diff --git a/trunk/src/app/srs_app_http.cpp b/trunk/src/app/srs_app_http.cpp
index af895cc3e..3d5324a6b 100644
--- a/trunk/src/app/srs_app_http.cpp
+++ b/trunk/src/app/srs_app_http.cpp
@@ -552,7 +552,7 @@ char* SrsHttpMessage::http_ts_send_buffer()
 void SrsHttpMessage::reset()
 {
     _state = SrsHttpParseStateInit;
-    _body->clear();
+    _body->erase(_body->length());
     _url = "";
 }
 
@@ -666,8 +666,8 @@ string SrsHttpMessage::body()
 {
     std::string b;
     
-    if (_body && !_body->empty()) {
-        b.append(_body->bytes(), _body->size());
+    if (_body && _body->length() > 0) {
+        b.append(_body->bytes(), _body->length());
     }
     
     return b;
@@ -675,16 +675,12 @@ string SrsHttpMessage::body()
 
 char* SrsHttpMessage::body_raw()
 {
-    if (_body && !_body->empty()) {
-        return _body->bytes();
-    }
-    
-    return NULL;
+    return _body? _body->bytes() : NULL;
 }
 
 int64_t SrsHttpMessage::body_size()
 {
-    return (int64_t)_body->size();
+    return (int64_t)_body->length();
 }
 
 int64_t SrsHttpMessage::content_length()
diff --git a/trunk/src/kernel/srs_kernel_buffer.cpp b/trunk/src/kernel/srs_kernel_buffer.cpp
index c29d02dfd..b96915742 100644
--- a/trunk/src/kernel/srs_kernel_buffer.cpp
+++ b/trunk/src/kernel/srs_kernel_buffer.cpp
@@ -44,43 +44,38 @@ SrsBuffer::~SrsBuffer()
 {
 }
 
-int SrsBuffer::size()
+int SrsBuffer::length()
 {
-    return (int)data.size();
-}
-
-bool SrsBuffer::empty()
-{
-    return size() <= 0;
+    int len = (int)data.size();
+    srs_assert(len >= 0);
+    return len;
 }
 
 char* SrsBuffer::bytes()
 {
-    return &data.at(0);
+    return (length() == 0)? NULL : &data.at(0);
 }
 
-void SrsBuffer::erase(int _size)
+void SrsBuffer::erase(int size)
 {
-    if (_size == size()) {
-        clear();
+    srs_assert(size > 0);
+    
+    if (size == length()) {
+        data.clear();
         return;
     }
     
-    data.erase(data.begin(), data.begin() + _size);
-}
-
-void SrsBuffer::clear()
-{
-    data.clear();
+    data.erase(data.begin(), data.begin() + size);
 }
 
 void SrsBuffer::append(const char* bytes, int size)
 {
     srs_assert(size > 0);
+
     data.insert(data.end(), bytes, bytes + size);
 }
 
-int SrsBuffer::ensure_buffer_bytes(ISrsBufferReader* skt, int required_size)
+int SrsBuffer::grow(ISrsBufferReader* reader, int required_size)
 {
     int ret = ERROR_SUCCESS;
 
@@ -90,11 +85,11 @@ int SrsBuffer::ensure_buffer_bytes(ISrsBufferReader* skt, int required_size)
         return ret;
     }
 
-    while (size() < required_size) {
+    while (length() < required_size) {
         char buffer[SOCKET_READ_SIZE];
         
         ssize_t nread;
-        if ((ret = skt->read(buffer, SOCKET_READ_SIZE, &nread)) != ERROR_SUCCESS) {
+        if ((ret = reader->read(buffer, SOCKET_READ_SIZE, &nread)) != ERROR_SUCCESS) {
             return ret;
         }
         
diff --git a/trunk/src/kernel/srs_kernel_buffer.hpp b/trunk/src/kernel/srs_kernel_buffer.hpp
index 466dc1f8c..147136210 100644
--- a/trunk/src/kernel/srs_kernel_buffer.hpp
+++ b/trunk/src/kernel/srs_kernel_buffer.hpp
@@ -50,7 +50,7 @@ public:
 * protocol recv data from socket, put into buffer, decode to RTMP message.
 * protocol encode RTMP message to bytes, put into buffer, send to socket.
 */
-class SrsBuffer
+ class SrsBuffer
 {
 private:
     std::vector<char> data;
@@ -58,14 +58,34 @@ public:
     SrsBuffer();
     virtual ~SrsBuffer();
 public:
-    virtual int size();
-    virtual bool empty();
+    /**
+    * get the length of buffer.
+    * never negative, empty if zero.
+    */
+    virtual int length();
+    /**
+    * get the buffer bytes.
+    * @return the bytes, NULL if empty.
+    */
     virtual char* bytes();
+    /**
+    * erase size of bytes from begin.
+    * if size equals to length(), clear buffer.
+    * @param size
+    */
     virtual void erase(int size);
-    virtual void clear();
+    /**
+    * append specified bytes to buffer.
+    * @param size the size of bytes, assert positive.
+    */
     virtual void append(const char* bytes, int size);
 public:
-    virtual int ensure_buffer_bytes(ISrsBufferReader* skt, int required_size);
+    /**
+    * grow buffer to the required size, loop to read from skt to fill.
+    * @param reader, read more bytes from reader to fill the buffer to required size.
+    * @param required_size, loop to fill to ensure buffer size to required.
+    */
+    virtual int grow(ISrsBufferReader* reader, int required_size);
 };
 
 #endif
\ No newline at end of file
diff --git a/trunk/src/rtmp/srs_protocol_rtmp_stack.cpp b/trunk/src/rtmp/srs_protocol_rtmp_stack.cpp
index dbbc7a8cd..b769f9de7 100644
--- a/trunk/src/rtmp/srs_protocol_rtmp_stack.cpp
+++ b/trunk/src/rtmp/srs_protocol_rtmp_stack.cpp
@@ -869,7 +869,7 @@ int SrsProtocol::read_basic_header(char& fmt, int& cid, int& bh_size)
     int ret = ERROR_SUCCESS;
     
     int required_size = 1;
-    if ((ret = buffer->ensure_buffer_bytes(skt, required_size)) != ERROR_SUCCESS) {
+    if ((ret = buffer->grow(skt, required_size)) != ERROR_SUCCESS) {
         if (ret != ERROR_SOCKET_TIMEOUT && !srs_is_client_gracefully_close(ret)) {
             srs_error("read 1bytes basic header failed. required_size=%d, ret=%d", required_size, ret);
         }
@@ -889,7 +889,7 @@ int SrsProtocol::read_basic_header(char& fmt, int& cid, int& bh_size)
 
     if (cid == 0) {
         required_size = 2;
-        if ((ret = buffer->ensure_buffer_bytes(skt, required_size)) != ERROR_SUCCESS) {
+        if ((ret = buffer->grow(skt, required_size)) != ERROR_SUCCESS) {
             if (ret != ERROR_SOCKET_TIMEOUT && !srs_is_client_gracefully_close(ret)) {
                 srs_error("read 2bytes basic header failed. required_size=%d, ret=%d", required_size, ret);
             }
@@ -902,7 +902,7 @@ int SrsProtocol::read_basic_header(char& fmt, int& cid, int& bh_size)
         srs_verbose("%dbytes basic header parsed. fmt=%d, cid=%d", bh_size, fmt, cid);
     } else if (cid == 1) {
         required_size = 3;
-        if ((ret = buffer->ensure_buffer_bytes(skt, 3)) != ERROR_SUCCESS) {
+        if ((ret = buffer->grow(skt, 3)) != ERROR_SUCCESS) {
             if (ret != ERROR_SOCKET_TIMEOUT && !srs_is_client_gracefully_close(ret)) {
                 srs_error("read 3bytes basic header failed. required_size=%d, ret=%d", required_size, ret);
             }
@@ -982,7 +982,7 @@ int SrsProtocol::read_message_header(SrsChunkStream* chunk, char fmt, int bh_siz
     srs_verbose("calc chunk message header size. fmt=%d, mh_size=%d", fmt, mh_size);
     
     int required_size = bh_size + mh_size;
-    if ((ret = buffer->ensure_buffer_bytes(skt, required_size)) != ERROR_SUCCESS) {
+    if ((ret = buffer->grow(skt, required_size)) != ERROR_SUCCESS) {
         if (ret != ERROR_SOCKET_TIMEOUT && !srs_is_client_gracefully_close(ret)) {
             srs_error("read %dbytes message header failed. required_size=%d, ret=%d", mh_size, required_size, ret);
         }
@@ -1092,7 +1092,7 @@ int SrsProtocol::read_message_header(SrsChunkStream* chunk, char fmt, int bh_siz
         mh_size += 4;
         required_size = bh_size + mh_size;
         srs_verbose("read header ext time. fmt=%d, ext_time=%d, mh_size=%d", fmt, chunk->extended_timestamp, mh_size);
-        if ((ret = buffer->ensure_buffer_bytes(skt, required_size)) != ERROR_SUCCESS) {
+        if ((ret = buffer->grow(skt, required_size)) != ERROR_SUCCESS) {
             if (ret != ERROR_SOCKET_TIMEOUT && !srs_is_client_gracefully_close(ret)) {
                 srs_error("read %dbytes message header failed. required_size=%d, ret=%d", mh_size, required_size, ret);
             }
@@ -1219,7 +1219,7 @@ int SrsProtocol::read_message_payload(SrsChunkStream* chunk, int bh_size, int mh
     
     // read payload to buffer
     int required_size = bh_size + mh_size + payload_size;
-    if ((ret = buffer->ensure_buffer_bytes(skt, required_size)) != ERROR_SUCCESS) {
+    if ((ret = buffer->grow(skt, required_size)) != ERROR_SUCCESS) {
         if (ret != ERROR_SOCKET_TIMEOUT && !srs_is_client_gracefully_close(ret)) {
             srs_error("read payload failed. required_size=%d, ret=%d", required_size, ret);
         }