Thursday, March 27, 2008
Sunday, March 16, 2008
Hibernate and BI
Business Intelligence (BI) requires a star schema for efficient analytics. (the difference between analytics and reporting is that reporting requires you to know up front what you want to report and analytics allows you to do ad-hoc reporting). BI operates in most cases from a data warehouse based on star schemas to allow fast and time-based (historical) reporting. Reporting from the operational data sources would jeopardize the transactional/operational systems and in most cases does not allow for historical reports.
An ordinary application based on a persistence engine like Hibernate uses obviously an operational schema - making analytics hard. It would be nice to let Hibernate also update a data warehouse - similar to updating the indexes for text based retrieval.
So when a transaction is comitted, a message (asynchronously) is send to a component that updates the data warehouse. Each operation has a time stamp - allowing time based reporting. You could even use the data warehouse as a kind of trash bucket to restore data that has been deleted inadvertently.
To summarize; the application has three data sources; operational, warehouse and text-indexes.
An application in this way allows for text based search and analytics reports.
An ordinary application based on a persistence engine like Hibernate uses obviously an operational schema - making analytics hard. It would be nice to let Hibernate also update a data warehouse - similar to updating the indexes for text based retrieval.
So when a transaction is comitted, a message (asynchronously) is send to a component that updates the data warehouse. Each operation has a time stamp - allowing time based reporting. You could even use the data warehouse as a kind of trash bucket to restore data that has been deleted inadvertently.
To summarize; the application has three data sources; operational, warehouse and text-indexes.
An application in this way allows for text based search and analytics reports.
Wednesday, March 5, 2008
Tomcat as Windows Service
To install Tomcat5 as a service follow the "Windows service HOW-TO" instructions on the Apache Tomcat side.
Calling Tomcat5 //IS//MyServiceName blabla will create an entry in the Windows registry located at:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MyServiceName
The new installed service when started does a call back to tomcat5.exe specifying the service name and the start parameter.
With tomcat5w //ES//MyServiceName you can monitor the service. Bit similar to the Windows Services application, but it has more functionality like specifying the log level and log location.
In my case the service did not start and I had an error in the log:
[2008-03-05 15:55:24] [443 javajni.c] [error] FindClass org/apache/catalina/startup/Bootstrap failed
[2008-03-05 15:55:24] [997 prunsrv.c] [error] Failed loading main org/apache/catalina/startup/Bootstrap class
[2008-03-05 15:55:24] [1260 prunsrv.c] [error] ServiceStart returned 3
So a classpath problem. I re-read the instructions and I noticed that the remark " If using tomcat5.exe, " put me on the wrong foot. I thought service.bat applied to versions prior 5. Appearently this is not the case because running service.bat worked fine. Looking into the content of service.bat I noticed that there is some classpath manipulation and after installing the service, the service is also updated with JVM options so this way is superior as to the excerpt installing Tomcat5. (In hindsight I completely misinterpreted this)
Deleting the service using //DS removes the entry from the registry.
Calling Tomcat5 //IS//MyServiceName blabla will create an entry in the Windows registry located at:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MyServiceName
The new installed service when started does a call back to tomcat5.exe specifying the service name and the start parameter.
With tomcat5w //ES//MyServiceName you can monitor the service. Bit similar to the Windows Services application, but it has more functionality like specifying the log level and log location.
In my case the service did not start and I had an error in the log:
[2008-03-05 15:55:24] [443 javajni.c] [error] FindClass org/apache/catalina/startup/Bootstrap failed
[2008-03-05 15:55:24] [997 prunsrv.c] [error] Failed loading main org/apache/catalina/startup/Bootstrap class
[2008-03-05 15:55:24] [1260 prunsrv.c] [error] ServiceStart returned 3
So a classpath problem. I re-read the instructions and I noticed that the remark " If using tomcat5.exe, " put me on the wrong foot. I thought service.bat applied to versions prior 5. Appearently this is not the case because running service.bat worked fine. Looking into the content of service.bat I noticed that there is some classpath manipulation and after installing the service, the service is also updated with JVM options so this way is superior as to the excerpt installing Tomcat5. (In hindsight I completely misinterpreted this)
Deleting the service using //DS removes the entry from the registry.
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