Author Archives: lornajane

22 Jun
2011

Gearman Priorities And Persistent Storage

I have been writing a bit about Gearman lately, including installing it for PHP and Ubuntu, actually using it from PHP and also how I use persistent storage with Gearman. I’m moving on to look at adding jobs of different priorities.

I use Gearman entirely as a point to introduce asynchronous-ness in my application. There is a complicated and image-heavy PDF to generate and this happens on an automated schedule. To do this, I use the GearmanClient::doBackground method. This inserts a priority 1 job into my queue.

Using the doHighBackground() and the doLowBackground() methods insert jobs into the queue and checking out my persistent storage I see that the priorities work like this:

priority method
0 doHighBackground()
1 doBackground()
2 doLowBackground()

Gearman works out which task is the next highest priority and will hand it to the next available worker – which means that I can set my automated reporting lower priority than the reports requested by real live people wanting them now, and everyone is happy!

20 Jun
2011

The Strpos Trap

This week I found myself again using strpos as an example of the difference between the == and === operators in PHP. The strpos function tells us where a string occurs within another string, by returning the character offset. If the string isn’t found, then the function returns false.

The problem arises because if we simply check that there’s a positive return value from the function, we’ll miss the case where the string appears at the start of the other string since the character offset will be zero:

$tagline = "PHP Made Easy";
if(strpos(strtolower($tagline), 'php')) {
    echo 'php tagline: ' . $tagline;
}

This code won’t find the “if” to be true, since strpos returns zero and PHP will type juggle that to be false (debates about dynamically typed languages can be saved for another day)

Correct Use of ===

This is a great example of where the === operator really helps, as it can tell the difference between false and zero:

$tagline = "PHP Made Easy";
if(false !== strpos(strtolower($tagline), 'php')) {
    echo 'php tagline: ' . $tagline;
}

This time, we’ll correctly get into the “if” even if the string appears at the start of the other string.

Not a particularly complex example but I think one that is simple enough to serve as a reminder as to what that extra = is for!

14 Jun
2011

Apache on Ubuntu/Debian

Apache on Debian. Ubuntu

When I first started using Ubuntu, I was coming from a distro journey that started with FreeBSD and took in Mandrake and Gentoo along the way; I hadn’t worked with any Debian-based systems before and was new to the way that Apache is configured on those platforms.

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07 Jun
2011

PHP North West 2011

We might still be in the thick of the summer conference season, but there’s an event coming up this autumn which has me very excited: PHP North West 2011.

This is a regional PHP conference based in Manchester, UK, and I’ve been involved with it since it began (I’m surprised to find this is our fourth edition, it still feels like a shiny new adventure!). This year the dates are 8th and 9th of October and with an added tutorial day on the Friday, it is bigger (and of course better) than ever. In case you missed the announcements, here are the main things you need to know:

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06 Jun
2011

PHP|Tek and a Hackathon

A couple of weeks ago I had the pleasure of speaking at php|tek in Chicago. As usual there were a few great talks, a good crowd of new folk and a selection of established speakers all at the event and I had a great time. This year, there was one particular highlight that I wanted to share: the hackathon.

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02 Jun
2011

Marking up Tables in LaTeX

Recently I’ve been writing a LOT of LaTeX for slides (using powerdot) and I’m trying to collect some of what I’ve learned here so I can refer back to it later (and so it’ll be in words I can understand, some LaTeX documentation is slightly too academic for my tastes!)

I find the default formatting for table output in LaTeX can look a bit … squashed, so I always precede my tables with this:

\renewcommand{\arraystretch}{1.5}

To define a table, you use the tabular keyword and define your columns using l, r or c depending whether you want each one right, left or centre justified:

\begin{tabular}{l | l}

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31 May
2011

PHP OAuth Provider: Authenticate User

I’ve been working with OAuth, as a provider and consumer, and there isn’t a lot of documentation around it for PHP at the moment so I thought I’d share my experience in this series of articles. This relates to the stable OAuth 1.0a spec, however OAuth2 has already started to be adopted (and differs greatly). This article uses the pecl_oauth extension and builds on Rasmus’ OAuth Provider post. This post is the third in the series, following on from the ones about the initial requirements and how to how to handle request tokens.

This phase is probably the most familiar to us as developers, as it’s simply a login form. The consumer will send the user to us at the URL we provided in the request token, and the user will have the request token key as a parameter. The access control on this page will look the same as on the rest of the website; if the user has a session already then the page is displayed, otherwise they must be logged in to see it.

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24 May
2011

Combining PDF Files With Pdftk

I’m currently delivering all my talks with PDF format slides, using Jakob’s PDF Presenter Console, which is awesome but lacks a “goto slide” button and is a little slow to click forward. It doesn’t matter for a short talk but I had 200+ slides for my ZCE preparation tutorial at the Dutch PHP Conference and I was concerned about losing my place! Therefore I split my slides up into several decks, but still need to publish them as a whole.

For years I’ve used PDF Shuffler for this sort of thing but I wondered if there was an easy way of doing this from the command line this time, since I literally wanted to glue together a bunch of files one after another. Predictably, there is and it’s called pdftk – the PDF Toolkit. Continue reading →

20 May
2011

PHP OAuth Provider: Request Tokens

I’ve been working with OAuth, as a provider and consumer, and there isn’t a lot of documentation around it for PHP at the moment so I thought I’d share my experience in this series of articles. This relates to the stable OAuth 1.0a spec, however OAuth2 has already started to be adopted (and differs greatly). This article uses the pecl_oauth extension and builds on Rasmus’ OAuth Provider post.

The consumer requests a request token (see my earlier post about consuming OAuth), and as a provider, we need to handle that request. In my example, I chose to pass the variables as GET parameters, but you could adapt this to handle POST variables or information contained in HTTP headers.

OAuth Provider Code

We have the same block of code called on every request where we’re negotiating OAuth, and it looks like this:

$this->provider = new OAuthProvider();

// set names of functions to be called by the extension
$this->provider->consumerHandler(array($this,'lookupConsumer'));
$this->provider->timestampNonceHandler(
array($this,'timestampNonceChecker'));
$this->provider->tokenHandler(array($this,'tokenHandler'));

// no access token needed for this URL only
$this->provider->setRequestTokenPath('/v2/oauth/request_token');

// now check the request validity
$this->provider->checkOAuthRequest();

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17 May
2011

A Prototype API for Joind.In

Following the principle of “release early, release often”, I put live a very early version of the v2 API for joind.in today (so that I can use it in another project!). I haven’t updated the documentation yet but in case anyone was thinking of consuming data from joind.in, this at least gives you an idea of the direction of the project so I thought I’d share.

Things you need to know:

  • The service is an HTTP Web Service. Meaning it’s RESTful apart from when it isn’t
  • The endpoint is here: http://api.joind.in
  • You can fetch data about events and talks (read-only) at this point
  • Formats available are HTML or JSON. The service will guess from your accept header but you can override it with ?format=json or ?format=html
  • If you need more columns than you get by default, you can add ?verbose=yes to your request
  • Pagination is available, with parameters resultsperpage (default 20, set to zero for no limits) and start (default zero)
  • The service supports OAuth1.0a, which isn’t useful at this point as we’re read-only but it will come into play as we add functionality

Examples

Events list: http://api.joind.in/v2/events

Information about DPC11: http://api.joind.in/v2/events/603

Talks at DPC11: http://api.joind.in/v2/events/603/talks

Your Thoughts

Comments are welcome on this post. Bugs and feature requests should go to http://joindin.jira.com, read more about Joind.in and its community at http://joind.in/about