Error 404 when calling Google Cloud Endpoint API from Google Apps Script - google-app-engine

Question

I am trying to call a Google Cloud Endpoint API (developed on App Engine) via Google Apps Script. The endpoint is up and running, honestly I don't know which URL I should use but through Google Chrome Web Tools it looks like the URL is something like:
https://myapp.appspot.com/_ah/api/myendpointapi/v1/myEndPointMethod/
Along with API parameters directly included in the URL, separeted by slashes:
https://myapp.appspot.com/_ah/api/myendpointapi/v1/myEndPointMethod/param1value/param2value/...
Now, in order to call that API from Google App Script I am using the following code snippet:
function myFunction() {
var params =
{
"param1" : "param1value",
"param2" : "param2value",
};
var result = UrlFetchApp.fetch('https://myapp.appspot.com/_ah/api/myendpointapi/v1/myEndPointMethod/', params);
DocumentApp.getUi().alert(result);
}
However I always get a 404 error. If I have to be honest I don't even know if UrlFetchApp is the correct way of calling the API. I noticed this thread on StackOverflow but no one answered. What's the correct URL to use? Many thanks.
EDIT: Now I am trying with an API method which does not require any parameter. I found a way to call a specific URL (using method='get' as suggested by the answer below) but now I get a 401 error because it says I am not logged in. I believe I need to use some kind of OAuth parameter now. Any idea? I tryed using OAuthConfig but no luck with that as well :( From App Engine logs I can see the following error:
com.google.api.server.spi.auth.GoogleIdTokenUtils verifyToken: verifyToken: null
com.google.api.server.spi.auth.AppEngineAuthUtils getIdTokenEmail:
getCurrentUser: idToken=null
function myFunction() {
var result = UrlFetchApp.fetch('myurl', googleOAuth_());
result = result.getContentText();
}
function googleOAuth_() {
var SCOPE = 'https://www.googleapis.com/auth/drive';
var NAME = 'myAPIName';
var oAuthConfig = UrlFetchApp.addOAuthService(NAME);
oAuthConfig.setRequestTokenUrl('https://www.google.com/accounts/OAuthGetRequestToken?scope='+SCOPE);
oAuthConfig.setAuthorizationUrl('https://www.google.com/accounts/OAuthAuthorizeToken');
oAuthConfig.setAccessTokenUrl('https://www.google.com/accounts/OAuthGetAccessToken');
oAuthConfig.setConsumerKey('anonymous');
oAuthConfig.setConsumerSecret('anonymous');
return {oAuthServiceName:NAME, oAuthUseToken:'always'};
}

Answer 1

UrlFetchApp is the only way to call a Google Cloud Endpoints API at the moment. The second parameter to UrlFetchApp.fetch is a special key-value map of advanced options. To pass POST parameters, you need to do the following:
UrlFetchApp.fetch(url, {
method: 'post',
payload: {
"param1" : "param1value",
"param2" : "param2value",
}
});

Answer 2

I was fighting a similar (not the same) problem, when testing feasibility of a GCM backed by EndPoints server. Basically testing if it is possible to get the Google Spreadsheet Appscript to send notification to an Android device. Please bear with me, the following explanation may be a bit convoluted;
Starting with a standard 'Cloud Messaging for Android', backed by the 'App Engine Backend with Google Cloud Messaging', I managed to build a test system that would send messages between Android devices (Github here).
Here is a VERY sparse EndPoints server code that handles register / un-register Android devices, as well as reporting registered devices and sending a message to a list of registered devices.
WARNING: This is not a production quality code, it is stripped of any logging, error handling in order to keep it short.
#Api( name = "gcmEP", version = "v1",
namespace = #ApiNamespace(ownerDomain = "epgcm.example.com", ownerName = "epgcm.example.com", packagePath = "" )
)
public class GcmEP {
#ApiMethod(name = "registToken")
public void registToken(#Named("token") String token) {
if (ofy().load().type(TokenRec.class).filter("token", token).first().now() == null) {
ofy().save().entity(new TokenRec(token)).now();
}
}
#ApiMethod(name = "unregToken")
public void unregToken(#Named("token") String token) {
TokenRec record = ofy().load().type(TokenRec.class).filter("token", token).first().now();
if (record != null) {
ofy().delete().entity(record).now();
}
}
#ApiMethod(name = "listTokens")
public CollectionResponse<TokenRec> listTokens() {
return CollectionResponse.<TokenRec>builder().setItems(ofy().load().type(TokenRec.class).list()).build();
}
#ApiMethod(name = "sendMsg")
public void sendMsg(#Named("message") String message) throws IOException {
if (message != null && message.length() > 0) {
Sender sender = new Sender(System.getProperty("gcm.api.key"));
Message msg = new Message.Builder().addData("message", message).build();
for (TokenRec record : ofy().load().type(TokenRec.class).list()) {
Result result = sender.send(msg, record.getToken(), 4);
if (result.getMessageId() != null) {
// handle CanonicalRegistrationId
} else {
// handle errors, delete record
}
}
}
}
}
Android code for registration and message sending is shown here, even if it is not relevant.
GcmEP mRegSvc;
String mToken;
// register device on EndPoints backend server
private void registerMe() {
new Thread(new RegisterMe(this)).start();
}
private class RegisterMe implements Runnable {
Activity mAct;
public RegisterMe(Activity act) { mAct = act; }
public void run() {
String senderId = null;
if (mAct != null) try {
if (mRegSvc == null) {
mRegSvc = new GcmEP
.Builder(AndroidHttp.newCompatibleTransport(), new AndroidJsonFactory(), null).setRootUrl(UT.ROOT_URL).build();
}
senderId = getString(R.string.gcm_defaultSenderId);
mToken = InstanceID.getInstance(mAct).getToken(senderId, GoogleCloudMessaging.INSTANCE_ID_SCOPE, null);
mRegSvc.registToken(mToken).execute();
GcmPubSub.getInstance(mAct).subscribe(mToken, "/topics/global", null); // subscribing to all 'topics' from 'mToken'
} catch (IOException e) { e.printStackTrace(); }
}
}
// send message to EndPoints backend server
new Thread(new Runnable() {
#Override
public void run() {
if (mRegSvc != null) try {
mRegSvc.sendMsg("hello").execute();
} catch (IOException e) { e.printStackTrace(); }
}
}).start();
// receive GCM message
public class GcmListenSvc extends GcmListenerService {
#Override
public void onMessageReceived(String senderId, Bundle data) {
Log.i("_X_", data.getString("message"));
}
}
What is relevant, thought, there is also an APIs Explorer created for the project, that can be used to send messages to your Android device from any browser.
If you use this Explorer, you can see the GET, POST requests for your EndPoints backend server, i.e.
list all registered devices:
GET https://epgcm.appspot.com/_ah/api/gcmEP/v1/tokenrec?fields=items
send a message to all registered devices:
POST https://epgcm.appspot.com/_ah/api/gcmEP/v1/sendMsg/Hello%20World!
Now, you can use this knowledge to send messages to your Android device from an AppScript code as shown:
Version 1: Get list of registered devices and send a GCM message to all of them (or a filtered set).
function sendMsg() {
var msg = 'test from CODE.GS';
var url = 'https://epgcm.appspot.com/_ah/api/gcmEP/v1/tokenrec?fields=items';
var params = { method : 'get'};
var response = UrlFetchApp.fetch(url, params);
var data = JSON.parse(response.getContentText());
var regIds = [];
for (i in data.items)
regIds.push(data.items[i].token);
var payload = JSON.stringify({
'registration_ids' : regIds,
'data' : { 'message' : msg }
});
var params = {
'contentType' : 'application/json',
'headers' : {'Authorization' : 'key=AIza............................'},
'method' : 'post',
'payload' : payload
};
url = 'https://android.googleapis.com/gcm/send';
UrlFetchApp.fetch(url, params);
}
This version relies on code from an old YouTube video, and I don't know if the call to 'android.googleapis.com' is still supported (but it works).
Version 2: Use the EndPoints's 'sendMsg' directly.
function sendMsg() {
var msg = 'test from CODE.GS';
var params = { method : 'post'};
var url = 'https://demoepgcm.appspot.com/_ah/api/gcmEP/v1/sendMsg/' + encodeURIComponent(msg.trim());
UrlFetchApp.fetch(url, params);
}
I have to admit I've never written a line of JavaScript code before, so it may not be up-to-par, but I made it work as a 'proof of concept'.
I would like to get feedback about this problem from people-who-know, since there is so little published info on this specific issue.