Template processor

Last updated
A diagram illustrating all of the basic elements and processing flow of a template engine. TempEngGen015.svg
A diagram illustrating all of the basic elements and processing flow of a template engine.

A template processor (also known as a template engine or template parser) is software designed to combine templates with a data model to produce result documents. [1] [2] [3] The language that the templates are written in is known as a template language or templating language. For purposes of this article, a result document is any kind of formatted output, including documents, web pages, or source code (in source code generation), either in whole or in fragments. A template engine is ordinarily included as a part of a web template system or application framework, and may be used also as a preprocessor or filter.

Contents

Typical features

Template engines typically include features common to most high-level programming languages, with an emphasis on features for processing plain text.

Such features include:

Embedded template engines

While template processors are typically a separate piece of software, used as part of a system or framework, simple templating languages are commonly included in the string processing features of general-purpose programming languages, and in text processing programs, notably text editors or word processors. The templating languages are generally simple substitution-only languages, in contrast to the more sophisticated facilities in full-blown template processors, but may contain some logic.

Simple examples include ‘printf’ print format strings, found in many programming languages, and snippets, found in a number of text editors and source code editors. In word processors, templates are a common feature, while automatic filling in of the templates is often referred to as mail merge.

An illustrative example of the complementary nature of parsing and templating is the s (substitute) command in the sed text processor, originating from search-and-replace in the ed text editor. Substitution commands are of the form s/regexp/replacement/, where regexp is a regular expression, for parsing input, and replacement is a simple template for output, either literal text, or a format string containing the characters & for "entire match" or the special escape sequences \1 through \9 for the nth sub-expression. For example, s/(cat|dog)s?/\1s/g replaces all occurrences of "cat" or "dog" with "cats" or "dogs", without duplicating an existing "s": (cat|dog) is the 1st (and only) sub-expression in the regexp, and \1 in the format string substitutes this into the output.

System elements

All template processing systems consist of at least these primary elements:

Data model

This may be a relational database, a source file such as XML, an alternate format of flat file database, a spreadsheet or any of other various sources of preformatted data. Some template processing systems are limited in the types of data that can be used. Others are designed for maximum flexibility and allow many different types of data.

Source template

Source templates are traditionally specified:

Template engine

The template engine is responsible for:

Additionally some template engines allow additional configuration options.

Result documents

These may consist of an entire document or a document fragment.

Uses

Template processing is used in various contexts for different purposes. The specific purpose is ordinarily contingent upon the software application or template engine in use. However, the flexibility of template processing systems often enables unconventional uses for purposes not originally intended by the original designers.

Template engine

A template engine is a specific kind of template processing module that exhibits all of the major features of a modern programming language. The term template engine evolved as a generalized description of programming languages whose primary or exclusive purpose was to process templates and data to output text. The use of this term is most notably applied to web development using a web template system, and it is also applied to other contexts as well. [4]

Document generation

Document generation frameworks typically use template processing as the central model for generating documents.

Source code generation

Source code generation tools support generation of source code (as the result documents) from abstract data models (e.g., UML, relational data, domain-specific enterprise data stores) for particular application domains, particular organizations, or in simplifying the production process for computer programmers.

Software functionality

A web template engine processes web templates and source data (typically from a relational database) to produce one or more output web pages or page fragments. It is ordinarily included as a part of a web template system or application framework. Currently, template processing software is most frequently used in the context of development for the web.

Comparison

XSLT is a template processing model designed by W3C. It is designed primarily for transformations on XML data (into web documents or other output).

Programming languages such as Perl, Python, PHP, Ruby, C#, Java, and Go support template processing either natively, or through add-on libraries and modules. JavaServer Pages, [5] Active Server Pages, [6] Genshi (for Python), and eRuby are examples of template engines designed specifically for web application development.

Moreover, template processing is sometimes included as a sub-feature of software packages like text editors, IDEs and relational database management systems.

Benefits of using template engines

See also

Related Research Articles

XSLT is a language originally designed for transforming XML documents into other XML documents, or other formats such as HTML for web pages, plain text or XSL Formatting Objects, which may subsequently be converted to other formats, such as PDF, PostScript and PNG. Support for JSON and plain-text transformation was added in later updates to the XSLT 1.0 specification.

In computer science, a preprocessor is a program that processes its input data to produce output that is used as input in another program. The output is said to be a preprocessed form of the input data, which is often used by some subsequent programs like compilers. The amount and kind of processing done depends on the nature of the preprocessor; some preprocessors are only capable of performing relatively simple textual substitutions and macro expansions, while others have the power of full-fledged programming languages.

A query language, also known as data query language or database query language (DQL), is a computer language used to make queries in databases and information systems. In database systems, query languages rely on strict theory to retrieve information. A well known example is the Structured Query Language (SQL).

A domain-specific language (DSL) is a computer language specialized to a particular application domain. This is in contrast to a general-purpose language (GPL), which is broadly applicable across domains. There are a wide variety of DSLs, ranging from widely used languages for common domains, such as HTML for web pages, down to languages used by only one or a few pieces of software, such as MUSH soft code. DSLs can be further subdivided by the kind of language, and include domain-specific markup languages, domain-specific modeling languages, and domain-specific programming languages. Special-purpose computer languages have always existed in the computer age, but the term "domain-specific language" has become more popular due to the rise of domain-specific modeling. Simpler DSLs, particularly ones used by a single application, are sometimes informally called mini-languages.

Extensible Application Markup Language is a declarative XML-based language developed by Microsoft for initializing structured values and objects. It is available under Microsoft's Open Specification Promise.

A GIS software program is a computer program to support the use of a geographic information system, providing the ability to create, store, manage, query, analyze, and visualize geographic data, that is, data representing phenomena for which location is important. The GIS software industry encompasses a broad range of commercial and open-source products that provide some or all of these capabilities within various information technology architectures.

<span class="mw-page-title-main">XWiki</span> Wiki engine

XWiki is a free wiki software platform written in Java with a design emphasis on extensibility. XWiki is an enterprise wiki. It includes WYSIWYG editing, OpenDocument based document import/export, semantic annotations and tagging, and advanced permissions management.

<span class="mw-page-title-main">LAMP (software bundle)</span> Acronym for a common web hosting solution

LAMP is an acronym denoting one of the most common software stacks for many of the web's most popular applications. However, LAMP now refers to a generic software stack model and its components are largely interchangeable.

Open Power Template is a web template engine written in PHP 5. A common strategy in designing web application is separation of the application logic from the presentation. OPT is a tool for implementing such separation. The presentation layer is represented by templates, text files with HTML code and extra instructions controlling the data substitution.

<span class="mw-page-title-main">Web template system</span> System in web publishing

A web template system in web publishing allows web designers and developers work with web templates to automatically generate custom web pages, such as the results from a search. This reuses static web page elements while defining dynamic elements based on web request parameters. Web templates support static content, providing basic structure and appearance. Developers can implement templates from content management systems, web application frameworks, and HTML editors.

The following outline is provided as an overview of and topical guide to software:

Knowledge extraction is the creation of knowledge from structured and unstructured sources. The resulting knowledge needs to be in a machine-readable and machine-interpretable format and must represent knowledge in a manner that facilitates inferencing. Although it is methodically similar to information extraction (NLP) and ETL, the main criterion is that the extraction result goes beyond the creation of structured information or the transformation into a relational schema. It requires either the reuse of existing formal knowledge or the generation of a schema based on the source data.

Thymeleaf is a Java XML/XHTML/HTML5 template engine that can work both in web (servlet-based) and non-web environments. It is better suited for serving XHTML/HTML5 at the view layer of MVC-based web applications, but it can process any XML file even in offline environments. It provides full Spring Framework integration.

<span class="mw-page-title-main">XML transformation language</span> Type of programming language

An XML transformation language is a programming language designed specifically to transform an input XML document into an output document which satisfies some specific goal.

The following outline is provided as an overview of and topical guide to the Perl programming language:

ProcessWire is a free and open source content management system (CMS), content management framework (CMF) and web application framework (WAF) written in the PHP programming language. It is distributed under the Mozilla Public License 2.0. ProcessWire is built around an API with usage and naming conventions similar to the JavaScript framework jQuery. The stated goal behind the API is to provide the level of accessibility and control to pages in a website that jQuery provides to the DOM. Content is managed either via the API or the web-based admin control panel. ProcessWire is largely used for development of web sites, web applications, services, content feeds and related applications.

Apache Attic is a project of Apache Software Foundation to provide processes to make it clear when an Apache project has reached its end-of-life. The Attic project was created in November 2008. Also the retired projects can be retained.

References

  1. ↑ Niemeyer, Patrick (2002). Learning Java. Sebastopol: O'Reilly. ISBN   0-596-00285-8.
  2. ↑ Manolescu, Dragos (2006). Pattern Languages of Program Design 5. Reading: Addison-Wesley Professional. ISBN   0-321-32194-4.
  3. ↑ Fowler, Martin (2003). Patterns of Enterprise Application Architecture. Boston: Addison-Wesley. ISBN   0-321-12742-0.
  4. ↑ (see e.g., Velocity, TemplateToolkit, Freemarker ).
  5. ↑ JavaServer Pages is a technology released by Sun for use with the Java programming language. "JavaServer Pages Technology". 2006-10-10. Retrieved 2006-10-10.
  6. ↑ ASP 1.0 was originally released for use with Microsoft VBScript and JScript. It was an extension to Microsoft IIS.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.