Paul Rouke and PRWD on User Centered Design

This post is the second in a series. The first post focussed on the strengths and weaknesses of the Zend Framework. This post about another leading PHP framework, Symfony.

Note: This post refers to Symfony 1.0. Version 1.1 has recently been released, but I have not had time to examine it in detail, though I imagine that most of my comments here apply equally to the new version.

Superficially, Symfony reminds me of Django. This is a Good Thing in my book. Symfony is a framework that is clearly designed to get applications up and running quickly, with a good ORM system and the facility to generate basic code automatically. The contrast with ZF is quite clear: Symfony is a tool that makes building web applications quick and easy as a top priority.

Features

Symfony provides all of the things that one would expect from a modern web framework, and a few more besides. The MVC components are all there – model development is supported by an ORM system that uses the Propel library, although there’s nothing to stop you using another library, such as Doctrine, instead (in fact, this is quite commonplace, and there is a well-supported plugin for Symfony that does just that). The controllers (’actions’ in Symfony parlance) are supported via a base class that provides useful abstractions over the HTTP request/response process. Views are rendered automatically for successful actions, with ‘partial’ views allowing sub-elements of a view to be templated, and ‘components’ fill a gap between heavyweight action-view combinations to provide ‘widgets’ which can be reused in different views throughout your app. Various helper functions save time and code by generating common HTML elements for you.

A lot of time spent on small Symfony projects will be spent editing configuration files as much as writing code. Some people might not like this, but I found it to be inrcredibly useful. Form validation, for example, can be set up using configuration files (although you can extend the basic set of validation options using custom classes). More importantly, your data model is defined using a configuration file which specifies your tables, their contents, and the relations between them. Once you have created your schema file, you can run command-line scripts to auto-generate the PHP class files that form the basis of your model. For example, for a table called ‘Posts’, Symfony (or, more accurately, the Propel library) will generate a PHP class called ‘Post’ which you can edit yourself, but this class inherits from the class ‘BasePost’ which provides getter/setter functions for the fields, as well as functions to retrieve related objects. Also created is the PostPeer class which provides (mostly static) functions to retrieve Post objects from the database. From here, you can run further commands which will generate basic CRUD modules – you can actually have a functional data-entry app without writing a single line of code. It will rarely be useful for production purposes out-of-the-box, but it provides a good foundation to build from.

There are plenty more configuration files, controlling database connections, caching, routing (URL paths), logging, security (access control) and default view settings, amongst other things. This approach won’t be to everyone’s tastes, but I have to admit that I liked it. One wrinkle is that many of these configuration files are in YAML format – a kind of strange hybrid of INI files, XML and Python’s whitespace handling that has been used in the Ruby on Rails. Again, it’s a matter of personal taste, but I found these files to be more readable than XML and certainly a lot less typing is involved in editing them.

Documentation

The documentation for Symfony is awesome. It is, quite simply, the best set of free documentation I have ever read for any software library, ever. The documentation on symfony-project.org consists largely of three main parts: The Book, the API reference, and Askeet. The Book, as the name suggests, consists largely of the content which makes up The Definitive Guide to Symfony, by Fabien Potençier (CEO and lead developer at Sensio Labs, where Symfony was created) and Francois Zaninotto, until recently the head of the Symfony documentation team. The Book is an invaluable reference to the core features of Symfony, and provides all of the introduction that anyone could need. The API reference provides a comprehensive backup for when you need the precise details, although it could be slightly easier to navigate. And, as if all of that were not enough, there’s ‘Askeet’, a 24-part mega-tutorial, in which Symfony is used to create a whole, functioning web 2.0 app, in easy-to-follow stages. Each stage represents a new achievement, with an emphasis on getting a new working piece of functionality in place. Often, code from earlier stages is substantially refactored during later ones, providing a good example of how to go about transforming a prototype into a final application. The bottom line: Symfony’s documentation rocks.

Community

Symfony’s community is not huge, but does seem to be fairly active. Symfony seems to follow the ‘benevolent dictatorship’ model of open source development, as exemplified by Linus Torvalds‘ leadership of Linux or, in the PHP realm, Dries Buytaert’s leadership of the Drupal project. Fabien Potençier appears to be the overall head of the Symfony project, although there are other major contributors. Symfony seems to have a particularly strong set of plugins – code modules which extend or enhance the framework, or provide substantial units of functionality which can be plugged in to Symfony apps. There certainly aren’t as many Symfony plugins as there are, say, Drupal modules, but this is a strength that does not seem to be present in many other PHP frameworks. The community is also active in contributing documentation, with Andréia Bohner’s Symfony cheat sheets being a shining example.

Conclusion

I have to admit, I’m now something of a fan of Symfony. There is a streak of common sense running through the way it works which makes it very fun to work with. The documentation is fantastic, and the community looks strong enough to support development for the long term. The only dark cloud on the horizon is the fact that questions have been raised by some long-standing community members about the direction that the newly-released version 1.1 is going in, suggesting that it may be sacrificing some simplicity and ease of development for a slightly more ‘purist’ approach to code structure. Time will tell whether or not these fears are well-founded but, for now, I think that Symfony is worthy of recommendation.

I have recently been researching various PHP frameworks, for use in upcoming projects.  These projects are large-scale, enterprise PHP systems which are going to be developed and maintained over a long period of time, so making the right choice of framework is crucial.  Also important is the ease of development – how easy the different frameworks make application development, and how they support rapid development, prototyping and agile development processes.  This post is the first in a series comparing the strengths and weakness of PHP frameworks.

The first two frameworks I have considered are the Zend Framework (currently at version 1.5) and Symfony (version 1.0, though version 1.1 has just been released).  I have considered a number of different factors and my judgements are very much a subjective view.  I have had plenty of experience of different software libraries, from coding C++ using the Microsoft Foundation Classes library in the late 90s, to PHP using the Drupal CMS/F (whether one considers Drupal to be a ‘framework’ is a matter of debate) and Python using Django.  In this time I think that I have learned to spot the strengths and weaknesses of frameworks and libraries, so, although subjective, my views aren’t totally uneducated.

Zend Framework

The first thing to say about ZF is that it wasn’t what I expected.  Having used Django and observed the general trend in web frameworks towards code generation and advanced ORM, ZF was surprising in that it bucked this trend entirely.  If you want CRUD code with ZF, you can write it yourself.  This, in itself, is not necessarily a bad thing, but it is slightly discouraging when you just want to get in and have a play about it with the framework.  In this day and age, the ability to rapidly assemble a working prototype is very important, and ZF could go further in making this easy.

Features

After a while of using ZF, it becomes apparent that my initial objection – that it doesn’t really speed up development during the very early phase of a project – is an intentional design choice.  The ZF developers refer to this as ‘use-at-will’ architecture; in old-fashioned software engineering lingo, we might say that ZF is ‘loosely-coupled’, in that the various classes it provides can be used separately, without reference to the rest of the framework.  This makes ZF a great choice for refactoring legacy code, as you can just plug in those bits of the framework that you need, without having to modify anything else.  If all you really want is the (very useful) ZF Akismet class (which interfaces with Automattic’s Akismet service), you don’t need to use the rest of the library at all.

In fact, after a while I started to think that the aims of ZF are actually somewhat different to the aims of other frameworks.  Most other PHP frameworks were funded and contributed to by developers who needed the functionality in their day jobs.  CodeIgniter came from the development of ExpressionEngine, Fabien Potencier’s Sensio Labs created Symfony to power their in-house projects, Drupal was started by Dries Buytaert to provide a basic community website and forum and Ruby on Rails began life as a basic library of functions used by 37 Signals for the development of Basecamp.  The Zend Framework, on the other hand, was funded by Zend specifically to create a strong, reliable PHP framework in order to give PHP a rival to Rails and Django.  It is, in effect, an ‘immaculately conceived’ framework, designed from first principles to support the widest-possible deployment, rather than to solve specific common problems.

In this respect, ZF is more of a ‘library’ than a ‘framework’.  It provides a set of classes that you can use as you see fit, taking out the ones that interest you, and leaving the rest.  What it does not really do is provide you with the basic foundational structure of an app that most other web development frameworks tend to do these days.  This is probably due to Zend’s different motivations in creating ZF – they are not a bunch of deadline-driven web developers trying to make their own jobs easier by creating a framework to build new apps with; instead they are attempting to create a set of classes that others can use in a whole variety of different ways, many of which the ZF developers cannot anticipate.

As such, ZF represents something similar to the C++ Standard Template Library – the object-oriented successor of the older C Standard Library.  Zend appear to be trying to give developers a new set of modern, object-oriented tools with which to build applications, perhaps replacing some of the reliance on the huge legacy PHP feature set.

Documentation

ZF’s documentation is poor.  There’s a reasonably good reference for each class, but there are nowhere near enough example applications and tutorials.  This is probably related to the fact that ZF classes can be used in isolation from each other and there isn’t always a clear way of constructing a basic app to make use of these classes, but this is no excuse.  For a developer considering ZF for the first time, it can be hard to see exactly how one is meant to make use of it.  What examples there are tend to be quite complex and focus on the arcana of the framework’s implementation than practical use cases.  This is my single biggest problem with ZF.

Community

The genesis of ZF also contributes to the slightly odd feel of the community.  Coming from a Drupal background, I’m used to a very self-reliant community, with a strong ‘do it yourself’ approach to improving the software, the kind of ethos that, to me, signifies a truly great open source development.  The Zend Framework doesn’t have that yet.  Too often, the ‘community’ seems to consist of ‘users’ rather than ‘doers’, people who would rather petition Zend to improve the software than submit a patch or create a new module.  Open source projects, if they work well, are a bit like crowd-surfing at a gig – you throw yourself out there and hope that enough people decide to catch you.  At the moment, it’s not apparent that there are enough people to catch the Zend Framework, so it can’t make the leap.  The developers can’t quite let go of their creation, either because they are unwilling to, or because there’s not enough people there to catch it.  This does lead to some unfortunate examples of developers reacting personally to criticism, rather than the standard open source response of ‘fix it yourself if you don’t like it!’.

Conclusion

ZF’s strengths are clear – the code is well-written, covers a range of common web development tasks, including some areas neglected by other frameworks, and succeeds in making it easy for developers to incorporate ZF code into legacy projects.  These strengths alone make it an important piece of software that is likely to remain relevant for cutting-edge PHP developers over the next few years.  The framework’s weaknesses – that it isn’t really a framework – are easily addressable; it’s not hard to imagine someone creating the additional ‘glue’ that would make ZF a viable framework in the mould of Rails and Django.  If that code came from the community rather than Zend, then it would be a sign of ZF blossoming into a truly useful framework.  And if this could all be documented, we might be getting somewhere!

Part two of this post will consider the Symfony framework. Stay tuned!