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Web Publisher Technical Architecture: A Primer

Overview

When you think of a web content management solution, you might envision a toolset that simplifies web content creation and maintenance for non-technical content authors. EMC Documentum fulfills this web content management vision through a suite of products. A basic Documentum web publishing environment configuration will utilize three Documentum products: Web Publisher, to simplify web content creation and modification, Content Server, to enable content management, and Site Caching Services (SCS), to publish content from a content repository to a website.

If you’re new to Web Publisher, you might want to start by checking out Marc Perlman’s Demo: The Power of Web Publisher to get a feel for how content is created in Web Publisher. Otherwise, a good way to gain an understanding of Documentum web publishing is to follow a piece of content through the system from creation to publication on a website.

  1. A content manager starts the process by accessing Web Publisher through a web browser.
  2. Within the Web Publisher application, the content manager creates a piece of web content by filling out a form using Web Publisher’s template based authoring tools. The content manager sets any number of attributes, such as title and content author, on the new piece of content.
  3. The new piece of content is created in the WIP (work in progress) lifecycle state and stored in the file store of the Documentum repository. Under the covers the content is stored as an XML file and the attributes that describe the content are stored in the relational database (RDBMS) within the repository. When the content manager selects the “webview” option in Web Publisher, the page template is transformed into a format that can be published to a website, such as JSP, ASP, or HTML.
  4. Next, Site Caching Services (SCS) performs a publish operation, which copies the transformed web page to the target website machine. Assuming the environment is configured to publish attribute values then the SCS database will also be updated with the content object attributes.
  5. The content and its attributes now reside on the WIP website where they can be reviewed for any typos or other errors.
  6. After the content manager is satisfied with the content, he or she launches the content on an approval workflow. The content is automatically promoted to the Staging lifecycle state and is forwarded to an editor for review. The editor approves the content which is then promoted to the Active lifecycle state. Both the content and its corresponding attributes are then published to the production web server(s).

basic-config

Figure 1:
Documentum WCM Environment Configuration

Documentum Web Publishing Environment Components

A typical Documentum web publishing environment requires three Documentum products: Web Publisher, Content Server, and Site Caching Services. In addition to these three products from Documentum, a custom website is required to complete a WCM environment. Below I’ve detailed some of the key elements within each of the required components.

Web Publisher

Web Publisher is a web application built on the EMC Documentum Web Development Kit (WDK) framework. The WDK toolkit is a Java based library of reusable components and controls that enable content management functions for Documentum through a web application. Web Publisher is an extension to the WDK framework that simplifies the creation and maintenance of web content using form based content editing. Web Publisher is installed in three parts: the web application, the DocApp, and the server files. The Web Publisher web application and WDK are installed in an application server such as Apache Tomcat, BEA WebLogic, or IBM WebSphere. For a complete list of supported application servers and versions, refer to the Web Publisher Release Notes for your version.

Web Publisher Contributor

Web Publisher Contributor is not a separate product or installation from Web Publisher. Contributor is another user interface option for the user to select at login time. Web Publisher Contributor is aimed at the casual content author. Contributor provides a simplified interface for the casual contributor by focusing on the tasks that they perform on a regular basis. For more information on the Contributor interface, read “Introduction to Web Publisher Contributor”.

Documentum Administrator

Documentum Administrator (DA) is a web application that provides access to administrative functions within Documentum. DA gives system administrators access to monitor, configure and maintain Documentum servers, repositories, and federations. As part of the Web Publisher installation, DA will also be updated with additional jobs for configuring and monitoring Web Publisher and site publishing functionality. DA access is required to complete the configuration of a Documentum web publishing environment.

Content Server

Documentum Content Server is the component responsible for managing the content. Content Server enables functions such as document versioning, workflow, and content security for content stored within a given repository. The Content Server handles all access to the content repository. Content Server is a required component in any Web Publisher solution.

Repository

A content repository (or docbase) stores the tables, indexes and content files used by Documentum Content Server. The repository is essentially a relational database to store content attribute values (or metadata) and a file store to house the content files.

In addition to the Web Publisher web application components and controls mentioned above, Web Publisher also requires a DocApp and a set of Web Publisher server files installed on the Content Server.

Web Publisher DocApp

The Web Publisher DocApp provides the additional workflows and lifecycle scripts for web content management, as well as a number of objects used to manage permissions, groups, and roles. The DocApp must be installed into any repository that will utilize the Web Publisher application. The DocApp is installed using Application Installer or DAR Installer, depending on the Web Publisher version.

Web Publisher Server Files

The Web Publisher server files are made up of two jars files that contain Java methods for changing permissions and executing the additional jobs and methods required for web content management. These files are installed on the Content Server to run in the separate Java Method Server application installed with Documentum Content Server.

Java Method Server

The Java Method Server is an application included by default with the Content Server installation. The Method Server is installed into an application server; either Apache Tomcat for DCTM version 5, BEA WebLogic for DCTM version 6, or JBOSS for DCTM version 6.5. The method server is a web application that allows custom code to execute on the server, independent of the client. The Method Server is often used to execute long-running processes or to execute processes that require super user privileges.

Site Caching Services

Site Caching Services is used to publish content from a Documentum repository to a website. SCS can also be configured to publish document attribute values (or metadata) to an external database for consumption by a website application. The published attribute values can be useful when creating dynamic web pages. For instance, the SCS (or webcache) database might be queried for all news items published with a press date in the last 30 days to create a dynamic news listing page. Additionally, SCS can be configured to write relation objects to an external database. The published relation object information can be useful when building a web page composed of related page snippets.

SCS is installed in two parts on different machines; the “source” is installed on the content server and the “target” on the web server host machine. SCS uses the source and target for communication between the content server and the web server machine(s). SCS can manage multiple websites for a single repository. For instance, a typical Web Publisher environment will support 3 distinct websites: WIP (Work In Progress), Staging, and Active. SCS can be configured to publish all content in the WIP lifecycle state to the WIP website, content in the Staging state to the Staging site, and so forth.

Published Website

Web Publisher is NOT a website presentation engine. In other words, you must create a custom web application framework to support dynamic web pages on your website. Unless the website being maintained and published from Web Publisher is a simple, static HTML site then a presentation engine is required to render the website. Using one of these presentation engines or web application frameworks requires custom development to handle things like database access, website security, and dynamic page rendering. To leverage all of the best features of Web Publisher, a presentation engine should also support querying the published SCS database for content attribute values and related objects. Here at Blue Fish, we’ve developed and refined a website component library to enable website security, display navigation enabled by Navigation Manager, and render many of the most common dynamic pages.

Optional Products and Add-Ons

There are a number of optional add-ons offered by EMC Documentum for simplifying content authoring, creating and deploying portlets, and managing replication of content to multiple web servers, among other things.

Page Builder

Web Publisher Page Builder is a browser based editor that enables web page development while viewing the web page as it will appear on the actual website. Page Builder also provides a tool for building additional content templates. The key benefit of Page Builder is that it allows the user to manage layout in addition to content. The content author will edit a page as it will appear on the end website, unlike the form based editing in the base Web Publisher product. Page Builder is simply another DocApp installed in a Web Publisher repository. Look out for an upcoming article about Page Builder in the near future.

Portlet Builder

Documentum Portlet Builder is an optional product add-on that is used to create and deploy portlets to a portal server. Portlet Builder provides additional templates and wizards for creating portlets, as well as a portal server target for identifying the portal servers to which portlets can be published. Like Page Builder, Portlet Builder is also a DAR (or DocApp) installed in a Web Publisher repository. A separate portal server is required to make use of the portlets published from Web Publisher.

Site Deployment Services

Site Deployment Services (SDS) is a Documentum product that facilitates the replication of content to multiple websites and databases. SDS is often used to keep multiple web servers in sync and refreshed with the latest content published from SCS. Site Caching Services can be configured to work with SDS, such that a publish operation from SCS to target server A will trigger the replication of content to targets B and C. Using the same example, if the replication of content from Target A to B is successful, but replication to Target C fails, then the entire transaction can be rolled back. This ensures a consistent website experience no matter which target site a visitor sees.

SDS is not dependent on the repository in any way. SDS is made up of a series of Tuners installed on each of the host machines. SDS uses Tuners to subscribe to various Channels through which content is replicated. Whenever a channel has changed (i.e. content has been added or removed), the Transmitter is responsible for distributing content and updates to each of the other Tuners subscribed to the updated Channel. The diagram below provides a simplified view of the communications between the various components. To learn more about installing and configuring SDS read “Site Deployment Services Rapid Install, Config and Troubleshooting”.

sds
Figure 2:
Simplified illustration of SDS content replication

Conclusion

The EMC Documentum product suite is capable of delivering a robust and comprehensive web publishing environment, but understanding all of the components is key to configuring a strong solution to meet the needs of your business. I hope this article has provided a basic understanding of those components required by any Documentum web publishing environment and an idea of when to use some of the optional components and add-ons.

References

  • Web Publisher Administration Guide
  • Web Publisher User Guide
  • Site Caching Services User Guide
  • Site Deployemnt Services Administrator’s Guide

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