
 #include <concordia/substring_occurence.hpp>
 #include <concordia/matched_pattern_fragment.hpp>
 #include <boost/shared_ptr.hpp>
 
 #include "simple_search_result.hpp"
+#include "db_connection.hpp"
 
 class UnitDAO {
 public:
@@ -21,14 +23,26 @@ public:
     virtual ~UnitDAO();
 
     int addSentence(
-             boost::shared_ptr<TokenizedSentence> sourceSentence,
-             std::string & targetSentence,
-             int tmId);
+             const TokenizedSentence & sourceSentence,
+             const std::string & targetSentence,
+             const int tmId);
 
-    std::vector<SimpleSearchResult> getSearchResults(std::vector<MatchedPatternFragment> concordiaResults);
+    std::vector<SUFFIX_MARKER_TYPE> addSentences(
+             const std::vector<TokenizedSentence> & sourceSentences,
+             const std::vector<std::string> & targetSentences,
+             const std::vector<int> & tmIds);
+
+    std::vector<SimpleSearchResult> getSearchResults(const std::vector<MatchedPatternFragment> & concordiaResults);
 
 private:
-    std::vector<int> _getTokenPositions(boost::shared_ptr<TokenizedSentence> ts);
+    std::vector<int> _getTokenPositions(const TokenizedSentence & ts);
+    
+    int _addSingleSentence(
+         DBconnection & connection,
+         const TokenizedSentence & sourceSentence,
+         const std::string & targetSentence,
+         const int tmId);
+
 };
 
 #endif
diff --git a/tests/testCurl.sh b/tests/testCurl.sh
index 9ebb6de..6e1d388 100755
--- a/tests/testCurl.sh
+++ b/tests/testCurl.sh
@@ -1,7 +1,12 @@
 #!/bin/sh
 
-#curl -H "Content-Type: application/json" -X POST -d '{"operation":"addSentence", "sourceSentence":"Marysia ma rysia", "targetSentence":"Mary has a bobcat", "tmId":1}' http://localhost
+# add sentence
+#curl -H "Content-Type: application/json" -X POST -d '{"operation":"addSentence", "sourceSentence":"I jeszcze jedno zdanie testowe", "targetSentence":"Yet another test sentence", "tmId":1}' http://localhost
+
+# add sentences
+#curl -H "Content-Type: application/json" -X POST -d '{"operation":"addSentences", "sentences":[[1,"test source one", "test target one"],[4,"test source two", "test target two"],[9,"test source three", "test target three"],[13,"test source four", "test target four"]]}' http://localhost
+
+# simple search
+curl -H "Content-Type: application/json" -X POST -d '{"operation":"simpleSearch", "pattern":"test source"}' http://localhost
 
 
-curl -H "Content-Type: application/json" -X POST -d '{"operation":"simpleSearch", "pattern":"ma rysia"}' http://localhost
-