diff --git a/src/od_backend.c b/src/od_backend.c
new file mode 100644
index 00000000..402c0c29
--- /dev/null
+++ b/src/od_backend.c
@@ -0,0 +1,281 @@
+
+/*
+ * odissey.
+ *
+ * PostgreSQL connection pooler and request router.
+*/
+
+#include <stdlib.h>
+#include <stdarg.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <string.h>
+#include <signal.h>
+
+#include <machinarium.h>
+#include <soprano.h>
+
+#include "od_macro.h"
+#include "od_version.h"
+#include "od_list.h"
+#include "od_pid.h"
+#include "od_syslog.h"
+#include "od_log.h"
+#include "od_daemon.h"
+#include "od_scheme.h"
+#include "od_lex.h"
+#include "od_config.h"
+#include "od_msg.h"
+#include "od_system.h"
+#include "od_instance.h"
+
+#include "od_server.h"
+#include "od_server_pool.h"
+#include "od_client.h"
+#include "od_client_pool.h"
+#include "od_route_id.h"
+#include "od_route.h"
+#include "od_route_pool.h"
+#include "od_io.h"
+
+#include "od_pooler.h"
+#include "od_router.h"
+#include "od_relay.h"
+#include "od_frontend.h"
+#include "od_backend.h"
+#include "od_auth.h"
+
+void od_backend_close(od_server_t *server)
+{
+	od_route_t *route = server->route;
+	od_serverpool_set(&route->server_pool, server, OD_SUNDEF);
+	if (server->io) {
+		machine_close(server->io);
+		machine_io_free(server->io);
+		server->io = NULL;
+	}
+	if (server->tls) {
+		machine_tls_free(server->tls);
+		server->tls = NULL;
+	}
+	server->is_transaction = 0;
+	server->idle_time = 0;
+	so_keyinit(&server->key);
+	so_keyinit(&server->key_client);
+	od_server_free(server);
+}
+
+static inline int
+od_backend_startup(od_server_t *server)
+{
+	od_instance_t *instance = server->system->instance;
+	od_route_t *route = server->route;
+
+	so_stream_t *stream = &server->stream;
+	so_stream_reset(stream);
+	so_fearg_t argv[] = {
+		{ "user", 5 },     { route->id.user, route->id.user_len },
+		{ "database", 9 }, { route->id.database, route->id.database_len }
+	};
+	int rc;
+	rc = so_fewrite_startup_message(stream, 4, argv);
+	if (rc == -1)
+		return -1;
+	rc = od_write(server->io, stream);
+	if (rc == -1) {
+		od_error(&instance->log, server->io, "S (startup): write error: %s",
+		         machine_error(server->io));
+		return -1;
+	}
+	server->count_request++;
+	return 0;
+}
+
+int od_backend_ready(od_server_t *server, uint8_t *data, int size)
+{
+	int status;
+	int rc;
+	rc = so_feread_ready(&status, data, size);
+	if (rc == -1)
+		return -1;
+	if (status == 'I') {
+		/* no active transaction */
+		server->is_transaction = 0;
+	} else
+	if (status == 'T' || status == 'E') {
+		/* in active transaction or in interrupted
+		 * transaction block */
+		server->is_transaction = 1;
+	}
+	server->count_reply++;
+	return 0;
+}
+
+static inline int
+od_backend_setup(od_server_t *server)
+{
+	od_instance_t *instance = server->system->instance;
+	so_stream_t *stream = &server->stream;
+	while (1) {
+		so_stream_reset(stream);
+		int rc;
+		rc = od_read(server->io, &server->stream, UINT32_MAX);
+		if (rc == -1) {
+			od_error(&instance->log, server->io, "S (setup): read error: %s",
+			         machine_error(server->io));
+			return -1;
+		}
+		uint8_t type = *server->stream.s;
+		od_debug(&instance->log, server->io, "S (setup): %c", type);
+		switch (type) {
+		/* ReadyForQuery */
+		case 'Z':
+			od_backend_ready(server, stream->s, so_stream_used(stream));
+			return 0;
+		/* Authentication */
+		case 'R':
+			rc = od_auth_backend(server);
+			if (rc == -1)
+				return -1;
+			break;
+		/* BackendKeyData */
+		case 'K':
+			rc = so_feread_key(&server->key,
+			                   stream->s, so_stream_used(stream));
+			if (rc == -1) {
+				od_error(&instance->log, server->io,
+				         "S (setup): failed to parse BackendKeyData message");
+				return -1;
+			}
+			break;
+		/* ParameterStatus */
+		case 'S':
+			break;
+		/* NoticeResponce */
+		case 'N':
+			break;
+		/* ErrorResponce */
+		case 'E':
+			return -1;
+		default:
+			od_debug(&instance->log, server->io,
+			         "S (setup): unknown packet: %c", type);
+			return -1;
+		}
+	}
+	return 0;
+}
+
+static inline int
+od_backend_connect(od_server_t *server)
+{
+	od_instance_t *instance = server->system->instance;
+	od_route_t *route = server->route;
+	od_schemeserver_t *server_scheme = route->scheme->server;
+
+	/* resolve server address */
+	char port[16];
+	snprintf(port, sizeof(port), "%d", server_scheme->port);
+	struct addrinfo *ai = NULL;
+	int rc;
+	rc = machine_getaddrinfo(server_scheme->host, port, NULL, &ai, 0);
+	if (rc < 0) {
+		od_error(&instance->log, NULL, "failed to resolve %s:%d",
+		         server_scheme->host,
+		         server_scheme->port);
+		return -1;
+	}
+	assert(ai != NULL);
+
+	/* connect to server */
+	rc = machine_connect(server->io, ai->ai_addr, UINT32_MAX);
+	freeaddrinfo(ai);
+	if (rc < 0) {
+		od_error(&instance->log, NULL, "failed to connect to %s:%d",
+		         server_scheme->host,
+		         server_scheme->port);
+		return -1;
+	}
+	rc = machine_set_readahead(server->io, instance->scheme.readahead);
+	if (rc == -1) {
+		od_error(&instance->log, NULL, "failed to set readahead");
+		return -1;
+	}
+
+	/* do tls handshake */
+#if 0
+	if (server_scheme->tls_verify != OD_TDISABLE) {
+		rc = od_tlsbe_connect(pooler->env, server->io, server->tls,
+		                      &server->stream,
+		                      &pooler->od->log, "S",
+		                      server_scheme);
+		if (rc == -1)
+			return -1;
+	}
+#endif
+
+	od_log(&instance->log, server->io, "S: new connection");
+
+	/* startup */
+	rc = od_backend_startup(server);
+	if (rc == -1)
+		return -1;
+
+	/* server configuration */
+	rc = od_backend_setup(server);
+	if (rc == -1)
+		return -1;
+
+	return 0;
+}
+
+od_server_t*
+od_backend_new(od_router_t *router, od_route_t *route)
+{
+	od_instance_t *instance = router->system->instance;
+
+	/* create new server connection */
+	od_server_t *server;
+	server = od_server_allocate();
+	if (server == NULL)
+		return NULL;
+	server->route = route;
+	server->system = router->system;
+
+	/* set network options */
+	server->io = machine_io_create();
+	if (server->io == NULL) {
+		od_server_free(server);
+		return NULL;
+	}
+	machine_set_nodelay(server->io, instance->scheme.nodelay);
+	if (instance->scheme.keepalive > 0)
+		machine_set_keepalive(server->io, 1, instance->scheme.keepalive);
+
+	/* set tls options */
+#if 0
+	od_schemeserver_t *server_scheme;
+	server_scheme = route->scheme->server;
+	if (server_scheme->tls_verify != OD_TDISABLE) {
+		server->tls = od_tlsbe(pooler->env, server_scheme);
+		if (server->tls == NULL) {
+			od_serverfree(server);
+			return NULL;
+		}
+	}
+#endif
+
+	/* place server to connection pool */
+	od_serverpool_set(&route->server_pool, server, OD_SCONNECT);
+
+	int rc;
+	rc = od_backend_connect(server);
+	if (rc == -1) {
+		od_backend_close(server);
+		return NULL;
+	}
+
+	/* server is ready to use */
+	od_serverpool_set(&route->server_pool, server, OD_SIDLE);
+	return server;
+}
diff --git a/src/od_backend.h b/src/od_backend.h
new file mode 100644
index 00000000..79c7d083
--- /dev/null
+++ b/src/od_backend.h
@@ -0,0 +1,13 @@
+#ifndef OD_BACKEND_H
+#define OD_BACKEND_H
+
+/*
+ * odissey.
+ *
+ * PostgreSQL connection pooler and request router.
+*/
+
+od_server_t*
+od_backend_new(od_router_t*, od_route_t*);
+
+#endif /* OD_BACKEND_H */
diff --git a/src/od_client.h b/src/od_client.h
index 71eb9350..533837a5 100644
--- a/src/od_client.h
+++ b/src/od_client.h
@@ -29,7 +29,7 @@ struct od_client
 	so_stream_t      stream;
 	od_server_t     *server;
 	void            *route;
-	void            *relay;
+	od_system_t     *system;
 	od_list_t        link_pool;
 	od_list_t        link;
 };
@@ -44,7 +44,7 @@ od_client_init(od_client_t *client)
 	client->scheme = NULL;
 	client->server = NULL;
 	client->route = NULL;
-	client->relay = NULL;
+	client->system = NULL;
 	so_bestartup_init(&client->startup);
 	so_keyinit(&client->key);
 	so_stream_init(&client->stream);
diff --git a/src/od_client_pool.c b/src/od_client_pool.c
index dbcb6617..4163b8c8 100644
--- a/src/od_client_pool.c
+++ b/src/od_client_pool.c
@@ -23,6 +23,7 @@
 #include "od_scheme.h"
 #include "od_lex.h"
 #include "od_config.h"
+#include "od_system.h"
 #include "od_server.h"
 #include "od_server_pool.h"
 #include "od_client.h"
diff --git a/src/od_frontend.c b/src/od_frontend.c
index 65d72242..1c098806 100644
--- a/src/od_frontend.c
+++ b/src/od_frontend.c
@@ -68,8 +68,7 @@ void od_frontend_close(od_client_t *client)
 static int
 od_frontend_startup_read(od_client_t *client)
 {
-	od_relay_t *relay = client->relay;
-	od_instance_t *instance = relay->system->instance;
+	od_instance_t *instance = client->system->instance;
 
 	so_stream_t *stream = &client->stream;
 	so_stream_reset(stream);
@@ -89,7 +88,7 @@ od_frontend_startup_read(od_client_t *client)
 		int rc = so_stream_ensure(stream, to_read);
 		if (rc == -1)
 			return -1;
-		rc = machine_read(client->io, (char*)stream->p, to_read, INT_MAX);
+		rc = machine_read(client->io, (char*)stream->p, to_read, UINT32_MAX);
 		if (rc < 0) {
 			od_error(&instance->log, client->io,
 			         "C (startup): read error: %s",
@@ -152,8 +151,7 @@ od_frontend_key(od_client_t *client)
 static inline int
 od_frontend_setup(od_client_t *client)
 {
-	od_relay_t *relay = client->relay;
-	od_instance_t *instance = relay->system->instance;
+	od_instance_t *instance = client->system->instance;
 
 	so_stream_t *stream = &client->stream;
 	so_stream_reset(stream);
@@ -177,8 +175,7 @@ od_frontend_setup(od_client_t *client)
 static inline int
 od_frontend_ready(od_client_t *client)
 {
-	od_relay_t *relay = client->relay;
-	od_instance_t *instance = relay->system->instance;
+	od_instance_t *instance = client->system->instance;
 
 	so_stream_t *stream = &client->stream;
 	so_stream_reset(stream);
@@ -198,8 +195,8 @@ od_frontend_ready(od_client_t *client)
 void od_frontend(void *arg)
 {
 	od_client_t *client = arg;
-	od_relay_t *relay = client->relay;
-	od_instance_t *instance = relay->system->instance;
+	od_relay_t *relay = client->system->relay;
+	od_instance_t *instance = client->system->instance;
 
 	od_log(&instance->log, client->io, "C: new connection");
 
diff --git a/src/od_relay.c b/src/od_relay.c
index e6d23c9c..56d055af 100644
--- a/src/od_relay.c
+++ b/src/od_relay.c
@@ -62,7 +62,7 @@ od_relay(void *arg)
 		{
 			od_client_t *client;
 			client = *(od_client_t**)machine_msg_get_data(msg);
-			client->relay = relay;
+			client->system = relay->system;
 			int64_t coroutine_id;
 			coroutine_id = machine_coroutine_create(od_frontend, client);
 			if (coroutine_id == -1) {
diff --git a/src/od_route_pool.c b/src/od_route_pool.c
index a43f40a9..dab70a43 100644
--- a/src/od_route_pool.c
+++ b/src/od_route_pool.c
@@ -23,6 +23,7 @@
 #include "od_scheme.h"
 #include "od_lex.h"
 #include "od_config.h"
+#include "od_system.h"
 #include "od_server.h"
 #include "od_server_pool.h"
 #include "od_client.h"
diff --git a/src/od_server.h b/src/od_server.h
index c008cbd2..8bc5301a 100644
--- a/src/od_server.h
+++ b/src/od_server.h
@@ -34,7 +34,7 @@ struct od_server
 	so_key_t          key;
 	so_key_t          key_client;
 	void             *route;
-	void             *pooler;
+	od_system_t      *system;
 	od_list_t         link;
 };
 
@@ -48,9 +48,9 @@ od_server_init(od_server_t *server)
 {
 	server->state          = OD_SUNDEF;
 	server->route          = NULL;
+	server->system         = NULL;
 	server->io             = NULL;
 	server->tls            = NULL;
-	server->pooler         = NULL;
 	server->idle_time      = 0;
 	server->is_transaction = 0;
 	server->is_copy        = 0;
diff --git a/src/od_server_pool.c b/src/od_server_pool.c
index 8bce5083..97487669 100644
--- a/src/od_server_pool.c
+++ b/src/od_server_pool.c
@@ -23,6 +23,7 @@
 #include "od_scheme.h"
 #include "od_lex.h"
 #include "od_config.h"
+#include "od_system.h"
 #include "od_server.h"
 #include "od_server_pool.h"