Next week sees the Zend/PHP Conference and Expo in San Francisco. It promises to be a great experience, with a goodly number of big industry keynote speakers, lots of hands-on tutorials, and three parallel session streams.
I'm presenting an introduction to Service Data Objects (SDO) on the first day which should give people the basic 101-level understanding of SDO and how to use it with XML and databases. I've included a few scenarios to hopefully keep it *real*. I'm really pleased to have been scheduled first on the parallel sessions, so I can then relax and enjoy the rest of the conference :-) .
I'm really looking forward to finally getting to meet members of the PHP community who've helped us in the creation of the SDO project. The support and guidance we've received throughout has been fantastic.
Graham Charters[Read More]
I got back from the Zend Conference a few days ago and thought it worth a mention (the conference, not my returning!). I got to attend quite a few session. Rob Richards gave an excellent XML and Web service tutorial. The Amazon and Google presentations were also very interesting. I particularly enjoyed Adam Trachtenberg's pitch on eBay and how to build a business using their API. The example he used was, "Dude, Where's My Used Car" (http://www.dudewheresmyusedcar.com/), a site that he wrote for fun, which mashes eBay Motor listings and Google maps. I'd like to give this a try with SCA, to see whether, a) it works! and b) whether it's any easier. Look out for http://www.excusemesirbutcouldyoupleasetellmewheremyusedmotorvehicleis.co.uk (the thoroughly British subsidiary ;-) ).
Of the main sessions, I found Chris Anderson's Long Tail pitch very interesting and I'm looking forward to reading his book. As ever, Robert "r0ml" Lefkowitz gave an entertaining and thought provoking pitch comparing the evolution of language and literacy over the centuries to the evolution of programming languages and programming literacy. Using this analogy, it appears programming is currently somewhere around the 10th century and programmers are the equivalent of scribes; being paid to read and write for someone else. Another nugget which I believe was attributed to Donald E Knuth's Literate Programming, was the idea of writing programs for humans (the fact that it runs on a computer is incidental). This is something I think we should all do to ensure what we create can be maintained, embraced and furthered by others.
All in all a very good conference, very well organized. A big pat on the back goes to the Zend folks...
Graham Charters[Read More]
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Foremost, we would like to thank the developerWorks editors for giving us the opportunity to christen this blog.
Wed like to begin by saying how excited we are with IBMs announcement of embracing PHP. In a way, this brings closure to our romance with IBM which has its roots in the very birth of PHP, as we know it, about eight years ago. Those who read the fine print at the bottom of the PHP 3.0 CREDITS file, may remember our joint thanks to Michael Rodeh, who taught our Compilation Techniques course in the Technion, Israel Institute of Technology, and also supervised our university project that was later to become PHP. During this period he played a decisive role in the way PHP history unfolded and today happens to be the Director of the IBM Research Labs in Haifa, Israel. As such, some of the first PHP brainstorming sessions happened within the corridors of IBM and therefore, this turn in events seems very natural.
Needless to say, the announcement doesnt only close a loop to a story that began eight years ago, but opens a brand new and exciting landscape. A company the magnitude of IBM putting its know-how and experience behind PHP is something PHP enthusiasts have been awaiting for a long time. We all followed what happened when IBM embraced Linux. Similar to how Linux was a few years ago, PHP today is a great technology that millions of people already use, and that is growing rapidly. However, it has been lacking the necessary endorsement from a serious industry player such as IBM in order to penetrate the mind share of many corporations and the software industry as a whole. We are confident that just like what happened with Linux, IBMs endorsement will lead to a whole new ballgame for this powerful technology.
In order to fully realize the significance of IBMs involvement in PHP, its important to note that it will not sum up in just a marketing stamp of approval. IBMs support will be backed by contributions of technology, and PHP will benefit from IBMs position in the forefront of the software industry. If previously PHP had to adapt itself to standards written with other languages in mind, the day where standards will evolve around PHP is right around the corner.
At this point you may wonder what exactly this blog will contain. Wonder no further. This shared blog will host thoughts and ideas regarding PHP and Web development at large, coming from people with first hand experience in development and deployment of open source technologies, primarily PHP and Apache. In addition to us, you can expect to read thoughts from evangelists including Sam Ruby, Ken Coar and Mark Pilgrim. In addition, this developerWorks section will host a variety of white papers and articles dealing with a wide range of PHP-related topics, from technical documents and all the way to roadmap discussions. It should be quite interesting around here!
To conclude our maiden post, wed like to extend a warm gratitude to the PHP community, including (but not limited to) the developers, documenters, bug fixers, quality testers, and anybody else who has contributed to the PHP project throughout the years. Each and every one of you has a share in IBMs announcement. PHP would have never been what it is today without you!
Andi Gutmans & Zeev Suraski[Read More]
Different programming languages excel at different things. I employ a number of different programming languages, and make my choice based on the task at hand. My presentations tend to be powered by Perl. My weblog is powered by Python. But my private applications tend to be written in PHP.
The developerWorks PHP Resources site will cover PHP from a perspective that may be new to some PHP users, covering such topics as Access an enterprise application from a PHP script
The developerWorks PHP Blog, however, will often touch on topics that may be new to enterprise (typically Java) programmers.
My first post on this site will cover an application I wrote in about an hour to cover a specific need. It breaks a number of "rules" that guide the development of scalable enterprise applications - in particular it does not separate presentation from content. Consequently, this application does not contain any reusable components that will ultimately find their way into a Customer Relationship Management system. I'm entirely OK with that.
Still, the application is centrally managed, requires zero deployment, is accessible everywhere and portable across a wide range of client operating systems and browsers. All good traits to have.
The application is a vocabulary test. My daughter weekly gets a list of words and their definitions to study. At the end of the week, there is a test where she needs to match the words with the definitions. At first, I helped her study using flash cards, but this seemed like an obvious candidate for automation.
The UI for this application was obvious... I precisely mimicked the layout of the test.
Nothing in this application couldn't have been done with JSP. However, to do so would have required additional effort, effort that does not result in a more functional end result.
And it wouldn't have been as much fun.
Not everybody may have the diverse set of skills required to pull together such an application in one sitting. However, a quite larger set of people can copy such an application and successfully make meaningful changes to it.
In my experience, that's how people tend to learn languages such as PHP. Some refer to this as Progressive Disclosure.
Sam Ruby[Read More]
At last month's Zend Conference I was fortunate enough to attend Christian Wenz's tutorial on XML and Web services. This covered the use of technologies such as DOM and SimpleXML for working with XML data. As the title of this blog entry suggests, SDO provide a simple way to construct or extend XML documents.
The example below shows an XML schema used by an application which records information regarding quotations people have made (Thanks go to Christian Wenz for the scenario which is from his book entitled, "PHP Phrasebook", SAMS Publishing.). An XML document following this schema will contain a quotes element containing a number of quote elements, each of which consists of a phrase and an author element and a year attribute.
The code extract below shows how SDO can be used to load the XML schema and a quotes document and then add a new quote entry to that document.
The eight lines of code above do the following:
1. create and configure a new XML Data Access Service (DAS) with an XML schema.
2. use the XML DAS to load and validate an instance document.
3. retrieve the quotes currently contained in the document.
4-7. create a new quote and populate it with information posted from a form.
8. save the quotes (including the new quote) back to the xml file.
The same task takes 14 lines of code in DOM and in my opinion, DOM code is far less intuitive. I found it more difficult to understand the data structure from the code, because of the generic XML vocabulary of the DOM APIs. However, it is worth noting that the XML Data Access Service requires the existence of an XML schema, whereas DOM does not.
Because SDO knows about the XML schema, it lets you access the elements and attributes directly by name. The same is true of SimpleXML, however SDO can also be used to create new documents from scratch, or in this case, new fragments of XML. SimpleXML is limited in this regard because it only has knowledge of an instance document, rather than the schema. Again, it is worth noting that SimpleXML does not require the existence of an XML schema.
The SDO API does not reveal which names correspond to XML elements and which to XML attributes, but still outputs XML which follows the provided XML schema. Personally, I think this is quite neat, because often the choice to use an element or attribute in schema design is arbitrary and down to personal taste. This article nicely sums up the feelings I had when I created my first ever XML schema.
Graham Charters[Read More]
Last week I attended the second UK PHP Conference in London. The organisers had clearly listened to the comments after the first conference, and this year's event was even better. It's the only event of its kind in the UK, and deservedly popular, with a large lecture theatre completely packed.
Like last year, the conference was a one-day, one-track event, and good value for money at £50. It kicked off with Cal Evans, the editor of the Zend dev zone, presenting "My First Mash-Up", getting down with the code to walk us through various ways of tracking a UPS parcel on GoogleMaps with a traditional server-side model and an AJAX model.
Next up was Simon Laws talking about SCA for PHP. Obviously I'm biased but I thought this went really well. Despite being a big lecture theatre, there were a lot of good questions raised throughout the talk, particularly from people who hadn't seen annotations used for dependency injection before: "are annotations bad for performance", "does it work asynchonously", and so on.
After lunch was Kevlin Henney on "Objects of Desire", a talk only loosely about PHP, and one of the highlights. Kevlin is an independent consultant and trainer, specialising in programming languages, OO design, agile development process, patterns and software architecture. He is widely published, but I hadn't heard him speak before. He turned out to be a witty and entertaining speaker, with a lot of wisdom to impart, and deserved the ovation he received.
The big name speaker came next, Rasmus Lerdorf on "Fast and Rich Web Applications with PHP 5". I'd seen Rasmus give a similar talk a couple of times, so there was not much new content for me, but watching him walk through the process of improving the throughput of a simple site one hundred-fold was as impressive as ever, and many of the audience said this was their highlight. Rasmus also got some good questions which were answered .. frankly!
The final wild card was Bill Gaver, a professor of design at Goldsmiths College on "Designing for the Curious Home". Bill and his team go way beyond conventional design issues, resarching some crazy technology ideas, for example wiring up a family home to try and detect the "mood" and then print a daily "horoscope". The one I'd like in my home was the "drift table", which has a viewing window that allows you to float over satellite views of the planet, rather like being in a hot air balloon. Bill says "through these examples, I suggest that computation can go beyond supporting problem solving, consumption and entertainment to enhance a far more varied and subtle range of domestic activities and values". I did notice some muttering around me about the relevance of this talk to the conference, but for me it was much more memorable than many a technical talk.
I had previously whinged to Marcus Baker that it was maybe a bit questionable to select the speakers without a public cfp, but I changed my mind after I'd enjoyed the sessions so much. The personal selection of speakers gave us a more stimulating selection that a committee would have come up with. It could be a new model for computing conferences, akin to the annual Meltdown festival at the South Bank where individual curators (John Peel, Nick Cave, Morrissey, David Bowie, this year Jarvis Cocker) preside over a quirky and personal selection of performances.
After the conference lots of attendees decamped to LivingSpace, where much beer was consumed, and I was happy to meet a small UK contingent of PHP Women. The conversation alternated wildly between PHP-related subjects and knitting and crochet. My male colleagues are always complaining about me expecting them to take part in two discussions simultaneously, so I revelled in this. I did have to go through a bit of a post-feminist reevaluation to get to grips with the interest of young women in handicrafts, a subject which I had personally cast off many years ago, but once I'd seized on the key role of the Jacquard loom in the history of computing as a rationale, my surprise dissolved. I wonder if the UK PHP Conference team would accept a paper on "Babbage and Knitting" as the wacky topic for the 2008 conference? We thought there were about fourteen women at the conference, of 235 attendees. Someone captured us on Flickr. Later at dinner it was nice to meet Steph Fox in person for the first time, too.
Some other people's photos from the conference are here. It seems Rasmus had a lot of people throw an arm around him and expect him to smile for the camera :-).
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One of the concepts that are most difficult for new Web developers to fully grasp, is just how dangerous it is to trust user input. Just in the last week, there've been around a dozen or so different reports of vulnerabilities found in Web applications - mostly all of them revolve around unchecked user input. Because of PHPs dominance in the Web application development world, many of the vulnerable applications were ones written in PHP, which hurt PHPs security track record, even though its not the language which is at fault (the same applications, written in any other language would have suffered from the same vulnerabilities).
The challenge of validating user input is not a simple one. The key to meeting this challenge is attention to details combined with knowledge.
At the end of the day - nothing other than the developer herself can ensure that an unsanitized piece of data finds itself as a part of a filename, and sometimes even a database query, which is why paying close attention to what goes where is important.
But that's actually not enough. Few people fully understand just how little of the Web environment can be trusted. Nowadays, most developers know that you cannot rely on GET or POST variables to have the values you expect (even if they're inside hidden form values) - but how many of them know that you cannot trust any $_SERVER variable that begins with HTTP (e.g., $_SERVER["HTTP_REFERER"])? These can be fully (and easily) spoofed by the remote users, and must not be trusted. Same goes with cookies - they may not be easily visible for or editable by the average user, but as they're saved on the client-side - a 'malicious hacker', or even down to earth script kiddies, can easily set them to their heart's content. And how about $SERVER_NAME ($_SERVER["SERVER_NAME"]), which actually depends on the Host: header sent by the remote user, and can therefore be spoofed under certain circumstances?
Paraphrasing agent Mulder's immortal words, 'Trust Nothing'.
PHP Security Consortium
More on trusting (or not trusting) user input
Zeev Suraski[Read More]
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A shameless bit of self-promotion here: I am pleased to say that my Service Component Architecture for PHP article was published in International PHP Magazine this week. It is more or less the same structure and same material as the presentation I gave at Frankfurt, since I wrote them one after another. It is nice to have the words written down, though. Sadly, I was lazy about submitting a photo, so I appear in the guise of International Man of Mystery:
The same issue has an article by colleagues of mine, Graeme Johnson and Zoe Slattery, in which they describe the outcome of a fairly radical experiment. Poor fools, they set out to make a PHP engine using technology already to hand (bits of the Java Virtual Machine, a bit from IBM Research) but absolutely not using the existing engine itself. And this is the hard bit: they wanted to be able still to host the PHP extensions, unchanged. The difficult thing, if I have understood the article correctly, is that the extensions often have quite deep dependencies on the internals of the engine: they depend heavily on macros which in turn expect to know where to find various fields in various structures. This surely must hold back the evolution of engine and extensions since no one can move without breaking something. In the Java world the equivalent interface (JNI = Java Native Interface) manages to keep all the details hidden behind a few opaque handles. Quite an interesting experiment, and an unusual perspective on the PHP engine, I thought.
Matthew Peters[Read More]
I've had a few requests for the
The slides give an overview of the main concepts behind SDOs, followed by a few scenarios showing how to use them to work with relational and XML data. As I mentioned in a previous blog, the presentation could have done with a few more scenarios to address SDO's strengths and the questions which arose, but unfortunately time was short. I therefore intend to use this blog to cover these over time.
If you have any comments or questions on the SDO project, please let us know.
I presented an introduction to
One question which came up during the presentation was to do with the Relational Database Access Service and whether it optimizes the SQL queries it creates in order to remove redundancies. The short answer is, "no", but that's simply because it doesn't have to; SDO does the optimization for it.
The first thing to note is that SDOs keep a change summary, however, this summary only holds the information required to re-create the data object's original state, not any intermediate states. This is important when it comes to understanding how the updates are optimized.
Consider an example of a contact database (as described in this article). The contact database table contains a "shortname" column (e.g. "Fred") and a "fullname" column (e.g. "Frederick Flintstone"). Let's assume we've retrieved a set of contact SDOs from the database into the variable
The create and delete cancel each other out and the intermediate value of "Sally Smith" is not recorded, so the resulting change summary would only show that "Sally Barker" had changed her name to "Sally Jones". Consequently, when the Relational Data Access Service is asked to apply the changes back to the database, the only update it would see and perform is the name change.
The resulting SQL UPDATE statement would look like this:
with a parameter list of ("Sally Jones", primary key value, "Sally Barker")
SDO for PHP Project
SDO for PHP documentation
Relational Data Access Service documentation
We've just made our first release of SCA on the PECL repository. The code has been added into what was the SDO project and which has now been imaginatively renamed to SCA_SDO (you won't believe how much thought went into that...). The main features of this release are:
Unfortunately, we were not able to include the json-rpc binding which was demonstrated at the recent Zend and International PHP Conferences. We hope to be able to include this support soon. It's nice to see some positive comments from people who attended those conference presentations. Greg Whitescarver said, "I’m very glad to say that SCA makes exposing services (especially web services) ridiculously easy", and a review on Developpez.com found SCA "...somewhat strange but nevertheless excellent!" (at least that's the Bablefish translation ;-) ).
If you'd like more information on SCA/SDO, please visit the project's community page.
Finally, I'd like to thank Pierre for his help in renaming the SDO project to SCA_SDO, and preserving the old SDO links in the process. Thanks Pierre!
Graham Charters[Read More]
Yesterday, I presented and demonstrated SCA for PHP at the Zend/PHP Conference and Expo 2006. You can download the slides here. The session was well attended and I got some good questions at the end. A few people came up asking for the samples I demonstrated (showed how one line of code could be modified to switch from providing a soap/http service to a json-rpc service - I think it's cool, but then I would :-D ).
We are in the process of moving the SCA code into PECL. It will appear in the recently renamed SDO project, which is now called SCA_SDO. I'll put the samples in as part of the move into PECL and blog once this is completed.
I'll blog more about the Zend Conference when I get back...
Graham Charters[Read More]
As promised in my previous entry (albeit a little late), here are the SDO slides I used at the PHP Quebec conference.
The conference was very well organised and there were a good number of very interesting talks. They don't appear to be available on the conference site, but Chris Shiflett's blog has a list of quite a few that are available elsewhere.
The SDO presentation was well received, with some very good feedback. The demos went well and were free from "gremlins", with a number of people expressing an interest in getting hold of the code. I'll see about adding them as samples to the SDO package.
Graham Charters[Read More]
Some people who attended my SDO for PHP talk at php|tek in Orlando wanted to be able to try out the demonstration programs. I've recently uploaded them to CVS. If you'd like to try them out, copy the whole /scenarios directory under your document root, and browse to it. Some of the commentary is bit terse, so do let us know if you can't make them work or find any problems.Incidentally, we've recently published a new article Streamline working with XML in PHP using Service Data Objects, which uses the same Half-baked Blog program shown in the demonstrations to illustrate working with SDOs and XML.
People at the talk had some interesting ideas about how they might use SDOs to solve problems - if you did go home and try them out, I'd be pleased to hear how you got on, and any opinions you'd like to share, positive or negative. I had great time at php|tek, especially hearing about so many diverse areas that people are working in - everyone seems to have something special about their requirements or their environment. I also liked watching the alligators in the lake, and taking my morning swim in the open air (not in the lake).
In recent months we've had some requests from developers who would like to contribute to the SDO for PHP project. We recently added a Contributor License Agreement file to the project, so we can now welcome any developer who would like to be involved. There are instructions in the file about where to send it. Our CLA is based on the Apache CLA, and does not ask you assign the rights to your code, or inhibit you from using it for any other purpose. It simply serves to state the the code is yours to give, and that you do not impose any restrictions on its use.
Caroline Maynard[Read More]
I went to the International PHP 2006 conference in Frankfurt this week and gave a presentation on "Service Component Architecture for PHP". I have uploaded my slides to this blog but have had to split them into two parts, since the PDFs are otherwise too large to upload. I split them into the beginning and end and a block of 10 slides from the middle
I went into Frankfurt for a few hours on the Sunday afternoon. I expected it to be full of skyscrapers, but I was very very wrong; it has instead a pleasant city centre ringed with a few thrilling skyscrapers in the distance. I put a few of my photos up on Flickr.I was struck once again by the contrast between English and German cities: in Germany the public spaces are so much better cared for and more pleasant than they are in England.
The team that ran the conference did a splendid job, as did the hotel itself. I had not realised what an ordered little world I ws living in until I got to Frankfurt airport on a busy Wednesday evening and had to tussle with the real world.
Graham also gave a presentation on SCA for PHP at the Zend conference last week. Once again, despite presenting on the same topic, our presentations are quite different. He does architecture really well; I like to get grubby with hello world in the debugger.
I enjoyed every talk I went to at the conference. I especially enjoy hearing people who know their subject forwards and backwards and who probably wrote the code too, even if I may never need to use what they are talking about, so most of all I enjoyed Tim Bray's talk and the talks by Derick Rethans and Sara Golemon.
Matthew PetersRead More]