Web Design & Development Guide

Web template

A web template is an element of a web template system that is used to rapidly generate and mass-produce web pages through a pre-defined schematic, layout, or finite number of programming language instructions.[1] In its simplest sense, a web template operates similarly to a form letter.[2] One of the primary design principles used to justify the use of web templates is the "separation of presentation and content".^[3]

Content (from a database), and "presentation specifications" (in a web template), are combined (through the template engine) to mass-produce web documents.

Basic concepts

A web template has certain basic defining characteristics. These characteristics can be described according to core principles.

Among these core principles:

The principle of Effective separation;
The principle of Flexible presentation; and
The principle of Reusability.

Effective separation

A common goal among experienced web developers is to develop and deploy applications that are flexible and easily maintainable. An important consideration in reaching this goal is the separation of business logic from presentation logic.[4] Developers use web template systems (with varying degrees of success) to maintain this separation.^[4]

One difficulty in evaluating this separation is the lack of well-defined formalisms to measure when and how well it is actually met.^[4] There are, however, fairly standard heuristics that have been borrowed from the domain of software engineering. These include 'inheritance' (based on principles of object-oriented programming); and the 'Templating and Generative programming', (consistent with the principles of MVC separation).^[5] The precise difference between the various guidelines is subject to some debate, and some aspects of the different guidelines share a degree of similarity.^[6]

Flexible presentation

One major rationale behind "effective separation" is the need for maximum flexibility in the code and resources dedicated to the presentation logic.^[5] Client demands, changing customer preferences and desire to present a "fresh face" for pre-existing content often result in the need to dramatically modify the public appearance of web content while disrupting the underlying infrustructure as little as possible.

The distinction between "presentation" (front end) and "business logic" (infrastructure) is usually an important one, because:

the presentation source code language may differ from other code assets;
the production process for the application may require the work to be done at separate times and locations;
different workers have different skillsets, and presentation skills do not always coincide with skills for coding business logic;
code assets are easier to maintain and more readable when disparate components are kept separate and loosely coupled;^[5]

Reusability

Not all potential users of web templates have the willingness and ability to hire developers to design a system for their needs. Additionally, some may wish to use the web but have limited or no technical proficiency. For these reasons, a number of developers and vendors have released web templates specifically for reuse by non-technical people. Although web template reusability is also important for even highly-skilled and technically experienced developers, it is especially critical to those who rely on simplicity and "ready-made" web solutions.

Such "ready-made" web templates are sometimes free, and easily made by an individual domestically. However, specialized web templates are sometimes sold online. Although there are numerous commercial sites that offer web templates for a licensing fee, there are also free and "open-source" sources as well.

Open source templates

The rise of the open source design movement has seen a slow but steady rise in the community of open source designers. Some sites offer open source templates in addition to other content.

Examples include:

As of this writing there are over 4000 unique templates available for modification and use by anyone under various open source licenses.

System elements

The following describes some of the common technical aspects associated with web templates.

Sub-template

Representation of sub-template T₁ referred by template T₂.

A web template may include other templates as "sub-templates". Page headers and page footers, for use in a primary template, are typical uses for sub-templates. A sub-template is similar to a subroutine in imperative programming languages. The sub-template supplies a document fragment to the primary template, which is then sent to the final output destination.

The specific functionality of sub-templates depends on the template language in use. For example, template code enclosed in sub-templates may not follow the same rules for variable interpolation and processing of template directives as code specified directly in a primary template.

Notes and references

^ Suh, Woojong (2005). Web Engineering: Principles and Techniques. Idea Group Inc (IGI). 1591404339.
^ Chamberlain, Darren (2004). Perl Template Toolkit. O'Reilly. 0596004761. "The basic task of a template processor is to output some amount of changeable data surrounded by unchanging data."
^ (Suh, p. 251)
^ ^a ^b ^c Parr, Terence John (2004). Enforcing strict model-view separation in template engines. Proceedings of the 13th international conference on World Wide Web. 1-58113-844-X.
^ ^a ^b ^c Paragon Corporation (2003-07-19). Separation of Business Logic from Presentation Logic in Web Applications.
^ MVC vs OOP

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