[IN PROGRESS] Features - 2g data GET request

[facultymatt]

Don't merge yet because there is a bug documented below

There is a bug that occurs when you end a script and then try running it again. You get the following stack trace.

{ message: 'Chain broke on AT+SAPBR=1,1', type: 'Error', name: 'Error', stack: 'stack traceback:
    /app/node_modules/gprs-sim900/index.js:208: in function 'f'
    /app/node_modules/gprs-sim900/index.js:194: in function 'temp'
    /app/node_modules/gprs-sim900/postmaster.js:152: in function 'reply'
    /app/node_modules/gprs-sim900/postmaster.js:166: in function 'f'
    /app/node_modules/gprs-sim900/postmaster.js:86: in function '?'
    /app/node_modules/gprs-sim900/packetizer.js:152: in function '?'
    builtin/tessel.js:738: in function 'func'
    [T]: src/colony/lua/colony-node.lua:54: in function <[T]: src/colony/lua/colony-node.lua:53>' }

To re-create do the following:

1. Create a simple script that makes a GET request, see example below.
2. Stop the script using control + c
3. Then run the script again

I think this is happening because we are doing something wrong with the init or termination commands. @johnnyman727, could a state or command remain lingering on the chip between power cycles? Otherwise this is likely do the network not being discovered in time.

---

requestGET(webAddress, callback)

This PR introduces data support to the GRPS module. It adds a method, #requestGET(webAddress, callback), that will perform a simple GET request to a given web address. The callback will return with any errors if the GET request fails.

For example:

gprs.requestGET('http://myapi.com?id=12345&location=xyz', function requestGETCallback(err, data) {
    if(err) {
        console.log('location was not saved');
        return;
    }
    console.log('location was saved to API');
});

new CommandChain()

This PR also introduces a helper method for generating command chains. Previously you needed to create three separate arrays, for example:

var commands = ['AT+INIT', 'AT+CMD'];
var patiences = [2000, 5000];
var replies = [ ['AT+INIT' , 'OK'], ['AT+CMD' , 'OK'] ];

This was cumbersome in that it required updating three arrays to add or remove commands. Now you can keep the command, patience, and reply together in one object. For example:

var commands = new CommandChain([{
    message: 'AT+INIT, 
    patience: 2000,
    expected: ['AT+INIT' , 'OK']
}, {
    message: 'AT+CMD',
    patience: 5000,
    expected: ['AT+CMD' , 'OK']
}]);

You can then get arrays from the command chain using the following methods:

commands.getMessages() // array of all messages
commands.getPatiences() // array of all patiences
commands.getExpected() // array of all expectations

[davidhq]

Is this abandoned? Would be great to have data support for gprs module.....
thank you for clarification

[facultymatt]

It's not abandoned per say... but hasn't been updated in a while and I'm not sure of its current working status.

I suggest you look at this project: https://github.com/heikki/tessel-tracker-demo. The author has done great work creating an abstract set of commands for chaining data. See https://github.com/heikki/tessel-tracker-demo/blob/master/index.js#L17-L26 and https://github.com/heikki/tessel-tracker-demo/blob/master/lib/commands.js

[davidhq]

Thank you for the answer! Actually I have tried tessel-tracker-demo code today already but it didn't work for me, not sure why.. I opened an issue there heikki/tessel-tracker-demo#1 .. maybe it's some obvious mistake from my side but still I think I tried everything, always Chain broke on AT+HTTPDATA=16,5000 .. so I wanted to ask for status here as well...