UNIT 04 - Webskins I

Objectives

In this unit we learn about webskins: the "view" for FarCry Framework. Webskins form the presentation tier of any FarCry application. By the end of this unit you should have a basic understanding of how webskins are managed, their relationship to content types and how to create your own.

The COAPI

The FarCry framework is based on a variation of the classic Model-View-Controller pattern. The COAPI (or Content Object API) is a high level name for the MVC engine inside FarCry. Without getting bogged down in the details of the framework, its good to have a high level or "helicopter" view of how things work under the hood. We'll expand on these themes gradually as you go through the course.

Requests from users are processed by FarCry's built-in "smart controller" which automatically determines wiring based on the URL convention or the friendly URL sub-system. The COAPI always ends up calling a principal content type (a special type of class) that manages how we interact with the model and view. When thinking of views (or webskins) its important to realise that they are always executed in the context of a specific content type.

It's not at all important for developers to understand how the COAPI works, but hey, for those that want the details we've added some advanced info boxes where relevant.

The Webskin

The webskin is a templating layer that effectively translates your data into a view. Typically this is a complete HTML page or fragment of HTML representing a content teaser or some other element used in assembling a page. But a webskin could just as easily be outputting a form, RSS, XML or other format.

In its basic form we can run a webskin on an object by using the following URL Syntax:

http://superheroes.local?objectid=E689D66F-96FD-E9F6-B1AF64B8DAE78A69&view=displayPageStandard

The url above is running the webskin "displayPageStandard" on the content item with the objectid of E689D66F-96FD-E9F6-B1AF64B8DAE78A69

Pretty ugly, eh. But not to worry. In practice the Friendly URL (FU) engine dynamically changes these links to beautiful looking URLs. For example, /hero/batman

Where to Find Webskins

Webskins are all located in a single folder under your project root called "webskin" funnily enough. Inside that directory branch you should find a single folder for each content type you want a webskin for.

[install-root]
\farcry-express-install
  \webroot
   \farcry
     \projects
       \myproject
         \webskin
           \dmHTML
           \dmNews
           \dmEvent
           \myContentType

Walkthrough: Call a Webskin on a HTML Object

In this walkthrough we're going to call the standard dmHTML webskins on the Home Page HTML object.

1. Login to the Webtop and click on the Home Page dmHTML object in the site tree (the white page icon... not the blue dmNavigation object)
2. Copy the objectid of this object to the ClipBoard (located at the bottom of the summary for the object or in version 6-0-16, under the Miscellaneous tab in the ObjectID section)  
3. Now, locate the ./webskin/dmHTML folder in your project
4. Take note of the current webskins in that folder.
5. Now enter a url to call each of the webskins in that folder using the following format
   Example URLs Only

   http://localhost:8888/index.cfm?objectid=E689D66F-96FD-E9F6-B1AF64B8DAE78A69&view=displayPageStandard
   
   http://localhost:8888/index.cfm?objectid=E689D66F-96FD-E9F6-B1AF64B8DAE78A69&view=displayPage3Col
   
   http://localhost:8888/index.cfm?objectid=E689D66F-96FD-E9F6-B1AF64B8DAE78A69&view=displayTeaserStandard
   

6. Discuss how this forms the basis of almost ALL web applications

Creating Webskins

The "smart controller" wires up the content type, the content item and webskin (view) by convention based on the parameters in the URL.

Webskins are literally just ColdFusion templates. Any file with a .cfm extension in a directory under ./myproject/webskin will be automatically registered as a webskin by the FarCry Framework. Consequently only files that you intend to be webskins should ever be stored here. To create a webskin simply create the template in the correct directory and RELOAD/RESTART the application.

Naming Webskin Templates

Although you can give your webskin template any file name, in practise it makes sense to follow the naming standards used by the rest of the community. The following table outlines common naming prefixes for templates and explains their uses within the FarCry framework. An asterisk (*) denotes a wildcard, where you would use your own unique name to differentiate templates of similar purpose.

These are just a few of the regularly used webskin names within the FarCry framework. For a complete list of reserved webskin template names review: https://farcry.jira.com/wiki/display/FCDEV50/Webskin+Templates

Hooking Up The Webskin To Data

Every time a webskin is invoked it is done so in the context of a specific content type.

For example, viewing a particular news article with a displayPageStandard, or a product item with displayPageProduct.cfm, or whatever. FarCry always provides the entire content item record to the webskin (or view) as a structure called stobj.

stobj contains the typename, and all the property keys and values for the object in question, including array properties.

The data contained in the stobj structure can be referenced as a simple ColdFusion variable, and then combined with mark-up to produce the desired output. The similarity between this and any normal procedural ColdFusion template is deliberate - the framework authors have tried hard to make the creation of webskins or views very similar to building a simple ColdFusion template.

<cfsetting enablecfoutputonly="true">
<!--- // Dead Simple Example Webskin Template --->
<cfoutput>
  <h1>#stobj.title#</h1>
  #stobj.body#
</cfoutput>
<cfsetting enablecfoutputonly="false">

Webskin Decorators

Every template can be supplemented with additional metadata, called a "decorator". You should make a habit of adding relevant decorators as it makes the whole system read much better, helping to provide human readable template names, inline documentation and so on. Metadata is incorporated by including a series of specific comments at the top of each template.

For a complete list of decorators and their uses, see:https://farcry.jira.com/wiki/display/FCDEV60/Summary+of+View+Decorators

Template metadata is always stored in a ColdFusion comment.

On initialisation, FarCry scans the registered webskins for their additional metadata and stores it in memory. If you make a change to the metadata you may need to re-start the application in order to see the change come into effect.

<!--- @@displayname: Core Home Page --->
<!--- @@description: Home page for the FarCry Core developer portal. --->
<!--- @@Cachestatus: 1 --->
<!--- @@Cachetimeout: 60 --->
<!--- @@Fualias: home --->

Walkthrough: Create displayPageSuper.cfm

In this walkthrough we're going to create a simple dmHTML webskin template to play with some of the ideas we've just considered.

1. Locate the ./webskin/dmHTML folder in your project
2. Create a file called displayPageSuper.cfm
3. Write up some basic HTML in a <cfoutput>
   ./webroot/farcry/projects/myproject/webskin/dmHTML/displayPageSuper.cfm

   <!--- @@displayname: Demo Template --->
   <cfoutput>
   <h1>Hello Cruel World</h1>
   </cfoutput>
   

4. Reload the application to pick up the template change. Use the [Reload Application] tool in the webtop.
5. Select the Site Overview Tab. Edit the FarCry Support HTML page and change its template to the one you just created.
6. Save and Preview the page. Check the HTML source and discuss with your instructor.
7. Edit your template and add a cfdump to the page for stobj

   <cfdump var="#stobj#" label="Content Object" />
   

8. Save and preview the page.

Static Media Assets

In a FarCry project we normally make a distinction between media assets (such as files, images, video, etc) that are managed by the application (ie. Content Managed) and assets which are hard-coded and fixed in the code base (ie. Application Chrome).

When you are dealing with the application's chrome, the fixed static images and so on that make up the graphic theme of the site, in most instances you do not want to have these mixed with assets that are content managed by users. The standard for managing media assets of this nature is to store them under the webroot (for obvious reasons) in a directory called ./wsimages/ or under the ./css/images directory if they are relative to the style sheet.

c:\farcry
    \projects
      \myproject
        \webskin
        \www (standard project webroot)
          \wsimages
          \css\images

Webskin Tag Libraries

Remember a webskin is just like a ColdFusion template - you can do all sorts of things. The webskin is strictly speaking a VIEW and following good programming practise you should refrain from doing business logic in this area. However, you can reference ColdFusion tags, FarCry service components and custom tag libraries as needed.

FarCry has a special custom tag library dedicated to making life easier when building webskins. In includes all sorts of goodies from building navigation, to breadcrumbs, to rendering other views and more. You can find this library in the core framework at: ./core/tags/webskin To make use of these tags you will need to import them first.

For a complete list of webskin tags see:http://docs.farcrycore.org/p600/

<!--- @@displayname: Home Page --->
<!--- @@author: Matthew Bryant (mbryant@daemon.com.au)--->

<!--- import tag libraries --->
<cfimport taglib="/farcry/core/tags/webskin" prefix="skin" />

<!--- breadcrumb; detects position in the site tree and builds a breadcrumb --->
<skin:breadcrumb />

Composite Views

In practice, web pages in FarCry are assembled from multiple webskins. While you can do a lot with custom tags, the best way to build web pages is by compositing multiple webskins together.

Consider the following real world examples of composite views from the Fandango theme.

Building a Composite View

A typical starting point for any composite view is working with headers and footers. Its very common to have a similar header across all web pages, albeit with slight variations such as page title, highlighted navigation and so on. Likewise the footer structure.

You can call another view directly using the skin:view tag. skin:view is a real workhorse - we use it all the time.

<div id="main">
	<div class="container_12">
		<div class="grid_12 content">
		<skin:view typename="#stobj.typename#" objectid="#stobj.objectid#" webskin="#url.bodyView#" />
		</div>
	</div>
</div>

View Inheritance

FarCry is an object oriented framework. All content types extend the core types component (an abstract class). Any views associated with types are automatically inherited by other content types, such as our dmHTML content type.

More on content types later. Long story short, you can assume that any view located in ./webskins/types is available to all content types.

Looking at our dmHTML content type in Fandango, we have at least the following views available:

• displayPageStandard
• displayTeaserStandard
• displayHeaderStandard
• displayFooterStandard
• displayBody
• displaySimpleSearchResult

Webskin Tracer

The tray that appears at the bottom of the website when you are logged in, contains a marvellous developer utility called the "Webskin Tracer". You can activate it for any page by simply selecting the webskin tracer option.

The entire pages composite of views is laid bare; highlighting each webskin executed for the page. Select a specific view and the HTML fragment is highlighted, with a tooltip detailing exactly where the webskin template can be found.

FarCry Profiler

The FarCry profiler details how long each part of your request is taking to execute on the server. This is a great tool for identifying slow running pages and candidates for caching.

Walkthrough: Creating a Composite View

1. turn on the webskin tracer
2. review various pages with your instructor
3. Add Header & Footer views to ./dmHTML/displayPageSuper.cfm

Walkthrough: Putting It All Together

Get comfortable with how webskins are assembled in the real world. You should be able to dissect the sample application webskins and understand how they have been put together.

1. Review the other templates in the ./webskin/dmHTML directory with your instructor
2. Consider the use of custom tags, headers, footers and other layout mechanisms