Content management with Plone 3.0
The Plone Zone
The simplicity and power of Plone make it the open source CMS of choice for sophisticated sites. Plone 3.0,
which was released in August, brings many improvements and enhanced support for enterprise applications.
By Jan Ulrich Hasecke
bigway, photocase.com
The class of tools known as Content Management Systems (CMS) includes everything from forum software
such as PHP-BB, through weblog programs like Wordpress, to complex systems such as Typo3. Many of
these tools are based on PHP. Because most major hosting services now support PHP, PHP-based CMS
applications are widespread. The PHP tools, however, quickly reach a limit if you require a high level of
security, powerful access management for users and workgroups, and workflow-driven process management.
In recent years, the CMS of choice for more sophisticated requirements has been Plone [1], which is based on
the Zope web application server.
The Plone Project recently released a new version. Plone 3.0 inherits a reputation for right security and
advanced workflow capabilities. The latest version also comes with new features such as inline editing, link
and reference checking, and full-text indexing of Word and PDF documents.
Zope is a professional system and the Python counterpart to the powerful web development systems in the
world of Java, such as JBoss, Websphere, or Weblogic. With its component architecture, Zope provides a
rock-solid basis for Plone, making it really interesting for business-critical applications. Like Zope, Plone is
also based on Python, an object-oriented programming language renowned for its elegance and simplicity.
The highly readable Python code is useful for projects in which teamwork is important. Python also has one of
the biggest and most active open source development communities, with 160 core developers and more than
500 extension programmers.
Plone will run on any major OS, including Windows, Linux, and Mac OS X, and there are installers that will
install everything for you. If you want to try out Plone, opt for this simple approach, which effortlessly takes
you to a Plone screen (see Figure 1).
The Plone Zone 1
Figure 1: The Plone CMS GUI after installation. Select the Get Started option for access to critical system
management functions.
For professional deployment, you might prefer to build all of the components - that is, Python, Zope, and
Plone - from the source code. Plone 3.0 requires version 2.4.4 of Python and Zope 2.10.4.
Plone does not require a relational database because the system uses the integrated Zope object database,
ZODB. ZODB is ACID-compliant; supports undo, replication, and hot-backup functionality; and can use
Zope Enterprise Objects (ZEOs) as a central database server solution to serve up data to multiple parallel
Zope instances for load balancing. This makes Plone highly scalable, but if you prefer to use an SQL
database, you can use object-relational mappers to bind it to Plone.
Simple Editing
Plone has a fairly intuitive GUI. Editing is integrated with the normal site layout, rather than requiring a
separate editing interface. This means users can immediately see the effects of their changes, rather than
fighting their way through the navigational tools of a separate editorial system. If you edit an article, the
article is simply displayed with an additional frame containing the required editing menus.
Assuming you have permissions, you can click to change isolated elements on a page, such as the heading, the
description, and the body text, to edit mode without affecting the rest of the page. This method is really useful
if you need to make some fast editorial changes. This effect is achieved by Ajax, which Plone supports thanks
to the KSS (Kinetic Style Sheets) framework [2].
Plone stores information in objects called article types. A schema exists for each article type, and users can
display the schema as a form in which to enter data. The system is flexible enough to handle different types of
information. Table 1 shows some standard Plone article types.
The Plone Zone 2
In all article types, content is categorized by means of a metadata system that complies with the Dublin Core
schema [3]. The metadata lets you link different content on the website or find content in a targeted way by
searching. For example, collections can list items by reference to their metadata.
Extensions for Media Types
Extensions for Plone provide additional article types, for example, for surveys or multimedia content, or they
add new functions to existing article types. Developers can use the archetype framework to define their own
individual article types; in many cases, web front-ends are available to help you with this task.
Besides browser-based content management, Plone also supports Webdav and ftp clients. A Plone folder can
be displayed on a client machine as a directory in a filesystem via Webdav. You can therefore store Office
documents directly in Plone from Word or Open Office.
Input Options
Users can choose fields, drop-down menus, or radio buttons to enter input. Plone also has many options for
creating body text with headings, bulleted lists, integrated images, and links. Plone supports mark-up
languages such as Restructured Text, Markdown [4], and Textile [5], which it converts to HTML after saving.
Techies will appreciate these input formats, which offer a convenient, simple, and fast approach to entering
formatting commands via the keyboard.
Most users will tend to prefer the Kupu text editor, which has menus reminiscent of other major word
processing programs (Figure 2). Besides various default styles, Kupu has tools for entering tables and
embedding links, images, and videos. Plone removes potentially harmful HTML tags before saving. Kupu
runs on Internet Explorer and Mozilla browsers, but it does not support Konqueror, Safari, or Opera.
The Plone Zone 3
Figure 2: The integrated Kupu editor lets users without HTML skills enter and edit content.
Access Management
Thanks to its well-considered access management scheme, Plone supports collaboration between larger user
groups in a secure web environment. Collaborative editing of information on the one hand and trustworthiness
on the other hand are the requirements that demand maximum flexibility from a CMS on a larger website. To
handle this, Plone has role-based access management that can give individual users or user groups highly
granular access privileges, either globally for the complete website or locally for a specific section of the site.
Put simply, roles are an abstraction layer containing a collection of specific and granular permissions that
Zope and Plone 3.0 support under the surface. Because a collection of numerous individual permissions is
difficult to handle, roles provide a kind of intuitive container. Administrators can enable or disable
permissions in roles at any time and thus change the configuration. Plone 3.0 defines the following roles by
default:
" Member is a registered user.
" Reader can read content.
" Contributor can add content.
" Editor can edit content.
" Publisher can publish content.
" Manager can modify the structure of the website.
" Owner is the user who originally created the content.
You can assign roles to individual users or groups either globally or for specific regions of the site.
Workflows
Closely linked to access management is the ability to map workflows. In Plone, workflows define the scope of
an organized editorial process. Content can assume several different states - for example, private or public.
Put simply, private content can only be viewed by its creator, whereas public content is accessible to all
website visitors. Users with appropriate permissions can effect state changes or transitions.
A workflow is a collection of states and transitions. Plone 3.0 comes with four different pre-configured
workflows:
" Single-state workflow - Content is published immediately and visible to all users.
The Plone Zone 4
" Simple publication workflow - Owners can publish the content themselves.
" Intranet workflow - Content is only visible to registered users. Editors can publish internally; if
needed, content can be made accessible to anonymous website visitors.
" Community workflow - Content is released to the public by publishers.
These workflows are all it takes to run both private websites and larger enterprise-wide intranet solutions.
Within a website, you can deploy several workflows in parallel; this means that you can define a workflow
globally for the whole website, but you could just as easily assign it to individual article types (for example
news, images, or dates) or just set it up locally for a specific section of the website.
The site administrator has a large degree of freedom to react to the users' needs. For example, you can set up
an area that is only accessible to an internal workgroup and assign the single-state workflow to give all users
immediate access to new information. Another area of the site might be governed by the multiple-stage
intranet or community workflow, to make sure that content is approved before it is released.
Versions and Events
Plone 3.0 has a version control system. To edit an existing article, the user first creates a working copy and
edits the content in the background, while the original version remains on display to the general public
(staging). After completing the edit, the author can then release the new version, compare the two versions,
and even revert to an older version. Articles are locked to prevent changes by other users when the article is
open for editing.
One major new feature in Plone 3.0 is event control, which automates various critical events. Administrators
can link events such as creating, modifying, and deleting items, or workflow transitions with other actions in
the CMS. This includes creating copies or sending notifications by email. The rules that govern how the
actions occur can also contain conditions. You can specify the conditions in a menu and assign them to
individual articles or folders.
Link Management
Moved or deleted content also leads to orphaned links. Plone 3.0 solves this problem by means of automated
integrity checks. When content is moved, Plone sends browser requests to the new destination. If somebody
deletes an article that other pages reference, the user sees a warning message and can either cancel the
operation or open the referencing documents for editing.
Search functions help users find information. Zope stores content and metadata in separate indexes, which can
be searched separately. Users can start a quick search of all catalogs, and if they have a Javascript-capable
browser, the results will be displayed while the user is typing the search key.
If the search does not return the desired results, the advanced search feature lets users define more complex
search keys and limit matches by time, status, keyword, author, or article type. In both cases, * is a wildcard
and the AND and OR logical operators are supported. If the wvware or xpdf/pdftotext packages are installed
on the server, Zope will also search the inside of Word and PDF files.
Google Sitemaps
Because Plone 3.0 supports the Sitemap Protocol standard, used by major search engines such as Google,
Yahoo, or MSN to find new pages faster and more efficiently, cooperation between Plone sites and search
engines is very efficient.
Zope Page Templates (ZPT, Listing 1) [6] allows users to create modular HTML pages in Plone. Zope has
used page templates to create dynamic websites for many years, and the feature is well documented. If you
want to write your own templates, the Internet is full of tools and HOWTOs. A standard page is made up of
The Plone Zone 5
several templates. To customize, you can modify the templates or just change the way they are arranged.
Listing 1: Page Template
01
02
03 # | Id | Meta-Type | Title |
04
|---|
05
06
07 # |
08 Id |
09 Meta-Type |
10 Title |
11
12
13 # |
14 Id |
15 Meta-Type |
16 Title |
17
18
19
Templates are responsible for displaying content; application logic, such as a search to list-specific content,
resides in external scripts, thus ensuring strict separation of content, application logic, and display
functionality.
Plone uses an XHTML-compliant, CSS-based, and barrier-free layout. It complies with the international W3C
Standard WAI-AA/WCAG 1.0 [7] and the requirements of US Law (Section 508, [8]) relating to barrier-free
websites. Web designers can use Cascading Style Sheets to change the appearance of every single element on
a web page, right down to the most basic elements. This means that you can radically change the appearance
of a predefined Plone site simply by modifying the stylesheets.
A special stylesheet lets users print Plone pages without irritating navigational elements. Version 3.0 also has
an S5 stylesheet that renders content in a browser for presentation via a video projector. The Plone GUI has
been translated into more than 50 languages, and the Linquaplone extension lets editors maintain multi-lingual
content. Plone creates a copy for each translation; the copy is linked to the original.
Single Sign-on
Plone has its own authentication mechanism. To implement single sign-on, you can add an LDAP or OpenID
extension to Plone; other central authentication mechanisms are supported but require more manual work.
Plone 3.0 offers registered users a personalized welcome page, or dashboard. From there, you can access
information on the website in an individual way and display, say, the latest news or any new content in a
custom view.
Despite the new functions, Plone is faster than ever. Tests with Apache Benchmark returned improved values
for Plone 3.0 across the bench compared with v2.5.3. Alexander Limi, one of the founders of Plone, published
test results on his blog showing that a page display requires less than half the number of HTTP requests
compared with the previous version [9]. Additionally, the HTML pages generated by Plone 3.0 have a smaller
footprint than those created with the previous version.
Faster with Caching
Dynamic page requests that run scripts and compile the final HTML page from a collection of templates hog
resources. To counteract this, Plone has various caching functions that reduce the time required by more
complex routines.
The Plone Zone 6
Although Zope has its own web server, Plone is typically deployed with Apache or a proxy cache like Squid
or Varnish. The ZEOs allow admins to distribute the database and spread the load over Zope servers to scale
Plone sites without having to mangle their structure.
The complexity and power of Plone does not rule it out for simple apps. In particular, the security that the
Zope application server offers makes Plone interesting for the smallest of sites, especially when you consider
that Plone gives you professional CMS at the press of a button. Of course, Plone really comes into its own
with larger enterprise or institutional websites.
Plone is licensed under the GNU Public License (GPL). The Plone brand and the program code belong to the
Plone Foundation, a reassuring fact for users thinking of investing time in Plone.
Update or Wait?
Plone 3.0 has many new functions that will make working with the CMS much easier for power users. Access
management for users and groups is one of Plone's stronger points, and the new version introduces major
improvements. Version 3.0 also gives administrators an easier path to implementing complex application
scenarios, and Plone's Zope roots make it a safe bet for security.
If you are launching a new project, you should consider Plone 3.0. Updating a system that you have not
customized to any great extent should be no problem. If you have added third party extensions to an existing
2.5.3 instance, you might prefer to wait for compatible extensions before you upgrade.
INFO
[1] Plone: http://plone.org
[2] KSS: http://kssproject.org
[3] Dublin Core: http://dublincore.org
[4] Markdown: http://daringfireball.net/projects/markdown
[5] Textile: http://hobix.com/textile
[6] Page Templates: http://zpt.sourceforge.net
[7] W3C Standard WAI: http:/www.w3.org/TR/WAI-WEBCONTENT
[8] Section 508: http://www.section508.gov
[9] Benchmarks: http://limi.net/articles/some-preliminary-plone-3.0-benchmark-results
The Plone Zone 7
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