**Update**: The answer is no longer up to date. Since Google&#39;s Cloud SQL is no longer in BETA that means that both AWS and GAE support java apps written to use a MySQL database and that migrating is no longer that difficult. The overall idea is that both cloud providers tend to get to a point where they offer &quot;everything&quot;: Google launched [Compute Engine][7] while Amazon is working on [Beanstalk][6]. However, Amazon&#39;s IaaS services are more mature than Google&#39;s while Google&#39;s PaaS services are more mature than Amazon&#39;s. It all boils down to whether you want IaaS or PaaS.

---

There is a key difference between AWS and Google App Engine: AWS is infrastructure as a service (IaaS) whereas GAE is platform as a service (PaaS). What this means is that with AWS you still need to administer your own servers (ec2 instances, db instances, load balancers and so on) =&gt; some sysadmin work required. With GAE you just need to code your app and deploy it to the google cloud without caring on what servers or on how many servers it runs. Google does all the sysadmin work for you.

Both use a pay-for-use model.

Answers for each question:

 1. Supported by AWS. For GAE you need to use their own data storage (it&#39;s called big table). You can use JPA for accessing big table data, but there are a lot of restrictions (like you can&#39;t do table joins for example). GAE has [support for relational databases][1] but it seems to be in beta.
 2. They both have some free plan: [AWS][2], [GAE][3]
 3. Difficult. As I said at point 1, gae uses a proprietary NoSql data storage. If you want to switch to a relational model you will need to redesign your models.
 4. Read their tutorials: [AWS][4], [GAE][5].

**Note**: AWS also has support for PaaS through [elastic beanstalk][6] , but that&#39;s still in BETA




  [1]: https://developers.google.com/appengine/docs/java/cloud-sql/developers-guide
  [2]: http://aws.amazon.com/free/
  [3]: https://cloud.google.com/pricing/
  [4]: http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/EC2_GetStarted.html
  [5]: https://developers.google.com/appengine/docs/java/gettingstarted/introduction
  [6]: http://aws.amazon.com/elasticbeanstalk/
  [7]: https://cloud.google.com/products/compute-engine

I want to use a `foreach` loop with a variable, but this variable can be many different types, `NULL` for example.

So before `foreach` I test it:

    if(is_array($var)){
      foreach($var as ...

But I realized that it can also be a class that implements `Iterator` interface. Maybe I am blind but how to check whether the class implements interface? Is there something like `is_a` function or `inherits` operator? I found `class_implements`, I can use it, but maybe there is something simpler?

And second, more important, I suppose this function exist, would be enough to check if the variable `is_array` or &quot;implements `Iterator` interface&quot; or should I test for something more?

How to check if variable is array?... or something array-like

I have seen `::` in variety of places involving postgres code I have seen on the net. For example:

    SELECT &#39;{apple,cherry apple, avocado}&#39;::text[];

It seems to be some sort of cast. What exactly is `::` in postgres and when should it be used?

I tried a bit of googling and searched the Postgres docs for `::` but got no good results.  
I tried following searches in Google: 

 - postgres double colon 
 - postgres :: 
 - :: 

I tried the following searches in the postgres docs search button 

 - double colon 
 - double colon cast 
 - :: 
 
This was almost embarrassing to ask on SO, but I figured Google will hopefully see this answer for other people in the future.

What does :: do in PostgreSQL?

I am a newbie to us cloud hosting. I want to know which is better to start with, either Google app engine or Amazon web service.

My questions are:

 1. My application is based on java, Database is MySQL. Do they support this?
 2. What are the free offers from both of them and which one is better to start? 
 3. How easy would it be to migrate from one platform to another?
 4. Any good link for getting started with these service as I am a novice here.

Additionally, I&#39;d appreciate some good links for getting started with these services as I am a novice here, and a high level view on how this works.

Google app engine or amazon web services

I am a newbie to us cloud hosting. I want to know which is better to start with, either Google app engine or Amazon web service.
My questions are:
<ol>
<li>My application is based on java, Database is MySQL. Do they support this?</li>
<li>What are the free offers from both of them and which one is better to start?</li>
<li>How easy would it be to migrate from one platform to another?</li>
<li>Any good link for getting started with these service as I am a novice here.</li>
</ol>
Additionally, I'd appreciate some good links for getting started with these services as I am a novice here, and a high level view on how this works.

It seems that, from [Google Cloud Console][1] there is no way to delete a project.

&gt; Note: As of 2013-09-19 this is no longer an issue because
&gt; Google had fixed it.  
- Now you can click on the check box and then
&gt; click delete


  [1]: https://cloud.google.com/console#c=l

How to delete a project from Google Cloud Console

A few days ago I&#39;ve started developing a Backend for Mobile Applications using Google App Engine and [Google Cloud Endpoints][1]. [This tutorial][2] shows how the endpoints are getting generated automatically, as well as the client library for Android.

So we have our Entity:

    @Entity
    public class Person implements IsSerializable{
    
    	@Id
    	@GeneratedValue(strategy = GenerationType.IDENTITY)
    	private Key key;
    
    	private String name;
    //...
    } 

And the endpoint for this class:

    @Api(name = &quot;personendpoint&quot;)
    public class PersonEndpoint {

        @ApiMethod(name = &quot;getPerson&quot;)
    	public Person getPerson(@Named(&quot;id&quot;) Long id) {
    ...




Besides, using the generated Android Endpoint Library (that uses the REST API) I would like to **add** a User Interface on the Server, build with **Google Web Toolkit (GWT)**. But how should I manipulate the date on Server Side? I can see different approaches...


**Option A1: Adding an RPC Service in GWT**

    public interface PersonServiceAsync {
    
    	void insertPerson(Person person, AsyncCallback&lt;Person&gt; callback);
    
    }
    
    @RemoteServiceRelativePath(&quot;api&quot;)
    public interface PersonService extends RemoteService {
    
    	public Person insertPerson(Person person);
    
    }
    public class PersonServiceImpl extends RemoteServiceServlet implements PersonService{
    	public Person insertPerson(Person person) {
    		EntityManager mgr = getEntityManager();
    		try {
    			if (containsPerson(person)) {
    				throw new EntityExistsException(&quot;Object already exists&quot;);
    			}
    			mgr.persist(person);
    		} finally {
    			mgr.close();
    		}
    		return person;
    	}
    
            //...
    }

But now my `PersonServiceImpl` and `PersonEndpoint` do roughly the same. So we didn&#39;t follow [DRY][3] :) Besides, that Person is not allowed to have `com.google.appengine.api.datastore.Key` so we would have to change our Entities.

**Option A2: Service calls endpoint class**
	

    @Override
    public Person insertPerson(Person person) {
    	return new PersonEndpoint().insertPerson(person);
    }

Should work , but still no `com.google.appengine.api.datastore.Key` Type in the Entity and since Endpoints are using `CollectionResponse&lt;Person&gt;` we would have to transform this into an `Collection&lt;Person&gt;` in case of `listPerson()`.
 
**Option B1: Using the Java Endpoint Client Library**

We could split the GWT Client from our App Engine API Backend and use the generated Endpoint Client Libraries for Java. So we call the REST/Endpoint-API from within a `RemoteServiceServlet`. But wouldn&#39;t this end up in two Requests, even if the GWT client and Endpoints are on the same server or even in the same project? 

*GWT Client --(RPC)--&gt; GWT Server --(HTTP Request)--&gt; App Engine Backend Server*

**Option B2: Using the JavaScript Endpoint Client Library**

Might be the best approach but would end up in massive JSNI.

-----

So what&#39;s best practice? I can&#39;t find any example projects using Google Cloud Endpoints AND GWT in one project :)

  [1]: https://developers.google.com/appengine/docs/java/endpoints/
  [2]: http://www.youtube.com/watch?v=NU_wNR_UUn4
  [3]: http://en.wikipedia.org/wiki/Don%27t_repeat_yourself

GWT and Google Cloud Endpoints

We are super excited about App Engine&#39;s support for [Google Cloud Endpoints](https://developers.google.com/appengine/docs/python/endpoints/).

That said we don&#39;t use OAuth2 yet and usually authenticate users with username/password
so we can support customers that don&#39;t have Google accounts.

We want to migrate our API over to Google Cloud Endpoints because of all the benefits we then get for free (API Console, Client Libraries, robustness, …) but our main question is …

How to add custom authentication to cloud endpoints where we previously check for a valid user session + CSRF token in our existing API.

Is there an elegant way to do this without adding stuff like session information and CSRF tokens to the protoRPC messages?

Custom Authentication for Google Cloud Endpoints (instead of OAuth2)

I am trying to build a simple hello world application for two days using Jersey + Google app engine. For simple AppEngine project I followed these tutorials and both works just fine
https://developers.google.com/appengine/docs/java/gettingstarted/creating
https://developers.google.com/appengine/docs/java/webtoolsplatform

But now I am trying to add Jersey and following this tutorial http://www.vogella.com/articles/REST/article.html.

But server keeps giving me 

&gt; java.lang.ClassNotFoundException: com.sun.jersey.spi.container.servlet.ServletContainer


when I add these lines in *web.xml*:

    &lt;?xml version=&quot;1.0&quot; encoding=&quot;UTF-8&quot;?&gt;
    &lt;web-app xmlns:xsi=&quot;http://www.w3.org/2001/XMLSchema-instance&quot;
	xmlns=&quot;http://java.sun.com/xml/ns/javaee&quot; xmlns:web=&quot;http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd&quot;
	xsi:schemaLocation=&quot;http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd&quot;
	id=&quot;WebApp_ID&quot; version=&quot;2.5&quot;&gt;
	&lt;display-name&gt;TestServer&lt;/display-name&gt;
    &lt;servlet&gt;
		&lt;servlet-name&gt;Jersey REST Service&lt;/servlet-name&gt;
		&lt;servlet-class&gt;com.sun.jersey.spi.container.servlet.ServletContainer&lt;/servlet-class&gt;
		&lt;init-param&gt;
			&lt;param-name&gt;com.sun.jersey.config.property.packages&lt;/param-name&gt;
			&lt;param-value&gt;com.test.myproject&lt;/param-value&gt;
		&lt;/init-param&gt;
		&lt;load-on-startup&gt;1&lt;/load-on-startup&gt;
	&lt;/servlet&gt;
	&lt;servlet-mapping&gt;
		&lt;servlet-name&gt;Jersey REST Service&lt;/servlet-name&gt;
		&lt;url-pattern&gt;/rest/*&lt;/url-pattern&gt;
	&lt;/servlet-mapping&gt;
    &lt;/web-app&gt;

I have downloaded Jersey `JAX-RS 2.1 RI bundle` from [here][1] and have added all jar files in `WEB-INF/lib` folder as described in tutorial. And even after two days nothing is working. I have searched several times on Google and apparently people who are using Maven have solved it somehow but I am not using Maven neither did the guy who wrote that tutorial. 

Just to check if even `com.sun.jersey.spi.container.servlet.ServletContainer` exists in imported  `Jersey jars` I tried to just write this fully qualified name in Java and let the intellisense finish names but I couldn&#39;t get any intellisense after `com.sun.je` so my last guess is that there have been some **package rearrangement** in latest Jersey build and `jersey` is no longer inside `com.sun`. I am exhausted and I would appreciate any kind of help. 


  [1]: https://jersey.java.net/download.html

java.lang.ClassNotFoundException: com.sun.jersey.spi.container.servlet.ServletContainer

I got this error in **Google App Engine&#39;s Python** have used Google Translate API,
But I don&#39;t know how to fix,

    &lt;module&gt;
    from apiclient.discovery import build
    ImportError: No module named apiclient.discovery

I&#39;ll try to **set environment which indicates to Google App Engine SDK**,
And upload to Google Apps Engine again, **always get the error**,

&gt; Error: Server Error
&gt;
The server encountered an error and could not complete your request.
If the problem persists, please report your problem and mention this error message and the query that caused it.

Please tell me how to fix,

Thanks

**UPDATE : Fixed**
Follow Nijjin&#39;s help,
I fixed problems by adding the following folders,

`apiclient, gflags, httplib2, oauth2client, uritemplate`

*If you still got problem, please consider below Answer of this page to get more info. ex. : Varum answer, etc ...*



Why is my Python App Engine app using the Translate API getting an error of ImportError: No module named apiclient.discovery?

At the end of last week I noticed a problem on one of my medium AWS instances where Nginx always returns a HTTP 499 response if a request takes more than 60 seconds.  The page being requested is a PHP script

I&#39;ve spent several days trying to find answers and have tried everything that I can find on the internet including several entries here on Stack Overflow, nothing works.

I&#39;ve tried modifying the PHP settings, PHP-FPM settings and Nginx settings. You can see a question I raised on the NginX forums on Friday (http://forum.nginx.org/read.php?9,237692) though that has received no response so I am hoping that I might be able to find an answer here before I am forced to moved back to Apache which I know just works.

This **is not** the same problem as the HTTP 500 errors reported in other entries.

I&#39;ve been able to replicate the problem with a fresh micro AWS instance of NginX using PHP 5.4.11.

To help anyone who wishes to see the problem in action I&#39;m going to take you through the set-up I ran for the latest Micro test server.

You&#39;ll need to launch a new AWS Micro instance (so it&#39;s free) using the AMI ami-c1aaabb5

This PasteBin entry has the complete set-up to run to mirror my test environment. You&#39;ll just need to change *example.com* within the NginX config at the end

http://pastebin.com/WQX4AqEU

Once that&#39;s set-up you just need to create the sample PHP file which I am testing with which is


    &lt;?php
    sleep(70);
    die( &#39;Hello World&#39; );
    ?&gt;

Save that into the webroot and then test.  If you run the script from the command line using php or php-cgi, it will work.  If you access the script via a webpage and tail the access log */var/log/nginx/example.access.log*, you will notice that you receive the HTTP 1.1 499 response after 60 seconds.

Now that you can see the timeout, I&#39;ll go through some of the config changes I&#39;ve made to both PHP and NginX to try to get around this.  For PHP I&#39;ll create several config files so that they can be easily disabled

**Update the PHP FPM Config to include external config files**

    sudo echo &#39;
    include=/usr/local/php/php-fpm.d/*.conf
    &#39; &gt;&gt; /usr/local/php/etc/php-fpm.conf

**Create  a new PHP-FPM config to override the request timeout**

    sudo echo &#39;[www]
    request_terminate_timeout = 120s
    request_slowlog_timeout = 60s
    slowlog = /var/log/php-fpm-slow.log &#39; &gt;
    /usr/local/php/php-fpm.d/timeouts.conf

**Change some of the global settings to ensure the emergency restart interval is 2 minutes**

    # Create a global tweaks
    sudo echo &#39;[global]
    error_log = /var/log/php-fpm.log
    emergency_restart_threshold = 10
    emergency_restart_interval = 2m
    process_control_timeout = 10s
    &#39; &gt; /usr/local/php/php-fpm.d/global-tweaks.conf

Next, we will change some of the PHP.INI settings, again using separate files

    # Log PHP Errors
    sudo echo &#39;[PHP]
    log_errors = on
    error_log = /var/log/php.log
    &#39; &gt; /usr/local/php/conf.d/errors.ini

    sudo echo &#39;[PHP]
    post_max_size=32M
    upload_max_filesize=32M
    max_execution_time = 360
    default_socket_timeout = 360
    mysql.connect_timeout = 360
    max_input_time = 360
    &#39; &gt; /usr/local/php/conf.d/filesize.ini

As you can see, this is increasing the socket timeout to 3 minutes and will help log errors.

Finally, I&#39;ll edit some of the NginX settings to increase the timeout&#39;s that side

First I edit the file */etc/nginx/nginx.conf* and add this to the http directive
    fastcgi_read_timeout 300;

Next, I edit the file */etc/nginx/sites-enabled/example* which we created earlier (See the pastebin entry) and add the following settings into the **server** directive

    client_max_body_size    200;
    client_header_timeout   360;
    client_body_timeout     360;
    fastcgi_read_timeout    360;
    keepalive_timeout       360;
    proxy_ignore_client_abort on;
    send_timeout            360;
    lingering_timeout       360;

Finally I add the following into the *location ~ \.php$* section of the server dir

	fastcgi_read_timeout 360;
	fastcgi_send_timeout 360;
	fastcgi_connect_timeout 1200;

Before retrying the script, start both nginx and php-fpm to ensure that the new settings have been picked up. I then try accessing the page and still receive the HTTP/1.1 499 entry within the NginX example.error.log.

So, where am I going wrong?  This just works on apache when I set PHP&#39;s max execution time to 2 minutes.

I can see that the PHP settings have been picked up by running **phpinfo()** from a web-accessible page.  I just don&#39;t get, I actually think that too much has been increased as it should just need PHP&#39;s *max_execution_time*, *default_socket_timeout* changed as well as NginX&#39;s *fastcgi_read_timeout* within just the server-&gt;location directive.

##Update 1##

Having performed some further test to show that the problem is not that the client is dying I have modified the test file to be

    &lt;?php
    file_put_contents(&#39;/www/log.log&#39;, &#39;My first data&#39;);
    sleep(70);
    file_put_contents(&#39;/www/log.log&#39;,&#39;The sleep has passed&#39;);
    die(&#39;Hello World after sleep&#39;);
    ?&gt;

If I run the script from a web page then I can see the content of the file be set to the first string. 60 seconds later the error appears in the NginX log. 10 seconds later the  contents of the file changes to the 2nd string, proving that PHP is completing the process.

##Update 2##
Setting **fastcgi_ignore_client_abort on;** does change the response from a HTTP 499 to a HTTP 200 though nothing is still returned to the end client.

##Update 3##
Having installed Apache and PHP (5.3.10) onto the box straight (using apt) and then increasing the execution time the problem does appear to also happen on Apache as well.  The symptoms are the same as NginX now, a HTTP200 response but the actual client connection times out before hand.

I&#39;ve also started to notice, in the NginX logs, that if I test using Firefox, it makes a double request (like this https://stackoverflow.com/questions/13261327/php-script-executes-twice-when-longer-than-60-seconds). Though that does appear to be the client requesting upon the script failing


NginX issues HTTP 499 error after 60 seconds despite config. (PHP and AWS)

While creating a new AWS EC2 instance using the EC2 command line API, I passed some user data to the new instance.

How can I know whether that user data executed or not?



How to check whether my user data passing to EC2 instance is working

I am using AWS ec2 instance.  On this instance I&#39;m resulting some files. These operations are done by user data.

Now I want to store those files on s3 by writing code in user data itself.

- So how can I store those files on s3?
- Have any tutorials on it?

How to transfer files between AWS s3 and AWS ec2

I am using S3 to host a javascript app that will use HTML5 pushStates. The problem is if the user bookmarks any of the URLs, it will not resolve to anything. What I need is the ability to take all url requests and serve up the root index.html in my S3 bucket, rather than just doing a full redirect. Then my javascript application could parse the URL and serve the proper page. 

Is there any way to tell S3 to serve the index.html for all URL requests instead of doing redirects? This would be similar to setting up apache to handle all incoming requests by serving up a single index.html as in this example: https://stackoverflow.com/a/10647521/1762614. I would really like to avoid running a web server just to handle these routes. Doing everything from S3 is very appealing. 

S3 Static Website Hosting Route All Paths to Index.html

Sorry if it is a newbie question. But I&#39;m trying to understand what should I use. As far as I understand Kafka is :

&gt; Apache Kafka is a distributed publish-subscribe messaging system.

And SNS is also pub/sub system.

My goal is to use some queue messaging system on AWS with application that will be distributed over few servers (By the way the main language is Python). And because it is on amazon, my first thought was to use SNS and SQS. But then I saw a lot of people using Kafka on AWS. What are the advantages of one over another?


Content Type	Original Author	Original Content on Stackoverflow
Question	Shruti Basu	View Question on Stackoverflow
Solution 1 - Google App-Engine	Ioan Alexandru Cucu	View Answer on Stackoverflow

Google app engine or amazon web services

Google App-Engine Problem Overview

Google App-Engine Solutions

Solution 1 - Google App-Engine

What does :: do in PostgreSQL?

How to check if variable is array?... or something array-like

Attributions