Apache Cocoon, usually abbreviated as Cocoon, is a web application framework built around the concepts of

Pipeline A pipeline is a system of Pipe (fluid conveyance), pipes for long-distance transportation of a liquid or gas, typically to a market area for consumption. The latest data from 2014 gives a total of slightly less than of pipeline in 120 countries ...

separation of concerns In computer science, separation of concerns (sometimes abbreviated as SoC) is a design principle for separating a computer program into distinct sections. Each section addresses a separate '' concern'', a set of information that affects the code o ...

, and component-based web development. The framework focuses on

XML Extensible Markup Language (XML) is a markup language and file format for storing, transmitting, and reconstructing data. It defines a set of rules for encoding electronic document, documents in a format that is both human-readable and Machine-r ...

and

XSLT XSLT (Extensible Stylesheet Language Transformations) 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. These formats c ...

publishing and is built using the

Java programming language Java is a high-level, general-purpose, memory-safe, object-oriented programming language. It is intended to let programmers ''write once, run anywhere'' ( WORA), meaning that compiled Java code can run on all platforms that support Jav ...

. Cocoon's use of XML is intended to improve compatibility of publishing formats, such as

HTML Hypertext Markup Language (HTML) is the standard markup language for documents designed to be displayed in a web browser. It defines the content and structure of web content. It is often assisted by technologies such as Cascading Style Sheets ( ...

and

PDF Portable document format (PDF), standardized as ISO 32000, is a file format developed by Adobe Inc., Adobe in 1992 to present documents, including text formatting and images, in a manner independent of application software, computer hardware, ...

. The

content management system A content management system (CMS) is computer software used to manage the creation and modification of digital content ( content management).''Managing Enterprise Content: A Unified Content Strategy''. Ann Rockley, Pamela Kostur, Steve Manning. New ...

s Apache Lenya and Daisy have been created on top of the framework. Cocoon is also commonly used as a

data warehousing In computing, a data warehouse (DW or DWH), also known as an enterprise data warehouse (EDW), is a system used for Business intelligence, reporting and data analysis and is a core component of business intelligence. Data warehouses are central Re ...

ETL tool or as middleware for transporting data between systems.

Sitemap

Apache Cocoon uses sitemaps to allow users to control a variety of components in the Cocoon software, as well as define the client-server interactions in what Cocoon refers to as the '' Pipelines.''

Components

The components within Cocoon are grouped by function.

Matchers

Matchers are used to match user requests such as URLs or
cookie, cookie
s against wildcard or

regular expression A regular expression (shortened as regex or regexp), sometimes referred to as rational expression, is a sequence of characters that specifies a match pattern in text. Usually such patterns are used by string-searching algorithms for "find" ...

patterns. Each user request is tested against matchers in the sitemap until a match is made. It is within a matcher that the response to a particular request is specified.

Generators

Generators create a

stream A stream is a continuous body of water, body of surface water Current (stream), flowing within the stream bed, bed and bank (geography), banks of a channel (geography), channel. Depending on its location or certain characteristics, a strea ...

of data for further processing. This stream can be generated from an existing XML document or there are generators that can create XML from scratch to represent something on the server, such as a directory structure or image data.

XSP

One type of generator is an XML Server Page (XSP), an XML document containing tag-based directives that specify how to generate dynamic content at request time. Upon Cocoon processing, these directives are replaced by generated content so that the resulting, augmented XML document can be subject to further processing (typically an XSLT transformation). XSPs are transformed into Cocoon producers, typically as Java classes, though any scripting language for which a Java-based processor exists could also be used. Directives can be either built-in ("XSP") or user-defined processing tags, both of which are defined in ''logic sheets''. Tags are defined using XSLT templates that describe how the tags (represented as XML nodes) are transformed into other XML nodes or into procedural code such as Java. The tags are used to embed procedural logic, substitute expressions, retrieve information from the webserver environment, and other operations. Note that XSP is deprecated in recent releases of Cocoon.

Transformers

Transformers take a stream of data and change it in some way. The most common transformations are performed with XSLT to change one

format into another. But there are also transformers that take other forms of data ( SQL commands for example).

Serializers

A serializer turns an XML event stream into a sequence of bytes (such as HTML) that can be returned to the client. Some serializers allow you to send the data in many different formats including

XHTML Extensible HyperText Markup Language (XHTML) is part of the family of XML markup languages which mirrors or extends versions of the widely used HyperText Markup Language (HTML), the language in which Web pages are formulated. While HTML, pr ...

, RTF, SVG, WML and

plain text In computing, plain text is a loose term for data (e.g. file contents) that represent only characters of readable material but not its graphical representation nor other objects ( floating-point numbers, images, etc.). It may also include a lim ...

, for example.

Selectors

Selectors offer the same capabilities as a

switch statement In computer programming languages, a switch statement is a type of selection control mechanism used to allow the value of a variable or expression to change the control flow of program execution via search and map. Switch statements function ...

. They are able to select particular elements of a request and choose the correct pipeline part to use.

Views

Views are mainly used for testing. A view is an exit point in a pipeline. You can put out the XML-Stream which is produced till this point. So you can see if the application is working right.

Readers

Publish content without parsing it (no

processing). Used for images and such.

Actions

Actions are Java classes that execute some business logic or manage new content production.

The Pipeline

A ''

pipeline A pipeline is a system of Pipe (fluid conveyance), pipes for long-distance transportation of a liquid or gas, typically to a market area for consumption. The latest data from 2014 gives a total of slightly less than of pipeline in 120 countries ...

'' is used to specify how the different Cocoon components interact with a given request to produce a response. A typical pipeline consists of a generator, followed by zero or more transformers, and finally a serializer.

References

External links

* /cocoon.apache.org/ The Apache Cocoon Project* {{DEFAULTSORT:Apache Cocoon Cocoon Web frameworks Java platform software