Introduction

gTLV is a transport protocol that can be used to exchange generic information between two peers by means of Type-Length-Value (TLV) data encapsulation.

Applications may take advantage of this protocol by extending this specification with their specific requirements (actually, gTLV does not provide any functionality by itself). To do this, several requirements must be observed:

Usage

1. Application-specific attribute definitions must extend Attribute class. E.g.:

class MoteId(Attribute): type = 0x01 typedef = 'i'

def __init__(self, value):
    Attribute.__init__(self)
    self.value = value

2. Application-specific packet definitions must extend Packet class. E.g.:

class DataRequest(Packet): application = 0x01 code = 0x01 mandatory_attributes = {MoteId: 1}

def __init__(self):
    Packet.__init__(self)

3. A list of supported packet and attribute classes must be created:

class ListManager():
packet_list = PacketList((DataRequest,)) attribute_list = AttributeList((MoteId,))

4. Extend GtlvServer class to write the callback function that will be called after a packet is received:

class Server(GtlvServer): def callback(self, raw_packet): packet = decode(raw_packet, self.list_manager) return packet.get_values(MoteId)

5. Start the server in the server application:

server = Server("localhost", 50000, ListManager) server.start()

6. In the client application, a Target instance must be created, pointing to the server.

target = Target("localhost", 50000, ListManager)

7. Now, packets can be created and sent to the server:

new_packet = DataRequest() new_packet.add_attribute(MoteId(123)) rsp = target.send(new_packet) # rsp is whatever the callback function returns

Requirements

gTLV has only been tested against Python 2.5

Installation

gTLV uses the standard distutils system for installation:

python setup.py install