This document focuses on the graphic tools from Denodo Technologies which allow to visually extract information from web sources. They can also be used to extract information from documents in Microsoft Word, Microsoft Excel and/or PDF format.
Development of Component-Based Wrappers¶
Most information obtained from WWW (Worldwide Web) sources is presented using the HTML language, which is aimed to the visualization of data by human beings but it is not adequate to allow processing by software applications.
Denodo ITPilot allows graphically creating web “wrappers”; wrappers are programs able to automate a certain process on a website. This usually involves automatically reproducing navigation sequences and extracting data from the website pages. In ITPilot, wrappers are defined as a process flow comprising a series of components. Each component accomplishes a specific task, and their behavior depends on the input data they receive. Denodo components allow practically any operation on HTML-based web sources, and also some capabilities for information extraction from Microsoft Word, Microsoft Excel and Adobe PDF files.
Graphically, users can select the components required for a specific Web automation process from a palette. Each component can be linked to others through information input and output relations. Thus, the result of a component may be used as input for others. For example, the data extraction component (the “extractor”) will return a list of results extracted from a web page that may be used as input for an iteration component (the “iterator”). This component, in turn, will return in each iteration one of the elements comprising the list, so further operations can be performed on each element (such as processing it or returning it as a result of the wrapper). There are also other components for tasks such as applying conditions, executing loops or filtering and transforming the extracted data. A full description of each component in the form of a reference guide can be found in section Appendix C: Catalog of Components.
The ITPilot Wrapper Generation Tool also allows testing and debugging the generated wrappers (both at the wrapper and component levels) before deploying it in the run server, as described in this manual.
This manual uses an example to illustrate some of the main features of the tool. The example is split into two different parts. The first part provides a small, detailed example of extracting e-mail information from a Web application. The second part expands on this example to observe and practice with functions such as the extraction of data dispersed in different detail pages, browsing through pages of “more results” and other advanced capacities.
The following section will describe the Generation Environment installation and configuration process.