diff --git a/include/sxmp/sxmp.h b/include/sxmp/sxmp.h
index edac276..6c68cf5 100644
--- a/include/sxmp/sxmp.h
+++ b/include/sxmp/sxmp.h
@@ -227,6 +227,14 @@ struct sxstream_ops {
   };
 };
 
+typedef enum {
+  SXCRITICAL_LOG = 0,
+  SXERROR_LOG,
+  SXWARNING_LOG,
+  SXINFO_LOG,
+  SXDEBUG_LOG,
+} sxlogtype_t;
+
 /**
  * \brief Hub subsystem structure.
  *
@@ -251,6 +259,7 @@ typedef struct __sxhub_type {
                                                           * during setting up a typed channel */
   void (*on_destroy)(sxlink_t *); /** < callback on connection destroy  */
   void (*on_pulse)(sxlink_t *, sexp_t *);  /** < callback on pulse emit */
+  int (*log)(const sxlogtype_t, const char *, ...); /** < this function is used to output logs with user way */
   SSL_CTX *ctx; /** < SSL context */
   void *priv;
 } sxhub_t;
@@ -263,6 +272,12 @@ typedef struct __sxhub_type {
 #define sxhub_set_onpulse(c, f)  (c)->on_pulse = (f)
 #define sxhub_set_priv(c, p)  (c)->priv = (p)
 #define sxhub_get_priv(c)  (c)->priv
+#define sxhub_set_logops(c, f)  (c)->log = (f)
+
+/* this macro is used to make calling sxhub log function easier */
+#define sxlink_log(c, type, fmt, ...)                                          \
+  (c)->hub ? (c)->hub->log((type), (fmt), ## __VA_ARGS__) :                    \
+  fprintf(stderr, (fmt), ## __VA_ARGS__);
 
 typedef struct __rpc_typed_list_type {
   int type_id;
diff --git a/sxmp/hub.c b/sxmp/hub.c
index a74ba4b..362aafe 100644
--- a/sxmp/hub.c
+++ b/sxmp/hub.c
@@ -524,6 +524,16 @@ static long __cmp_cstr(const void *a, const void *b)
   return (long)strcmp((const char *)a, (const char *)b);
 }
 
+static int __sxhub_log_dummy(const sxlogtype_t type, const char *fmt, ...)
+{
+  int r;
+  va_list arglist;
+  va_start(arglist, fmt);
+  r = vfprintf(stderr, fmt, arglist);
+  va_end(arglist);
+  return r;
+}
+
 int sxhub_init(sxhub_t *ssys)
 {
   int r = 0;
@@ -573,6 +583,9 @@ int sxhub_init(sxhub_t *ssys)
     }
   }
 
+  /* set function pointers to default implementation */
+  sxhub_set_logops(ssys, __sxhub_log_dummy);
+
   return 0;
 
  __lfini:
diff --git a/sxmp/sxmplv2.c b/sxmp/sxmplv2.c
index 722c6f5..5d216af 100644
--- a/sxmp/sxmplv2.c
+++ b/sxmp/sxmplv2.c
@@ -95,7 +95,7 @@ static int __conn_read(sxlink_t *co, void *buf, size_t buf_len)
   ofcmode = fcntl(rfd, F_GETFL,0);
   ofcmode |= O_NDELAY;
   if(fcntl(rfd, F_SETFL, ofcmode))
-    fprintf(stderr, "[sxmplv2] (RD)Couldn't make socket nonblocking");
+    sxlink_log(co, SXERROR_LOG, "[sxmplv2] (RD)Couldn't make socket nonblocking");
 #endif
 
  __retry:
@@ -120,26 +120,26 @@ static int __conn_read(sxlink_t *co, void *buf, size_t buf_len)
     case SSL_ERROR_SYSCALL:
       if(errno == EAGAIN || errno == EINTR) goto __try_again;
       else {
-        fprintf(stderr, "[sxmplv2] (RD)SSL syscall error.\n");
+        sxlink_log(co, SXERROR_LOG, "[sxmplv2] (RD)SSL syscall error.\n");
         goto __close_conn;
       }
       break;
     case SSL_ERROR_WANT_CONNECT:
     case SSL_ERROR_WANT_ACCEPT:
-      fprintf(stderr, "[sxmplv2] (RD)SSL negotiation required. Trying again.\n");
+      sxlink_log(co, SXERROR_LOG, "[sxmplv2] (RD)SSL negotiation required. Trying again.\n");
       goto __try_again;
       break;
     case SSL_ERROR_SSL:
-      fprintf(stderr, "[sxmplv2] (RD)SSL error occured. Connection will be closed.\n");
+      sxlink_log(co, SXERROR_LOG, "[sxmplv2] (RD)SSL error occured. Connection will be closed.\n");
       goto __close_conn;
       break;
     case SSL_ERROR_ZERO_RETURN:
-      fprintf(stderr, "[sxmplv2] (RD)SSL connection is cleary closed.\n");
+      sxlink_log(co, SXERROR_LOG, "[sxmplv2] (RD)SSL connection is cleary closed.\n");
     default:
     __close_conn:
       ERR_free_strings();
       co->flags |= SXMP_CLOSED;
-      fprintf(stderr, "[sxmplv2] (RD)Unknown error on %s (errno = %d)\n", co->uuid, errno);
+      sxlink_log(co, SXERROR_LOG, "[sxmplv2] (RD)Unknown error on %s (errno = %d)\n", co->uuid, errno);
       ERR_remove_state(0);
       return -1;
     }
@@ -154,12 +154,12 @@ static int __conn_read(sxlink_t *co, void *buf, size_t buf_len)
     r = select(rfd + 1, &readset, NULL, NULL, NULL);
     if(r < 0) {
       if(errno == EINTR || errno == EAGAIN) goto __select_retry;
-      fprintf(stderr, "[sxmplv2] (RD)Select (%d) on %s\n", errno, co->uuid);
+      sxlink_log(co, SXERROR_LOG, "[sxmplv2] (RD)Select (%d) on %s\n", errno, co->uuid);
       ERR_remove_state(0);
       return -1;
     }
     if(!r) {
-      fprintf(stderr, "[sxmplv2] (RD)Nothing to wait for\n");
+      sxlink_log(co, SXERROR_LOG, "[sxmplv2] (RD)Nothing to wait for\n");
       ERR_remove_state(0);
       return 0;
     }
@@ -209,7 +209,7 @@ static int __conn_write(sxlink_t *co, void *buf, size_t buf_len)
       /* set closed flag */
       ERR_free_strings();
       co->flags |= SXMP_CLOSED;
-      fprintf(stderr, "[sxmplv2] (WR)Unknown error on %s (%d)\n", co->uuid, r);
+      sxlink_log(co, SXERROR_LOG, "[sxmplv2] (WR)Unknown error on %s (%d)\n", co->uuid, r);
       ERR_remove_state(0);
       return -1;
     } else return r;
@@ -811,7 +811,7 @@ static void *__sxmpl_thread(void *b)
           /* reply came ... */
           if(mid > (MAX_MSGINPROCESS - 1)) {
           __inval_idx_nor:
-            fprintf(stderr, "[sxmplv2] Invalid index of the message (%lu).\n", mid);
+            sxlink_log(co, SXERROR_LOG, "[sxmplv2] Invalid index of the message (%lu).\n", mid);
             goto __again;
           }