On his Systems Architect site Lukasz Kujawa has posted an introduction to Apache Zookeeper and how to use it in your PHP applications. Zookeeper is "a centralized service for maintaining configuration information, naming, providing distributed synchronization, and providing group services."

Apache ZooKeeper is the coolest technology I recently came across. I found it when I was doing a research about Solr Cloud features. [...] Running multiple application as one logical program is nothing new. In fact creating such a software was one of my first jobs many years ago. This type of architecture is confusing and very tricky to work with. Apache ZooKeeper tries to provide a generic set of tools to manage such a software.

He shows you how to get the PHP extension for Zookepper (along with needed libraries) compiled and installed in your server setup. He includes a sample class that shows you how to connect to the Zookepper server and add a "watcher" your PHP script will respond to when changes happen. The post also has a "Watcher" class example, showing how to use Zookeeper as part of a distributed application. There's some links at the bottom of the post that can also help you get more details on Zookeeper and the PHP interface.

DPCRadio (recordings of the sessions at this year's Dutch PHP Conference) has posted its latest episode - a recording of Josh Kalderimis' talk Travis CI - Distributed CI for the Masses!.

Continuous Integration has typically been a practice only performed by companies who want that piece of mind for their client software, but does it need to be like this? Travis CI is a continuous integration service for the open source community. We make testing OS projects dead simple and fun. But most importantly, we help improve code quality for large projects like Doctrine2 and symfony, to smaller libraries like FOSRest. The vision behind Travis CI is to become for builds what PEAR is for distributing libraries. In this talk Josh, one of the core members of the Travis CI team, will introduce you to the vision behind Travis, the how it is implemented, and why it matters to everyone in the OS community.

You can listen to this latest episode either by using the in-page player or by downloading the mp3. You can also subscribe to this podcast.

If you're a PHP developer and are working on distributed applications (or might be in the future), you should probably read through this new article on PHPMaster.com with 8 common fallacies about these applications and their needs.

These fallacies directly relate to us as PHP developers since we build distributed applications each and every day. We build mashups, applications that interact with SOAP and REST services, authenticate users via Facebook, Google, or Twitter APIs, retrieve information from remote databases and caching services, etc. Make no mistake, we’re building distributed computer applications. Given that we are building distributed applications, it’s important that we understand the eight fallacies and how they affect us.

Among the list of their fallacies are things like:

• The Network is Reliable
• Bandwidth is Infinite
• The Network is Secure
• There is One Administrator

Check out the full article for the rest of them and summaries of each.

If you haven't gotten a chance to try out git for your version control system, now's the perfect time. PHPMaster has an introduction to using git for a simple PHP project. It introduces you to some of the basics and gets you up to speed quickly.

Some of the more commonly used version control systems that you have likely heard about are CVS and Subversion. This tutorial will take a "forget everything you know about CVS or Subversion" approach. As someone who has used all three of these systems in the professional realm, I can testify that some knowledge of CVS or Subversion can be useful when approaching Git, but it is not necessary. The best way to learn Git is to start using Git for what Git is.

They break it up into a few different sections - why use git, how to create a new repository, adding/staging files for commit, viewing the project history and viewing diffs for different versions. This is the first part in a series, so keep tuned for future parts touching on branching, merging and working with remote repositories.

On the Ibuildings techPortal today they've posted the latest episode of their DPC Radio series of podcasts, recordings of sessions from this year's Dutch PHP Conference. In this new episode they share the presentation by Kore Nordmann "Distributed Couch Apps - Embracing eventual consistency".

CouchDB is a prominent representative of the NoSQL movement. Using its integrated web server and eventual consistent replication you can not only distribute data, but also full application code. This even works for clients which are not always connected to the internet, like e.g. mobile devices. This session gives you an insight Couch apps, their beauty and pitfalls.

You can either listen via the in-page player, by downloading the mp3 or by subscribing to their feed. You can find his slides over on talks.qafoo.com.

A little while back, the PHP development group posted a survey of developers asking them which version control system they'd like to see the PHP project use. By an overwhelming margin, git has won and things are already in motion to move parts of the project away from subversion.

In his mailing list post, David Soria Parra explains:

After 2 weeks of voting and discussion, I closed the votes today. The results are fairly straightforward. Most of the users want to move to a decentralized version control system. [...] I don't want to make a difference of who voted for what. I think the results are overwhelming in favor of Git.

He'll be working on the spec to make the move for the PHP source over to git and is planning a cut over some time in December. Stay tuned to the php.internals mailing list for more details about the move as they come up.

On PHPBuilder.com today Jason Gilmore has written up a new tutorial about using memcached distributed caching for better performance in your web applications.

You probably know one of the easiest ways to improve performance is by caching all or parts of a page. But what might not be so obvious is exactly how this is accomplished. As it happens, a great solution called Memcached makes it trivial to incorporate caching into your website with great effect. In fact, relied upon by some of the largest websites in the world, among them Facebook, Twitter, Zynga, and YouTube, Memcached has essentially become the de facto website caching solution!

He walks you through installing the memcache extension for PHP (from PECL) and includes a bit of sample code that caches some fetched MySQL results to to the memcache server. With the extension installed you're just a few simple function calls away from better performance.

In a new post to the Ibuildings techPortal today, Patrick van der Velden shares some of his thoughts about one of the presentations given at this year's Dutch PHP Conference - Think like an ant, distribute the workload.

[Helgi's] presentation started off explaining to us why distributing can be a good thing by pointing out three significant aspects: budget, efficiency and perception. Budget-wise, for a distributed application there is no need to invest in a big, expensive and hard to maintain server that runs the entire application by itself. A company can save a significant amount of money investing in a collection of smaller or virtual servers or even use "the cloud".

Patrick goes on to mention some of the other key points Helgi made about distributing the workload out from a point of user contact to other "workers", decoupling your application into functional pieces, designing for distributed computing from the start and making internal APIs between the sections of the application to make communication simpler. The slides of Helgi's presentation are also posted on Slideshare.

On Developer.com today there's a new article talking about memcache and how you can implement it in your application to provide a performance boost for applications in a distributed environment.

As distributed system is part of the Memcached definition, you can install Memcached on various servers to make a larger caching server. In this way, Memcached helps reduce database loads to a minimum, resulting in faster and more responsive Web applications

They take some time to explain what memcache is - a simple to use caching system that reduces the dependency on other data sources - and how to get it installed (via the package manager of your choice). They suggest times on when and when not to use it as well as some of the security implications you'll need to worry about when implementing it. There's also a bit of sample code to help you get started in your application. You'll need the memcached extension to make it all work, though.

The Ibuildings techPortal has published the latest episode in their Dutch PHP Conference series of recordings - Andrei Zmievski's talk All the Little Pieces: Distributed systems with PHP.

Quick, what do memcache, MogileFS, and Gearman have in common? They are scalable, distributed technologies, and they can also interface with PHP, your ubiquitous Web development language. Digg uses all 3 (and a few more) in its quest for social news domination, and this session will share much of what we’ve learned about them and how they are best utilized with PHP.

You can either listen to this latest episode on the in-page player or you can download it directly. If you'd like to follow along with the slides, you can find them here.