def data_stream(size = -1, offset = 0, &block)
headers = {'content-type'=>'application/json'}
if size.to_i > 0
range = sprintf("bytes=%d-%d", offset.to_i, (offset.to_i + size.to_i) - 1)
headers['Range'] = range
end
server = @container.swift.connection.service_host
path = @container.swift.connection.service_path + URI.encode("/#{@containername}/#{@name}")
port = @container.swift.connection.service_port
scheme = @container.swift.connection.service_scheme
response = @container.swift.connection.csreq("GET", server, path, port, scheme, headers, nil, 0, &block)
raise OpenStack::Exception.raise_exception(response) unless response.code.match(/^20.$/)
response
end