embedded devices in the ethernet network

[polarized]

Hi all,


What kind of server software and software in global on the server side would be necessary to implement or install or write to build a system in which embedded devices(clients) could be able to send some data to a server in the ethernet network and he would be able to correctly receive them and process the data. The system should not be complicated, I mean I would prefer it if its very simple without any complicated software. Is it possible to test this with a ordinary PC with a network card connected with the clients in a ethernet network? The embedded clients initiate a tcp/ip connection and send some data. I think this is called socket programming. The other side, the server side should receive the data and this is my question.


Regards.

 

[bogdanm]

Hello,

This is entirely possible, even trivial in some cases. If you are using Windows look in **broken link removed** or http://www.codeguru.com/ you'll find very good tutorials and libraries for socket applications. Basically all you need to do is to set up a socket server with some port number on the PC and then make connections to it. Yes, you can test it with an ordinary PC and a network card. And a hub or some other connection device between the PC and the Ethernet clients. All you have to do is to set up this connection, write some very simple software, setup all the IP addresses in the same network (192.168.x.x/netmask 255.255.0.0 is a good choice) and everything should work just fine.

 

[polarized]

Hi,

What would happen if I would like for instance to place the server application on the internet, for example is it possible to have an internet web page on which an server application or whatever is running and the embedded clients which are also on the internet are transmitting data towards it? What kind of server software is needed in this case? I do not have experience in network software matters, so every practical advice and hint will help me. Is this matter related to the Apache Tomcat server or any other kind of servers, or maybe JAVA language etc... What is the easiest method?



Regards.

 

[bogdanm]

There are many ways to do what you wish. Probably one of the easiest one is to use a simple HTTP server somewhere on the Internet. Just run a simple HTTP server and have your Ethernet devices send command to it in the URL, something like this:

GET hxxp://your.server.name/scriptname?devid=x@cmd=y@param1=p@...@paramn=q HTTP/1.0

"scriptname" is a script written in whatever language you want (CGI in C or PERL, PHP and many others) that is called when the web server gets this query and can act accordingly (even send a response back if required). It receives all the parameters you specify after "scpritname?". I used this method with a Bluetooth module that was connected with a simple PIC16F84 and it worked quite well. Be very careful though, just placing a web server on the Internet and letting him talk to your devices in this way in very unsecure. There are ways to overcome this, but when it comes to security I'm just a mere apprentice ...

 

[polarized]

embedded devices on the internet or ethernet

Hi again,



If I have an embedded device which is not capable of generating a real http GET request at the moment, but it is capable of communicating using tcp/ip sockets, requesting for a TCP/IP connection and sending data towards another device, is it possible for that embedded device to communicate with a http server? Is it possible to write a script or something else on the http server side which can intepret request for a socket connection, but not a real http GET request? This is all related to an GPRS module which has a limited TCP/IP stack inside, but only for socket communication. Everthing additional like http requests, ftp requests etc... has to be implemented with the outside electronics. I would like to minimise the system and use the limited tcp/ip capability of the GPRS modem. If this is not possible I would have to implement a whole TCP/IP and PPP stack or use an already made module(Rabbit, TINI etc...) My other question is: what is the easiest way of implementing some kind of security because data is coming from the embedded devices to the http server without any protection? Maybe some kind of coding of the data itself??

Regards.

 

[bogdanm]

You're a bit off my league here, but I'll try to answer anyway, please correct me if I'm wrong. As far as I know the HTTP server alone can only interpret HTTP comands (ex GET) by itself, for anything more you'll need some additional support. For example you could design a software converter on the server side that listens to your embedded devices (using sockets) and translates their requests into HTTP requests and then forwards them to the browser. However, if you do that, it might become more convenient to use that software alone, without the HTTP server. I can't give you a straight answer as I'm not aware of the specifications of your application. Anyway, this converter seems the best solution for you as it moves all the work to the software instead of the hardware.
As for the security part, I'm afraid I can't tell you much. You could of course encrypt the data as you said, but on the other hand you mentioned that you want to use the modules as they are. So maybe you could move the problem to the server side again. Add firewalls and use password protection for your software. Anything more would require modifying the hardware.