Re: Reading from a socket with GJS (Gnome Shell extension) -- failure to read from Gio.InputStream

["Alan Knowles" <alan roojs com>]

The best way I've found so far is to use DataInput/Output streams.

http://www.roojs.com/seed/gir-1.2-gtk-3.0/gjs/Gio.DataInputStream.html

This is an example of some code that writes binary arrays.

    writeBinaryArray : function (path, stringAr) {
        var f = Gio.file_new_for_path(String(path));
        var data_out = new Gio.DataOutputStream({base_stream:f.replace(null, false, Gio.FileCreateFlags.NONE, null)});
        for(var i =0; i < stringAr.length; i++) {
            data_out.put_byte(stringAr[i], null);
            if (i % 10000 == 0) {
                print("wrote " + i + "/" + stringAr.length + "\n");
            }
            
        }
        data_out.close(null);
    },

With a bit of guesswork, you should be able to create an dataInputstream and use the get_byte() method.

Regards
Alan

 --- On 05/Aug/2012, gdfc wrote: 
> Hi!
> 
> I'm currently writing an extension for Gnome Shell using gjs and have to read some gpsd data from a socket. I've gotten this far:
> 
>             const Gio = imports.gi.Gio;
>             let sockCl = new Gio.SocketClient();
>             let sockCon = sockCl.connect_to_host("localhost:2947", null, null);
>             let outStr = sockCon.get_output_stream();
>             outStr.write('?WATCH={"enable":true,"json":true};', null);
>             let inStr = sockCon.get_input_stream();
>             let b = new Array(128);
>             inStr.read(b, 1, null);
> 
> However, the read method always fails with the following error:
> 
>             Error: Argument 'buffer' (type void) may not be null
> 
> I've tried all read* methods described in the only more or less current gjs API reference I've found [1], but they all seem to have the same problem. This is regardless of what type b is -- it can be an array, a string, a number or even a function, but it doesn't get recognised as anything other than null. I'm aware of [2] (this is the only web search result I've stumbled upon), but it is of little help.
> 
> So my question here: does anyone know a way to read from a socket in gjs? It doesn't have to be Gio, any standard lib would do... I've tried some Soup and GLib methods, but they don't seem to work either. In Gio, I do at least get the OutputStream to write reliably...
> 
> Any advice is highly appreciated. Thank you!
> 
> [1] http://www.roojs.com/seed/gir-1.2-gtk-3.0/gjs/Gio.InputStream.html
> [2] https://mail.gnome.org/archives/javascript-list/2012-January/msg00003.html
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