Nowadays many companies have gone cloud, which covers most needs, but leaves space for homegrown small applications, ideas, prototypes, etc. It is convenient to organize user login into these applications using already existing Google Apps login infrastructure.

This is about using it with PHP.

Since previous post, I've updated PHP library used to the latest versions and tested them again. Also I rewrite bundled example to work in more transparent way and made it more clear.

Libraries version

php-openid-apps-discover-1.0.2.zip
openid-php-openid-2.2.2-0-ga287b2d.zip

Online demo

http://a32.me/other/ga-open-id/

Downloads

All-in-one-pack includes libraries and example

Installation

Unpack, make sure make TMP folder with sub-folders are writable.

Example code

<?php
/**
 * @date Created on Feb 22, 2011
 * @author		Constantin Bosneaga <ameoba32@gmail.com>
 * 
 */
 
// Include files
require_once "Auth/OpenID/Consumer.php";
require_once "Auth/OpenID/AX.php";
require_once "Auth/OpenID/google_discovery.php";
require_once "Auth/OpenID/FileStore.php";
require_once "Auth/OpenID/SReg.php";
require_once "Auth/OpenID/PAPE.php";
 
// Init login
$tmp = dirname(realpath(__FILE__)).DIRECTORY_SEPARATOR."tmp";
if (!file_exists($tmp)) die('Temp path '.$tmp.' does not exists'); 
if (!is_writable($tmp)) die('Temp path '.$tmp.' is not writable');
$config['tmp_path'] = $tmp;
 
// Return URL
$config['return_server'] = ($_SERVER["HTTPS"]?'https://':'http://').$_SERVER['SERVER_NAME'].":".$_SERVER['SERVER_PORT'];
$config['return_url'] = $config['return_server'].$_SERVER['REQUEST_URI']."?module=return";
 
// Cache for google discovery (much faster)
$config['cache'] = new FileCache($config['tmp_path']);
 
// Open id lib has many warnig and notices
error_reporting(E_ALL ^ E_NOTICE ^ E_WARNING ^ E_USER_NOTICE);
 
$module = $_GET['module']?$_GET['module']:$_POST['module'];
switch ($module) {
 
	/**
	 * Login form
	 * 
	 * 
	 */	
	case '':
	?>
	<h1>Login with Google Apps</h1>
	<form method="POST">
	<input type="hidden" name="module" value="login">
	Your Google Apps domain:
	<input type="text" name="domain" value="">
	<input type="submit" name="submit" value="Login">
	</form>	
 
	<h1>Login with Google</h1>
	<form method="POST">
	<input type="hidden" name="module" value="login">
	<input type="hidden" name="domain" value="https://www.google.com/accounts/o8/id">
	<input type="submit" name="submit" value="Login">
	</form>
 
	<h1>Login with Yahoo</h1>
	<form method="POST">
	<input type="hidden" name="module" value="login">
	<input type="hidden" name="domain" value="http://me.yahoo.com">
	<input type="submit" name="submit" value="Login">
	</form>
		<?	
	break;	
 
 
	/**
	 * Process login 
	 */
	case 'login':
		$store = new Auth_OpenID_FileStore($config['tmp_path']);
		$consumer = new Auth_OpenID_Consumer($store);
		new GApps_OpenID_Discovery($consumer, null, $config['cache']);
 
		try {
			$auth_request = $consumer->begin($_POST['domain']);
			if (!is_object($auth_request)) die('Auth request object error. Try again');
		} catch (Exception $error) {
			die($error->getMessage());
		}
 
		/// Request additional parameters
		$ax = new Auth_OpenID_AX_FetchRequest;
		$ax->add( Auth_OpenID_AX_AttrInfo::make('http://axschema.org/contact/email',2,1,'email') );
		$ax->add( Auth_OpenID_AX_AttrInfo::make('http://axschema.org/namePerson/first',1,1, 'firstname') );
		$ax->add( Auth_OpenID_AX_AttrInfo::make('http://axschema.org/namePerson/last',1,1, 'lastname') );
 
		$ax->add( Auth_OpenID_AX_AttrInfo::make('http://axschema.org/namePerson/friendly',1,1,'friendly') );
		$ax->add( Auth_OpenID_AX_AttrInfo::make('http://axschema.org/namePerson',1,1,'fullname') );
		$ax->add( Auth_OpenID_AX_AttrInfo::make('http://axschema.org/birthDate',1,1,'dob') );
		$ax->add( Auth_OpenID_AX_AttrInfo::make('http://axschema.org/person/gender',1,1,'gender') );
		$ax->add( Auth_OpenID_AX_AttrInfo::make('http://axschema.org/contact/postalCode/home',1,1,'postcode') );
		$ax->add( Auth_OpenID_AX_AttrInfo::make('http://axschema.org/contact/country/home',1,1,'country') );
		$ax->add( Auth_OpenID_AX_AttrInfo::make('http://axschema.org/pref/language',1,1,'language') );
		$ax->add( Auth_OpenID_AX_AttrInfo::make('http://axschema.org/pref/timezone',1,1,'timezone') );
 
		$auth_request->addExtension($ax);
 
		// Request URL for auth dialog url 
		$redirect_url = $auth_request->redirectURL(
			$config['return_server'],
			$config['return_url']
		);
 
		if (Auth_OpenID::isFailure($redirect_url)) {
			die('Could not redirect to server: ' . $redirect_url->message);
		} else {
			header('Location: '.$redirect_url);
		}	
	break;
 
 
	/**
	 * Return URL, google redirects here after login
	 */
	case 'return':
		$store = new Auth_OpenID_FileStore($config['tmp_path']);
		$consumer = new Auth_OpenID_Consumer($store);
		new GApps_OpenID_Discovery($consumer, null, $config['cache']);
 
		$response = $consumer->complete($config['return_url']);
 
		// Check the response status.
		if ($response->status == Auth_OpenID_CANCEL) die('Verification cancelled.');
		if ($response->status == Auth_OpenID_FAILURE) die("OpenID authentication failed: " . $response->message);
		if ($response->status != Auth_OpenID_SUCCESS) die('Other error');
 
		// Successful login
 
		// Extract returned information
		$openid = $response->getDisplayIdentifier();
		$ax = new Auth_OpenID_AX_FetchResponse();
		if ($ax) $ax = $ax->fromSuccessResponse($response);
 
		$sreg = Auth_OpenID_SRegResponse::fromSuccessResponse($response);
		if ($sreg ) $sreg = $sreg->contents();
 
		# print response
		?>
		<h1>OK</h1>
		You have successfully verified <a href="<?=$openid?>"><?=$openid?></a> as your identity.<br/><br/>
		<p>The following AX response received:</p>
		<pre><?=nl2br(print_r($ax->data,true))?></pre>
 
		<p>The following sreg response received:</p>
		<pre><?=nl2br(print_r($sreg,true))?></pre>
		<?
	break;	
 
}
 
 
class FileCache {
	var $cache_file;
 
	function __construct($tmp_path) {
		$this->cache_file = $tmp_path.DIRECTORY_SEPARATOR."google.tmp";
	}
 
	function get($name) {
		$cache = unserialize(file_get_contents($this->cache_file));
		return $cache[$name];
	}
 
	function set($name, $value) {
		$cache = unserialize(file_get_contents($this->cache_file));
		$cache[$name] = $value;
		file_put_contents($this->cache_file, serialize($cache));
	}
 
}
 
 
?>
 

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Isolation gives the querying user the feeling that he owns the database. It does not matter that hundreds or thousands of concurrent users work with the same database and the same schema (or even the same data). These other uses can generate new data, modify existing data or perform any other action. The querying user must be able to get a complete, consistent picture of the data, unaffected by other users’ actions.

Let’s take the following scenario, which is based on an Orders table that has 1,000,000 rows, with a disk size of 20 GB:

1. 8:00: UserA started a query “SELECT * FROM orders”, which queries all the rows of the table. In our scenario, this query usually takes approximately five minutes to complete, as the database must fully scan the table’s blocks from start to end and extract the rows. This is called a FULL TABLE SCAN query, and is not recommended from a performance perspective.
2. 8:01: UserB updates the last row in the in the Orders table, and commits the change.
3. 8:04: UserA’s query process arrives at the row modified by UserB. What will happen?

Any guess? Will UserA get the original row value or the new row value? The new row value is legitimate and committed, but it was updated after UserA’s query started.

The answer is not clear cut, and depends on the isolation level of the transaction. There are four isolation levels, as follows (see more information at: http://en.wikipedia.org/wiki/Isolation_(database_systems):

1. READ UNCOMMITTED: UserA will see the change made by UserB. This isolation level is called dirty reads, which means that read data is not consistent with other parts of the table or the query, and may not yet have been committed. This isolation level ensures the quickest performance, as data is read directly from the table’s blocks with no further processing, verifications or any other validation. The process is quick and the data is asdirty as it can get.
2. READ COMMITTED: UserA will not see the change made by UserB. This is because in the READ COMMITTED isolation level, the rows returned by a query are the rows that were committed when the query was started. The change made by UserB was not present when the query started, and therefore will not be included in the query result.
3. REPEATABLE READ: UserA will not see the change made by UserB. This is because in the REPEATABLE READ isolation level, the rows returned by a query are the rows that were committed when the transaction was started. The change made by UserB was not present when the transaction was started, and therefore will not be included in the query result.This means that “All consistent reads within the same transaction read the snapshot established by the first read” (from MySQL documentation. See http://dev.mysql.com/doc/refman/5.1/en/innodb-consistent-read.html).
4. SERIALIZABLE: This isolation level specifies that all transactions occur in a completely isolated fashion, meaning as if all transactions in the system were executed serially, one after the other. The DBMS can execute two or more transactions at the same time only if the illusion of serial execution can be maintained.In practice, SERIALIZABLE is similar to REPEATABLE READ, but uses a different implementation for each database engine. In Oracle, the REPEATABLE READ level is not supported and SERIALIZABLE provides the highest isolation level. This level is similar to REPEATABLE READ, but InnoDB implicitly converts all plain SELECT statements to “SELECT … LOCK IN SHARE MODE.

The default isolation level in MySQL’s InnoDB is REPEATABLE READ, which provides a rather high isolation. Consider again this key sentence for the REPEATABLE READ isolation level: “All consistent reads within the same transaction read the snapshot established by the first read”.

Since old values of row data are required for current queries, databases use a special segment to store old row values and snapshots. MySQL calls this segment a Rollback Segment. Oracle once called it this as well, but now calls it an Undo Segment. The premise is the same.

During query execution, each row is examined and if it is found to be too new, an older version of this row is extracted from the rollback segment to comprise the query result. This examination‑lookup‑comprise action chain takes time to complete, resulting in a performance penalty. It also produces a snowball effect. Updates occur during a query, which makes that query slower so that it takes more time. During the time it takes to process the query, more updates come in, making query execution time even longer!

This is why a query that executes in 10 seconds in our testing environment may take a full 10 minutes to execute in a much stronger production environment.

Author: Liran Zelkha

Source: http://highscalability.com/blog/2011/2/10/database-isolation-levels-and-their-effects-on-performance-a.html

You can read the entire post here

http://www.scalebase.com/isolation-levels-in-relational-databases/

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What was the problem?

I do not have any other copy of files stored on my mobile phone or PDA, I do not like this. Mobile devices are tended to be lost, sink, squash, etc (: I hate to lose my music or book collection.

Second, each time I want to upload something useful to the device, I must find cable-which-is-always-not-here, connect it, etc..  Vice versa when file from mobile device are needed on the computer.

The solution

Bi-directional file sync. How it works? Easy

I have a local folder on my hard drive named after my device

d:\device\htc_tattoo

this folder contains exact copy of all file structure of mobile device. Since most devices allows them to be mounted like a USB flash drive it is easy to maintain.

File sync software compares this local folder with mounted mobile device and propagates any file or directory changed from left-to-right and from right-to-left, including new files, modified files and deleted files. It simple keeps my device and local folder locations in identical sync.

This way I can upload new files to the local folder and on the next sync they will be transferred to the mobile device, all at once. I can defer sync as much as I want if this is not urgent or do it immediately.

Usage scenarios

Backup

First, I have a backup copy of all my files. In case something happens to device I can upload all info once again to the new one.

Podcasts

I like listening podcasts. Unfortunately mine Nokia 3110 does not support RSS with media attachments. Usually while browsing podcast RSS in Google Reader I save interesting podcasts to the local folder and it gets synced with mobile device. Even more, when I am done with podcast I delete it from mobile device and this deletion is propagated back to local folder on the PC.

Music

I fill up my music collection on the desktop, by downloading, converting, etc... On the next sync it is going to be on the device.

Audio-books

Usual source of these books is internet, and it is much more convenient to look for them on the desktop.

Books

I always get something interesting in FB2 on the Internet. Just drop into local folder.

Photos

All photos and videos taken by device camera are on my HD for browsing because of two way syncing.

Cleaning

Remove old files, sort files and check space usage it much-much easier on the desktop computer.

The Software

I use GoodSync, it has nice GUI and very easy to use. It handles conflicts well, when file was modified on both ends. It creates additional _gsdata_ folder to help with more precise sync. It was free some time ago and I still old use v.7-2-9-5, Built: Jul 11 2008  17:06:18 which seems to be portable and survived several OS changes  :)

You may download newest version of official site http://www.goodsync.com/ it is only $30

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Personally I like Chrome behavior better, comparing to FF.  It just opens the new window allowing other tabs be active. My tip is more Chrome related.

This also is useful when needed to login into same web program as two users simultaneously (user and admin) while debugging or so.

With FireFox it is possible by create second account, see user profile

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and this solution is...Store important information outside Skype But, thats not what I am talking about.

Some of Skype call recording software support brilliant feature to store call recording and chat session in GMail account! Thus make it possible to search through them using powerful Gmail search.

The winner is:

G-recorder

14-day trial for free, $25 for personal and $40 for corporate.
Supports GMail and Google Apps. Upload chats and call records.
http://www.g-recorder.com/usage.htm for more info.

Other related software

Piston. Saves chat messages too, never tried. $25. Visit http://www.pistonsoft.com/skype-recorder.html

Free call recording. Never tried, but seems to be free. Visit http://voipcallrecording.com/

Linux skype call recorder. Seems to work. Visit: http://atdot.ch/scr/download/

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What are Differential and Incremental backups?

Incremental backup

is a backup method in which multiple backups are kept (not just the last one). These backups will be incremental if each original piece of backed up information is stored only once, and then successive backups contain only the information that changed since a previous backup.

Differential backup

is a cumulative backup of all changes made since the last full or normal backup, i.e., the differences since the last full backup

I am talking about Differential backup, which contains one FULL archive and several DIFFERENTIAL archives on different date each.

Using 7zip for automated backup

Is really great tool for archiving files. Linux and win32 platform support, crossplaform archiving, multi threading support.

7zip installation

1. Windows, download
2. Ubuntu: aptitude install p7zip

7zip commands to create a backup of files

First step is to create full backup which is fairly easy:

7za a c:\archive.7z  c:\folder_to_archive

Next is to create differential backup with name diff1.7z

7za u c:\archive.7z  c:\folder_to_archive  -ms=off -mx=9 -t7z -u- -up0q3r2x2y2z0w2!c:\diff1.7z

• Where command switches stand for:
• -mx=9 - best compression
• -t7z - 7z archive type

Wtf "-up0q3r2x2y2z0w2!c:\diff1.7z" is ?

Actions mask to determinite 7z behavior

p - File exists in archive, but is not matched with wildcard.

q - File exists in archive, but doesn't exist on disk.

r - File doesn't exist in archive, but exists on disk.

x - File in archive is newer than the file on disk.

y - File in archive is older than the file on disk.

z - File in archive is same as the file on disk

w - Can not be detected what file is newer (times are the same, sizes are different)

Number means action:

0	Ignore file (don't create item in new archive for this file)

1	Copy file (copy from old archive to new)

2	Compress (compress file from disk to new archive)

3	Create Anti-item (item that will delete file or directory during extracting). This feature is supported only in 7z format

More detailes on this switch here:

http://www.bugaco.com/7zip/MANUAL/switches/update.htm

How to extract files from 7zip differential backup

First step is to extract full backup  archive:

7za.exe x c:\archive.7z -oc:\recovery_path\

Next,  to extract needed differential  backup on top to the same folder

7za.exe x c:\archive.7z -aoa -y -oc:\recovery_path\

-aoa Overwrite All existing files without prompt.

-y (assume Yes on all queries) switch

After extraction destination folder will contain exact structure and files on date of backup!

What is 7zip anti-item

When creating differential archive 7zip matches files that have been deleted and creates anti-file entry which tells 7zip extractor actually do delete file when overriding master archive. Thats why resulting recovery folder will look the same as on archiving stage.

7zip backup limitations

DO NOT USE the 7-zip format on Linux/Unix  for system backup purposes, because of 7zip does not store the owner/group of the file.

On Linux/Unix, in order to backup directories you should use tar

to backup a directory

tar cf – directory | 7za a -si directory.tar.7z

to restore your backup :

7za x -so directory.tar.7z | tar

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It uses Greasmonkey as an easy way to writing browser extenstions.

Installation instruction

1. Install Greasmonkey here (FireFox restart is needed)

2. Install plugin here

Transation ID

CATS uses transaction id for identifying users. Plugin will ask for it for the first time making API call to CATS. To change it later, use Greasemonkey menu:

1. Right mouse click on GM menu

2. Select UserMenu

3. Enter new ID. Be sure to trim any spaces on the end.

How does it look like ?

While viewing any message, plugin embedds "Add to CATS" button. By pressing this button selected text or entire message will be opened for pre-editing and posting in new form.

On the left there is a searching text box to look for candidate to add this email to. Once search is done, candidates are listed below search box, select one by clicking.

On the right form handles editing of email text for submitting.

Plugin will ask for TransactionID if it was not entered before.

Links

• http://userscripts.org/scripts/show/82047

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I have got it working for PHP. Here is the story.

Having spent about 3 hours to get it work, I do not consider OpenID simple protocol that will conquer the Net soon. Why it shouldn't be as simple as adding Paypal payment to a site ?

Nevertheless, I make working sample. I used php-openid-2.1.3.zip quite standard OpenId library and php-openid-apps-discover.tar.gz helper for Google Apps.

It does not need any installation, just make "tmp" directory writable. Do not test it using local apache, upload somewhere to the web.

Note: The Federated Login Service is disabled by default for Google Apps Premier and Education Editions. The domain admin can enable it from the Control Panel at http://www.google.com/a/cpanel/<your-domain>/SetupIdp.

Test here

Download library

UPDATE!! Please look a this post for an updated libraries and example code

.

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You probably know about static port forwarding, local and remote. It allows to map local port to any host via SSH gateway or map incoming port on SSH gateway to local one. It is very useful in some situations. But what is dynamic port forwarding ?

Dynamic port forwarding allows you to initiate connections on Behalf-Of SSH gateway, using any port.

This is done through emulating SOCKS proxy server on local side. See the picture:

SSH client(putty) opens local port and starts SOCKS proxy server on it.

Putty configuarion

–

After every application that supports socks proxy can use it. Just configure your browser to use local SOCKS proxy and voila.

Possible usages:

• Access to intranet sites from internet via ssh gateway
• Temporary changing of your IP to visit sites
• Access to server localhost services like apache status

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If not, better to read official white paper.  It is called "SPDY", another endless attempt to fix this world.

But will Google make something that won't have big chances to succeed ? I did not think so.

This protocol affect server side(web server) and client side(browser). To deploy it well both parts need to be changed. That is almost impossible in Internet reality. Many improvements to Internet were developed recently, including ones to improve email, fighting spam, etc... Where are they ? Penetration is not more than 5-10%.

Think again about Google.

They have their own browser, which is not so poplar as other leaders, but it is well designed, stable, fast and gained his part or market. For sure Google will add support of this protocol for their Google Chrome browser. It is matter of several months.

Do not forget, Google is biggest content/service provider on the net, that means - all web servers are under their control. Sure they will add support of SPDY to web server part.

Very soon, users who use Google Chrome and Google Mail|Docs|Wave services will experience much better performance of these apps. Even now I prefer Chrome for Gmail and Docs. This will lead to increased popularity of Chrome.

Will Mozilla stay aside ? I don't think so. Will Apache stay aside ? I don't think so.

Google+Mozilla+Apache and revolution is almost over.

Links

• http://en.wikipedia.org/wiki/SPDY

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