2001 04 Xml Content Management

�ł056infozoneed.qxd 02.03.2001 13:19 Uhr Seite 56
KNOW HOW CONTENT MANAGEMENT
XML Content Management
with Infozone and Prowler
CONTENT
HEAVY
FALKO BR�UTIGAM, GERD M�LLER AND ROBERT STRUNZ
The term content management has
become somewhat overused these
days, with a confusing range of
providers and products trying very
hard to distinguish themselves
through specialised solutions. The
following article takes a more
detailed look at the approach of the
open-source project Infozone.
term prospects for providers of appropriate tools
make this new market very attractive. Many large,
and even more small, companies want a piece of
the action. Consequently, they market their
products under the term content management.
This has led to confusion in the market, but has
at the same time made it very dynamic and
interesting, especially as there is by no means a
consensus on its future development and everyone
is trying to make their mark.
One distinguishing feature is the ability of
individual products to be integrated into existing IT
structures. At this point the sophistication of different
providers becomes apparent. While small providers
concentrate on Web site administration, larger
companies can and must also deliver integration into
Content management is closely linked to the existing software systems such as ERP, document
development of large Web sites and their inherent management or messaging solutions.
problems. The sheer volume of data, the complexity In this context, Web sites are no longer
of the structures and the related workflow make understood and used solely as a presentation
the use of software tools inevitable. medium, but are increasingly extended to become
As the strategic importance of companies Web the company s central information platform. This
sites to their business activity increases, the long- leads to completely new content management
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CONTENT MANAGEMENT KNOW HOW
requirements. In addition to the editorial content,
Transactional XML file system
data from other sources now also has to be
included and administered. At the heart of Prowler is a transactional XML file
system, which makes it possible to insert the
contents of the underlying data sources at any point
Infozone and Prowler
of a hierarchical structure. Basically, any number of
A very general approach to the issue of content systems can be integrated as data sources, for
management comes from the open-source instance application servers, ERP systems, mail or
community. The Infozone project (see the Infozone groupware servers, RDBMS, OODBMS and anything
framework box) has as its aim the development and else that is important for business IT.
integration of components for building company Unlike normal file systems, Prowler uses XML to
portals (Enterprise Information Portal EIP). The display data and transactions are secure. Data from
content management framework Prowler plays a sources that cannot themselves supply XML are
central part in this. automatically converted into XML using special
Unlike other systems, Prowler is not a complete content adapters. This leads to a uniform XML view
application but a Java framework, whose API of all data, which substantially reduces the effort
follows the Java servlet model. This framework required for presentation via Cocoon and SchemoX
provides important content management functions, (see the Infozone framework box), as well as for
such as the administration of users, rights, versions data queries and processing.
and transactions, but in addition gives programmers Apart from the consistent use of XML, another
the opportunity to integrate their own functions of Prowler s distinctive features is the integration of
Figure 1: Prowler
and extensions. a JTA/XA compliant transaction manager. This architecture
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KNOW HOW CONTENT MANAGEMENT
Listing 1: Prowler configuration file
Info

http://www.infozone-
group.org
loglevel= info warn error debug debug2 debug3 name= intranet >
http://java.sun.com/products/jta

http://tyrex.exolab.org
http://www.postgresql.org ger />

http://www.ozone-db.org
http://xml.apache.org/cocoon
factory= org.infozone.prowler.adapter.ProwlerDocumentAdapter
http://java.apache.org/jetspeed
xmlcache= ozonexml >

%
factory= org.infozone.prowler.adapter.sql.DB2XMLAdapter
xmlcache= ozonexml >

ctory />

enables access to different transactional data page. The transaction manager ensures data
sources, for instance databases or application consistency through a two phase commit.
servers, within one global transaction or one HTML In addition, it is responsible for the flexible
allocation of transactions to server threads, which
makes it an important scalability factor, particularly
Listing 2: Exemplary Java code
for Web applications with thousands of
import org.infozone.prowler.*;
simultaneous users.
import org.w3c.dom.*;
Prowler, therefore, is not an extended editing
import javax.xml.parsers.DocumentBuilder;
system, but data integration technology that enables
public class ProwlerTest {
transactional access to the contents of a large variety
public static void main( String[] args ) throws Exception {
of data sources through an XML interface.
// 1. Initialise Prowler
Prowler prowler = new Prowler( "prowler.xproperties" );
// 2. Open Session
An example
session = prowler.newSession( "root", "" );
session.open( null );
Before things get too abstract, we will demonstrate
// 3. Parse root document and set
Prowler s functionality by way of a simple example.
DocumentBuilder db = ProwlerServices.newDocumentBuilder();
Our little application is intended to perform two
Document doc = db.parse( "rootdoc.xml" );
tasks: query and display the content of an SQL
session.setRootDocument( doc );
database and file an XML document in a database.
// 4. Parse and link 'hamlet.xml'
The following data sources are provided to
doc = db.parse( "hamlet.xml" );
Prowler as resources: an SQL database in the form
session.addDocument( doc, Prowler.newAdapterID( "document" ),
of PostgreSQL and a database that can store XML
new ProwlerRepositoryPath( "/root/hamlet", session.rootDocument() ) );
directly in the form of Ozone/XML.
// 5. Close session and shut down Prowler
session.close(); Which data sources are used with which
prowler.shutdown();
parameters in Prowler applications is described in an
}
XML file, independent of the actual logic itself.
}
Listing 1 shows the configuration for the example.
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CONTENT MANAGEMENT KNOW HOW
We are assuming that Prowler has already been
installed and that all files are in the current directory.
We are defining two resources: postgres_jdbc
establishes the connection to PostgreSQL via JDBC and
ozonexml is responsible for the link to Ozone. To make
the content of both resources available as XML we
define two adapters: db2xml converts the relational
data from PostgreSQL to XML using the RDBMS/XML
mapping tool DB2XML. document on the other hand
does not convert data, but caches the XML documents
in ozonexml, from where it can also retrieve them.
Now for the application itself. In principle there
are two ways of working with Prowler, either
directly through a Java API or through a Cocoon
XSP library for the realisation of Web pages. We will
demonstrate both methods briefly.
The Java API
In the first part of the application we will build a
repository using the Java API and file an XML
document in Prowler. For the XML document we are
using that universally known and loved Shakespeare
drama, hamlet.xml. The SQL database on the other
hand contains a simple table addresses with the
columns name, firstname and town, which already
contains a few entries. The code, minus the
exception handling, can be seen in Listing 2.
Prowler is initialised in steps 1 and 2 and then a
session is opened. In step 3 the application-specific
Figure 2:
Listing 3: An XML page for Cocoon
Infozone
architecture

xmlns:xsp="http://www.apache.org/1999/XSP/Core"
xmlns:response="http://www.apache.org/1999/XSP/Response"
xmlns:prowler="http://www.infozone-group.org/prowler">

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Prowler structure is created (i.e. the root document).
processor.xsp.logicsheet.prowler.java =
This structure is also XML and, in our example, looks resource://org/infozone/ui/xsp/prowler.xsl
like this:
The aim of our example page is to show the

addresses of people called Jones. This is shown in

Listing 3.

query. For this we have to specify an explicit path
"adapter"/>
through the repository. The pathorder attribute

determines in which sequence the specified paths
It is interesting to note that the link to the address are to be processed.
table is already inserted here. This linkage could of We start with the root document at
course also be created via the API. prowler:href /root/addresses and then move from link to link. As
points to the adapter db2xml with the table there is only one link to negotiate, the next part of
addresses, which means that the table is displayed XPath already contains the actual query:
as an XML document at this point if required. /database/table0/ record0 [name/text() = Jones ].
Next we use addDocument() to store The result is returned as a DOM tree and is
Shakespeare s hamlet.xml and put a link to it into integrated into the XML document via XSP. A style
the hamlet tag. That is the first application finished, sheet that is not shown here converts the output
and after its execution we have created a small into HTML and sends it to the browser. This little
repository. Web application makes do without a single line of
Java code, but it achieves quite a lot.
Using Prowler s other functions via a Java API or
Cocoon as front end
an XSP library is just as easy as the data access itself.
However, the Java API is only used for programming These are, for instance, user, rights and version
the specific presentation logic of applications. administration, workflow support, transaction
Anything else can be done much more easily, for administration and the export/import of the entire
The authors
instance with the Prowler XSP library. With this it is content into a file system or other formats.
The authors Gerd M�ller, possible to dynamically integrate Prowler content in All of that cannot be described in detail in the
Falko Br�utigam and Robert XML documents via Cocoon and to then convert it context of this article. Nevertheless, we hope to
Strunz work as computer into HTML, WML, PDF or another output format. In have given some idea of content management in
scientists. Apart from their order to be able to use the Prowler XSP library in general and Prowler in particular. Questions relating
managerial tasks, Falko and Cocoon, the Cocoon configuration file must first be to the article or to Prowler are welcome, either to
Gerd primarily deal with extended as follows: the authors or straight to the Prowler mailing list. %
technological questions
concerning Infozone. Robert is
responsible for SMB s business The Infozone framework rationalisation through integration
communication.
Infozone was started in June 2000. The project, distributed under an Apache licence, is a
Java/XML component framework for the professional creation of complex Enterprise
Information Portals (EIP), providing access to a large variety of electronic data sources
through integration. EIPs are designed to trigger rationalisation effects in larger companies
and organisations by channelling information flows.
In this context, Infozone provides a company s employees with personalised browser-based
access to all business-related information. But other user groups, such as customers,
suppliers and partners can also access any of the company s data sources that they have
been authorised to use.
Within the framework itself, some very central components are developed directly as part
of the Infozone group. Others originate from the Apache project and have been selected
and adapted for use in Infozone. Figure 2 shows the Infozone architecture. At the moment
the following components are used:
" Web Server/Servlet Engine Apache/Tomcat
" XML Publishing Framework Cocoon
" XML Content Management Engine Prowler
" Object Oriented XML Database System ozone/XML
" Forms Generator SchemoX
For the future, the Infozone group is planning the integration and development of a
number of further modules. Top of the list is Jetspeed from Apache XML, which is intended
to simplify the creation of personalised Web applications.
60 LINUX MAGAZINE 7 � 2001

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