How to fix dialogflow authentication issue

Question

I have a dialogflow project that I'm trying to access from Java with a rest call. It is giving me an authentication issue. I have followed all online instructions (and many forum suggestions) to no avail.

I have tried generating the key json, as per the instructions here:

https://dialogflow.com/docs/reference/v2-auth-setup

and setting my environment variable as described, but nothing seems to work. I have checked my projectID, and am running off the same machine with the environment variable, and have double, triple and quadruple checked it's name and location, but I still get the following error:

java.net.HttpRetryException: cannot retry due to server authentication, in streaming mode

Here is my code (though it's a REST call, so I don't know if it's so relevant):

String url = https://dialogflow.googleapis.com/v2/projects/MYPROJECT/agent/sessions/SESSION_NUM:detectIntent
URL url = new URL(full_url);
String inText = "Hello World";
String outText = "";
HttpURLConnection con = (HttpURLConnection) url.openConnection();
try {
    con.setDoOutput(true);
    con.setRequestMethod("POST");

    // set body of http post
    Map<String,String> arguments = new HashMap<>();
    JSONObject inTextJsn = new JSONObject();
    inTextJsn.append("text",inText);
    inTextJsn.append("languageCode","en");
    JSONObject fieldJsn = new JSONObject();
    fieldJsn.append("text", inTextJsn);
    arguments.put("queryInput", fieldJsn.toString());
    StringJoiner sj = new StringJoiner("&");
    for(Map.Entry<String,String> entry : arguments.entrySet())
        sj.add(URLEncoder.encode(entry.getKey(), "UTF-8") + "="
                + URLEncoder.encode(entry.getValue(), "UTF-8"));

    // post http post as bytes
    byte[] bytes_out = sj.toString().getBytes(StandardCharsets.UTF_8);
    con.setFixedLengthStreamingMode(bytes_out.length);
    con.connect();
    try (OutputStream os = con.getOutputStream()) {
        os.write(bytes_out);
    }
    BufferedReader reader = new BufferedReader(new InputStreamReader(con.getInputStream(),
            "UTF-8"));

    // read all lines to a string
    String line;
    String response = "";
    while ((line = reader.readLine()) != null) {
        response += line;
    }


    JSONObject responseJsn = new JSONObject(response);
    outText = responseJsn.get("fulfillmentText").toString();

} catch (Exception e) {
    System.err.println(e);
} finally {
    con.disconnect();
}

return restResponse;

The gist of the code is to simply send a message ("Hello World!") to my dialogflow, and get back my agent's response (the code may have bugs - it's a bit hard to test when I can't get passed this authentication issue, so please help with the authentication, not code bugs).

Thanks all!

Answer 1

The directions at that page assume you're going to use the gcloud program to generate a currently valid bearer token, which is then sent along with the HTTP headers. That page illustrates

Your code doesn't seem to be generating an Authorization HTTP header at all, which is why you're getting the error you do.

Since you're using Java, you should look at the google-auth-library-java library, which will give you the tools to generate the token you need to provide in the Authorization header.

You may also wish to check out the google-cloud-java library. This contains Java classes to directly perform operations against Dialogflow instead of coding the REST/HTTP calls yourself. (However, it is still at an Alpha level for Dialogflow, so may not be stable or forwards compatible.)