At the Forge - Databases and Calendars
Sure enough, the result of invoking db-calendar.py is a fully iCalendar-compliant file, suitable for importing into Sunbird or any other calendar program. Moreover, simply by modifying the contents of our Events database table, we can ensure that everyone who subscribes to our calendar gets the latest version.
We can go one step further than this, modifying db-calendar.py such that it includes only certain events in its result. For example, perhaps the calendar needs to contain only events in the future; there is no need to clutter someone's calendar (and bandwidth) with events from the past. By adding a simple WHERE clause to our SQL query, we easily can remove all of the events from the past.
More intriguing is the possibility of supporting different groups and access levels to a calendar. HTTP supports authentication with user names and passwords, and although Sunbird doesn't support such protections at the present time, I would expect it (and other programs) to do so in the future. Given that a CGI program easily can determine the user name of the person making an authenticated HTTP request, it's not too far-fetched to say that db-calendar.py could produce different output for different users, depending on a set of assigned permissions or roles.
Finally, although we have focused on iCalendar-format output for the last few months, there isn't any reason why we can turn only the contents of the database into an iCalendar file. Indeed, it's quite possible that we would want to display our events database in plain-old HTML, as well as in iCalendar. Once again, it's easy to see how we could do that using HTML tables—demonstrating once again that relational databases make it easy to display a set of data in a number of different ways.
This month, we have seen how to use a database to store event information that eventually will be transformed into an iCalendar-compliant file. Using a database makes us not only more confident that stored data is valid, but it allows us to create dynamically generated files quickly and easily that are suitable for use in programs that use the iCalendar format.
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Practical Task Scheduling Deployment
July 20, 2016 12:00 pm CDT
One of the best things about the UNIX environment (aside from being stable and efficient) is the vast array of software tools available to help you do your job. Traditionally, a UNIX tool does only one thing, but does that one thing very well. For example, grep is very easy to use and can search vast amounts of data quickly. The find tool can find a particular file or files based on all kinds of criteria. It's pretty easy to string these tools together to build even more powerful tools, such as a tool that finds all of the .log files in the /home directory and searches each one for a particular entry. This erector-set mentality allows UNIX system administrators to seem to always have the right tool for the job.
Cron traditionally has been considered another such a tool for job scheduling, but is it enough? This webinar considers that very question. The first part builds on a previous Geek Guide, Beyond Cron, and briefly describes how to know when it might be time to consider upgrading your job scheduling infrastructure. The second part presents an actual planning and implementation framework.
Join Linux Journal's Mike Diehl and Pat Cameron of Help Systems.
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With all the industry talk about the benefits of Linux on Power and all the performance advantages offered by its open architecture, you may be considering a move in that direction. If you are thinking about analytics, big data and cloud computing, you would be right to evaluate Power. The idea of using commodity x86 hardware and replacing it every three years is an outdated cost model. It doesn’t consider the total cost of ownership, and it doesn’t consider the advantage of real processing power, high-availability and multithreading like a demon.
This ebook takes a look at some of the practical applications of the Linux on Power platform and ways you might bring all the performance power of this open architecture to bear for your organization. There are no smoke and mirrors here—just hard, cold, empirical evidence provided by independent sources. I also consider some innovative ways Linux on Power will be used in the future.Get the Guide