The Verification Environment adds functionality on top of the Execution Environment, and complements it by verifying the deployed wrappers operation, and reducing the manual effort. As Web sources are autonomous and independent of the wrappers, they can change over time, and these changes can invalidate the current access mode, whereby the wrappers no longer extract the data properly. Denodo ITPilot offers an automated verification tool that detects the changes referred to above. Although this will be dealt with in more depth in section Configuring the Verification Server, its basic functioning is as follows:
The Wrapper Server stores all the wrappers in each of the Web sources.
The system periodically checks each wrapper for changes, monitoring the results of the queries executed against them.
When a change is detected in a source, the system sends a notification of the change.
The components of this environment, apart from those already mentioned in the execution environment, are as follows:
Verification Server: component responsible for detecting automatically any change happened in the sources and for notifying those changes. It communicates with the Wrapper Server to request all the wrappers to verify, and to obtain the query execution results over them (which will be used to check possible changes).
As mentioned earlier, a detailed explanation of this environment is provided in section Distribution of the Verification Environment of this same manual.
The next section recommends different distribution architectures for these components. Chapter Installation and Initial Configuration gives details of the installation and configuration processes for each of the ITPilot environments.