diff --git a/mio/bin/t04.c b/mio/bin/t04.c
index ed54832..364e2f1 100644
--- a/mio/bin/t04.c
+++ b/mio/bin/t04.c
@@ -6,6 +6,7 @@
 
 #include <mariadb/mysql.h>
 
+#if 0
 static void mar_on_disconnect (mio_dev_mar_t* dev)
 {
 }
@@ -111,3 +112,79 @@ oops:
 	if (mio) mio_close (mio);
 	return 0;
 }
+#endif
+
+
+
+
+
+
+
+
+
+int main (int argc, char* argv[])
+{
+
+	mio_t* mio = MIO_NULL;
+	mio_svc_marc_t* marc;
+	mio_svc_marc_connect_t ci;
+
+	if (argc != 6)
+	{
+		fprintf (stderr, "Usage: %s ipaddr port username password dbname\n", argv[0]);
+		return -1;
+	}
+
+	mio = mio_open(MIO_NULL, 0, MIO_NULL, 512, MIO_NULL);
+	if (!mio)
+	{
+		printf ("Cannot open mio\n");
+		goto oops;
+	}
+
+
+	memset (&ci, 0, MIO_SIZEOF(ci));
+	ci.host = argv[1];
+	ci.port = 3306; /* TODO: argv[2]; */
+	ci.username = argv[3];
+	ci.password = argv[4];
+	ci.dbname = argv[5];
+
+	marc = mio_svc_marc_start(mio, &ci);
+	if (!marc)
+	{
+		printf ("Cannot start a mariadb client service\n");
+		goto oops;
+	}
+
+	mio_svc_mar_querywithbchars (marc, 0, "SHOW STATUS", 11, MIO_NULL);
+
+#if 0
+	memset (&mi, 0, MIO_SIZEOF(mi));
+	/*mi.on_write = mar_on_write;
+	mi.on_read = mar_on_read;*/
+	mi.on_connect = mar_on_connect;
+	mi.on_disconnect = mar_on_disconnect;
+	mi.on_query_started = mar_on_query_started;
+	mi.on_row_fetched = mar_on_row_fetched;
+
+	mar = mio_dev_mar_make(mio, 0, &mi);
+	if (!mar)
+	{
+		printf ("Cannot make a mar db client device\n");
+		goto oops;
+	}
+
+	if (mio_dev_mar_connect(mar, &ci) <= -1)
+	{
+		printf ("Cannot connect to mar db server\n");
+		goto oops;
+	}
+#endif
+
+	mio_loop (mio);
+
+oops:
+	if (mio) mio_close (mio);
+	return 0;
+}
diff --git a/mio/lib/mar-cli.c b/mio/lib/mar-cli.c
index f29fa9a..67589e0 100644
--- a/mio/lib/mar-cli.c
+++ b/mio/lib/mar-cli.c
@@ -36,11 +36,16 @@ struct mio_svc_marc_t
 {
 	MIO_SVC_HEADER;
 
+	mio_svc_marc_connect_t ci;
+
 	struct
 	{
 		sess_t* ptr;
 		mio_oow_t capa;
 	} sess;
+
+
+	
 };
 
 struct sess_qry_t
@@ -48,19 +53,32 @@ struct sess_qry_t
 	mio_bch_t*   qptr;
 	mio_oow_t    qlen;
 	void*        qctx;
+	int          sent;
 
 	sess_qry_t*  sq_next;
 };
 
 struct sess_t
 {
+	mio_oow_t sid;
+	mio_svc_marc_t* svc;
 	mio_dev_mar_t* dev;
+	int connected;
 
 	sess_qry_t* q_head;
-	sess_qry_t* q_tail
+	sess_qry_t* q_tail;
 };
 
-mio_svc_marc_t* mio_svc_marc_start (mio_t* mio)
+typedef struct dev_xtn_t dev_xtn_t;
+
+struct dev_xtn_t
+{
+	sess_t* sess;
+};
+
+
+
+mio_svc_marc_t* mio_svc_marc_start (mio_t* mio, const mio_svc_marc_connect_t* ci)
 {
 	mio_svc_marc_t* marc = MIO_NULL;
 
@@ -69,6 +87,7 @@ mio_svc_marc_t* mio_svc_marc_start (mio_t* mio)
 
 	marc->mio = mio;
 	marc->svc_stop = mio_svc_marc_stop;
+	marc->ci = *ci;
 
 	MIO_SVCL_APPEND_SVC (&mio->actsvc, (mio_svc_t*)marc);
 	return marc;
@@ -89,22 +108,119 @@ void mio_svc_marc_stop (mio_svc_marc_t* marc)
 	mio_freemem (mio, marc);
 }
 
+
+/* ------------------------------------------------------------------- */
+
+static sess_qry_t* make_session_query (mio_t* mio, const mio_bch_t* qptr, mio_oow_t qlen, void* qctx)
+{
+	sess_qry_t* sq;
+
+	sq = mio_allocmem(mio, MIO_SIZEOF(*sq) + (MIO_SIZEOF(*qptr) * qlen));
+	if (MIO_UNLIKELY(!sq)) return MIO_NULL;
+
+	MIO_MEMCPY (sq + 1, qptr, (MIO_SIZEOF(*qptr) * qlen));
+
+	sq->sent = 0;
+	sq->qptr = (mio_bch_t*)(sq + 1);
+	sq->qlen = qlen;
+	sq->qctx = qctx;
+	sq->sq_next = MIO_NULL;
+
+	return sq;
+}
+
+static MIO_INLINE void free_session_query (mio_t* mio, sess_qry_t* sq)
+{
+	mio_freemem (mio, sq);
+}
+
+static MIO_INLINE void enqueue_session_query (sess_t* sess, sess_qry_t* sq)
+{
+	/* the initialization creates a place holder. so no need to check if q_tail is NULL */
+	sess->q_tail->sq_next = sq;
+	sess->q_tail = sq;
+}
+
+static MIO_INLINE void dequeue_session_query (mio_t* mio, sess_t* sess)
+{
+	sess_qry_t* sq;
+
+	sq = sess->q_head;
+	MIO_ASSERT (mio, sq->sq_next != MIO_NULL); /* must not be empty */
+	sess->q_head = sq->sq_next;
+	free_session_query (mio, sq);
+}
+
+static MIO_INLINE sess_qry_t* get_first_session_query (sess_t* sess)
+{
+	return sess->q_head->sq_next;
+}
+
+/* ------------------------------------------------------------------- */
+
+static int send_pending_query_if_any (sess_t* sess)
+{
+	sess_qry_t* sq;
+
+	sq = get_first_session_query(sess);
+	if (sq)
+	{
+		sq->sent = 1;
+printf ("sending... %.*s\n", (int)sq->qlen, sq->qptr);
+		if (mio_dev_mar_querywithbchars(sess->dev, sq->qptr, sq->qlen) <= -1) 
+		{
+			sq->sent = 0;
+			return -1; /* failure */
+		}
+
+		return 1; /* sent */
+	}
+
+
+	return 0; /* nothing to send */
+}
+
+/* ------------------------------------------------------------------- */
+
 static void mar_on_disconnect (mio_dev_mar_t* dev)
 {
+	dev_xtn_t* xtn = (dev_xtn_t*)mio_dev_mar_getxtn(dev);
+	sess_t* sess = xtn->sess;
+
+printf ("disconnected on sid %d\n", sess->sid);
+	sess->connected = 0;
+	sess->dev = MIO_NULL;
+
+
+	//if (there is a query which has been sent  but not processed... ) <--- can this be handled by the caller?
 }
 
 static void mar_on_connect (mio_dev_mar_t* dev)
 {
-/*
-	if (mio_dev_mar_querywithbchars(dev, "SHOW STATUS", 11) <= -1)
+	dev_xtn_t* xtn = (dev_xtn_t*)mio_dev_mar_getxtn(dev);
+	sess_t* sess = xtn->sess;
+
+	sess->connected = 1;
+printf ("connected on sid %d\n", sess->sid);
+
+	if (send_pending_query_if_any (sess) <= -1)
 	{
-		mio_dev_mar_halt (dev);
+		mio_dev_mar_halt (sess->dev);
 	}
-*/
 }
 
 static void mar_on_query_started (mio_dev_mar_t* dev, int mar_ret)
 {
+	if (mar_ret != 0)
+	{
+	}
+	else
+	{
+		if (mio_dev_mar_fetchrows(dev) <= -1)
+		{
+			mio_dev_mar_halt (dev);
+		}
+	}
 #if 0
 	if (mar_ret != 0)
 	{
@@ -142,21 +258,31 @@ static void mar_on_row_fetched (mio_dev_mar_t* dev, void* data)
 		//printf ("GOT ROW\n");
 	}
 #endif
+
+	dev_xtn_t* xtn = (dev_xtn_t*)mio_dev_mar_getxtn(dev);
+	sess_t* sess = xtn->sess;
+
+	if (!data)
+	{
+		/* no more rows */
+		
+		//marc->on_row_fetched (marc, void* data, sess->sid, sess->qctx);
+printf ("there is no more row...\n");
+	}
+	else
+	{
+printf ("there is row...\n");
+	}
+
 }
 
-static mio_dev_mar_t* alloc_device (mio_svc_marc_t* marc)
+static mio_dev_mar_t* alloc_device (mio_svc_marc_t* marc, sess_t* sess)
 {
 	mio_t* mio = (mio_t*)marc->mio;
 	mio_dev_mar_t* mar;
 	mio_dev_mar_make_t mi;
 	mio_dev_mar_connect_t ci;
-
-	MIO_MEMSET (&ci, 0, MIO_SIZEOF(ci));
-	ci.host = "localhost"; /* TOOD: use marc configuration */
-	ci.port = 3306; /* TODO: use marc configuration */
-	ci.username = ""; /* TODO: use marc configuration */
-	ci.password = ""; /* TODO: use marc conifguration */
-	ci.dbname = ""; /* TODO: use marc configuration */
+	dev_xtn_t* xtn;
 
 	MIO_MEMSET (&mi, 0, MIO_SIZEOF(mi));
 	mi.on_connect = mar_on_connect;
@@ -164,38 +290,20 @@ static mio_dev_mar_t* alloc_device (mio_svc_marc_t* marc)
 	mi.on_query_started = mar_on_query_started;
 	mi.on_row_fetched = mar_on_row_fetched;
 
-	mar = mio_dev_mar_make(mio, 0, &mi);
+	mar = mio_dev_mar_make(mio, MIO_SIZEOF(*xtn), &mi);
 	if (!mar) return MIO_NULL;
 
-	if (mio_dev_mar_connect(mar, &ci) <= -1) return MIO_NULL;
-	
+	xtn = (dev_xtn_t*)mio_dev_mar_getxtn(mar);
+	xtn->sess = sess;
+
+	if (mio_dev_mar_connect(mar, &marc->ci) <= -1) return MIO_NULL;
+
 	return mar;
 }
 
+/* ------------------------------------------------------------------- */
 
-static sess_qry_t* make_session_query (mio_t* mio, const mio_bch_t* qptr, mio_oow_t qlen, void* qctx)
-{
-	sess_qry_t* sq;
-
-	sq = mio_allocmem(mio, MIO_SIZEOF(*sq) + (MIO_SIZEOF(*qptr) * qlen));
-	if (MIO_UNLIKELY(!sq)) return MIO_NULL;
-
-	MIO_MEMCPY (sq + 1, qptr, (MIO_SIZEOF(*qptr) * qlen));
-
-	sq->qptr = (mio_bch_t*)(sq + 1);
-	sq->qlen = qlen;
-	sq->qctx = qctx;
-	sq->sq_next = MIO_NULL;
-
-	return sq;
-}
-
-static MIO_INLINE void free_session_query (mio_t* mio, sess_qry_t* sq)
-{
-	mio_freemem (mio, sq);
-}
-
-static sess_t* get_session (mio_svc_marc_t* marc, int sid)
+static sess_t* get_session (mio_svc_marc_t* marc, mio_oow_t sid)
 {
 	mio_t* mio = marc->mio;
 	sess_t* sess;
@@ -212,13 +320,22 @@ static sess_t* get_session (mio_svc_marc_t* marc, int sid)
 		tmp = mio_reallocmem(mio, marc->sess.ptr, MIO_SIZEOF(sess_t) * newcapa);
 		if (MIO_UNLIKELY(!tmp)) return MIO_NULL;
 
-		MIO_MEMSET (&marc->sess.ptr[marc->sess.capa], 0, MIO_SIZEOF(sess_t) * (newcapa - marc->sess.capa));
+		MIO_MEMSET (&tmp[marc->sess.capa], 0, MIO_SIZEOF(sess_t) * (newcapa - marc->sess.capa));
 
 		marc->sess.ptr = tmp;
 		marc->sess.capa = newcapa;
+
+		sess = &marc->sess.ptr[sid];
+		sess->svc = marc;
+		sess->sid = sid;
+	}
+	else
+	{
+		sess = &marc->sess.ptr[sid];
+		MIO_ASSERT (mio, sess->sid == sid);
+		MIO_ASSERT (mio, sess->svc == marc);
 	}
 
-	sess = &marc->sess.ptr[sid];
 	if (!sess->dev)
 	{
 		sess_qry_t* sq;
@@ -226,13 +343,14 @@ static sess_t* get_session (mio_svc_marc_t* marc, int sid)
 		sq = make_session_query(mio, "", 0, MIO_NULL); /* this is a place holder */
 		if (MIO_UNLIKELY(!sq)) return MIO_NULL;
 
-		sess->dev = alloc_device(marc);
+		sess->dev = alloc_device(marc, sess);
 		if (MIO_UNLIKELY(!sess->dev)) 
 		{
 			free_session_query (mio, sq);
 			return MIO_NULL;
 		}
 
+		/* queue initialization with a place holder */
 		sess->q_head = sess->q_tail = sq;
 	}
 
@@ -240,62 +358,47 @@ static sess_t* get_session (mio_svc_marc_t* marc, int sid)
 }
 
 
-int mio_svc_mar_querywithbchars (mio_svc_marc_t* marc, int sid, const mio_bch_t* qptr, mio_oow_t qlen, void* qctx)
+int mio_svc_mar_querywithbchars (mio_svc_marc_t* marc, mio_oow_t sid, const mio_bch_t* qptr, mio_oow_t qlen, void* qctx)
 {
 	mio_t* mio = marc->mio;
 	sess_t* sess;
+	sess_qry_t* sq;
 
 	sess = get_session(marc, sid);
 	if (MIO_UNLIKELY(!sess)) return -1;
 
+	sq = make_session_query(mio, qptr, qlen, qctx);
+	if (MIO_UNLIKELY(!sq)) return -1;
 
-	if (!sess->q_head)
+	if (get_first_session_query(sess))
 	{
-		/* the first query for the device */
-		sess_qry_t* sq;
-		sq = make_session_query(mio, qptr, qlen, qctx);
-		if (MIO_UNLIKELY(!sq)) return -1;
-
-		sess->q_head = sq;
-		sess->q_tail = sq;
-
-/* what if it's not connected??? */
-
-		if (mio_dev_mar_querywithbchars(sess->dev, qptr, qlen) <= -1) 
-		{
-			sess->q_head = MIO_NULL;
-			sess->q_tail = MIO_NULL;
-			free_session_query (mio, sq);
-			return -1; /* TODO: need a context pointer */
-		}
+printf ("XXXXXXXXXx\n");
+		/* there are other ongoing queries */
+		enqueue_session_query (sess, sq);
 	}
 	else
 	{
-		/* there is an ongoing query for the device */
-		sess_qry_t* sq;
-		sq = make_session_query(mio, qptr, qlen, qctx);
-		if (MIO_UNLIKELY(!sq)) return -1;
+		/* this is the first query */
+		sess_qry_t* old_q_tail = sess->q_tail;
+		enqueue_session_query (sess, sq);
 
-		/* push it at the back */
-		sess->q_tail->sq_next = sq;
-		sess->q_tail = sq;
+printf ("YYYYYYYYYYYYYY\n");
+		if(sess->dev->connected && !sq->sent)
+		{
+			sq->sent = 1;
+			if (mio_dev_mar_querywithbchars(sess->dev, qptr, qlen) <= -1) 
+			{
+				sq->sent = 0;
+
+				/* ugly to unlink the the last item added */
+				old_q_tail->sq_next = MIO_NULL;
+				sess->q_tail = old_q_tail;
+
+				free_session_query (mio, sq);
+				return -1;
+			}
+		}
 	}
 
-
-#if 0
-	dev = get_session(marc, sid);
-	if (!dev)
-	{
-	}
-	if (mio_dev_mar_querywithbchars(dev, qptr, qlen) <= -1) return -1; /* TODO: need a context pointer */
-#endif
+	return 0;
 }
-
-
-#if 0
-mio_svc_mar_querywithbchars (1, "select...");
-for (each row)
-{
-mio_svc_mar_querywithbchars (2, "xxxxxx");
-}
-#endif
diff --git a/mio/lib/mio-mar.h b/mio/lib/mio-mar.h
index 7fcb2ee..071c0aa 100644
--- a/mio/lib/mio-mar.h
+++ b/mio/lib/mio-mar.h
@@ -153,6 +153,16 @@ typedef enum mio_dev_mar_ioctl_cmd_t mio_dev_mar_ioctl_cmd_t;
 /* -------------------------------------------------------------- */
 
 typedef struct mio_svc_marc_t mio_svc_marc_t;
+typedef mio_dev_mar_connect_t mio_svc_marc_connect_t;
+
+typedef void (*mio_svc_marc_on_row_fetched) (
+	mio_svc_marc_t* marc,
+	mio_oow_t       sid,
+	void*           data,
+	void*           qctx
+);
+
+/* -------------------------------------------------------------- */
 
 #ifdef __cplusplus
 extern "C" {
@@ -206,7 +216,8 @@ static MIO_INLINE void mio_dev_mar_halt (mio_dev_mar_t* mar) { mio_dev_halt ((mi
 /* ------------------------------------------------------------------------- */
 
 MIO_EXPORT mio_svc_marc_t* mio_svc_marc_start (
-	mio_t*          mio
+	mio_t*                        mio,
+	const mio_svc_marc_connect_t* ci
 );
 
 MIO_EXPORT void mio_svc_marc_stop (
@@ -219,6 +230,15 @@ static MIO_INLINE mio_t* mio_svc_marc_getmio(mio_svc_marc_t* svc) { return mio_s
 #       define mio_svc_marc_getmio(svc) mio_svc_getmio(svc)
 #endif
 
+
+MIO_EXPORT int mio_svc_mar_querywithbchars (
+	mio_svc_marc_t*   marc,
+	mio_oow_t         sid,
+	const mio_bch_t*  qptr,
+	mio_oow_t         qlen,
+	void*             qctx
+);
+
 #ifdef __cplusplus
 }
 #endif