diff --git a/include/sxmp/limits.h b/include/sxmp/limits.h
index e532fb0..79f7cba 100644
--- a/include/sxmp/limits.h
+++ b/include/sxmp/limits.h
@@ -33,9 +33,11 @@
 
 #define MAX_SXMPLTHREADS  8
 
-#define MAX_MSGINPROCESS  1024
+#define MAX_MSGINPROCESS     1024
+#define MAX_CHANNELSOPENED   512
+#define MAX_STREAMSOPENED    256
 
-#define MAX_STREAMS_TYPES  32767
+#define MAX_STREAMS_TYPES    32767
 
 #define MAX_LINKS  32768
 
diff --git a/include/sxmp/sxmp.h b/include/sxmp/sxmp.h
index 44a2324..60d5bf7 100644
--- a/include/sxmp/sxmp.h
+++ b/include/sxmp/sxmp.h
@@ -41,6 +41,7 @@
 
 #include <sxmp/errno.h>
 #include <sxmp/version.h>
+#include <sxmp/limits.h>
 
 #define VERIFY_DEPTH  1  /* FIXME: */
 
@@ -100,12 +101,13 @@ typedef struct __sxlink_t {
   pthread_mutex_t write_pending_lock;
   volatile uint8_t pending_messages; /** < pending message count */
   /* stream part */
-  pthread_rwlock_t stream_rwlock;
-  usrtc_t *stream_list;
-  usrtc_t *remote_streams;
+  struct sxstream_opened **streams;
+  idx_allocator_t idx_streams;
+  pthread_mutex_t idx_streams_lock;
+  usrtc_t *remote_streams; /** < streams from remote host */
   /* Other stuff */
   sxmp_proto_version_t cp_version;
-  pthread_t thrd_poll[8];
+  pthread_t thrd_poll[MAX_SXMPLTHREADS];
   volatile uint8_t flags; /** < flags of the connection */
   volatile uint8_t usecount; /** < use count for the connection link */
   usrtc_node_t csnode; /** < node to store the link within list */
@@ -191,11 +193,11 @@ struct sxstream_opened {
   void *priv;
   uint64_t off;
   uint16_t flags;
-  usrtc_node_t node;
+  uint16_t pin_channelid;
 };
 
 struct sxstream_ops {
-  int (*s_open)(struct sxstream_opened *, const char *);
+  int (*s_open)(sxlink_t *, struct sxstream_opened *, const char *);
   int (*s_close)(struct sxstream_opened *);
   union {
     size_t (*s_bread)(struct sxstream_opened *, size_t, uint64_t, void *);
diff --git a/lib/stream.c b/lib/stream.c
index 2e42b8e..20eff30 100644
--- a/lib/stream.c
+++ b/lib/stream.c
@@ -478,18 +478,184 @@ list_head_t *sxstream_readnamed(sxstream_t *stream)
 }
 
 /* builtin functions for streams */
+static struct sxstream_opened *__alloc_stream(sxlink_t *link)
+{
+  int idx;
+  struct sxstream_opened *stream;
+
+  pthread_mutex_lock(&link->idx_streams_lock);
+  idx = idx_allocate(&link->idx_streams);
+  pthread_mutex_unlock(&link->idx_streams_lock);
+  if(idx == IDX_INVAL) return NULL;
+  else stream = link->streams[idx];
+
+  if(!link->streams[idx] && !(stream = malloc(sizeof(struct sxstream_opened)))) {
+  __inval:
+    pthread_mutex_lock(&link->idx_streams_lock);
+    idx_free(&link->idx_streams, idx);
+    pthread_mutex_unlock(&link->idx_streams_lock);
+
+    return NULL;
+  } else if(link->streams[idx]) goto __inval;
+
+  memset(stream, 0, sizeof(struct sxstream_opened));
+  stream->sto_id = idx;
+  link->streams[idx] = stream;
+
+  return stream;
+}
+
+static void __free_stream(sxlink_t *link, struct sxstream_opened *stream)
+{
+  pthread_mutex_lock(&link->idx_streams_lock);
+  idx_free(&link->idx_streams, stream->sto_id);
+  link->streams[stream->sto_id] = NULL;
+  pthread_mutex_unlock(&link->idx_streams_lock);
+
+  free(stream);
+
+  return;
+}
+
 int _builtin_stream_open(void *m, sexp_t *sx)
 {
   sxmsg_t *msg = (sxmsg_t *)m;
+  sxchnl_t *channel = msg->pch;
+  sxlink_t *link = NULL;
+  sxhub_t *hub;
+  sexp_t *isx, *iisx;
+  char *rbuf = NULL, *opt = NULL, *s_opt = NULL;
+  usrtc_node_t *node;
+  struct sxstream_description *s_desc;
+  struct sxstream_opened *strea;
+  size_t rbuf_len;
+  int chan_type, idx, r = SXE_FAILED;
+  int flags = 0, des_type, iidx;
 
-  return sxmsg_return(msg, SXE_FAILED);
+  if(!channel) goto __fail;
+  link = channel->link;
+  chan_type = channel->type_id;
+
+  if(!link || !channel->rpc_list) goto __fail; /* paranoid test */
+
+  /* parse incoming builtin function */
+  SEXP_ITERATE_LIST(sx, isx, idx) {
+    if(!idx && isx->ty == SEXP_LIST) {
+    __badproto:
+      r = SXE_BADPROTO;
+      goto __fail;
+    } else if(idx && isx->ty != SEXP_LIST) goto __badproto;
+
+    if(isx->ty == SEXP_LIST) {
+      SEXP_ITERATE_LIST(isx, iisx, iidx) {
+        if(iisx->ty == SEXP_LIST) goto __badproto;
+        switch(iidx) {
+        case 0:
+          opt = iisx->val;
+
+          if(*opt != ':') goto __badproto;
+          break;
+        case 1:
+          if(!strcmp(opt, _SXSTREAMTYPE_PREFIX)) des_type = atoi(iisx->val);
+          else if(!strcmp(opt, _SXSTREAMFLAGS_PREFIX)) flags = atoi(iisx->val);
+          else if(!strcmp(opt, _SXSTREAMOPT_PREFIX)) s_opt = iisx->val;
+          else goto __badproto;
+          break;
+        default: goto __badproto; break;
+        }
+      }
+    } else goto __badproto;
+  }
+
+  /* check availability */
+  hub = link->ssys;
+  if(!hub->streams) {
+  __nostream:
+    r = SXE_NOSUCHSTREAMTYPE;
+    goto __fail;
+  }
+  if(!(node = usrtc_lookup(hub->streams, &des_type))) goto __nostream;
+  else s_desc = (struct sxstream_description *)usrtc_node_getdata(node);
+
+  if(s_desc->pcid != chan_type) { /* check permission by channel */
+  __eperm:
+    r = SXE_EPERM;
+    goto __fail;
+  }
+  if(__flag_check(s_desc->flags, flags)) goto __eperm; /* by flags */
+
+  /* create a new remote side channel */
+  if(!(strea = __alloc_stream(link))) {
+    r = SXE_ENOMEM;
+    goto __fail;
+  }
+
+  /* rbuf length */
+  rbuf_len = _SXSTREAMCLOSE_ADDLEN + strlen(_SXSTREAMOPEN_CMD_R);
+
+  /* set stream details */
+  strea->desc = s_desc;
+  strea->flags = flags;
+  strea->pin_channelid = channel->cid;
+
+  r = s_desc->ops->s_open(link, strea, s_opt);
+  if(r != SXE_SUCCESS) {
+    /* deallocate stream */
+    __free_stream(link, strea);
+    goto __fail;
+  }
+  rbuf = sxmsg_rapidbuf(msg);
+  rbuf_len = snprintf(rbuf, rbuf_len, "(%s %lu)", _SXSTREAMOPEN_CMD_R,
+                      strea->sto_id);
+
+  return sxmsg_rreply(msg, rbuf_len + sizeof(char));
+
+ __fail:
+
+  return sxmsg_return(msg, r);
 }
 
 int _builtin_stream_close(void *m, sexp_t *sx)
 {
   sxmsg_t *msg = (sxmsg_t *)m;
+  sxchnl_t *channel = msg->pch;
+  sxlink_t *link = NULL;
+  struct sxstream_opened *stream = NULL;
+  sexp_t *isx;
+  uint64_t sid = 0;
+  int r = SXE_FAILED, idx;
 
-  return sxmsg_return(msg, SXE_FAILED);
+  if(!channel) goto __fini;
+  link = channel->link;
+
+  if(!link || !channel->rpc_list) goto __fini; /* paranoid test */
+
+  /* parse input */
+  SEXP_ITERATE_LIST(sx, isx, idx) {
+    if(isx->ty == SEXP_LIST) {
+    __badproto:
+      r = SXE_BADPROTO;
+      goto __fini;
+    }
+    switch(idx) {
+    case 0: r = SXE_BADPROTO; break;
+    case 1: sid = strtoul(isx->val, NULL, 0); r = SXE_SUCCESS; break;
+    default: goto __badproto; break;
+    }
+  }
+  if(r != SXE_SUCCESS) goto __fini;
+
+  /* get this */
+  stream = link->streams[(int)sid];
+  if(stream) {
+    if(stream->pin_channelid == channel->cid) {
+      r = SXE_SUCCESS;
+      r = stream->desc->ops->s_close(stream);
+    } else r = SXE_EPERM;
+  } else r = SXE_NOSUCHSTREAMTYPE;
+
+ __fini:
+  return sxmsg_return(msg, r);
 }
 
 int _builtin_stream_eread(void *m, sexp_t *sx)
diff --git a/lib/sxmplv2.c b/lib/sxmplv2.c
index 35c0556..79d708d 100644
--- a/lib/sxmplv2.c
+++ b/lib/sxmplv2.c
@@ -445,17 +445,28 @@ sxlink_t *__link_minimal_alloc(struct in_addr *addr)
   return NULL;
 }
 
+static long __cmp_u64(const void *a, const void *b)
+{
+  return *(uint64_t *)a - *(uint64_t *)b;
+}
+
 static int __link_second_alloc(sxlink_t *co)
 {
   usrtc_node_init(&co->csnode, co);
 
+  /* initialize index allocators */
   memset(&co->idx_ch, 0, sizeof(idx_allocator_t));
   memset(&co->idx_msg, 0, sizeof(idx_allocator_t));
-  if((idx_allocator_init(&co->idx_ch, 512, 0))) goto __fail;
+  memset(&co->idx_streams, 0, sizeof(idx_allocator_t));
+  if((idx_allocator_init(&co->idx_ch, MAX_CHANNELSOPENED, 0))) goto __fail;
   if((idx_allocator_init(&co->idx_msg, MAX_MSGINPROCESS, 0))) goto __fail;
+  if((idx_allocator_init(&co->idx_streams, MAX_STREAMSOPENED, 0))) goto __fail;
 
-  if(!(co->channels = malloc(sizeof(uintptr_t)*512))) goto __fail;
-  else memset(co->channels, 0, sizeof(uintptr_t)*512);
+  if(!(co->channels = malloc(sizeof(uintptr_t)*MAX_CHANNELSOPENED))) goto __fail;
+  else memset(co->channels, 0, sizeof(uintptr_t)*MAX_CHANNELSOPENED);
+
+  if(!(co->streams = malloc(sizeof(uintptr_t)*MAX_STREAMSOPENED))) goto __fail;
+  else memset(co->streams, 0, sizeof(uintptr_t)*MAX_STREAMSOPENED);
 
   /* init mutexes */
   pthread_mutex_init(&co->idx_ch_lock, NULL);
@@ -463,6 +474,7 @@ static int __link_second_alloc(sxlink_t *co)
   pthread_mutex_init(&co->write_pending_lock, NULL);
   pthread_mutex_init(&co->sslinout[0], NULL);
   pthread_mutex_init(&co->sslinout[1], NULL);
+  pthread_mutex_init(&co->idx_streams_lock, NULL);
 
   /* init list */
   list_init_head(&co->write_pending);
@@ -470,22 +482,29 @@ static int __link_second_alloc(sxlink_t *co)
   return SXE_SUCCESS;
 
  __fail:
+  if(co->channels) free(co->channels);
+  if(co->streams) free(co->streams);
   idx_allocator_destroy(&co->idx_msg);
   idx_allocator_destroy(&co->idx_ch);
+  idx_allocator_destroy(&co->idx_streams);
+
   return SXE_ENOMEM;
 }
 
 static void __link_second_free(sxlink_t *co)
 {
   if(co->channels) free(co->channels);
+  if(co->streams) free(co->streams);
   idx_allocator_destroy(&co->idx_msg);
   idx_allocator_destroy(&co->idx_ch);
+  idx_allocator_destroy(&co->idx_streams);
 
   pthread_mutex_destroy(&co->idx_ch_lock);
   pthread_mutex_destroy(&co->idx_msg_lock);
   pthread_mutex_destroy(&co->write_pending_lock);
   pthread_mutex_destroy(&co->sslinout[0]);
   pthread_mutex_destroy(&co->sslinout[1]);
+  pthread_mutex_destroy(&co->idx_streams_lock);
 
   return;
 }