Webserver via GPRS

[crystal_lattice]

Hi there, this question is intended for the gurus of the comms world... or anybody else that can help...

I will make reference to the following so here are the links:

FTP Micro Server:

GSM/GPRS + GPS Module:

I recently stumbled upon the FTP Micro website and thought it looked very simple and quite basic.(basic meaning: all the hard work is done, you just have to build the kit and program the chip...) After discussing it with a friend we thought it would be nice to be able to combine an emmbeded webserver with its own independent internet connection (independent meaning: no land line required, no fixed power source and no pc running the software) So to end up with a "Black Box" that could be powered from a battery and would use GPRS and PIC to host a small web page or Blog.

Looking at this whole thing i do have a few questions, but first i will try and explain how i understand the whole thing so we can start off on the same page (or should i say "memory bank"...), so here goes:

The GSM/GPRS module output is RS232 so this will be considered the first layer
Then comes the TCP/IP which fits on top of that, namely the second layer
Now on top of that runs the HTTP
And this is being converted to GPRS data and sent via rf/gsm signals

So the way i understand it is that the link between the GSM/GPRS module and the PIC side of things is based on TCP/IP running over normal TTL Level signals, just like the FTP Micro communicates with a computer/network except no "Ethernet" conversion (eg. no funny 8 core cable with all kinds of signals, just plain Tx & Rx) so by implementing TCP/IP on PIC i can transfer data to/from GSM/GPRS module using two data lines. (TCP/IP just being the format or packets in which the data is represented, right?)


Now by implementing the appropriate protocols like HTTP or FTP on top of the TCP/IP (all ready running on the PIC) the TCP/IP can actually access web pages.

Now the questions:
******************

1. Is the above statements/structure correct? I don't know that much about all the operations of TCP/IP and all the related layers and things but want to know if i'm on the right track, and not hopelessly confusing myself...

2.Seeing that the GPRS module is running a TCP/IP stack does that mean it also has its own IP address, like another nodes on a network? So if one wants to simplify it, can it be said that this project is a FTP Micro communicating with a GPRS modem via TCP/IP?

3. Would it be possible to implement an Apache server? I know this might sound a bit difficult to answer with a simple yes or no, but would this be practically obtainable with the PIC regarding the resources available (i'm no expert in this field so i don't know what something like this entails, but if possible, would like to try it.)

4.I don't know much about servers and the internet but a server is supposed to be connected to the internet 24/7, so how is this done eg. how do i establish a connection to the net so OTHER users/computers can connect to me. i understand that i have to have a domain name and this gets directed to my site but it will only work once i'm connected. If a pc is connected to a network, the connection is there and data can be sent to a IP address, but with the gprs thing how are things started so that i'm "always" connected, eg. what am i connected to and how is it initiated?

5. Considering the HTTP, FTP and TCP/IP stack is already written (source code at FTP Micro site) the only things needed is a driver for the GPRS module (eg. initialize module) and the code to glue the parts together, not too difficult... right?

6. Has anyone used this module before, and if so how well did it work. I have only read the brocure and the hardware spec and was quite impressed with what i saw, but would like to know if it actually performs just as impressive or are there better/more user friendly devices out there?



PS. Yes i know the module also has GPS... It will be implemented at a later stage, seeing that these modules are expensive, i thought i will buy one with many features (within my budget of course!). An SD card formatted with FAT will be used for storage media, i didn't mention it here because i didn't want to clutter the explanation with unnecessary stuff, will sort that part out in another post... (have to implement SD card in other project as well)

[ckielstra]

The links to the FTP Micro Server and GPRS module are missing so hard to say anything specific about them.

In general your explanation makes sense, but ....
I do know many projects exist using a PIC as webserver but all those projects suffer from limitations by the small program and data memory sizes on the PIC. It will take a lot of time and effort to work around those limitations and why? There are other processor platforms out there that have much more power for only a few bucks extra.

Have you considered to write your software directly on the GPRS module itself? For example the Siemens TC65 is a GPRS modem that can be programmed in Java and has 400kbyte of RAM and 1.7Mbytes of ROM.

Another alternative is the Wavecom Fastrack Supreme modem which has 256kbyte RAM and 1.5Mbyte Flash. These modems are programmed with the OpenAT API using the free GNU compiler. Nice feature is the open standard for creating your own expansion boards which fit into the modem's enclosure. Several I/O-boards already exist for this modem like: IO, USB and GPS.

[crystal_lattice]

Hi sorry about the links, forgot to put them in before posting...

FTP Micro:
http://www.ftpmicro.com/index_en.html

GSM/GPRS Module:
http://www.telit.com/en/products/gsm-gprs.php?p_id=12&p_ac=show&p=7

Very valid point about the PIC limitations, problem is i have compiler + icd for PIC so i don't wan't to spend lots more on something i might not use that often again (who knows i might always use it) What processor would you recommend? As for the storage problem, i was planning on using SD card.

Java program sounds very nice, except i am clueless when it comes to Java. I have been doing some research on these modules as not many of them are readily/easily/cheaply available in South Africa and one of the suppliers that got back to me recommended the XT65 will speak to him shortly regarding price...

will look more into the wavecom devices, tried but got tired of there website navigation...

This project is not for production (...yet...) so i'm not to worried about running at a slow speed, i just want to know if something like this is possible eg. webserver using GPRS. My main concern is the problem with static IP address and whether or not the IP is publicly accessible.

ps. ckielstra do you check your private mesages? i sent you one some time ago re. bootloading