st-settings.html

<link rel="import" href="../polymer/polymer.html">

<link rel="import" href="st-rest.html">

<dom-module id="st-settings">
    <template>     
        <st-rest id="rest" on-getdone='_configReceived'></st-rest>
    </template>

    <script>
        Polymer({
            is:'st-settings',
            properties: {        
            },  
            _configReceived(res){
                this.cfg = res.detail.response;
                this._setGlobals();
            },
            _setGlobals(){
                window.st = {};
                window.st.endpoint = this.cfg.endpoint ?  this.cfg.endpoint : "http://localhost:8080/v1.0";
                window.st.maxEntities = this.cfg.maxEntities ? this.cfg.maxEntities : 20;

                if(this.cfg.mqtt){
                    window.st.mqtt = this.cfg.mqtt;
                } else {
                    window.st.mqtt = {
                        host: "localhost",
                        port: 9001,
                        path: "",
                        ssl: false
                    };
                }
            }   ,
            ready(){
                this.cfg = {};
                this._setGlobals();
                this.$.rest.get('client_config.json');
            }
        });
    </script>
</dom-module>