Does my fat-client application belong in the MVC pattern? - php

The web-based application I’m currently working on is growing arms and legs! It’s basically an administration system that helps users to keep track of bookings, user accounts, invoicing, etc. It can also be accessed via a couple of different websites using a fairly crude API.
The fat-client design loosely follows the MVC pattern (or perhaps MVP) with a PHP/MySQL backend, Front Controller, several dissimilar Page Controllers, a liberal smattering of object-oriented and procedural Models, a confusing bunch of Views and templates, some JavaScripts, CSS files and Flash objects.
The programmer in me is a big fan of the principle of “Separation of Concerns” and on that note, I’m currently trying to figure out the best way to separate and combine the various concerns as the project grows and more people contribute to it.
The problem we’re facing is that although JavaScript (or Flash with ActionScript) is normally written with the template, hence part of the View and decoupled from the Controller and Model, we find that it actually encompasses the entire MVC pattern... Swap an image with an onmouseover event - that’s Behaviour. Render a datagrid - we’re manipulating the View. Send the result of reordering a list via AJAX - now we’re in Control. Check a form field to see if an email address is in a valid format - we’re consulting the Model.
Is it wise to let the database people write up the validation Model with jQuery? Can the php programmers write the necessary Control structures in JavaScript? Can the web designers really write a functional AJAX form for their View? Should there be a JavaScript overlord for every project?
If the MVC pattern could be applied to the people instead of the code, we would end up with this:
Model - the database boffins - “SELECT * FROM mind WHERE interested IS NULL”
Control - pesky programmers - “class Something extends NothingAbstractClass{…}”
View - traditionally the domain of the graphic/web designer - “”
…and a new layer:
Behaviour - interaction and feedback designer - “CSS3 is the new black…”
So, we’re refactoring and I’d like to stick to best practice design, but I’m not sure how to proceed. I don’t want to reinvent the wheel, so would anyone have any hints or tips as to what pattern I should be looking at or any code samples from someone who’s already done the dirty work? As the programmer guy, how can I rewrite the app for the backend and front end whilst keeping the two separate?
And before you ask, yes I’ve looked at Zend, CodeIgnitor, Symfony, etc., and no, they don’t seem to cross the boundary between server logic and client logic!

You and everyone else with a brain is asking this question and it's a sticky one. A really good Information Architect thinks in terms of usability, behaviors and flow, although he/she may not even know how to use design tools or be able to draw or program. If they can get an interface into a sketch, the designers can make it pretty. Let the designers do the looky feely STATIC stuff--that's what they are good at. Provide IA with a library of front-end behaviors that they can specify for screen objects. They don't implement this stuff, they only USE it. This is much easier if you use a front end tool such as JQuery, and it's great if you have a front end guru who understands both design & the back end quite well. Separate your javascripts into their own directory and always link them as external files. All the PHP frameworks have methods to do this dynamically. I have toyed with the idea of a config structure that maps files to all the front end stuff that they load so each individual view only loads what it needs. But you are absolutely right: There is a whole nother sub-MVC for the clientside that lives primarily within the views of the overall MVC. I think you can partition off the Ajax stuff (when the view needs to refer back to the server) I document Ajax controller methods as ajax methods and don't call them otherwise. A lot of it is having everyone on your team buy into the division of labor paradigm. It will just cause them to write more decoupled reusable code whatever framework you ultimately choose to hang it on. And you're right, you can do the front end encapslation with all of them, but NONE of them enforce good front end encapsulation, I think that's still in the realm of DYI. Good luck.

Related

CMS design patterns and considerations

I am creating the cms for a relatively simple site - portfolio, some general content pages, custom blog etc.
What are some of the best patterns to consider before diving into the design.
I want the system to be as flexible as possible without being too complex.
I have looked for some good resources that discus cms and blog design but can't find anything too good.
My language is php but I suppose I am looking for more language independent advice.
Flexibility without complexity... nice program.
Maybe you're a genius and you will make something that feet your needs. But I think the biggest problem you will face is security and robustness. So really, take other advices on this page and have a look at wordpress, drupal, joomla and ezpublish. A lot of security stuff is already done. And not only security...
So, study some of these tools, track their flaws, check their security policy. Study how they handle caching, sessions, bootstrap, absolute & relative url managment, documents (images, videos, etc), ajax, authentification, identification, acl, user interfaces, rich-text editing, migrations, templating, page composition, content filtering (I try to remove the things you won't need, plugins, database abstraction, fine caching, css and js minification, all the extra-complex stuff not needed for a single instance simple CMS). Soon you'll have a 'picture' of the stuff they've done.
By doing this work, you'll certainly notice some big differences, and mistakes. You'll start going on irc and flaming developpers, telling them that others have done better choices. You'll start forgetting to shave. You'll maybe do some contributions. Some will be accepted, others won't. Old core devs doesn't like when someone explain why they made mistakes (and they make mistakes).
Now, comes the day you have a beard. Some of your contributions will start looking like forks. You will have ennemies, and friends, or followers. And you will start feeling the force.
And you will go on irc and tell god that the world is ugly and that you'll make the first CMS which will be flexible without being complex. And people will cry. And birds will run in circles. And you will be able to explain what are the design pattern of a CMS.
I am a user. I know what I want. Doing what I want will make user happy. I'm happy.
You shall not trust code from people with glasses
"MVC MVC MVC" : and the people responds 'that shall be done'
Seriously, There's still a place for a good CMS with disruptive innovation, the fork history has started long time ago with phpNuke (as far as I can remember). But some of the actual products are really fine for most tasks.
I'm probably risking the reputation here, but my experience shows that building your own CMS can be a very justified decision, especially when you get familiar with current opensource systems and understand what exactly they lack in terms of features, security or what not. Open-source often means a lot of backward-compatibility concerns and bad architecture decisions that cannot be easily changed.
I strongly suggest that instead of just taking on MVC you take a look at ideas that make it attractive.
One main problem with CMSes is the range of technologies involved in driving dynamic web-sites: imperative php for logic, declarative SQL for data queries, markup HTML for interface, imperative/functional javascript for dynamic interface, JSON for ajax calls etc. To keep the system manageable you have to keep these technologies in a controlled and understandable environment, but yet allow for smooth integration. Knowledge and best practices are out there. MVC is but one approach to manage this problem.
My choice at the time was to use the following principles:
Object-oriented code with static calling (php is a one-run thing, many instances of code objects are rarely justified), nothing except for one line of init code in global context
100% code-design separation with the use of XSLT and custom content processor
Custom router that can take any http request and reroute it to registered methods
Custom content processor that can take arbitrary method output and convert it into any usable format such as xhtml, xml, json etc. based on the request parameters (i.e. http://local/class/method.xhtml, http://local/class/method.json)
One copy of code for as many virtual web servers as necessary
SQL query builder (chosen for flexibility over ORM) for all database queries
Mandatory filtering of method input with filter_* functions
I believe you can choose a few that you like :) And good luck!
A good pattern to start with is the Model View Controller pattern, or MVC.
This pattern suggests to seperate your application's logic in the following layers: data logic(model), manipulation or business logic (controller) and display logic (view).
This is a good pattern to start with as you'll run into other problems (and thus patterns) along the way.
The following website explains the MVC concept quite well: MVC Principles
There is no point reinventing the wheel unless you are trying to better it in anyway.
THere are a lot of CMS available already. I personally have worked with ezpublish. There are other options such as drupal etc. This is the list of all open source cms avaliable - Click here
If you are just trying to learn then you can perhaps pick any one of the popular opensource and work on them to find its architecture and design.
Besides, I dont think anyone can give you a list of design patterns that would be best for a CMS tool. Because each design pattern solves some particular problem. And, you just have to choose a design pattern depending on a specific problem you want to solve in your project.
These days, writing your own CMS is a horrible waste of time. The usual open source solutions -- these days Joomla, WordPress and Drupal are popular -- are written by thousands of people and while you might loose a little flexibility by using on that's ready made this is by far offset by not needing to redo everything from scratch. If you go with Drupal, you can also enjoy high quality, massively scalable etc code :)
If Your rquiremnt is portfolio, some general content pages, custom blog only, Wordpress will be simple and Better.
In PHP so many CMS available , most popular one is Joomla.

Separation of logic from presentation: HTTP variable names?

This could probably be considered an academic question, rather than a real world one - but throwing it out to see if anyone has any great ideas! We all know that keeping the business logic of an application separate from the presentation is a good idea (I'm looking at web-apps atm), but there needs to be an understanding between the business logic for what HTTP variables to expect (and then process) and the variable names which are sent by the presentation layer.
Is this simply a matter of telling the designer what variable names to use in a template? The template doesn't need to know what the variable names are (unless using them for JS/CSS selectors), so why should they be 'hardcoded' in there. Or should the business logic put the names into variables to be printed out? Another layer of complexity for the templates?
Does anyone have any experience of this, or thoughts on how to deal with it?
Thanks,
Allan
My thoughts ... I guess it depends on the developer. Whenever I build apps, I , as you suggested, seperate the business and view logic, and usualy define a ViewModel. The viewModel then becomes the contract between business logic and the view. This allows both teams (UI and business logic developers) to develop independantly and of course allows easy testing etc..
I appreciate there are various approaches to view logic seperation, but, through experience if you can define a contract bewteen the two (in whichver form it takes depending on what pattern you are using) it makes development easier, especially when you have seperate teams building sperate components.
When I'd previously worked in web-development (currently I'm in admin/support) the problem was that the designers couldn't get their heads around the idea of using placeholders which would be substituted later - and for some complex layouts (e.g. a dynamic accordion type hierarchical navigation menu) there was a chicken and egg problem around designing the parts of the stylesheets which handled animation and functionality vs controlling fonts and colours.
Even with the most capable of designers, the tools they use don't lend themselves to solving the problem.
The approach we ended up taking was that the developers would provide examples of HTML fragments which the designers would then build the pages around, and then the developers would replace the fragments with the dynamically generated content and clean up the style sheets, merging any classes.
It was the most pragmatic solution we could arrive at.
C.

friendly code to transition from page controller to front controller

I am in the early stages of creating a small-medium sized web application by myself. I read "PHP Objects, Patterns, and Practice," and I decided to use page controllers because quick production is a high priority. Page controllers were also appealing because I am unfamiliar with PHP frameworks and creating an elaborate front controller seems to currently outweigh the project. My plan is to release the page controller version of the website ASAP and see if the audience likes it before committing to more complex software designs.
That said, I might decide to add more 'modules' and developers down the road...at which point I really should switch to a front controller. The above mentioned book describes that "it is not impossible to start with page controller and move toward the front controller pattern," but the wording of "not impossible" has me worried that it may be fairly difficult.
My questions are:
How 'hard' is it to make the transition from page controller to front controller design? While working on my page controller-based app, what should I be careful with to create code that allows a smooth transition to front controller design? The ideal situation would be to rewrite/restructure the code as little as possible and tack on the front controller with related classes/objects. Right now I'm only cautious about maintaining MVC, so any advice from experienced developers would be great. Thank you.
I think your main concerns should be to put "business logic" into properly designed model classes. In other words, don't put such logic in your page controllers directly. Instead, use your page controllers to parse input, such as GET and POST, instanciate the correct business logic objects, and call the correct methods on those to do the actual data crunching.
The page controllers should also be responsible for choosing a view to display - don't output things in the business objects, simply return data for the controller.
By using this approach, you should have most of your code in the model classes, and if/when you want to rewrite to using front controller, you will only need to change the page controllers to work with a front controller, hopefully not having to modify anything else.
I read the book you mentioned about 3 or 4 years ago as a first introduction to object oriented programming and I found it a great book, but I have to say that I only really got to grips with the whole thing once I started to use CakePHP and root around in its code to see how things are done in practice. The examples in the book can be a little confusing at times.
I recommend having a second look at some of the frameworks out there, Cake is good, Yii is meant to be even better. It doesn't long to get a system set up with them, and as long as you're prepared to have a good look under the hood, they can be an invaluable learning tool.

MVC as best practice for professional level programming?

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.

Fully Object Oriented framework in PHP

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.

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