244 Implementation

A schematic diagram of the architecture is shown in the Figure 24.3. The first web service allows the user to browse through and select any of the registered data sources. The second web service transforms the selected data source into a PLCS-XML compatible file. This web service maps the proprietary data model of the source application onto the PLCS standard data model using XSLT. The knowledge of the data mapping is encapsulated in the XSLT files and therefore easy to change and adapt for any future needs. The output XML is validated against the PLCS schema before being used as the data source for the Product Information Explorer application.

The exact sequence of events are enumerated below:

a) First, the database source is queried using a SOAP (Simple Object Access Protocol) service, according to a set of SQL statements held in a text file. This allows easy modification of the SQL queries if required;

b) This query process returns a bunch of XML record sets.

c) The record sets are then processed using XSLT. This processing integrates the multiple record sets to a single file and transforms the source data into a PLCS representation d) The end of the chain is the Product Information Explorer application which queries the XML database using XPath. The query process is done whilst the user is browsing the data to improve system performance.

The multi-tier architecture works in real-time and the PLCS-XML data source presented to the user is derived in real-time when selected by the user. The information browser is an ASP.NET application running on a web server. The front-end presents a graphical view of the information and allows the user search and navigates the information using any web browser.

Figure 24.3 Implementation Architecture
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