[appengine-java] How to produce a synchronized timestamp?

[Ivan]

Hi there,

What is the best way to produce a timestamp that is synchronized (more
or less, couple of seconds clock skew don't matter) among all running
instances of an app?

The problem I need to solve is the following:

In a mobile game, a user can use a certain boon, that is valid for 12
hours. I store a timestamp that reflect creation time + validity
period. This is then persisted to the datastore. Of course then I need
to check if this boon has expired by comparing current timestamp and
the creation timestamp + validity. So far I've been using simply
new Date(), but then I realized that this could very well differ if
the clocks are not synced. Any thoughts?

Cheers,
Ivan

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[appengine-java] Re: How to produce a synchronized timestamp?

[Peter Ondruška]

I would be interested on Google's answer whether instances' clock are 
guaranteed to be in sync.. I would hope so.

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Re: [appengine-java] Problem Authenticating against App Engine

[Fabrizio Accatino]

Perhaps your authentication token was expired.

In the android app, call .invalidateAuthToken(account.type, authToken)
on AccountManager class.
This releases the current authentication token. Then call again getAuthToken
to obtain a new and fresh authentication token.

A note: AFAIK Android uses ClientLogin and not OAuth.
http://code.google.com/apis/accounts/docs/AuthForInstalledApps.html


   Fabrizio


On Fri, Feb 4, 2011 at 11:57 PM, Sky skysoftwaredes...@googlemail.comwrote:

 Hi all,

 I am using the oauth authentication process to authenticate Android to
 App Engine described in Nick's blog:

 http://blog.notdot.net/2010/05/Authenticating-against-App-Engine-from-an-Android-app

 This worked fine until today. Today the authentication on app engine
 fails - boolean authenticated = userServiceManager.isUserLoggedIn();
 returns always false.

 Is anyone out there using the same authentication process and has the
 same problem?
 Are there any changes concerning the URL the cookie is fetched?
 HttpGet http_get = new HttpGet(https://yourapp.appspot.com/_ah/login?
 continue=http://localhost/auth=https://yourapp.appspot.com/_ah/login?continue=http://localhost/auth=
 + tokens[0]);


 thanks!

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