Friday, January 25, 2013

Render Unto c#

When it comes to CMS development (among other things in life) I’m a big fan of granularity and reusability. I believe that in a good solution architecture, both content and code are managed in discreet, granular pieces, which promotes both consistency and reusability.

That’s why it bothers me that so many Sitecore professionals react to the word “rendering” the same way a horse would. To my mind, a good solution has a geometric ratio of layouts to sublayouts, and sublayouts to renderings. Yet I see projects that are extremely sublayout-centric, with content IA and logic governing page layout.

Sitecore’s arsenal of presentation management tools, such as layout details, placeholder settings and rendering parameters, allows us as developers to truly empower our content owners. When implemented well, these features give the content authors what I like to call “controlled control” over their pages.

Unfortunately, we often see solutions where sublayouts are the dominant presentation component. Sublayouts are far less efficient than renderings, both in terms of performance and management. With sublayouts, there are all the ascx files to manage and deploy. And using sublayouts to present content seems to promote having a single component (sublayout) present multiple fields. This can dramatically reduce the solution’s flexibility – or worse, lead to having multiple components that are slight variations on each other, or have cumbersome logic (often wired to “control” fields in the content) to suppress content or change the presentation behavior.

Worse, some solutions rely almost entirely on the content tree to govern layout, such as by having fields in page templates that change the behavior of the layout, and/or by having sets of child items that code “bubbles up” into the page when they are present.

So why are renderings so often left out of solution architecture? I suspect that the problem lies in Sitecore training. Although Sitecore trainers do point out the different ways that renderings can be created, they tend to use XSL as the example technology in class (probably because it’s quicker to demonstrate --the trainer can show changes to an XSL rendering immediately, without compiling). Regrettably, this leaves many with a linkage in their minds between renderings as a Sitecore artifact and XSL as a technology. The oft-maligned rendering can be implemented using multiple technologies, yet many, many developers believe that renderings can only be developed using XSL.

I’m not going to wade into the great XSL debate here. I personally like XSL, but I rarely use it in Sitecore projects, for a number of reasons that I’ll get into that in a separate post. Suffice it to say that many developers, even if they know XSL, want to avoid it if for no other reason than to make their projects sustainable. XSL is a far more rare skill than c#, so it makes sense to ensure that future developers will be able to extend and maintain the project. And since there’s this misconception that “renderings = XSL”, the “baby” of a rendering-based architecture gets thrown out with the “bathwater” of XSL. And that’s a shame.

So let’s set the record straight. Renderings can and should be developed in c#. Actually, John West points out in his book “Professional Sitecore Development,” there are four types of renderings:
  1. XSL renderings
  2. Method renderings
  3. URL renderings
  4. Web Controls
Of these, Web Control renderings – controls that are implemented entirely in code and deployed in assemblies – are the least used yet most useful presentation component available. (In my next post, I’ll delve into the anatomy of a web control rendering.)

As a simple example, consider a page with a “core content” (“body”) area consisting of a title, a main image, and some body text. These three fields are defined in the page’s template. One way of handling this is to create a sublayout that renders these fields to the output (hopefully, at least, using field renderers). But what happens when the author does not want a title on a particular page (this is a simple example, so let’s not quibble over usability or SEO). Sure, the sublayout’s code-behind could suppress the <h1> when the field is empty or null. Or we could have a checkbox in the template to suppress the title.

What if the content author wants something other than a main image, like a flash or a video? What if they need to insert something between the image and the body? And after the body, they might need set of “spots” to point to other content?

So we might resort to having different sublayouts with variations on the content. This can lead to an unmanageable mess, creating confusion as to which sublayout does what. It also leads to redundant code, which makes ongoing maintenance and modification to the site much more challenging.

Another solution would be to put fields in the template to suppress content, or add content, or modify the presentation of content. Or we might create templates for child items that, when present, are bubbled up into the page. This puts management of presentation into the data. Sitecore is so well architected to give us excellent separation of content and presentation, so why fight that and force content to manage presentation?

I much prefer solutions that have very “light” layouts and sublayouts, with lots of renderings bound to placeholders. For the simple example, I would have a separate rendering each for title, main image, and body text, which I would bind to a placeholder in the sublayout for the core content area. Standard values in the item’s template would bind them by default, but the content owner would have the freedom to change the presentation as required. We can use features like thumbnails, rendering parameters, placeholder settings and compatible renderings both to assist them in the layout process, and to enforce brand or visual design requirements.

Most of my layouts and sublayouts are little more than div’s and placeholders. They exist to manage the geometry of the page or of regions of the page, not to present the actual content. Renderings bound to placeholders actually emit the content. Rendering parameter templates allow the editor to influence the source and behavior of the content in the page. Now, control over presentation and layout are managed in the presentation layer, and content is managed in the content layer. The design of the IA can break the content down into more manageable chunks, promoting reusability and avoiding redundancy.

To be fair, there are times when sublayouts are a better choice than renderings. For example, for forms or other situations where postback is required, I refer to use sublayouts (ascx) controls.. Also, in cases where the parts of the page structure are immutable, it is more efficient to statically bind renderings into sublayouts (by including them in the sublayout markup). This is fine for cases like fixed headers and footers, or when the site design requires an element (like a title) to always be present. There are also rare occasions when I allow a folder of child items to bubble up into a page, but even then, I usually use a placeholder-bound rendering to do the bubbling.

A highly granular architecture, which maintains separation of content from presentation, is hugely empowering to both developers and content editors. It promotes reusability of both code and content, shifts much of the responsibility for page assembly from code to configuration, and empowers editors with more control over the layout of their pages.

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