Set EXPIRE_TIME for token in opentok of 15 minutes from current time in .net dynamically

Question

This is how I pass token expiry in days:

tokenOptions.Add(TokenPropertyConstants.EXPIRE_TIME, new DateTime(2014, 03, 24));   //date of tomorrow

My main problem is that I need to set EXPIRE_TIME from the server side. How do I fix EXPIRE_TIME 15 minutes from creation time?

I tried this, but it's not working:

tokenOptions.Add(TokenPropertyConstants.EXPIRE_TIME, new DateTime(2014, 03, 23, 18, 20, 00));  //15 minutes more than current time

The code under tokenOptions where EXPIRE_TIME is going looks like this

public string GenerateToken(string sessionId)
        {
            Dictionary<string, object> options = new Dictionary<string, object>();

            return GenerateToken(sessionId, options);
        }

        public string GenerateToken(string sessionId, Dictionary<string, object> options)
        {
            NameValueCollection appSettings = ConfigurationManager.AppSettings;

            options.Add("session_id", sessionId);
            options.Add("create_time", (int)(DateTime.UtcNow - new DateTime(1970, 1, 1)).TotalSeconds);
            options.Add("nonce", RandomNumber(0, 999999));
            if (!options.ContainsKey(TokenPropertyConstants.ROLE))
            {
                options.Add(TokenPropertyConstants.ROLE, "publisher");
            }
            // Convert expire time to Unix Timestamp
            if (options.ContainsKey(TokenPropertyConstants.EXPIRE_TIME))
            {
                DateTime origin = new DateTime(1970, 1, 1, 0, 0, 0);
                DateTime expireTime = (DateTime)options[TokenPropertyConstants.EXPIRE_TIME];
                TimeSpan diff = expireTime - origin;
                options[TokenPropertyConstants.EXPIRE_TIME] = Math.Floor(diff.TotalSeconds);
            }

            string dataString = string.Empty;
            foreach (KeyValuePair<string, object> pair in options)
            {
                dataString += pair.Key + "=" + HttpUtility.UrlEncode(pair.Value.ToString()) + "&";
            }
            dataString = dataString.TrimEnd('&');

            string sig = SignString(dataString, appSettings["opentok_secret"].Trim());
            string token = string.Format("{0}{1}", appSettings["opentok_token_sentinel"], EncodeTo64(string.Format("partner_id={0}&sdk_version={1}&sig={2}:{3}", appSettings["opentok_key"], appSettings["opentok_sdk_version"], sig, dataString)));

            return token;
        }

Answer 1

When tokens expire, users do not automatically get kicked out of a session. The session continues until the users leaves the session. When the user tries to join the session again, their expired token will prevent them from joining.

What I would do is set a timeout on the client side and call session.disconnect() after 15 minutes. If they try to connect again, it will not work since the token would have expired.