Welcome to MDProxy Home Page
MDProxy works as a proxy for many devices in a server machine,
abstracting all this devices to be tcp/ip reachable sources.
It support "multicast " and "issolation" communication.
Actually it can work opening:
- rs232 ports (actually only at 38400 bauds but will be able
to configure it in next release)
- sockets connections, acting like "client".
- PIPE, for read or write.
- peer to peer to another mdproxy.
MDProxy was created?
MDProxy was created due as a part of another bigger project that reads
many rs232 ports.
The project works with an industrial machine, it reads some data at the
start of the process and automatically take care of the rest of the
preocess. The problem raise when one of the cheaf wanted to serialize
the process. So, now we have two machines, one behind the
other, and only one entry point.
Instead of split rs232 connections, I though that create a proxy to
share with N clients could be a better idea, so, here we are.
The other reason, that I think that this proxy is important, is because
it abstract the clients from hardware details and anything that could
be a problem.
Using MDProxy for testing
This is VERY usefull in TESTING, due you can change a serial device for
a PIPE or even a TCP/IP socket connection WITHOUT CHANGING your
application! Now you can send/recive data from PIPE while you
are TESTING and you can use rs232 in REAL installation without problems!
Just go to sourceforge download section for this project.
How it works?
Just let us explain using some examples how MDProxy works.
Case 1) Simple
connection to one resource.
MDProxy configuration: Is connected to one serial port device (rs232)
named "SA" (see protocol spec).
ClientA connects to MDProxy and ask about resource SA (client does not
need to know what kind of resource is, just needs it's name).
MDProxy accepts the query so henceforth ClientA and SA are
connected. So, every data that SA sends, will forwarder to
ClientA, and vice versa. Note that the connection is
Case 2) One client to many resources.
MDProxy configuration: Is connected to two serial ports (rs232) named
SA and SB.
ClientA connects to MDPRoxy and ask about resource SA and SB (rs232
both). MDProxy accept the connection, so, ClientA and resources SA and
SB are connected.
In this case, when SA sends data, this data will be forwarder to
ClientA. The same when SB sends data. (SA and SB don't see
each other). BUT when ClientA sends data, both, SA and SB will recive
Case 3) Many clients to many resources.
MDProxy configuration: you have 3 serial ports (rs232) named SA, SB and
This example will continue the case 2. Please, read it before.
Now, ClientB connects to mdproxy asking for resource SB and
SC. Now, ClientB, SB and SC are connected. (Note that SB in
shared by ClientA too).
So, when SB sends data, this will be forwarder to ClientA AND
ClientB. BUT, when ClientB send data, that will be forwarder
to SB and SC, but NOT to ClientA. (Client Isolation).
Protocol is very simple at this version. Please, see
"Protocol in the future" to see the direction of new releases.
When a new client is connected, MDProxy will expect for resources
query, this must be done using:
1000 R1 R2 R3 R4 R5...
Where 1000 is the "header" for query for resources and Rn are the name
of the resources (SA, SB and SC in the examples before).
If all is OK, you will recive "1001", if something is wrong (ie. the
resource name that not exist) you will recive "1002 R1 R2.." where 1002
is a NOTOK response, and Rn are the name of the problematic resources.
If you recive 1002 response, with n resources, and n is minor that the
number of resource that you asked for, the resources not in 1002
message where connected OK.
Important! READ IT!
Once the connection are
established, all data will be raw forwarder, so, if you where conected
to 2 or more devices, the proxy will no indicate from where of the
devices come from! Please, see "Protocol in the future" to see the
direction of new releases.
Protocol in the future
The protocol actually has 2 major inconvenients:
* The are no
autentication and/or encryptation when you connect to proxy or during
it's operation. Please, be carefull with
that. Perhaps using ipchains would help at least filter by ip.
* When a
connection sends data to MDProxy (resource or client), and it is
forwarder to the entities associated with this connection, the data
will be "raw" forwarded to ALL the connected devices/clients.
So, if you where conected to 2 or more devices, the proxy will NOT
indicate from where of the devices comes! or if you send data, this
data will be forwarder to ALL of the devices that you were connected!
This WAS INTENTIONAL done to be "legacy" compatible, so, if you have
electronic devices or application that you need to use, MDProxy will be
transparent for them.
Obviusly, the future in the protocol will be considering this two
* Add ssl connection and
login to secure communication between client and proxy.
* Add a "resource
identification" to know which of the devices has sended data or to be
able to select the device/s you want to send data.
This "resource identification", will only work in client/proxy
connections. For resources connections will strip the
protocol data, and sended only data, just to be "legacy" compatible
with devices/applications connected to ie. rs232.
Project Home Page
Please, do not hesitate to contact me at aguirrel at xuar.com.ar .