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To start with I'm not exactly sure if this question will fit the question model of SO so moderators please close it if it doesn't fit...
I have been reading a lot on MVC and SoC lately and how they relate to programming in PHP and am having some difficulty grasping how the concepts differ to my current programming style. Any application I write uses url_rewrite routes, with the routing handled by a single file which selects the appropriate controller.php file based on the sub system requested. Then within that controller file the final smarty template file is assigned and the PHP file which contains the business logic of the page in question is included into the stack.
The issue I am having is that while I review MVC and SoC information all the examples I see are written as extensive inter-dependant classes and some rather deep namespaces, but when I code I only use objects where I need an object for reusable but distinct code (in line with object examples on the PHP site itself), and so wind up with some code being classed and namespaced nearly 70% of my application remains in the global namespace with no classing. It seems to me that this coding technique still meets the design principal of separation of concerns, though i'm not so sure about being MVC as every example of MVC I can find is built solely out of a very large number of classes.
Could someone please explain if I am way off base here or if I am achieving SoC and possibly even MVC with my current coding and explain to me if embedding the entire application within a range of classes is a requirement for SoC and MVC.
Thanks
OK I usually take on these open ended questions :P
Let me rephrase your whole thing to a new question – and feel free to tell me I am wrong!
I think you are asking - “Is my coding style in-line with best practice for x y z?”
Now look – i have been in a variety of roles, and I strongly believe that no one has ever cracked a complete SoC architecture – at some point there is always a trade-off between enabling someone at the view end to do their job, and someone upstream ingesting the input and making it work such that it ties to the database and logic.
For example - I am actually right now building a system that takes HTML files as input, reads them via PHP. PHP converts the HTML elements to a bunch of JSON and adds logic to that JSON based on x, y and z, then shoves it out to Facebook React components – which converts it all back to HTML / DOM – when you explain to someone that there is a sausage machine that takes, as input, HTML, and outputs HTML, you can see why they might go – holy shit what are you doing!!
Now – why did we do this? Because it made sense for the project, and it made sense for the team. We could have equally used some pre-defined framework and blah blah blah – however this worked for us.
(a caveat here would be, if you need a highly performant application, this might be the wrong approach, however – bear in mind that what you read (inter dependant classes etc.) may also not be performant – optimisation of PHP code is hard work – my advice here is, get it working first, then if the product is successful, pay someone to fix your shitty code – server time is cheap – your time is not)
My statement for you would be, without concrete examples and use cases – people will struggle to comment on your approach – but understand that there are many different ways of doing things and you may see much open source code written in one way or another, but if you write something that achieves a goal, your only concern should be that it is performant and that it has ‘enough’ separation such that your designer can work on design, your coder can work on code and your CEO can look at sales figures.
Hope this helps.
From the information you've given, you're doing a good job. I think you have a grasp at Separation of Concerns and probably MVC. I think you should take a closer look at how things are abstracted in other codebases, how things are modularized, and think about how you would handle things that potentially come up in web development.
What if I want to have some code run before every controller? Or middleware that runs between the request and the controller? Or inject a variable into the view after every controller is processed? How are you separating POST, GET, PUT, DELETE logic but still grouping them within a resource? Some of these can be achieved with your architecture but I think many of the solutions would be cleaner with a class-heavy architecture. Of course, something being cleaner is in the eye of the beholder.
Frameworks released to the public try to be generic and tackle as many use cases as possible. One issue I see is that you make the assumption that the controller file would be called last and then setup the view. So, even though the logic in there is in the global state, it only exists within that file. In essence, the file acts as a namespace. I don't think that's an assumption a generic web framework should make, but it's something you can get away with when writing something for yourself.
Long time lurker, first time poster...
I'm now at the point where I'd almost call myself a professional grade PHP programmer and have a lot of code I re-use in various projects. Also, a lot of Open Source packages I've worked with use the MVC model and as a result I've done a lot of research recently into how it all works so I can better edit them as required.
At this point, I'm considering taking a bare-bones MVC framework (from a tutorial) and extending it as required for my forthcoming programming jobs.
My question is whether the MVC model with pretty much all application logic separated from the presentation layer is considered best practice over a well structured OOP website with coding on the page as necessary e.g setting function variables.
Or will I run into issues when I want coding flexibility e.g.
using something like PHPthumb for a gallery where I want different output
sizes on different pages and currently set parameters in the head
of the page
a contact form with x fields and a feedback form with y fields - will this require 2 differrent models rather than a generic form class again with some parameters set in the head of the page
some pages requiring ob_start() and ob_flush() but not others?
Please don't tell me not to build my own framework - I'd rather know how each little bit works than use a slab of code I know nothing about - I'm really interested in the opinion of people who have gone this route and build sites every day. What are the real pros and cons of this over plain (but well structured) OOP and bunch of pages to a site as opposed to 1 index.php page and separate files.
Cheers,
Niggles
I know you say you don't want this advice, but don't write your own. The first thing I've done at every single job I've ever worked at is picked up some existing code or framework, often commercial but highly modified, and begun maintaining it. You'll seldom get the option to write your own, and doing so is a bad idea. It's hard, expensive, and somebody else has already written a better MVC PHP framework than you're likely to write.
There are literally dozes of mature PHP frameworks, most of which have been around for over a decade. Choose one of them. It doesn't matter which one - they're all maintained by a dozen people at least as smart as you who've been writing MVC frameworks a lot longer, and have spent months or years refining their frameworks and listening to user input.
All that said, if you want to write your own on your own time, as a hobby, so you're not wasting your boss's money, then by all means. There's a huge variety of interpretations of MVC. Some frameworks view views as basically templates. I personally think you can throw as much raw PHP in there as you'd like, so long as it's purpose is display, and you do the usual smart things like distilling out shared code into functions. Some frameworks have virtually no business logic in the models (where it belongs IMO) but have very heavy controllers. The best thing you can do is try other frameworks and see how they work, and which you like best, and decide what you'd like to see changed. Then, set out to change it in your own.
You say you're almost ready to consider yourself a professional? The hardest lesson I had to learn was that professionals don't write their own low-level libraries. They don't reinvent the wheel on the company buck. They use off-the-shelf components and get the job done today, rather than a month from now. You don't want to use a slab of unfamiliar code? That's the biggest part of your life to come as a programmer - get used to it.
Writing your own framework is great for your own edification and for truly understanding the language.
Personally I find its as time consuming using a third party framework as it is to write your own. Yet I have total control of my own code, not something you can claim with any third party framework.
I also think many MVC frameworks are very resource intensive. For high volume sites you need to be prepared to throw hardware at them to get them to run nicely. For low volume sites (the majority) the rapid development of a third party MVC framework is a huge bonus.
So in my opinion if you have the time, roll your own and be proud of it. Just make sure you learn from others especially where security is concerned.
It all depends on what are you project requirements are and how you design your application objects. MVC do not force you to use an specific class or view design, It will only provide you with an architecture that will help you isolate the business logic from the presentation and the data layer making you application more scalable and easy to test.
In MVC you are not tied to one view per controller you can use as many views as you want per controller since every exposed method can call a view itself and control how it looks and behave based on the business logic you define. That said you can have 2 methods to return a full size image and a thumbnail without having to create two pages. You can set everything on the view from the controller, header meta-data, scripts, links, theme, content, etc...
In regard to the models, it again depends on your project requirements but definitely, in any case, if you have several pages with different purposes and they require to modify different data sources there should be a model for each one of them and what you can do after is to create a class that encapsulates the form functionality by calling the model for getting the fields to create form, get and save the data. This is just an idea you can do it in a lot of different ways, that is the beauty of OOP.
In the end it is not a matter of comparing a well structured OOP site against an OOP MVC site, It is more an analysis of the time and effort you spend working on building a site architecture that can succeed in isolating concerns at the same time it still readable and scalable while it meets your project requirements.
If you want to get more ideas about design patterns you can use google MVP design pattern and/or MVVM design pattern.
I have written my own framework. It does not take time to create the architecture and raw code. It's great if someone writes there own framework. But If documentation is not proper than definitely pain in asses. Completely depends upon yourself. I have written mine as well. It took almost 7 days to make framework QA ready :). but the main issue is to get satisfied by the piece of code you write in your framework. You would always like to improvise your framework and wanted it to be best ever. BLAH! BLAH! If you wish to write your own and you are confident enough for sustenance. GO for it.
Any MVC -- homegrown or not -- will allow you flexibility and re-usable code.
ob_start() / ob_* calls are no problem, they go in your model and called from your template, e.g.:
Hello <?php echo $this->getFormattedName(); ?>
where your model is
function getFormattedName() {
ob_start();
echo '' . $this->getName() . '';
$return = ob_end_clean();
return $return;
}
For your form scenario, you would probably want an abstract form class that defines how a field is made and its validation, then each specific form would extend your abstract.
You may want to consider using something like Zend Framework -- while it's an MVC library in its own right, you can pull in single components super easily (for example, you can pull in Zend_Form and Zend_Mail for your contact and feedback forms & validation and use your own models for everything else). This would also give you the extra benefit of having a fallback when/if the time comes when your homebrew MVC framework starts to outgrow its original design. Or, at the very least, speed up your development time so that you're not held up for days because you suddenly realize you need an e-mail model.
I work in a web shop as a PHP programmer. Most of the time we use good coding practices but not much structure to the site as a whole.
I have now entered my phase of being bored with some of our practices and want to branch out and simplify and generate some things in a helpful way not just for me, but the hybrid-programmer web developers in the office.
One employee left us with a MVC site written in PHP, and I have had to maintain it a bit, and I get how it works but have my complaints, my main complaint is that it is tightly coupled with each piece dependent on another. I see the advantage of the seperation of concerns, but this would be confusing to anyone but me looking at the code.
So for example, if I need to add a new page to the site, I have to go add a view, and then add a model, then update the controller. The ad-hoc method of making a new page is way simpler than this and doesn't require a programmer.
My judgement was this was a much better method to build, rather then maintain, a website.
Still, it would be nice if I had some design patterns where I could reuse code effectively without it being dependent on a multiple places in the site.
So my question is, is there a design pattern for building and maintaining websites that is much more loosely-coupled? I'm not looking for slight variations on MVC, I need something quite different to look at, maybe some type of plugin approach.
EDIT:
Thanks for the answers so far! A different way of putting it is I want the code to be done better in my office. Do I A) Push for MVC or B) find/build an alternative not as confusing to the half-programmers. We already use classes for things like DB connectivity and Form helping. The point of this question was to explore B.
There's always a compromise between the code being confusing because it's highly deconstructionist, and the code being confusing because absolutely everything needed to do X is randomly scattered around a single file.
The problem with the latter is that exactly what is an "intuitive" way to split things up into monolithic modules differs between people. Highly decomposed and factored code is nearly always more difficult to wrap your head around, but once you do that, maintenance becomes both easy to do. I disagree that it would be confusing to anyone else but the author looking at it. Large-scope patterns like MVC are used because it becomes easier to spot them and work on projects structured around them over time.
Another advantage of using MVC is that you generally won't make the application more difficult to maintain for someone who comes after you if you don't stick to the layering. This is because now you have a predetermined place where to place any aspect of implementing a new feature.
As far as the tight coupling is considered, you can't really implement a feature without there being some connection between the layers. Loose coupling doesn't mean that the layers are ignorant of each other completely - it means that a layer should be unaware of how the other layers are implemented. E.g.: the controller layer doesn't care whether you're using a SQL database or just writing binary files to persist data at the data access layer, just that there is a data access layer that can get and store model objects for it. It also doesn't care about whether you use raw PHP or Smarty at the view layer, just that it should make some object available under some predetermined names for it. All the while the view layer doesn't even need to know there is a controller layer - only that it gets called with the data to display ready under the abovementioned names provided by /something/.
As frameworks templates go, I find the MVC pattern to be one of the most "loosely coupled" ways of building an application.
Think of the relationships like interfaces, or contracts between the parts of the application. The Model promises to make this data available to the View and the Controller. No one cares exactly how the Model does that. It can read and write from a typical DBMS, like MySQL, from flat files, from external data sources like ActiveResource, as long as it fulfills its end of the deal.
The Controller promises to make certain data available to the View, and relies on the Model to fulfill its promises. The view doesn't care how the Controller does it.
The View assumes that the Models and the Controllers will keep their promises, and can then be developed in a vacuum. The Model and Controller don't care if the view is generating XML, XHTML, JSON, YAML, plaintext, etc. They are holding up their end of the contracts.
And, of course, the View and the Controller need to agree that certain things exist. A View without some corresponding Controller activity might work fine, but could never be used. Even if the Controller doesn't do anything, as might be the case in static pages:
<?php
class StaticController extends ApplicationController
{
/**
* Displays our "about" page.
*/
public function about ()
{
$this->title = 'About Our Organization';
}
}
Then the associated View can just contain static text. (Yes, I have implemented things like this before. It's nice to hand a static View to someone else and say "Just write on this.")
If you look at the relationships between the M, V, and C as contracts or interfaces, MVC suddenly looks very "loosely coupled." Be wary of the lure of stand-alone PHP files. Once you start including and requiring a half-dozen .inc files, or mixing your application logic with your display (usually HTML) you may have coupled the individual pages more loosely, but in the process made a mess of the important aspects.
<?php
/**
* Display a user's profile
*/
require_once 'db.php';
$id = $db->real_escape_string($_GET['id']);
$user_res = $db->query("SELECT name,age FROM users WHERE id = $id;");
$user = $user_res->fetch_assoc();
include 'header.php';
?>
<h1><?php echo $user['name']; ?>'s Profile</h1>
<p><?php echo $user['name']; ?> is <?php echo $user['age']; ?> years old!</p>
<?php
include 'footer.php';
?>
Yeah, "profile.php" and "index.php" are completely unrelated, but at what cost?
Edit: In response to your edit: Push for MVC. You say you have "half-programmers," and I'm not sure which half (do you have front-end people who are good at HTML and CSS but not at server-side? writers with some programming experience?) but with an MVC framework, you can hand them just the views, and say "work on this part."
I have to say that I don't really see your problem with MVC, since your already using templates anyway. I kind of think of it as the pattern that evolves naturally when you try to add structure to an application.
When people first start developing PHP application, the code is usually one big mess. Presentation logic is mixed with business logic which is mixed with database logic. The next step that people usually take is to start using some kind of templating approach. Whether this involves a specialized template language such as smarty or just separating out the presentation markup into a separate file isn't really important.
After this most of us discovers that it's a good idea to use dedicated functions or classes for the database access logic. This really doesn't have to be any more advanced than creating specialized functions for each commonly executed query and placing all those functions in a common include file.
This all seems very natural to me, and I don't believe that it's very controversial. But, at this point you're basicly already using an MVC approach. Everything beyond this is just more or less sophisticated attempts to eliminate the need to rewrite commonly used code.
I understand that this might not be what to you wanted to hear, but I think you should re-evaluate MVC. There's a countless number of implementations, and if it's really the case that none of them suits your needs, then you could always write your own and more basic implementation.
Look at it this way: Since you're already using a template language you'll typically need to create first a regular PHP file, and then a templare file each time you create a new page. MVC doesn't have to be any more advanced than this, and in many cases it isn't. It might even be that all you really need to do is to investigate more sophisticated approaches for handeling data access and add it to your current system.
The fact that you have to create a new Model and Controller Action when you need a new page I don't think means that your M, V, and C layers are tightly coupled. This is just the separation of concerns and contributes to a decoupled system.
That said, it is quite possible to royally screw up the intent of MVC (and I've worked on an app like this) and make it make the components tightly coupled. For instance, a site might put the 'rendering engine' directly in the Controller layer. This would obviously add more coupling. Instead a good MVC will be designed so that the controller is only aware of the name of the view to use and then pass that name to the separate rendering engine.
Another example of bad design in an MVC is when the views have URLs hard-coded into them. This is the job of the Routing engine. The view should only be aware of the action that needs to be called and the parameter that action needs. The Routing engine will then provide the correct URL.
Zend framework is very loosely coupled and is very good. Check it out:
http://framework.zend.com
This article might be of use too:
http://blog.fedecarg.com/2009/02/22/zend-framework-the-cost-of-flexibility-is-complexity/
You can try code Igniter. Its very easy to learn and does not strictly adopt MVC whilst giving your code good structure.
Code Igniter and Kohana (a CI descendent) are OK, but also loosely MVC. I like the simple php framework. It doesn't get in your way and it provides the important stuff, without forcing a structure or complicated conventions on you.
Ah... good old MVC arguments.
I have to maintain a multi-faceted PHP application, pieces of which are written "MVC" style, but not all. Worse, different parts have different ways of doing MVC, all of which are homegrown. And some pages just do it all themselves.
The main problem is not that there is a diversity in framework code, but that the coders clearly did not understand how to abstract APIs. IMO, ths is the biggest problem with MVC frameworks. Almost all of the code I have to work with uses "models" as places to put functions. It is a nightmare to maintain.
To make this maintainable, IME you need a few things:
A distinct and well-defined data-access layer, the API boundary of which looks after retrieving and storing persistent storage and very little else.
I don't like to use the term "model" for that because that is contentious. Whatever calls that layer should not care how the data is stored, should not even be worrying about things like database handles: that is all the job of the data-access layer.
A dispatcher that is very light and doesn't do any magic outside of just dispatching.
Now you can put everything else in one place that accepts requests and parameters, probably normalised and error checked from the dispatcher, fetches the data (usually as objects) it needs, makes the changes it needs to do, saves the data it needs to, hands the data is needs to display to the view. Two hundred lines of code plodding through the task works for this step. You don't need to hive off bits into functions in another file that are called from nowhere else. You can even put the view on the end of this file! Idealism is nice to aspire to but pragmatism needs a look-in because this is maintainable.
(Okay, rant over... )
PHP's lack of enforcing a framework means that the best frameworks do what PHP does: they stay out of the way. Some of the most maintainable code I've worked on had a single require() statement at the top, did all the data-manipulation with data objects (no SQL in sight), then output HTML surrounded by template functions, with form control being done by a consistent function API.
I'm trying to design a solid server side architecture and came up with this :
http://www.monsterup.com/image.php?url=upload/1235488072.jpg
The client side only talks to a single server file called process.php, where user rights are checked; and where the action is being dispatched. The business classes then handle the business logic and perform data validation. They all have contain a DataAccessObject class that performs the db operations.
Could you point the different weaknesses such an architecture may have? As far as security, flexibility, extensiveness, ...?
Your architecture isn't perfect. It never will be perfect. Ever. Being perfect is impossible. This is the nature of application development, programming, and the world in general. A requirement will come in to add a feature, or change your business logic and you'll return to this architecture and say "What in the world was I thinking this is terrible." (Hopefully... otherwise you probably haven't been learning anything new!)
Take an inventory of your goals, should it be:
this architecture perfect
or instead:
this architecture functions where I need it to and allows me to get stuff done
One way that you could improve this is to add a view layer, using a template engine such as Smarty, or even roll-your-own. The action classes would prepare the data, assign it to the template, then display the template itself.
That would help you to separate your business logic from your HTML, making it easier to maintain.
This is a common way to design an application.
Another thing you could do is have another class handle the action delegation. It really depends on the complexity of your application, though.
The book PHP Objects, Patterns and Practice can give you a real leg-up on application architecture.
I see a couple of things.
First, I agree with others that you should add a view layer of some kind, though I am not sure about Smarty (I use it frequently and I am really having doubts these days, but I digress). The point is you need to separate your HTML somewhere in a template so it's easy to change. That point does not waver if you use a lot of AJAX. AJAX still requires you (usually) to put divs around the page, etc. So your layout should be separated from processing code.
The second thing I would throw out there is the complexity of your data model matters. If this is a straightforward CRUD application over an existing, or fairly flat, db model, you are probably fine with these db access classes. But, the minute your model gets to be more complex, with hierarchies or polymorphic in any way, this will break down. You'll need a more robust ORM of some kind.
Your "controller/dispatcher" methodology seems sound. The switch statements avoids the need for any kind of URL -> code mappings, which are a pain to manage and require caching to scale.
That's my $0.02
From a security perspective your class and action are coming in from your post variables and this can be dangerous because you should never trust anything coming from the user. Assumingly your class/action will look something like this:
class1
{
action1.1
action1.2
...
action1.N
}
class2
{
action2.1
action2.2
...
action2.N
}
As an attacker my first place to look would be getting into a state where an action doesn't match to it's appropriate class. I would try to submit class1 with action2.1 instead of action1.1.
With that said, my assumption is that you've already got some form of validation and so this wouldn't happen. Which leads me to my original post: If your architecture works for you, then it works for you. Take a look at the things which you're asking about: security, flexibility, extensibility and evaluate them yourself. Find your own flaws. If you don't know how to evaluate for security/flexibility/other read up on the subject, practice it and apply it.
You'll become a better developer by making mistakes and then learning from them (except missile guidance software, you only get one try there.)
Since others have suggested various changes like adding a view layer, etc. let me concentrate on the various criteria for a good architecture:
Extensibility: Usually, the more abstract and loosely coupled the architecture is, the more extensible it is. This is exactly why others have recommended you use a view layer which would abstract out the presentation layer templates for each class:action pair into its own file.
Maintainability: This goes hand-in-hand with extensibility. Generally, the more extensible the architecture is, the more maintainable it is (take that with a grain of salt because it is not always the case). Consider adding a model layer below your model logic layer. This would help you swap out your data access logic from the model business logic.
Security: The downside to the architecture you have posed is that you really need to invest in security testing. Since all your redirecting/routing code is in process.php, that file has a lot of responsibility and any changes to it may result in a potential security loophole. This isn't necessarily wrong, you just need to be aware of the risks.
Scalability: Your architecture is balanced and seems very scalable. Since you have it broken down by class:actions, you can add caching at any layer to improve performance. Adding an addition data access model layer will also help you cache at the layer closest to the database.
Finally, experiment with each architecture and don't be afraid to make mistakes. It already seems like you have a good understanding of MVC. The only way to get better at architecting is to implement and test it in the 'real world'.
I want to create a 100% object oriented framework in PHP with no procedural programming at all, and where everything is an object. Much like Java except it will be done in PHP.
Any pointers at what features this thing should have, should it use any of the existing design patterns such as MVC? How creating objects for every table in the database would be possible, and how displaying of HTML templates etc would be done?
Please don't link to an existing framework because I want to do this on my own mainly as a learning excercise. You will be downvoted for linking to an existing framework as your answer and saying 'this does what you want'.
Some features I'd like to have are:
Very easy CRUD page generation
AJAX based pagination
Ajax based form validation if possible, or very easy form validation
Sortable tables
Ability to edit HTML templates using PHP
I've gone through many of problems on your list, so let me spec out how I handle it. I am also OOP addict and find object techniques extremely flexible and powerful yet elegant (if done correctly).
MVC - yes, hands down, MVC is a standard for web applications. It is well documented and understandable model. Furthermore, it does on application level what OOP does on class level, that is, it keeps things separated. Nice addition to MVC is Intercepting Filter pattern. It helps to attach filters for pre- and post-processing request and response. Common use is logging requests, benchmarking, access checking, caching, etc.
OOP representation of database tables/rows is also possible. I use DAO or ActiveRecord on daily basis. Another approach to ORM issues is Row Data Gateway and Table Data Gateway. Here's example implementation of TDG utilising ArrayAccess interface.
HTML templates also can be represented as objects. I use View objects in conjunction with Smarty template engine. I find this technique EXTREMELY flexible, quick, and easy to use. Object representing view should implement __set method so every property gets propagated into Smarty template. Additionally __toString method should be implemented to support views nesting. See example:
$s = new View();
$s->template = 'view/status-bar.tpl';
$s->username = "John Doe";
$page = new View();
$page->template = 'view/page.tpl';
$page->statusBar = $s;
echo $page;
Contents of view/status-bar.tpl:
<div id="status-bar"> Hello {$username} </div>
Contents of view/page.tpl:
<html>
<head>....</head>
<body>
<ul id="main-menu">.....</ul>
{$statusBar}
... rest of the page ...
</body>
</html>
This way you only need to echo $page and inner view (status bar) will be automatically transformed into HTML. Look at complete implementation here. By the way, using one of Intercepting Filters you can wrap the returned view with HTML footer and header, so you don't have to worry about returning complete page from your controller.
The question of whether to use Ajax or not should not be important at time of design. The framework should be flexible enough to support Ajax natively.
Form validation is definitely the thing that could be done in OO manner. Build complex validator object using Composite pattern. Composite validator should iterate through form fields and assigned simple validators and give you Yes/No answer. It also should return error messages so you can update the form (via Ajax or page reload).
Another handy element is automatic translation class for changing data in db to be suitable for user interface. For example, if you have INT(1) field in db representing boolean state and use checkbox in HTML that results in empty string or "on" in _POST or _GET array you cannot just assign one into another. Having translation service that alters the data to be suitable for View or for db is a clean way of sanitizing data. Also, complexity of translation class does not litter your controller code even during very complex transformations (like the one converting Wiki syntax into HTML).
Also i18n problems can be solved using object oriented techniques. I like using __ function (double underscore) to get localised messages. The function instead of performing a lookup and returning message gives me a Proxy object and pre-registers message for later lookup. Once Proxy object is pushed into View AND View is being converted into HTML, i18n backend does look up for all pre-registered messages. This way only one query is run that returns all requested messages.
Access controll issues can be addressed using Business Delegate pattern. I described it in my other Stackoverflow answer.
Finally, if you would like to play with existing code that is fully object oriented, take look at Tigermouse framework. There are some UML diagrams on the page that may help you understand how things work. Please feel free to take over further development of this project, as I have no more time to work on it.
Have a nice hacking!
Now at the risk of being downvoted, whilst at the same time being someone who is developing their own framework, I feel compelled to tell you to at least get some experience using existing frameworks. It doesn't have to be a vast amount of experience maybe do some beginner tutorials for each of the popular ones.
Considering the amount of time it takes to build a good framework, taking the time to look into what you like and loathe about existing solutions will pale in comparison. You don't even need to just look at php frameworks. Rails, Django etc are all popular for a reason.
Building a framework is rewarding, but you need a clear plan and understanding of the task at hand, which is where research comes in.
Some answers to your questions:
Yes, it should probably use MVC as the model view controller paradigm translates well into the world of web applications.
For creating models from records in tables in your database, look into ORM's and the Active Record pattern. Existing implementations to research that I know of include Doctrine, more can be found by searching on here.
For anything AJAX related I suggest using jQuery as a starting point as it makes AJAX very easy to get up and running.
Creating your own framework is a good way to gain an appreciation for some of the things that might be going on under the hood of other frameworks. If you're a perfectionist like me, it gives you a good excuse to agonize over every little detail (e.g. is should that object be called X or Y, should I use a static method or an instance method for this).
I wrote my own (almost completely OO framework a while ago), so here's my advice:
If you've worked with other frameworks before, consider what you liked/didn't like and make sure yours gives you exactly what you want.
I personally love the MVC pattern, I wouldn't dream of doing a project without it. If you like MVC, do it, if you don't don't bother.
If you want to do JavaScript/AJAX stuff, do use a JavaScript library. Coding all your own JavaScript from scratch teaches you a bit about the DOM and JavaScript in general, but ultimately its a waste of time, focus on making your app/framework better instead.
If you don't want to adopt another framework wholesale, take a look at whether there are other open source components you like and might want to use, such as Propel, Smarty, ADOdb, or PEAR components. Writing your own framework doesn't necessarily mean writing everything from scratch.
Use design patterns where they make sense (e.g. singletons for database access perhaps), but don't obsess over them. Ultimately do whatever you think produces the neatest code.
Lastly, I learned a lot by delving into a bit of Ruby on Rails philosophy, You may never use RoR (I didn't), but some of the concepts (especially Convention over Configuration) really resonated with me and really influenced my thinking.
Ultimately, unless your needs are special most people will be more productive if they adopt an existing framework. But reinventing the wheel does teach you more about wheels.
At the risk of sounding glib, this seems to me like any other software project, in this sense:
You need to define your requirements clearly, including motivation and priorities:
WHY do this? What are the key benefits you hope to realize? If the answer is "speed" you might do one thing, if it's "ease of coding" you might do another, if it's "learning experience" you might do a thid
what are the main problems you're trying to solve? And which are most important? Security? Easy UI generation? Scalability?
The answer to "what features it should have" really depends on answers to questions like those above.
Here are my suggestions:
Stop what you're doing.
It's already been done to death.
Click this Zend Framework or that CakePHP or maybe even this Recess Framework.
Now, my reasons:
... if you've worked with developers at all, you've worked with developers that love reinventing the wheel for no good reason. This is a very, very common failure pattern.
... they would go off and write hundreds and thousands of the crappiest languages you could possibly imagine ...
... "Oh, I'm gonna create my own framework, create my own everything," and it's all gonna be crappier than stuff you could just go out and get ...
from StackOverflow Podcast # 3.
So, save yourself some time, and work on something that solves a problem for people like a web app that lets people automatically update Twitter when their cat's litter box needs cleaning. The problem of "Object Oriented PHP Framework" is done. Whatever framework you slap together will never be as reliable or useful or feature rich as any of the freely available, fully supported frameworks available TODAY.
This doesn't mean you can't have a learning experience, but why do it in the dark, creating a framework that will grow into a useless blob of code, leaving you without anything to show for your time? Develop a web app, something for people to use and enjoy, I think you'll find the experience incredibly rewarding and EDUCATIONAL.
Like Jim OHalloran said, writing your own framework gives you a very good insight into how other frameworks do things.
That said, I've written a data-access layer before that almost completely abstracted away any SQL. Application code could request the relevant object and the abstraction layer did lots of magic to fetch the data only when it was needed, didn't needlessly re-fetch, saved only when it was changed, and supported putting some objects on different databases. It also supported replicated databases, and respected replication lag, and had an intelligent collection object. It was also highly extensible: the core was parameter driven and I could add a whole new object with about 15 lines of code - and got all the magic for free.
I've also written a CRUD layout engine which was used for a considerable percentage of a site. The core was parameter driven so it could run list and edit pages for anything, once you wrote a parameter list. It automatically did pagination, save-new-delete support etc etc, leveraging the object layer above. It wasn't object-oriented in and of itself, but it could have been made so.
In other words, a object-oriented framework in PHP is not only possible, it can be very efficient. This was all in PHP 4, BTW, and I bumped up against what was possible with PHP 4 objects a couple of times. :-)
I never got as far as a central dispatch that called objects, but I wasn't far away. I've worked with several frameworks that do that, though, and the file layout can get hairy quickly. For that reason, I would go for a dispatch system that is only as complex as it needs to be and no more. A simple action/view (which is almost MVC anyway) should get you more than far enough.
I initially started creating my own framework with similar ideals to your own. However, after a couple of months I realised I was re-creating work that had been done many times over. In the end I found an open source framework which was easily extendable and used it as a basis for my own development.
The features I implemented myself:
MVC Architecture
Authentication object
Database access class
URL rewriting config
Pagination class
Email class
Encryption
The features I looked at and thought, forget it! I'll build on top of someone elses:
Caching class
Form validation class
FTP class
Plugin-ability classes
Of course, writing a framework that outperforms the open source options is possible, but why would you bother?
It's true that some developers reinvent the wheel for no good reason. But because there are already good frameworks around doesn't mean that it's a waste of time doing one yourself. I started on one a while ago with no intention of using it for anything more than an exercise. I highly recommend doing it.
I've got the perfect link for you my friend: http://nettuts.com/tutorials/php/creating-a-php5-framework-part-1/. This is an awesome tutorial I have looked at, and its not too overwhelming. Plus look around the PHP section of that site I saw an article on CRUD. As for the AJAX look elsewhere, but you have to start somewhere, and this tutorial is awesome.
Note: this tutorial has 3 parts and I think it brings up MVC in the second instalment, but starts the first part using other methods.
The one, huge selling point I would look for in a new framework is that it would make writing testable code easy.
We typically work with Zend Framework, and it's mostly awesome, but trying to unit test/test drive ZF-based code is not far short of masochism.
If you could provide a framework that replaces the MVC parts of ZF with something that allows us to write testable code, whilst still allowing us to use the library parts of ZF, I will - quite literally - buy you a beer.
I'll buy you two beers if you ditch the AJAX. There's a huge gulf between an OO PHP framework and a JavaScript framework.
Please don't link to an existing framework
I will not, I started writing my own for learning purposes, and took a peek into some of the mainstream frameworks, and even with my limited knowledge see so many mistakes and bad ideas in them.
They're built by hardcore developers, not end users.
I'm in no way saying I could write better than the "big boys" but I (along with most of you I imagine) could point out why some things they do are bad, even if just because they're not end user/non-developer friendly...
I wonder how your framework is doing, some 6 years on?
Are you still working on it? Did you stop?
Should You Write Your Own Framework
This is probably a little late for you, but for anyone else, writing your own framework is a fantastic thing to do for learning purposes.
If, however, you are wanting to write one other than learning purposes, because you cannot work out the one you are using, or because it's too bloated, then do not!
Believe me, and don't be insulted, you would not be here contemplating it if you are a knowledgeable enough developer to do so successfully!
Last year I wanted to learn OOP/classes, and more advanced PHP.
And writing my own framework was the best thing I did (am actually still doing), as I have learned so much more than I anticipated.
Along the way I've learned (to name a few):
OOP/Classes many best practices which come with it - such as
Dependency Injection, SRP
Design patterns, which help you write code and structure your system
in such a way that it makes many things logical and easy. For an
example see Wiki - SOLID
Namespaces
PHP Error Handling and all of the functionality which that provides
A more robust (and better) understanding of MVC, and how to apply it
appropriately (as there is no clear cut way to use it, just guides
and best practices).
Autoloading (of classes for OOP)
Better code writing style and more structured layout, and better
commenting skills
Naming conventions (it's fun making your own, even if based on
common practices).
And many other basic PHP things which you invariably come across accidentally from reading something.
All of this not only vastly improved my grasp of PHP and things which come with it, to a more advanced level, but also some of the commercially/widely used methods and principles.
And this all boosted my confidence in using PHP in general, which in turns makes it easier to learn.
Why Write a Framework To Learn All of This
When you start out, you learn the basics - A (variables), then B (how to write a basic function), etc.
But it doesn't take long when you're trying to learn more advanced things, that to learn and use D and E, you also have to learn and understand F, G, H, and J, and to know those you have to know K, L, and M, and to know parts of L and M you first need to understand N and O...
It becomes a minefield as trying to learn one thing brings the need to first learn a few other things, and those other things often bring a need to understand various other things.
And you end up a mile away from where you started, your mind tingling and shooting sparks from it, and about 20 tabs open all with various advanced PHP things, none of which you are 100% comfortable with.
But over time, with practice and most certainly dedication, it will all fit into place, and you'll look back at code, even a collection of files/classes, and think "Did I write that.."?
Writing a framework helped greatly with this "minefield" because:
I had specific tasks to do, which brought about the need to learn and
implement other things, but specific things. This allowed me to focus
on less things at once, and even when something branches off to
various other things, you can reel it back in to where you started
because you are working on something specific. You can do this with
any learning, but if you do not have some goal, or specific task you
are focusing on, you can easily get distracted and lost in the ether
of things to learn.
I had something practical to work with. Often reading tutorials about
an animal class, and how cat and dog classes extend animal etc,
can be confusing. When you have a real life task in your own
framework, such as how do I manage XYZ, then you can learn how
classes work easier because you have trial and error and a solid
requirement which you understand, because you created the
requirement! Not just theory-like reading which means nothing
usually.
I could put it down when my mind was blown, although as it was my
framework (my Frankenstein's monster in the beginning :P) I wanted to
press on, because it was interesting, and a personal goal to learn
and sort the next stage, to resolve an issue I was stuck with, etc.
You can do it how you want. It might not be best practice, but as long as you are trying to learn best practice, over time you will improve, and likely easier than just reading tutorials, because you are in control of what and how you do something.
Wait, I Shouldn't Re-invent the Wheel Though
Well, firstly, you cannot reinvent the wheel, it is impossible, as you will just make a wheel.
When people say "Don't reinvent the wheel", they of course mean "there are already frameworks out there", and to be fair, they are written by skilled developers.
That's not to say the frameworks don't have problems or issues, but in general they are pretty solid, secure and well written.
But the statement is nonsensical in relation to writing your own framework!
Writing your own framework for learning purposes is really useful.
Even if you plan to use it commercially, or for your own website, you haven't just "re-invented the wheel", you've made something else.
Your framework won't be like the others, it won't have many features and functionality, which might be a major advantage to you!
As long as you understand about best security practices etc, because you can think you are writing a great system, which is super fast and without all the bloat other frameworks have, but in fact you have holes in places which someone could crawl into...
But a project for learning which you don't use on the internet is ideal - or use it, eventually, when you are advanced enough to know it's secure!
With all that said, you should write your own framework IF:
You are not needing it any time soon! It takes a lot of time as
there are so many aspects to consider, learn, and trial and error
leads to refactoring (a lot at first!)
You are willing to read, code, test, change, read, code, and read
some more. There is a lot of good advice on the internet for advanced
PHP, most of it mind blowing at first, like reading all the design
patterns. But they eventually make sense, and end up helping you
resolve problems you face, and how to do things within your
framework.
Willing to put the time in, and keep trying to improve, and head
towards best practice, especially with security. Speed issues shouldn't be an issue with a small framework, and besides, if you have a fairly decent system, you can usually refactor and make speed improvements. usually if you have significant speed issues it means you've chosen intensive operations, which can usually be addressed by doing it a different way.
.
Without previous experience, or an advanced knowledge of PHP, you will likely spend some time writing a framework, further reading and knowledge will show you that your approach is skewed, and so you might delete everything and start again.
Don't be disheartened by this.
I did exactly that, as I learned so much advanced patterns and ways of doing things along the way in the first month, I ended up where refactoring was no good, and a blank canvas with a whole new approach was the only option.
However, this was quite pleasing, as I saw a much better structure take form, and I could see not only a better framework foundation start to take place, but realised it was because I had a better understanding of advanced PHP.
Just do it! Just make sure you have a plan of what you want it to do before you even write some code.
Seriously, write down on paper how you are going to load error checking, are you going to have auto loading, or include files when needed? Are you going to have a centralised loading mechanism, which instantiates classes when you need them, or some other method?
Whatever you do, and whatever stage you are at, if you are heading into new territory, plan it first. You'll be glad of it when you hit a brick wall, can go back to your plans, and realise a slight deviation to your plans will resolve it.
Otherwise you just end up with a mess and no plan or way to re-deign it to resolve the current problem or requirement you face.
You are looking to build exactly same thing I've worked on for a few years and the result is Agile Toolkit.
Very easy CRUD page generation
$page->add('CRUD')->setModel('User');
AJAX based pagination
All pagination and many other things are implemented through a native support for AJAX and Object Reloading. Below code shows a themed button with random label. Button is reloaded if clicked showing new number.
$b=$page->add('Button')->setLabel(rand(1,50));
$b->js('click')->reload();
Ajax based form validation if possible, or very easy form validation
All form validations is AJAX based. Response from server is a JavaScript chain which instructs browser to either highlight and display error message or to redirect to a next page or perform any other javascript action.
Sortable tables
Table sorting and pagination has a very intuitive and simple implementation when you can really on object reloading.
Ability to edit HTML templates using PHP
This seems out of place and a wrong thing to do. Templates are better of in the VCS.