The Web template system is used in web publishing to allow web designers and developers to work with web templates for the automatic generation of custom web pages, such as search results. It's possible to reuse the static elements of web pages, while allowing dynamic elements to be determined based on web request parameters. Web templates are also used in static content creation, providing basic structure and appearance characteristics for web content. These can be present in content management systems, web application frameworks, and HTML editors.
Video Web template system
Overview
The web template system consists of the following:
- Template engine: the main processing element of the system;
- Content resources : one of a variety of input data streams, such as from a relational database, an XML file, an LDAP directory, and other types of local or network data;
- Template resources : web templates defined according to the template language;
Content templates and resources are processed and combined by template engines to mass produce web documents. For the purposes of this article, web documents include various output formats for transmission over the web via HTTP, or other Internet protocols.
Maps Web template system
Typical motivation and usability
Apps
Web templates can be used by any individual or organization to set up their website. Once a template is purchased or downloaded, users will replace all generic information included in web templates with their own personal information, organization or products. Common Template usage examples are listed below:
- Display personal information or daily activities like on a blog.
- Sell products online.
- Displays information about a company or organization.
- Show family history.
- Displays a photo gallery.
- Place a music file like an on-line MP3 file to play through a web browser.
- Place an online video for public viewing.
- To set up a private inbox online.
Mass production
Various agencies and organizations use web template systems to mass produce content when slower production alternatives prove to be inadequate.
For an introductory overview, grab the news website as an example. Consider a "static website," where all static web pages are created by a web designer. It will be a very repetitive job to change individual pages as often as news changes. Typical strategies for automating "recurring work" from web designers using Templates are as follows:
- select web template system to maintain the website;
- groups of news items with different presentation needs;
- specify "presentation standard" via web template, for each news group;
- specify content resources to create or update content from each news item .
Style standardization
Separation of worries
A common goal among experienced web developers is to develop and deploy applications that are flexible and easy to maintain. An important consideration in achieving this goal is the separation of business logic from presentation logic. Developers use a web template system (with varying degrees of success) to maintain this separation.
For web designers, when every web page comes from a web template, they can think of structured modular web pages with components that can be modified separately from each other. These components may include header, footer, global navigation bar (GNB), local navigation bar and content such as articles, images, videos etc.
For programmers, the template language offers more limited logic, just for adaptation and presentation decisions, not for complex algorithms (business models).
For other members of the "site team", the template system frees webmasters to focus on technical maintenance, content suppliers to focus on content, and gives them more reliability.
In addition, it has the following advantages for its use:
- Ease of design changes : the presentation variations in the template are "invariant content", which means that web designers can update presentations without the fun of a wider infrastructure. Example of this type of website
- Ease localization interface : other menu and standard presentations are easy to create uniformly, for users browsing the site. Using Breadcrumb (navigation) makes any website more user friendly and flexible.
- Possibility to work separately on design and code by different people at the same time. This can be done while all the code in the template is a clean design and every block or part of the website is written with an individual comment system.
- Responsive web design is now a compulsory factor for any website. Everything should come up without any change in the responsive design.
- Ease of documentation Useful documentation saves more time to understand the entire template and also speeds up the modification process. Professional website designers strongly emphasize documentation.
One of the difficulties in evaluating separation of concerns is the lack of a well-defined formalism to measure when and how well it is actually fulfilled. Nevertheless, fairly standard heuristics have been borrowed from the software engineering domains. This includes 'inheritance' (based on the principles of object-oriented programming); and 'templating and generative programming', (consistent with the principle of MVC separation). The precise difference between the various guidelines is subject to some debate, and some aspects of different guidelines share the same degree of similarity.
Flexible presentation
One of the main reasons behind "effective separation" is the need for maximum flexibility in code and resources dedicated to presentation logic. Client demands, changing customer preferences and the desire to present "fresh faces" to pre-existing content often result in the need to dramatically modify the public appearance of web content without disrupting the underlying infrastructure as little as possible.
The difference between "front end" and "business logic" (infrastructure) is usually important, because:
- the source code of the presentation language may differ from other code assets
- the production process for the app may require work to be done at separate times and locations
- Different workers have different skills, and presentation skills do not always coincide with the skills for business logic encoding
- code assets are easier to maintain and easier to read when different components are kept separate and loosely coupled
Reusability
Not all potential users of web templates have the will and ability to hire developers to design systems for their needs. In addition, some may wish to use the web but have limited or no technical capabilities at all. For this reason, a number of developers and vendors have released custom web templates for reuse by non-technical people. Although the reuse of web templates is also important for highly skilled and technically experienced developers, it is very important for those who rely on simplicity and "ready-to-use" web solutions.
This "ready to use" web template is sometimes free, and easily made by individuals in the country. However, custom web templates are sometimes sold online. While there are many commercial websites that offer web templates for license fees, there are also free sources and "open-source" as well.
Example
With models usually held in relational databases, the remaining components of the MVC architecture are control and display. In the simplest system, they are not separate. However, adapting to the separation of principles of concern to one can actually separate relationships.
For example, the template view might look like this:
Then the control template will load the view and then can use the xpath address to include components from the database, for example:
Various template systems
Web browsers and web servers are client server architectures; often the web cache is also used to improve performance. Overall, there are five types of templating systems, classified based on when assembly occurs - placeholder replaced for variable information (such as name, address, and product info) and sub-templates:
- Server side - run-time substitution occurs on the web server
- The client-side - run-time substitution occurs in the web browser
- Edge-side - run-time substitution occurs in the proxy between web server and browser
- Outside servers - static web pages produced offline and uploaded to web servers; no run-time substitution
- Distributed - run-time substitution occurs on multiple servers
Template language might be:
- Embedded or triggered by events.
- Simple, forwardable, programmable, or complex.
- Defined by a consortium, individually defined, or de facto defined by an open implementation. Ownership affects the stability and credibility of a specification. However, in most jurisdictions, language specifications can not be copyrighted, so controls are rarely absolute.
The source code of the template engine can be proprietary or open source.
Many template systems are components of a larger platform or programming framework. They are referred to as "platform template systems". Some template systems have the option of changing different languages ​​or machine templates.
Programming languages ​​such as Perl, Ruby, C, and Java support native template processing, or through add-on libraries and modules. JavaServer Pages (JSP), PHP, and Active Server Pages (ASPs with VBScript, JScript or other languages) are examples, on their own, from the web template engine. This technology is typically used in server side templating systems, but can be adapted for use on "edge-side" proxies or for static page generation.
Static site generator
HTML editors often use web template systems to generate only static web pages. This can be seen as a ready-made web design, used to mass produce "cookie cutter" web sites for rapid deployment. They also usually include themes in place of CSS style. In general, the template language is only used with editor software.
FrontPage and Dreamweaver were once the most popular editors with sub-system templates. Flash web templates using Macromedia Flash to create interactive visual sites.
Many server-side templates systems have the option to publish an output page on the server, where the published page will be static. This is a common feature of content management systems, such as Vignette. But this should not be considered an out-of-server generation.
In most cases this "publishing option" does not interfere with the template system, and it can be created by external software, such as Wget.
Server-side system
The server-side dynamic side begins generating by templates with pre-existing software tailored for this task. This initial software is a preprocessor and macro language, adapted for web use, running on CGI. Furthermore, a simple but relevant technology is a direct execution performed on the extension module, starting with SSI.
Many template systems are typically used as server-side templates :
Technically, the methodology embeds programming languages ​​in HTML (or XML, etc.), which is used in many "scripting languages ​​including sides" is also a template. Everything is an embedded complex language.
There are also preprocessors that are used as server side templates. Example:
Edge-side system
Edge-Side templates and inclusion systems. "Edge-side" refers to the web server that is in the space between the client (browser) and the origin server. They are often referred to as "reverse-proxy" servers. These servers are generally tasked with reducing the load and traffic on the origin server by storing content such as images and page fragments, and sending them to the browser in an efficient manner.
Basic Edge Side Includes (ESI) is a SSI-like language. ESI has been applied to content delivery networks. The ESI template language can also be implemented in web browsers using JavaScript and Ajax, or via a "plug-in" browser.
Client-side system
Many web browsers can apply XSLT stylesheets to XML data that convert data into XHTML documents, thus providing the template functionality in the browser itself. Another system implements template functionality in browsers using JavaScript or other client side script languages, including:
- Mustache
Distributed system
The simplest form is transclusions (HTML frames). In other cases, dynamic web pages are required.
Example:
- Ajax
- Rich Internet applications
See also
References
External links
- comparison of JavaScript template library from 2009
- Enforcing Strict Display-Model Separation in the Template Engine
- Double-Model Approach for Achieving Effective Model-Display Separation in Template-Based Web Applications
- Comparison of PHP template engine with graphic chart
- A benchmark/comparison of some Python template engines and some general thoughts about template-engines
- web-mode.el is emacs major for editing web templates
Source of the article : Wikipedia
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