HTTP and JSON

[Michal Panek]

Hi,

I would like to know whether in Gama Platforrm I can use http to connect with some server to download some informations with GET?

I would like also to send them back in order to retrieve data which is processed by some distance engine.

Moreover is it possible to parse JSON which I would like to receive by HTTP protocol?

If not, what could the solution to do that? Write my own plugin and use it during simulation?

Michal

[Patrick Taillandier]

Hi Michal,

Concerning the http connection (and the database access), GAMA provides some tools: https://code.google.com/p/gama-platform/wiki/Ext_DB_SQL16. I think, other tools are currently under development (Viet ? )

I don't think someone has already developed a plug-in to parse JSON. You will maybe have to write your own plug-in (you will see if you follow the documentation that it is quite easy.... at least if you have some knowledge in Java - https://code.google.com/p/gama-platform/wiki/CreationPlugins15).

Cheers,

Patrick 

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[Robin Cura]

Hi,

Or you can call R from GAMA, and use some of the many packages that are dedicated to web querying.

HTH,

Robin

[Michal Panek]

So to sum up:

What will the best (the easiest and the fastest) way to connect to a serwer by HTTP, send some information and the received back (and processed) and use it during simulation?

Thanks for your help, I am kind of a newbie.

[Viet Truong Xuan]

Hi Mr Michal,

Calling JSON from RESTful WebServices isn't committed yet because it isn't carefully verified. But in a simple way,  you can create a new operator as you want and add the code like:

//static String getGeocodingAPIOnline(String address, String sensor)
//    {
        String url = "https://maps.googleapis.com/maps/api/geocode";
        Client client = Client.create();
        client.setFollowRedirects(true);
        WebResource resource = client.resource(url);
        MultivaluedMap<String,String> params = new MultivaluedMapImpl();
        params.add("address", address);
        params.add("sensor", sensor);
       
        String res = resource.path("json").queryParams(params).get(String.class);

        // PARSING CODE IF NEEDED

        System.out.print(res);
        return res;
  //  }

Because the JSON data structure is so open, then a its parser to GAMA data structure is not really easy, so you can code it if needed.

The external library are as following:

(1) JERSEY: https://jax-rs-spec.java.net/

(2) Additional jar files:

activation.jar

jaxb-api.jar

jsr173_api.jar

Cheers,

Viet

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[Michal Panek]

Thank you very much, I was thinking that the easiest way to connect thorugh HTPP is to write some simple code as a GAMA function or something and you have showed me the way :)

I also will handle JSON parsing, that wouldn't be a problem so only as it would be JAVA programming :)