TAG | PHP
18
Zend Framework 1.8 Web Application Development Book
0 Comments | Posted by Žilvinas Šaltys in Books, Frameworks, Reviews
I was recently asked by Packt Publishing to review a copy of one of their books called Zend Framework 1.8 Web Application Development book. This book is about designing, developing and deploying feature-rich PHP MVC based web applications using Zend framework. Guys from Packt Publishing were generous to send me a hard copy of the book. I owe them a thanks.
Even though I feel fairly familiar with Zend Framework I believe this book will be a great opportunity to dwell into the darker corners of the framework. The fact the Zend Framework is now at version 1.9.5 and version 2.0 is on the horizon is a bit worrying but having had a quick glimpse at the table of contents I see that some topics of particular interest to me like chapters about model design, optimizations and testing are not the ones that change at the same pace as the framework does which makes this book even more worthwhile to read.
I believe I will have a great time reading and reviewing this book.
This is my summary of PHPNW09 conference that I was lucky to attend. This was my first real conference and I was blown away. Talks that I enjoyed most are the keynote about the uncertainty principle, Lorna’s talk about the Joel Test and Rob Alen’s talk about project management. It was also very interesting to hear about the state of the PHP project and it’s internal development teams. Did you know that PHP has only about 100 active developers of whom only ~10 are core developers?
The event itself was perfectly organised. I don’t have a single complaint. Timings were perfect and don’t get me started about the food. It was delicious!
I also had an epic opportunity to see how Microsoft fails to demo their flowchart software which was highly amusing. Though I feel highly thankful to these guys because they were the major sponsors of the event not to mention their help on PHP windows builds.
In the evening we were invited to a SUN sponsored bar where I had an opportunity to meet and chat with really interesting people. Met a PHP star Derick Rethans, had a really great conversation with the event’s organizer Jeremy Coates and even met people from my own homeland.
All in all this was a great experience and I’m definitely coming back next year. There are also other conferences coming up in Barcelona and London which I hope to attend.
Internaly GoogleTalk uses XMPP messaging protocol. XMPP - The Extensible Messaging and Presence Protocol. Often also called as Jabber. Since it’s an open protocol means it’s possible to develop your own clients to connect to other XMPP servers.
There are quite a few xmpp libraries that provide client functionality. The one I tried myself is XMPPHP. It’s usage is really simple. For example to send a message you would do something like this:
require_once('XMPPHP/XMPP.php');
$conn = new XMPPHP_XMPP('talk. ', 5222, '[email protected]',
'password', 'xmpphp', 'gmail.com', $printlog = false,
$loglevel = XMPPHP_Log::LEVEL_INFO);
try {
$conn->connect();
$conn->processUntil('session_start');
$conn->presence();
$conn->message('[email protected]', 'Hi!');
$conn->disconnect();
} catch(XMPPHP_Exception $e) {
die($e->getMessage());
}
I find this to be quite valuable. Who these days does not keep their IM live all the time? I imagine it’s like a cellphone. Meaning you can use it for many different services.
For example I developed a small application that checks if every one of my collegues is “Working on a task” in FogBugz and if not it sends an automated message to them to remind them that they should select a task they are working on. I also have a small tracker that tracks a local torrents network looking for high rated IMDB movies. I have an idea that it would be nice to integrate my tracker with GTalk so that it would inform me when a new episode of House MD is available or a new highly rated movie appears. The sky is the limit 
A while ago I blogged about an XML Beautifier Tool which is able to tokenize an XML string and output it in human readable format. Strangely enough I noticed that I get quite a few pageviews from people searching for such a tool. Though this tool may be useful to a lot of people I think it is flawed and has serious issues with formatting, speed and memory consumption.
This inspired me to write a new version of XML formatter. It’s based on a SAX parser which is kind of “ugly” to implement and build around but because of it’s event based nature it’s super fast and has a very low memory footprint. The new version of the formatter shouldn’t peak higher in memory than 200 - 300kb even when the XML files start to weight over a megabyte. It also should not have any problems with indentation because it no longer tries to tokenize the XML itself and uses libxml to do the job. I also tried to make the tool documented and extendable.
It’s usage is really simple. All you have to do is initialize an object of XML_Formatter by passing an xml input stream, xml output stream and an array of options and call the format method. You might wonder why it requests input and output streams instead of a file name or a string. It does that to avoid high memory consumption. Here’s an example of how one might use XML_Formatter:
require('XMLFormatter.php');
$input = fopen("input.xml", "r");
$output = fopen("output.xml", "w+");
try {
$formatter = new XML_Formatter($input, $output);
$formatter->format();
echo "Success!";
} catch (Exception $e) {
echo $e->getMessage(), "\n";
}
Nevertheless this tool is quite powerful in what it can do (I was able to format other website’s XHTML or tidied HTML sources) it also has some problems which are not actually related to the formatter but may seem odd to the user. The PHP xml parser does not understand such entities as or unsescaped ampersands like in ?x=1&y=1. So it’s the user’s responsibility to provide “correct” XMLs to the formatter.
Other than that I hope it will prove useful to someone. Download the latest version of the XML_Formatter.
Every web developer probably at some point heard something about MVC unless he or she was living in a cave. I definately have heard and read a lot about it. I won’t probably lie too much to say that most people know that MVC is the nowdays defacto design pattern for web applications. Atleast for PHP it is.
If you have ever had interest in design patterns and did some research on them you may know that design patterns may be interpreted and implemented different every time one tries to. And MVC is no exception to this rule. In my own career path I have seen many projects that claim to implement the MVC design pattern. And if it actually doesn’t - it may be called a hybrid of MVC. As ridiculous as it may be I think because of the MVC hype and everyone trying to be able to claim “yes we use MVC” it is one of the most misunderstood patterns of them all. And because of this … There are a LOT and i mean a LOT of articles and blogs and forums trying to explain MVC the way it should be.
And I myself have read a lot of versions of these blogs and articles. And to be honest I couldn’t answer to you for example what a controller should do and should not do. Well ofcourse I know it shouldn’t contain any business logic. If you would try to research that you would probaly find people saying that the controller should initiate the model, do something with the model and pass the result to the view and render it. You can even find some examples..
But to some extent I find it all synthetic and not very realistic. Most examples are of the level of Hello World program. I think the devil is in the details. If you would try to find any sample php mvc applications you probably wouldn’t find much. There are a few very simplistic sample MVC projects but I don’t find that to be an eye opener that goes deep into details.
I think the PHP community needs such an example. I believe Zend Framework is a great start for MVC. But it isn’t enough. It still doesn’t show you how a real life model or controller would look like. What each part of MVC would do and would not. I believe that one good example is better than a thousand words. I feel trully interested to try and find the “Equilibrium” of the famous MVC design pattern. Don’t you?
Reading planet-php.org I found this great post about how to solve PHP session clustering in an easy way. Though it’s no silver bullet but it’s definitely worth knowing about. It uses few insantances of memcache that stores the same copies of sessions. And if one instance gets down the other keeps serving the sessions. It’s nice to have such kind of failover. Ofcourse after recovery you have to sync the instances. And your performance is going to suffer more and more if you add more memcache instances.
Though myself I feel this is a great poor man’s solution Might end up using it myself.
I have been a user of FireBug for quite a long time and it saved me a lot of hours of pain debugging AJAX applications. When I see developers trying to figure out why their AJAX applications are not working without using FireBug it sometimes looks like an inexperienced woman trying to park a car without any luck whatsoever.
And then recently i found FirePHP while reading php|architect and it seems to me a such a nice tool it’s well worth to blog about it. If you want to debug ajax applications with FireBug you must do your own variable dumps which break the output. While FirePHP is capable of sending all this data through http headers without breaking the response of your json, xml, image responses. It also provides a very nice library for logging various stuff.
One of the things I really liked is the ability to easily view backtraces through FirePHP. Though it seems to me it can only view backtraces of your own defined local php function calls. It would be nice to see FirePHP integrated with Xdebug. Then it could do a full stack trace with all the parameters involved and even memory usage.
I also love the fact that there is a Zend_Log_Writer for Firebug. It also can send information to firebug console. But it’s not as “sweet & cute” like FirePHP.
I believe that FireBug, FirePHP, Xdebug are the must have tools for every php web developer. It saves more than a reasonable amount of time spent debugging.
23
Anti Asynchronous AJAX calls and PHP sessions
4 Comments | Posted by Žilvinas Šaltys in PHP
Few days ago we found a strange bug in one of our applications we are developing. We were creating a certain feature that made up to 2 - 6 asynchronous ajax calls when certain pages were hit. Those ajax requests contact various services providers and it takes a different amount of time for each one of them to respond. We found it odd that none of the calls were actually asynchronous and they were starting to execute one after another. For example we fire 3 asynchronous ajax calls:
- ajax call 1 takes 2sec.
- ajax call 2 takes 3 sec. but responds after 5 sec. only
- ajax call 3 takes 4 sec. but responds after 9 sec. only
It didn’t took long to figure out that it had something to do with our php handler scripts that are accepting these ajax calls. We found out that the session_start() function call did not allow these scrips to run in paralel. It soon became clear that two php scripts can’t use the same session in paralel because without locking they could both do some changes to session and one script would override other script’s changes.
Turns out there is a function for exactly these kinds of situations in PHP and it’s named session_write_close(); It’s purpose is to write session data and end session. After it is done writing it releases the lock for other scripts to use the session. So now our php handler scripts initialize the session to check that the user is logged in, writes the session changes and ends it, contacts services providers and then starts the session again to make the final session changes. That way one script doesn’t hold the session locked for it’s whole execution time.
I’ve recently got listed on the Zend yellow pages. Even managed to get a comment from a Zend employee on my last blog post about PHP5 certification.
I’m also interested in MySQL developer and MySQL DBA exams. I have been working with MySQL for more than 5 years and I still don’t feel that I know all it’s angles really well. Recently I’ve started reading the MySQL 5.0 certification study guide. It will be interesting to compare the Zend and MySQL certification programs. While reading the book it was odd to find out that MySQL Query Browser was the third chapter of the book. And you must be able to know your way around the tool to take the developer exam. I have never used MySQL Query Browser and phpmyadmin has allways sufficed my needs as a web applications developer. Though I agree it is very useful tool. The study guide book comes with a CD that has training exercises in it. I was a little disappointed when I didn’t find a mock exam application to test what I’ve learned but instead found a PDF e-book with questions from every chapter. Still better than nothing. Even though the guide states that it is designed to make you think instead of memorize the material I think it is more effective to learn by taking tests.
Finally! After months of battles with myself delaying the day out of pure laziness I took the PHP 5 Zend Certificate exam and passed it! Should be visible in the yellow pages in the following 7 days. I’m really happy I have done this and I hope this will help me in the future to prove my worth to current and future employers.
I’d love to share some details about my experiences with my readers who might one day take the exam themselves.
First of all.. It’s sad that companies such as Zend or PearsonVUE can’t store my firstname and lastname with a proper encoding. Surprising that such world famous international companies don’t use UTF8 encoding. The paper I got after taking the exam had my name written as “?ilvinas ?altys”. When I forgot my password and had to fill in my first name and last name to get a new one I had to use question marks to make it work.
Before taking the exam I’ve done about 13 mock exam tests. I also had problems to order them and had to contact Zend and wait for weeks to complete my order, the tests them selves aren’t very good. You get 70 questions and 90 minutes to answer them. Tests had lots of mistakes and sometimes rather dumb questions. For example .. Which methods are required to implement when implementing the Iterator interface. Tests give 5 choices and ask to select 5 choices. Then there are questions which you cannot answer correctly because either they are out of date or they are wrong from the start. Then there are questions that ask you questions about the PHP virtual machine implementation or PDO extension options or Sqlite performance configuration settings. Good luck knowing all that. After 10 tests you start shooting answers like darts because questions start to repeat a lot. The most frustrating thing is that it’s really hard to learn from these mock tests. They don’t tell you which questions you have answered correctly and why were you wrong. When you start doing a test you look for answers on the internet to find out what is the correct answer and it may some time to do it for any single question. Funny enough I have never got a completely excellent score from the mock exams. I always failed in at least one category and couldn’t figure out why.
About the exam itself. A heard a lot of poeple saying. “Oh it’s easy!”, “Oh it’s easier than the mock exams!”, “It’s basic level!” If you can complete that exam and you are confident that you have answered atleast 90% of the questions correctly you are a walking bible of PHP that knows the manual really well, all the possible configuration options, all the nonsense tricks in PHP and have some profesional experience. It’s not that easy. A lot of questions are hard to answer. Most of the time you can be only 80% sure. Unless of course you have a very good memory and can remember all the details. Not many developers know what PHP does with floating point array keys or how exactly PHP handles type juggling. When I was about to end the exam I was not sure I will pass it. I knew for sure that there were a lot of questions that I wasn’t 100% sure of. There are tons of questions where the exam tries to TRICK you. For example .. You have a lot of code with classes, abstractions and it asks you what does it output? And you can get confused and not notice that there is no echo statement anywhere and there’s no output. Somewhere I’ve found that noone completed the exam with perfect score and I think it was a statement by Zend itself but I’m not completely sure. You have to answer about 50 - 60% of the questions correctly to pass the test.
A few things were disappointing and could have been better but in the end I’ve achieved my goal and would like to thank Zend for making it possible. Certificates can’t tell if someone is a great developer or a nice person but they can definitely tell how much someone knows about the details of a programming language.
