Question

This side says that it can support https through the code provided. However, the Appengine SDK complains that:

java.net.InetAddress is not supported by Google App Engine's Java runtime environment

java.net.Socket is not supported by Google App Engine's Java runtime environment 

javax.net.ssl.SSLSession is not supported by Google App Engine's Java runtime environment

Answer 1

See urlfetch (for both Java and Python): https://developers.google.com/appengine/docs/java/urlfetch/

App Engine applications can communicate with other applications or
access other resources on the web by fetching URLs. An app can use the
URL Fetch service to issue HTTP and HTTPS requests and receive
responses. The URL Fetch service uses Google’s network infrastructure
for efficiency and scaling purposes.

Example:

import java.net.MalformedURLException;
import java.net.URL;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;

// ...
        try {
            URL url = new URL("http://www.example.com/atom.xml");
            BufferedReader reader = new BufferedReader(new InputStreamReader(url.openStream()));
            String line;

            while ((line = reader.readLine()) != null) {
                // ...
            }
            reader.close();

        } catch (MalformedURLException e) {
            // ...
        } catch (IOException e) {
            // ...
        }

---

About HTTP(S):

The URL to be fetched can use any port number in the following ranges:
80-90, 440-450, 1024-65535. If the port is not mentioned in the URL,
the port is implied by the scheme: http://… is port 80, https://…
is port 443.