Tag Archives: architecture

Mixing content and functionality with DD4T

Architecture, DD4T, Tridion, , ,

Today I received a question from a developer who is just starting on DD4T. He wants to have a page which consists of regular Tridion content but also contains a form. Being a .NET MVC developer he naturally wants to handle this form with a controller and various  actions to handle GET and POST and perform validation as well as sending an email on successful submission.

I call this type of web page, which combines plain content with application logic, a ‘mixed’ or ‘hybrid’ page. DD4T was designed to handle such pages (as well as the more simple content pages). To understand how DD4T does this, you need to know that the framework uses controllers and actions on two different levels:

  • The level of the page (just like in any MVC app)
  • The level of the component presentation

Let’s start by looking at a very simple page, which does NOT contain any forms or other application logic:

 

As you see, there are two views involved to build this rather simple page. The controller and action are predefined by the framework – unless you override them, which I will explain later. The controller/action for the page retrieves the page from the Tridion broker and uses that as its model. The controller/action for the component uses the component as its model. All YOU need to do is write the views.

You may wonder how DD4T knows which views to call. This is achieved by configuring the name of the view in the metadata of the page template and component template.

Now I’m coming back to the question of mixed pages. A mixed page has application logic as well as plain content. To handle application logic in MVC, you need a controller and an action. For example: you might want to display a form when the method is GET, and validate it when the method is POST.

In a diagram, this is how it will look:

The page now contains two component presentations: one that represents (and contains) just plain content and another one that represents the form. The neat thing is that your custom action will automatically be called by DD4T. All you need to do is configure your custom controller and action using metadata on the component template. So instead of just specifying a view, you will now have to specify a controller and action as well.

Advantages of this ‘mixed page’ approach:

  • Tridion stays in control of the URL
  • Editors can decide where to put a form, and which other pieces of content to put next to it
  • The placement of the form and other pieces of content is handled by the exact same view as on normal pages, so you do not have to do extra coding.
  • All MVC functionality like model binding and validation are fully supported

Happy coding!

 

What is DD4T and why should I care?

Architecture, DD4T, , ,

Imagine this: you are an engineer or web developer, and the company you work for has just got itself a license for Tridion. So they send you off to get yourself trained. After a grueling week of getting to grips with Yet Another Complex Piece of Software, you feel that you at least understand the basics. You have created your first schema, written your first template, and you just can’t wait to build your first web site – until you run into some guy at the coffee machine, who asks you if you shouldn’t be using “DD4T”.

Sound familiar? Keep reading! In this post I will explain what DD4T is, and why it might or might not be useful for you.

DD4T is short for Dynamic Delivery for Tridion. It is a thin layer of functionality on top of the Tridion APIs that exposes the Tridion object model to dynamic web applications. The goal of DD4T is to allow you to develop a Tridion-based web application directly, without having to code templates.

Maybe a picture will make this clearer. The “classic” Tridion style of implementation (which is still used in 95% of the cases) looks like this:

blog - template development

The logic of your web site is built by a template developer. However, he or she does not develop this logic directly. They write templates which operate on the content management server. These templates generate server / client logic that runs on the web application server.

About two years ago, a group of seasoned Tridion geeks decided that this was no longer the way of the future. The templating approach – they felt – was prohibiting them from using their favourite web development tools optimally. The java-fans among them would really like to develop web apps with Spring MVC, using Eclipse as their IDE, and storing all the code in Git or SVN. The .NET-buffs were dying to write their sites in ASP.NET MVC, using Visual Studio and Team Foundation Server.

They decided there was another way. Before long, their initiative had a name – DD4T – and a home on the internet. The open source project was launched in September 2011.

Compared to a templating implementation, a DD4T implementation looks slightly but significantly different:

blog - dynamic development

Here, the template developer has been replaced by a web (application) developer, who writes his/her code directly in a web application environment.

Of course, that does not mean that the developer is working in the same environment as the people visiting your site. You would normally set up a development environment for this. Or better still: each developer can develop and run / debug the entire web application on his own work station. But logically, there is no difference between what the developer sees and what the visitors of your site see.

This paves the way for the total leverage of Visual Studio, or Eclipse, or whichever programming environment the developer happens to be a fan of.

The DD4T approach has many advantages, not only for developers, but also for their managers, as well as the content editors / marketers who actually use Tridion to manage their web sites. I’ll try to sum them up.

Advantages for developers

  • Developers have Intellisense for the code that really matters: the .NET / Java code that makes up the web site
  • They can use step-through debugging for the web application
  • They can use unit tests to check the consistency of the website after every change
  • They can store their code in a source code management system (like TFS, Git or SVN)
  • They can make local changes without interfering with the other developers on the team
  • And most importantly: they can take their skills in creating .NET / Java web applications and put them to use very easily, without having to deal with the complex and often confusing ‘detour’ of templating

 

Advantages for IT / project managers

  • Teams are much easier and cheaper to staff (there are many more .NET / Java developers than there are Tridion developers)
  • Even if your team is lacking the required .NET / Java skills, it is much easier to train them, with all the available resources on the net
  • Better leverage of investments in developer tooling (e.g. SCM, automated build systems, etc)
  • A new version of the entire site can be deployed at the click of a button (without lengthy republishing of entire site)
  • Very well suited for agile development processes
  • Releases can be managed better (they can be planned more easily, rolled back more easily, etc)

 

Advantages for editors

  • Publishing is much quicker (because the templates are very simple)
  • They don’t have to wait so long for  bugs to be fixed and enhancements to be made

 

Of course there are some disadvantages as well. When you decide to go with DD4T, you are not going to use Tridion as a web site development platform, but only as a content management platform. Hence, changes to your web site cannot (easily) be deployed by publishing from Tridion. Instead, you need a separate web development platform, for example Visual Studio + TFS (or Eclipse + Git/SVN if you’re building a java web site). If you do not already have such a development environment, you are incurring extra costs.

A second drawback is the fact that DD4T is not supported by SDL. That sounds more dramatic than it really is. Tridion only supports its own public APIs, not the code that customers write on top of it. In a ‘classic’ Tridion implementation, the template code is not covered by your support contract with SDL Tridion. However, the interaction of your templates with the Tridion API is completely supported.

Similarly, DD4T itself is not supported by Tridion, but the calls it makes to the Tridion API are. And since DD4T is open source, you have unrestricted access to the source code. On top of that, the framework is supported by an active community, consisting of long-time Tridion experts.

 

A lot has happened in the last year. Big companies have decided that the pros outweighed the cons, and have launched web sites based on this framework. Even more are busy migrating towards DD4T, or are staging proofs of concept. SDL itself has recently launched its new flagship web site, completely built on DD4T. It may still be a relatively new initiative, but that is apparently not stopping them from giving it a try!

 

Summary

DD4T is a very attractive alternative to templating as a way to build web sites out of Tridion. It makes the lives of your developers easier, resulting in a shorter time to market and a higher quality of work. Plus it makes it much easier to deploy changes. The main caveat is that the framework itself is not part of the Tridion product suite, and as such not formally supported.

The value of DD4T is demonstrated by the fact that many Tridion customers are either switching to it, or are seriously considering switching. If you own or support a Tridion-driven web site, you should at least give this some consideration.

Ready to try it out, or just interested in finding out more? Go to http://code.google.com/p/dynamic-delivery-4-tridion/.