Content Management Systems have evolved over the years and there are a few different options available to choose from. Picking the right solution that will be agile and meet the rapidly changing requirements of an online presence is an important decision. This article provides a brief summary of Coupled, Decoupled and Headless architectures, which are the three most common architectures for CMS solutions available today.

Coupled

A coupled or monolith architecture for CMS is one of the oldest models. Since it is a mature model and the code is in a monolithic structure it is easy to install on a single server and get a template up and running. In most cases these solutions have some type of WYSIWYG (what you see is what you get) editor for page layout and there is an ecosystem of plugins for extending the features. These monolithic solutions can seem appealing due to the perceived ease of entry and for a small site it might be the right solution. 

Advantages

1. The ability to quickly get a small site up and running
2. Simple to maintain for a small scale website

Disadvantages

1. Does not scale well for websites that have large number of users
2. Susceptible to security flaws
3. Challenging to upgrade and patch

A CMS utilizing a coupled architecture have some significant disadvantages, especially so for mid-sized and large sites. The first disadvantage is that they do not scale well. The only scaling option is to obtain a larger server to run the site on. This quickly becomes expensive and in most cases does not happen quickly. This means that if you run a campaign that is successful and there is a spike in traffic your site may become unavailable. 

The second area of significant disadvantage is with security. There are two reasons these systems tend to be more susceptible to security issues. They tend to have a large install base and can be challenging to keep updated with the latest security patches. When there are lots of sites using the same CMS, there is more incentive for hackers to spend the time to find weaknesses to exploit as there are lots of potential targets. Add this with the fact that most of the sites will not get upgraded quickly even when an exploit is known means the exploits have a long shelf life. 

In a coupled CMS the content is very tightly integrated with the layout of the pages. In many cases, if the same content needs to appear in multiple places the content needs to be retyped into each of those places. This means more work for you, but it also means that there can be inconsistencies in the marketing message across you online presence. In addition, the content cannot be reused in different channels like mobile apps.

Decoupled

A Decoupled CMS is more commonly used in an enterprise situation. The front-end is separated from the back-end. This separation or decoupling has two primary advantages. It allows the front-end to be scaled and since the front-end is typically deployed to a DMZ that is locked down it is more secure. 

Advantages

1. Scales well for larger websites with more users
2. Can be better secured by locking down external facing components

Disadvantages

1. Many components that are challenging to manage and maintain
2. Administering requires a high degree of skill that is expensive to retain
3. Cumbersome to add custom features

The downside to the Decoupled CMS is that it is big, expensive and difficult to maintain. They require administrators with a high degree of specialized skills to operate effectively and securely. 

One of the most challenging aspects of this architecture is that your team will spend a lot of time in the care and feeding of the platform which can reduce the time they have available for developing innovative features. Many innovative features that would make your online presence stand out are simple to implement in a standalone site, but take days and weeks to implement in a large CMS due to the inherent complexity of the architecture.

A Decoupled CMS usually has the capability to organize content separate from the display, however that requires the users to organize the content in a specific way. It is easy to fall into the trap of embedding the content into the layout of the pages when using the WYSIWYG page editor and often the content does not get structured for reuse.

Headless

Where a Decoupled CMS is an attempt to address the failings of the Coupled CMS, a Headless CMS is a complete paradigm shift. By completely separating the content management into a hosted service, your team is now free to use the technology that best suits their skills as well as your marketing requirements for presentation of the content. 

Advantages

1. Ability to rapidly deliver large and small sites
2. Virtually no limitations on the ability to scale up and down dynamically
3. Potentially the most secure CMS option 
4. Content has a longer shelf life and can be reused in multiple channels
5. A large portion of the CMS is managed and maintained by vendor 
6. Utilizes commonly held web developer skill sets

Disadvantages

1. There is no drag-and-drop WYSIWYG page designer
2. Hosting costs can be less predictable based on site traffic

Instead of spending time pushing innovative features into a CMS with a proprietary and restrictive structure, your team will be able to complete projects in significantly shorter timelines that are much more predictable. 

The Headless CMS architecture is the easiest and least expensive solution scale up or down. Since the front-end is small and can be easily hosted in a dynamically scaled cloud environment the ability to scale both up and down becomes just a matter of turning a dial. The ability to scale back down easily means that you can scale up for a spike in traffic and then scale back down when the spike is over. 

Another significant benefit of Headless CMS is that content is not tightly coupled with the presentation. This makes the content reusable for multiple channels and multiple places in your online presence. This means your team is not spending time editing the same content in multiple places and ensures your marketing message is consistent across channels.

Decoupling the content from presentation also means that your content editors can start working on content before the web developers are finished with the pages. This avoids the end-of-project crush that the content editors often experience in a traditional CMS project.

A Headless CMS has the potential to be the most secure CMS solution. As with any CMS the security depends on the diligence of your IT team and web developers. However, since the externally exposed portion of your site is proprietary to your organization it is less likely that a weakness hackers found on another organization's site will be used against your site. 

As with anything there are always downsides. In this case there is no WYSIWYG editor to layout pages. However, this could also be an advantage. Imagine a world where your marketers are not spending time wrestling with a WYSIWIG to layout pages and instead are using their creative talents to build wireframes that they hand off to web developers who turn them around in reasonable and predictable timelines. This is possible with a Headless CMS.