UnityのWWWでjsonをポーリング

1秒ごとにjsonを読みに行くコード。
コルーチンが何なのかよくわかってませんが、とりあえず動いた。

using System;
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Polling : MonoBehaviour {

    private string path = "https://hoge.com/json/hoge.json";

    void Start () {  
        Request();      
    }

    void Request()
    {
        // コルーチンを実行  
        StartCoroutine ( RequestJson(OnRequest) );      
    }

    void OnRequest()
    {
        Debug.Log("complete");
        Invoke("Request",1f);
    }

    IEnumerator RequestJson (Action callback) {

        using(WWW www = new WWW(path)){

            yield return www;

            if(!string.IsNullOrEmpty(www.error)){
                Debug.LogError("www Error:" + www.error);
                yield break;
            }

            Debug.Log( www.text );
            JSONObject json = new JSONObject(www.text);

            callback();

        }

    }

}

※追記　WWW → UnityWebRequest　に改造

using System;
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.Networking;

public class ApiPolling : MonoBehaviour {

    protected string _url = "https://hoge.com/json/hoge.json";
    protected string _json = "";
    protected JSONObject _jsonObject;


    void Start () {  
        Request();      
    }

    void Request()
    {

        // コルーチンを実行  
        StartCoroutine ( RequestJson(OnRequest,OnError) );      
    }

    void OnRequest()
    {
        Debug.Log("OnRequest");
        Invoke("Request",1f);
    }

    void OnError(){
        //error
        Debug.LogWarning("ApiPolling err");
        Invoke("Request",1f);
    }

    IEnumerator RequestJson (Action callback,Action callbackError) {

                UnityWebRequest www = UnityWebRequest.Get(_url);
                www.timeout = 1;

                yield return www.Send();

                if(www.isNetworkError) {
                    Debug.LogWarning(_url);
                    //Debug.LogError("www Error:" + www.error);
                    callbackError();
                    yield break;
                }
                else {
                    _json = www.downloadHandler.text;
                    _jsonObject = new JSONObject(_json);
                    callback();
                }
    }

}