diff --git a/core/communication.c b/core/communication.c
index b754b1f..e458c0c 100644
--- a/core/communication.c
+++ b/core/communication.c
@@ -69,6 +69,14 @@ int srv_close (struct service *srv)
 
 int srv_close_proc (struct process *p)
 {
+    // struct msg m_ack_dis;
+    // memset (&m_ack_dis, 0, sizeof (struct msg));
+    // m_ack_dis.type = MSG_TYPE_ACK_DIS;
+
+    // if (msg_write (p->proc_fd, &m_ack_dis) < 0) {
+    //     handle_err ("srv_close_proc", "msg_write < 0");
+    // }
+
     return usock_close (p->proc_fd);
 }
 
@@ -128,6 +136,7 @@ int app_connection (int argc, char **argv, char **env
     return 0;
 }
 
+// send a DIS message then close the socket
 int app_close (struct service *srv)
 {
     struct msg m;
@@ -137,6 +146,14 @@ int app_close (struct service *srv)
         handle_err ("app_close", "msg_write < 0");
     }
 
+    // if (msg_read (srv->service_fd, &m) < 0) {
+    //     handle_err ("app_close", "msg_read < 0");
+    // }
+
+    // if (m.type != MSG_TYPE_ACK) {
+    //     handle_err ("app_close", "msg received != ACK");
+    // }
+
     return usock_close (srv->service_fd);
 }
 
@@ -165,8 +182,14 @@ int app_write (struct service *srv, const struct msg *m)
  */
 
 int srv_select (struct array_proc *ap, struct service *srv
-        , struct process **proc)
+        , struct array_proc *proc)
 {
+    assert (ap != NULL);
+    assert (proc != NULL);
+
+    // delete previous read process array
+    array_proc_free (proc);
+
     int i, j;
     /* master file descriptor list */
     fd_set master;
@@ -183,14 +206,17 @@ int srv_select (struct array_proc *ap, struct service *srv
     /* add the listener to the master set */
     FD_SET(listener, &master);
 
-    for(i=0; i < ap->size; i++) {
+    for (i=0; i < ap->size; i++) {
         FD_SET(ap->tab_proc[i]->proc_fd, &master);
     }
 
     /* keep track of the biggest file descriptor */
     fdmax = getMaxFd(ap) > srv->service_fd ? getMaxFd(ap) : srv->service_fd; 
 
-    while (1) {
+    int is_listener = 0;
+
+    do {
+        // printf ("loop srv_select main_loop\n");
         readf = master;
         if(select(fdmax+1, &readf, NULL, NULL, NULL) == -1) {
             perror("select");
@@ -199,20 +225,27 @@ int srv_select (struct array_proc *ap, struct service *srv
 
         /*run through the existing connections looking for data to be read*/
         for (i = 0; i <= fdmax; i++) {
+            // printf ("loop srv_select inner loop\n");
             if (FD_ISSET(i, &readf)) {
                 if (i == listener) {
-                    return CONNECTION;
+                    is_listener = 1;
                 } else {
                     for(j = 0; j < ap->size; j++) {
+                        // printf ("loop srv_select inner inner loop\n");
                         if(i == ap->tab_proc[j]->proc_fd ) {
-                            *proc = ap->tab_proc[j];
-                            return APPLICATION;
+                            add_proc (proc, ap->tab_proc[j]);
                         }
                     }
                 }
             }
         }
-    }
+    } while (0);
+
+    if (proc->size > 0 && is_listener)
+        return CON_APP;
+    if (proc->size > 0)
+        return APPLICATION;
+    return CONNECTION;
 } 
 
 /*calculer le max filedescriptor*/
diff --git a/core/communication.h b/core/communication.h
index 5a7bb82..ad10601 100644
--- a/core/communication.h
+++ b/core/communication.h
@@ -18,8 +18,9 @@
 
 #define PATH_MAX BUFSIZ
 
-#define CONNECTION 0
+#define CONNECTION  0
 #define APPLICATION 1
+#define CON_APP     2
 
 struct service {
     unsigned int version;
@@ -42,7 +43,7 @@ int srv_accept (struct service *srv, struct process *p);
 int srv_read (const struct process *, struct msg *m);
 int srv_write (const struct process *, const struct msg *m);
 
-int srv_select(struct array_proc *, struct service *, struct process **);
+int srv_select (struct array_proc *, struct service *, struct array_proc *);
 
 int getMaxFd(struct array_proc *);
 
diff --git a/core/msg.h b/core/msg.h
index c2c904b..70cd632 100644
--- a/core/msg.h
+++ b/core/msg.h
@@ -5,11 +5,12 @@
 #include <stdlib.h>
 #include <string.h>
 
-#define MSG_TYPE_CON    1
-#define MSG_TYPE_DIS    2
-#define MSG_TYPE_ERR    3
-#define MSG_TYPE_ACK    4
-#define MSG_TYPE_DATA   5
+#define MSG_TYPE_CON                1
+#define MSG_TYPE_DIS                2
+#define MSG_TYPE_ERR                3
+#define MSG_TYPE_ACK                4
+#define MSG_TYPE_DATA               5
+#define MSG_TYPE_ACK_DIS            6
 
 struct msg {
     char type;
diff --git a/core/process.c b/core/process.c
index 507a3ac..4e2f7df 100644
--- a/core/process.c
+++ b/core/process.c
@@ -52,25 +52,36 @@ int add_proc (struct array_proc *aproc, struct process *p)
 int del_proc (struct array_proc *aproc, struct process *p)
 {
     assert(aproc != NULL);
+    assert(aproc->tab_proc != NULL);
     assert(p != NULL);
 
+    if (aproc->tab_proc == NULL) {
+        return -1;
+    }
+
     int i;
     for (i = 0; i < aproc->size; i++) {
         if (aproc->tab_proc[i] == p) {
 
             aproc->tab_proc[i] = aproc->tab_proc[aproc->size-1];
             aproc->size--;
-            aproc->tab_proc = realloc(aproc->tab_proc
-                    , sizeof(struct process) * aproc->size);
-
-            if (aproc->tab_proc == NULL) {
-                return -1;
+            if (aproc->size == 0) {
+                array_proc_free (aproc);
             }
+            else {
+                aproc->tab_proc = realloc(aproc->tab_proc
+                        , sizeof(struct process) * aproc->size);
+
+                if (aproc->tab_proc == NULL) {
+                    return -2;
+                }
+            }
+
             return 0;
         }
     }
 
-    return -2;
+    return -3;
 }
 
 void process_print (struct process *p)
@@ -91,6 +102,9 @@ void array_proc_print (struct array_proc *ap)
 
 void array_proc_free (struct array_proc *ap)
 {
-    if (ap->tab_proc != NULL)
-        free (ap->tab_proc), ap->tab_proc = NULL;
+    if (ap->tab_proc != NULL) {
+        free (ap->tab_proc);
+        ap->tab_proc = NULL;
+    }
+    ap->size = 0;
 }
diff --git a/core/process.h b/core/process.h
index f6ed0fe..cf65f45 100644
--- a/core/process.h
+++ b/core/process.h
@@ -12,11 +12,9 @@ struct array_proc {
 	int size;
 };
 
-// TODO
-// tout revoir
-int add_proc(struct array_proc *, struct process *);
+int add_proc (struct array_proc *, struct process *);
 
-int del_proc(struct array_proc *, struct process *);
+int del_proc (struct array_proc *aproc, struct process *p);
 
 void array_proc_print (struct array_proc *);
 void array_proc_free (struct array_proc *);
diff --git a/core/usocket.c b/core/usocket.c
index 4a6a12b..908d79e 100644
--- a/core/usocket.c
+++ b/core/usocket.c
@@ -10,8 +10,8 @@
 
 int usock_send (const int fd, const char *buf, const int msize)
 {
-    print_hexa ("msg send", (unsigned char *)buf, msize);
-    fflush(stdout);
+    // print_hexa ("msg send", (unsigned char *)buf, msize);
+    // fflush(stdout);
 
     int ret = 0;
     //printf ("%ld bytes to write\n", msize);
@@ -53,8 +53,8 @@ int usock_recv (const int fd, char **buf, size_t *msize)
         return ret;
     }
     *msize = (size_t) ret;
-    print_hexa ("msg recv", (unsigned char *)*buf, *msize);
-    fflush(stdout);
+    // print_hexa ("msg recv", (unsigned char *)*buf, *msize);
+    // fflush(stdout);
     return ret;
 }
 
diff --git a/pong/app/Makefile b/pong/app/Makefile
index 6972c25..239c6f7 100644
--- a/pong/app/Makefile
+++ b/pong/app/Makefile
@@ -9,6 +9,10 @@ TESTS=$(addsuffix .test, $(EXEC))
 
 all: $(SOURCES) $(EXEC)
 
+test:
+	rm /tmp/ipc/pongd-0-0
+	./pongd.bin
+
 $(EXEC): $(OBJECTS) $(CFILES)
 	$(CC) $(CFLAGS) $(LDFLAGS) $(OBJECTS) $@.c -lcbor -o $@.bin
 
diff --git a/pong/app/pingpong.c b/pong/app/pingpong.c
deleted file mode 100644
index f795018..0000000
--- a/pong/app/pingpong.c
+++ /dev/null
@@ -1,108 +0,0 @@
-#include "../../core/communication.h"
-#include <sys/socket.h>
-#include <sys/un.h>
-#include "../../core/process.h"
-#include <unistd.h>
-
-#define PONGD_SERVICE_NAME "pongd"
-#define handle_error(msg) \
-    do { perror(msg); exit(EXIT_FAILURE); } while (0)
-
-
-
-/*
- * main loop
- *
- * opens the application pipes,
- * reads then writes the same message,
- * then closes the pipes
- */
-
-void main_loop (struct service *srv)
-{
-
-    size_t msize = BUFSIZ;
-    char *buf = NULL;
-    if ( (buf = malloc (BUFSIZ)) == NULL) {
-        handle_error ("malloc");
-    }
-    memset (buf, 0, BUFSIZ);
-
-    int i,ret, cpt = 0; 
-
-    struct array_proc ap;
-    memset(&ap, 0, sizeof(struct array_proc));
-
-    struct process *p2 = malloc(sizeof(struct process));
-
-    while(cpt < 5) {
-        ret = srv_select(&ap, srv, &p2);
-        
-        if (ret == CONNECTION) {
-            struct process *p = malloc(sizeof(struct process));
-            memset(p, 0, sizeof(struct process));
-            if (srv_accept (srv, p) < 0) {
-                handle_error("srv_accept < 0");
-            }else {
-                printf("new connection\n");
-            }
-
-            if (add_proc(&ap, p) < 0) {
-                handle_error("add_proc < 0");
-            }
-            cpt++;
-        } else {
-            if (srv_read(p2, &buf, &msize) < 0) {
-                handle_error("srv_read < 0");
-            }
-            
-            if (srv_write (p2, buf, msize) < 0) {
-                handle_error("srv_write < 0");
-            }
-        }
-    }
-
-    for (i = 0; i < ap.size; i++) {
-        if (srv_close_proc (ap.tab_proc[i]) < 0) {
-            handle_error( "srv_close_proc < 0");
-        }
-    }
-}
-
-
-/*
- * service ping-pong
- *
- * 1. creates the named pipe /tmp/<service>, then listens
- * 2. opens the named pipes in & out
- * 3. talks with the (test) program
- * 4. closes the test program named pipes
- * 5. removes the named pipe /tmp/<service>
- */
-
-int main(int argc, char * argv[], char **env)
-{
-    struct service srv;
-    memset (&srv, 0, sizeof (struct service));
-    srv.index = 0;
-    srv.version = 0;
-    unlink("/tmp/ipc/pongd-0-0");
-    if (srv_init (argc, argv, env, &srv, PONGD_SERVICE_NAME) < 0) {
-        handle_error("srv_init < 0");
-        return EXIT_FAILURE;
-    }
-    printf ("Listening on %s.\n", srv.spath);
-
-    printf("MAIN: server created\n" );
-
-    // the service will loop until the end of time, a specific message, a signal
-    main_loop (&srv);
-
-    // the application will shut down, and remove the service named pipe
-    if (srv_close (&srv) < 0) {
-        handle_error("srv_close < 0");
-
-    }
-
-    return EXIT_SUCCESS;
-}
diff --git a/pong/app/pong.c b/pong/app/pong.c
new file mode 100644
index 0000000..966c91c
--- /dev/null
+++ b/pong/app/pong.c
@@ -0,0 +1,117 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "../../core/msg.h"
+#include "../../core/error.h"
+#include "../../core/communication.h"
+
+#define MSG "coucou"
+#define SERVICE_NAME "pongd"
+
+void non_interactive (int argc, char *argv[], char *env[])
+{
+    struct msg m;
+    memset (&m, 0, sizeof (struct msg));
+    struct service srv;
+    memset (&srv, 0, sizeof (struct service));
+
+    // index and version should be filled
+    srv.index = 0;
+    srv.version = 0;
+
+    // init service
+    if (app_connection (argc, argv, env, &srv, SERVICE_NAME, NULL, 0) < 0) {
+        handle_err("main", "srv_init < 0");
+        exit (EXIT_FAILURE);
+    }
+
+    printf ("msg to send: %s\n", MSG);
+    msg_format_data (&m, MSG, strlen(MSG) +1);
+    printf ("msg to send in the client: ");
+    print_msg (&m);
+    if (app_write (&srv, &m) < 0) {
+        handle_err("main", "app_write < 0");
+        exit (EXIT_FAILURE);
+    }
+    msg_free (&m);
+
+    if (app_read (&srv, &m) < 0) {
+        handle_err("main", "app_read < 0");
+        exit (EXIT_FAILURE);
+    }
+
+    printf ("msg recv: %s\n", m.val);
+    msg_free (&m);
+
+    if (app_close (&srv) < 0) {
+        handle_err("main", "app_close < 0");
+        exit (EXIT_FAILURE);
+    }
+}
+
+void interactive (int argc, char *argv[], char *env[])
+{
+    struct msg m;
+    memset (&m, 0, sizeof (struct msg));
+    struct service srv;
+    memset (&srv, 0, sizeof (struct service));
+
+    char buf[BUFSIZ];
+    memset (buf, 0, BUFSIZ);
+    int n;
+
+    // index and version should be filled
+    srv.index = 0;
+    srv.version = 0;
+
+    // init service
+    if (app_connection (argc, argv, env, &srv, SERVICE_NAME, NULL, 0) < 0) {
+        handle_err ("main", "srv_init < 0");
+        exit (EXIT_FAILURE);
+    }
+
+    while (1) {
+        printf ("msg to send: ");
+        fflush (stdout);
+        n = read (0, buf, BUFSIZ);
+
+        if (n == 0 || strncmp (buf, "exit", 4) == 0)
+            break;
+
+        msg_format_data (&m, buf, strlen(buf) +1);
+        memset (buf, 0, BUFSIZ);
+
+        // print_msg (&m);
+
+        if (app_write (&srv, &m) < 0) {
+            handle_err("main", "app_write < 0");
+            exit (EXIT_FAILURE);
+        }
+        msg_free (&m);
+
+        if (app_read (&srv, &m) < 0) {
+            handle_err("main", "app_read < 0");
+            exit (EXIT_FAILURE);
+        }
+
+        printf ("msg recv: %s", m.val);
+        msg_free (&m);
+    }
+
+    if (app_close (&srv) < 0) {
+        handle_err("main", "app_close < 0");
+        exit (EXIT_FAILURE);
+    }
+}
+
+int main (int argc, char *argv[], char *env[])
+{
+    if (argc == 1)
+        non_interactive (argc, argv, env);
+    else
+        interactive (argc, argv, env);
+
+    return EXIT_SUCCESS;
+}
diff --git a/pong/app/pongd.c b/pong/app/pongd.c
new file mode 100644
index 0000000..de9adcf
--- /dev/null
+++ b/pong/app/pongd.c
@@ -0,0 +1,144 @@
+#include "../../core/communication.h"
+#include "../../core/process.h"
+#include "../../core/error.h"
+
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <unistd.h>
+
+#define PONGD_SERVICE_NAME "pongd"
+
+int cpt = 0;
+
+void handle_new_connection (struct service *srv, struct array_proc *ap)
+{
+    struct process *p = malloc(sizeof(struct process));
+    memset(p, 0, sizeof(struct process));
+
+    if (srv_accept (srv, p) < 0) {
+        handle_error("srv_accept < 0");
+    } else {
+        printf("new connection\n");
+    }
+
+    if (add_proc (ap, p) < 0) {
+        handle_error("add_proc < 0");
+    }
+
+    cpt++;
+    printf ("%d client(s)\n", cpt);
+}
+
+void handle_new_msg (struct array_proc *ap, struct array_proc *proc_to_read)
+{
+    struct msg m;
+    memset (&m, 0, sizeof (struct msg));
+    int i;
+    for (i = 0; i < proc_to_read->size; i++) {
+        // printf ("loop handle_new_msg\n");
+        if (srv_read (proc_to_read->tab_proc[i], &m) < 0) {
+            handle_error("srv_read < 0");
+        }
+
+        // close the process then delete it from the process array
+        if (m.type == MSG_TYPE_DIS) {
+            cpt--;
+            printf ("disconnection => %d client(s) remaining\n", cpt);
+
+            if (srv_close_proc (proc_to_read->tab_proc[i]) < 0)
+                handle_error( "srv_close_proc < 0");
+            if (del_proc (ap, proc_to_read->tab_proc[i]) < 0)
+                handle_error( "del_proc < 0");
+            if (del_proc (proc_to_read, proc_to_read->tab_proc[i]) < 0)
+                handle_err( "handle_new_msg", "del_proc < 0");
+            i--;
+            continue;
+        }
+
+        printf ("new message : %s", m.val);
+        if (srv_write (proc_to_read->tab_proc[i], &m) < 0) {
+            handle_error("srv_write < 0");
+        }
+    }
+}
+
+/*
+ * main loop
+ *
+ * accept new application connections
+ * read a message and send it back
+ * close a connection if MSG_TYPE_DIS received
+ */
+
+void main_loop (struct service *srv)
+{
+    int i, ret = 0; 
+
+    struct array_proc ap;
+    memset(&ap, 0, sizeof(struct array_proc));
+
+    struct array_proc proc_to_read;
+    memset(&proc_to_read, 0, sizeof(struct array_proc));
+
+    while(1) {
+        ret = srv_select (&ap, srv, &proc_to_read);
+        // printf ("on peut lire ces process:\n");
+        // array_proc_print (&proc_to_read);
+        // printf ("-- \n\n");
+
+        if (ret == CONNECTION) {
+            handle_new_connection (srv, &ap);
+        } else if (ret == APPLICATION) {
+            handle_new_msg (&ap, &proc_to_read);
+        } else { // both new connection and new msg from at least one client
+            handle_new_connection (srv, &ap);
+            handle_new_msg (&ap, &proc_to_read);
+        }
+        array_proc_free (&proc_to_read);
+    }
+
+    for (i = 0; i < ap.size; i++) {
+        if (srv_close_proc (ap.tab_proc[i]) < 0) {
+            handle_error( "srv_close_proc < 0");
+        }
+    }
+}
+
+
+/*
+ * service ping-pong
+ *
+ * 1. creates the named pipe /tmp/<service>, then listens
+ * 2. opens the named pipes in & out
+ * 3. talks with the (test) program
+ * 4. closes the test program named pipes
+ * 5. removes the named pipe /tmp/<service>
+ */
+
+int main(int argc, char * argv[], char **env)
+{
+    struct service srv;
+    memset (&srv, 0, sizeof (struct service));
+    srv.index = 0;
+    srv.version = 0;
+
+    // unlink("/tmp/ipc/pongd-0-0");
+
+    if (srv_init (argc, argv, env, &srv, PONGD_SERVICE_NAME) < 0) {
+        handle_error("srv_init < 0");
+        return EXIT_FAILURE;
+    }
+    printf ("Listening on %s.\n", srv.spath);
+
+    printf("MAIN: server created\n" );
+
+    // the service will loop until the end of time, a specific message, a signal
+    main_loop (&srv);
+
+    // the application will shut down, and remove the service named pipe
+    if (srv_close (&srv) < 0) {
+        handle_error("srv_close < 0");
+    }
+
+    return EXIT_SUCCESS;
+}