Version 5.0 The LEDA User Manual

4.14 Socket Streambuffer ( socket streambuf )
1. Definition
An instance sb of class socket streambuf can be used as an adapter: It turns a leda socket
s into a C++-streambuf object. This object can be used in standard C++ ostreams and
istreams to make the communication through the socket easier. A socket streambuf can
also be applied within an encoding ostream or a decoding istream provided by LEDA to
send compressed or encrypted data over a socket connection (see Sections 9.19 and 9.20).
Observe that socket streambuf itself does not apply cryptography to secure the transmitted
data. All data is sent as it is. If you want to secure your data, consider using the
class secure socket streambuf (see Section 10.7).
If two parties want to use the class socket streambuf to exchange data they have to do
the following. First they establish a connection through leda sockets. Then each party
contructs an instance of the class socket streambuf which is attached to its socket. This
is shown in an example at the end of this manual page.
Every instance sb has an out-buffer where outgoing data is buffered before it is sent
through the socket over the internet. In addition it has an in-buffer to store data that
has been received through the socket. The user may specify the maximum size of each
buffer. The actual size of each buffer is determined in a negotiation between the server
and the client at the beginning of the communication. The size of outgoing packets from
the server is set to the minimum of the out-buffer size of the server and the in-buffer size
of the client. The size of the incoming packets is determined in an analogous way.
#include < LEDA/coding/socket streambuf.h >
2. Creation
socket streambuf
sb(leda socket& s, uint32 out buf sz = DefaultBufferSize,
uint32 in buf sz = DefaultBufferSize,
bool send acknowledge = false);
creates a sb and attaches it to the socket s. The parameters
out buf sz and in buf sz determine the maximum size of the outbuffer
and the in-buffer. send acknowledge specifies whether an
acknowledgement is sent for every received packet.
Precondition: The connection between the server and the client
must have been established when sb is created.
3. Operations
The class socket streambuf inherits most of its operations from the class streambuf that
belongs to the C++ standard library. Usually there is no need to call these operations
explicitly. (You can find documentation for streambuf at http://www.cplusplus.com)