Add RendezvousServlet to App Inventor Server. This is used to help the

Blocks Editor find the associated phone for debugging over wireless.

Change-Id: I8f825746b4d2df2a31ce6f6898bdc2009280ddd3

appinventor/appengine/src/com/google/appinventor/server/RendezvousServlet.java

+// -*- mode: java; c-basic-offset: 2; -*-
+// Copyright 2009-2011 Google, All Rights reserved
+// Copyright 2011-2012 MIT, All rights reserved
+// Released under the MIT License https://raw.github.com/mit-cml/app-inventor/master/mitlicense.txt
+
+/*
+ * RendezvousServlet -- This servlet acts as the rendezvous point
+ *      between the blocks editor and a phone being used for debugging
+ *      with a WiFi connection.  This was originally written in Python
+ *      using the "Bottle" micro-framework. Here is that code:
+ *
+ * #!/usr/bin/python
+ * from bottle import run,route,app,request,response,template,default_app,Bottle,debug,abort
+ * from flup.server.fcgi import WSGIServer
+ * from cStringIO import StringIO
+ * import memcache
+ *
+ * app = Bottle()
+ * default_app.push(app)
+ *
+ * @route('/', method='POST')
+ * def store():
+ *     c = memcache.Client(['127.0.0.1:11211',])
+ *     key = request.POST.get('key')
+ *     if not key:
+ *         abort(404, 'No Key Specified')
+ *     d = {}
+ *     for k,v in request.POST.items():
+ *         d[k] = v
+ *     c.set('rr-%s' % key, d, 1800)
+ *     return d
+ *
+ * @route('/<key>')
+ * def fetch(key):
+ *     c = memcache.Client(['127.0.0.1:11211',])
+ *     return c.get('rr-%s' % key)
+ *
+ * debug(True)
+ *
+ * ##run(host='127.0.0.1', port=8080)
+ * WSGIServer(app).run()
+ *
+ * # End of Python Code
+ *
+ *      This code is a little bit more complicated. In part because it
+ *      is written in Java and it is intended to be run within the
+ *      Google App Engine.  The App Engine can sometimes disable
+ *      memcache, which this code uses both for speed and to avoid
+ *      using the datastore for data which is valuable for typically
+ *      10 to 15 seconds!
+ *
+ *      When memcache is disabled we use the datastore. However when
+ *      memcache is available we do *NOT* use the datastore at
+ *      all. This is a little different from the way most code uses
+ *      memcache, literally as a cache in front of a real data
+ *      store. Again, this is driven by the desire for speed and the
+ *      short life of the data itself.
+ *
+ *      Note: At the moment there is no code to cleaup entries left in
+ *      the datastore. However each entry is marked with a used date,
+ *      so it is pretty easy to write code at a later date to remove
+ *      stale entries. Where stale can be defined to be data that is
+ *      more then a few minutes old!
+ *
+ */
+
+package com.google.appinventor.server;
+
+import com.google.appengine.api.capabilities.*;
+
+import javax.servlet.http.HttpServlet;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+import javax.servlet.ServletConfig;
+import javax.servlet.ServletRequest;
+import javax.servlet.ServletResponse;
+import javax.servlet.ServletException;
+
+import java.io.PrintWriter;
+import java.io.IOException;
+import java.io.BufferedReader;
+import java.io.InputStreamReader;
+import java.util.Map;
+import java.util.HashMap;
+
+import com.google.appengine.api.memcache.MemcacheService;
+import com.google.appengine.api.memcache.MemcacheServiceFactory;
+import com.google.appengine.api.memcache.Expiration;
+
+import org.json.JSONObject;
+import org.json.JSONException;
+
+import com.google.appinventor.server.storage.StorageIo;
+import com.google.appinventor.server.storage.StorageIoInstanceHolder;
+
+@SuppressWarnings("unchecked")
+public class RendezvousServlet extends HttpServlet {
+
+  private final MemcacheService memcache = MemcacheServiceFactory.getMemcacheService();
+
+  private final String rendezvousuuid = "c96d8ac6-e571-48bb-9e1f-58df18574e43"; // UUID Generated by JIS
+
+  private final StorageIo storageIo = StorageIoInstanceHolder.INSTANCE;
+
+  public void init(ServletConfig config) throws ServletException {
+    super.init(config);
+  }
+
+  protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException {
+    String uriComponents[] = req.getRequestURI().split("/", 5);
+    String key = uriComponents[uriComponents.length-1];
+    resp.setContentType("text/plain");
+    PrintWriter out = resp.getWriter();
+    JSONObject jsonObject = new JSONObject();
+
+    if (memcacheNotAvailable()) {
+      // Don't have memcache at the moment, use the data store.
+      String ipAddress = storageIo.findIpAddressByKey(key);
+      if (ipAddress == null) {
+//        out.println("");
+      } else {
+        try {
+          jsonObject.put("key", key);
+          jsonObject.put("ipaddr", ipAddress);
+        } catch (JSONException e) {
+          e.printStackTrace();
+        }
+        out.println(jsonObject.toString());
+      }
+      return;
+    }
+
+    Object value = memcache.get(rendezvousuuid + key);
+    if (value == null) {
+//      out.println("");
+      return;
+    }
+
+    if (value instanceof Map) {
+      Map map = (Map<String, String>) value;
+      for (Object mkey : map.keySet()) {
+        try {
+          jsonObject.put((String) mkey, map.get(mkey));
+        } catch (JSONException e) {
+          e.printStackTrace();
+        }
+      }
+      out.println(jsonObject.toString());
+    } else
+      out.println("");
+  }
+
+  protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws IOException {
+    PrintWriter out = resp.getWriter();
+    BufferedReader input = new BufferedReader(new InputStreamReader(req.getInputStream()));
+    String queryString = input.readLine();
+
+    if (queryString == null) {
+      out.println("queryString is null");
+      return;
+    }
+
+    HashMap<String, String> params = getQueryMap(queryString);
+    String key = params.get("key");
+    if (key == null) {
+      out.println("no key");
+      return;
+    }
+
+    if (memcacheNotAvailable()) {
+      String ipAddress = params.get("ipaddr");
+      if (ipAddress == null) {  // Malformed request
+        out.println("no ipaddress");
+        return;
+      }
+      storageIo.storeIpAddressByKey(key, ipAddress);
+      out.println("OK (Datastore)");
+      return;
+    }
+
+    memcache.put(rendezvousuuid + key, params, Expiration.byDeltaSeconds(300));
+    out.println("OK");
+  }
+
+  public void destroy() {
+    super.destroy();
+  }
+
+  private static HashMap<String, String> getQueryMap(String query)  {
+    String[] params = query.split("&");
+    HashMap<String, String> map = new HashMap<String, String>();
+    for (String param : params)  {
+      String name = param.split("=")[0];
+      String value = param.split("=")[1];
+      map.put(name, value);
+    }
+    return map;
+  }
+
+  private boolean memcacheNotAvailable() {
+    CapabilitiesService service = CapabilitiesServiceFactory.getCapabilitiesService();
+    CapabilityStatus status = service.getStatus(Capability.MEMCACHE).getStatus();
+    if (status == CapabilityStatus.DISABLED) {
+      return true;
+    } else {
+      return false;
+    }
+  }
+
+}

appinventor/appengine/src/com/google/appinventor/server/storage/ObjectifyStorageIo.java

@@ -21,6 +21,7 @@ import com.google.appinventor.server.storage.StoredData.ProjectData;
 import com.google.appinventor.server.storage.StoredData.UserData;
 import com.google.appinventor.server.storage.StoredData.UserFileData;
 import com.google.appinventor.server.storage.StoredData.UserProjectData;
+import com.google.appinventor.server.storage.StoredData.RendezvousData;
 import com.google.appinventor.shared.rpc.Motd;
 import com.google.appinventor.shared.rpc.project.Project;
 import com.google.appinventor.shared.rpc.project.ProjectSourceZip;
@@ -109,6 +110,7 @@ public class ObjectifyStorageIo implements  StorageIo {
     ObjectifyService.register(FileData.class);
     ObjectifyService.register(UserFileData.class);
     ObjectifyService.register(MotdData.class);
+    ObjectifyService.register(RendezvousData.class);
   }
 
   ObjectifyStorageIo() {
@@ -1370,6 +1372,46 @@ public class ObjectifyStorageIo implements  StorageIo {
     return userData.id;
   }
 
+  @Override
+  public String findIpAddressByKey(final String key) {
+    Objectify datastore = ObjectifyService.begin();
+    RendezvousData data  = datastore.query(RendezvousData.class).filter("key", key).get();
+    if (data == null) {
+      return null;
+    } else {
+      return data.ipAddress;
+    }
+  }
+
+  @Override
+  public void storeIpAddressByKey(final String key, final String ipAddress) {
+    Objectify datastore = ObjectifyService.begin();
+    final RendezvousData data  = datastore.query(RendezvousData.class).filter("key", key).get();
+    try {
+      runJobWithRetries(new JobRetryHelper() {
+          @Override
+          public void run(Objectify datastore) {
+            RendezvousData new_data = null;
+            if (data == null) {
+              new_data = new RendezvousData();
+              new_data.id = null;
+              new_data.key = key;
+              new_data.ipAddress = ipAddress;
+              new_data.used = new Date(); // So we can cleanup old entries
+              datastore.put(new_data);
+            } else {
+              new_data = data;
+              new_data.ipAddress = ipAddress;
+              new_data.used = new Date();
+              datastore.put(new_data);
+          }
+          }
+        });
+    } catch (ObjectifyException e) {
+      throw CrashReport.createAndLogError(LOG, null, null, e);
+    }
+  }
+
   private void initMotd() {
     try {
       runJobWithRetries(new JobRetryHelper() {

appinventor/appengine/src/com/google/appinventor/server/storage/StorageIo.java

@@ -393,4 +393,28 @@ public interface StorageIo {
    */
   String findUserByEmail(String email) throws NoSuchElementException;
 
+  /**
+   * Find a phone's IP address given the six character key. Used by the
+   * RendezvousServlet. This is used only when memcache is unavailable.
+   *
+   * @param key the six character key
+   * @return Ip Address as string or null if not found
+   *
+   */
+  String findIpAddressByKey(String key);
+
+  /**
+   * Store a phone's IP address indexed by six character key. Used by the
+   * RendezvousServlet. This is used only when memcache is unavailable.
+   *
+   * Note: Nothing currently cleans up these entries, but we have a
+   * timestamp field which we update so a later process can recognize
+   * and remove stale entries.
+   *
+   * @param key the six character key
+   * @param ipAddress the IP Address of the phone
+   *
+   */
+  void storeIpAddressByKey(String key, String ipAddress);
+
 }

appinventor/appengine/src/com/google/appinventor/server/storage/StoredData.java

@@ -166,4 +166,20 @@ public class StoredData {
     // More MOTD detail, if any
     String content;
   }
+
+  // Rendezvous Data -- Only used when memcache is unavailable
+  @Unindexed
+  static final class RendezvousData {
+    @Id Long id;
+
+    // Six character key entered by user (or scanned).
+    @Indexed public String key;
+
+    // Ip Address of phone
+    public String ipAddress;
+
+    public Date used;           // Used during (manual) cleanup to determine if this entry can be pruned
+
+  }
+
 }

appinventor/appengine/war/WEB-INF/web.xml

@@ -52,6 +52,7 @@
       <url-pattern>/learn/*</url-pattern>
       <url-pattern>/about/*</url-pattern>
       <url-pattern>/forum/*</url-pattern>
+      <url-pattern>/rendezvous/*</url-pattern>
     </web-resource-collection>
   </security-constraint>
 
@@ -67,6 +68,16 @@
 
   <!-- Servlets -->
 
+  <!-- rendezvious -->
+  <servlet>
+    <servlet-name>rendezvousServlet</servlet-name>
+    <servlet-class>com.google.appinventor.server.RendezvousServlet</servlet-class>
+  </servlet>
+  <servlet-mapping>
+    <servlet-name>rendezvousServlet</servlet-name>
+    <url-pattern>/rendezvous/*</url-pattern>
+  </servlet-mapping>
+
   <!-- download -->
   <servlet>
     <servlet-name>downloadServlet</servlet-name>