Question

There is boost::asio::buffer that creates buffer sequence with only one element. Is there any wrapper that allows to create buffer sequence from several buffers?

Answer 1

There is no wrapper, but you can provide multiple buffers in any container that meets the MutableBufferSequence and ConstBufferSequence concepts requirements, such as std::vector, std::list, or boost::array. Most functions are implemented in terms of the BufferSequence concepts, and boost::asio::buffer provides a conveinent way to wrap a single buffer into a type that meets the requirements. This documentation briefly mentions it.

Here is a snippet from the Boost.Asio serialization example:

// Write the serialized data to the socket. We use "gather-write" to send
// both the header and the data in a single write operation.
std::vector<boost::asio::const_buffer> buffers;
buffers.push_back(boost::asio::buffer(outbound_header_));
buffers.push_back(boost::asio::buffer(outbound_data_));
boost::asio::async_write(socket_, buffers, handler);

Note that the buffers collection does not need to remain in scope, as the documentation states that Boost.Asio may create copies as necessary. However, the underlying memory , outbound_header_ and outbound_data_, need to remain valid until the handler is called.