More with Three-Tiered Design
Now that we have looked at a very simple three-tier project, it's time to look at some of the problems associated with such a design. I am not saying that three-tier solutions are inherently evil, but neither are they a panacea. Like most solutions, they are appropriate under certain circumstances. In many cases, splitting the design and implementation among several people can be easier when you divide the work into different layers, as we saw with our web-based appointment calendar. One person could write all of the necessary code, but two people could probably do it more quickly and easily, given a well-documented interface between them.
As with any engineering solution, there are always trade-offs. With a three-tiered design, perhaps the most important trade-off is time. Such an architecture takes longer to specify and design, even if it will eventually be more robust, easier to write, easier to test and easier to divide among a number of programmers.
While dividing a project into many parts might make it easier to specify and test each part, it makes integration testing all the more important and difficult. If everyone sticks to the published and agreed-to API, such testing does not have to be terribly difficult. But there are always differences between the specification and the implementation, and integration testing tends to bring these out. The more tiers in a project, the more important and difficult such testing can be.
Finally, it can be difficult and frustrating to create an object middleware layer that provides an interface to the database. SQL is not a perfect language, but it allows us to express a very large number of queries with a very small number of commands.
Removing SQL from the Mason components and forcing programmers to work with an object API, means that the programmer will be limited to a small subset of the database's power and flexibility. Every time more functionality is needed, the programmer will have to request it be added to the middleware's API. Being able to specify any database query inside of an HTML template (e.g., a Mason component) is a liberating experience for a programmer, and taking that freedom away can be frustrating.
Programmers designing large or complex web applications are finding it increasingly useful to adopt the three-tiered architecture beginning to replace the simpler client/server model that has been favored for the last decade. Indeed, creating three-tiered applications can often make life easier. In the end, however, you will have to decide whether this solution is appropriate for your needs or if it's overkill given your time frame and specifications.
Practical Task Scheduling Deployment
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.
Free to Linux Journal readers.View Now!
|The Firebird Project's Firebird Relational Database||Jul 29, 2016|
|Stunnel Security for Oracle||Jul 28, 2016|
|SUSE LLC's SUSE Manager||Jul 21, 2016|
|My +1 Sword of Productivity||Jul 20, 2016|
|Non-Linux FOSS: Caffeine!||Jul 19, 2016|
|Murat Yener and Onur Dundar's Expert Android Studio (Wrox)||Jul 18, 2016|
- Stunnel Security for Oracle
- The Firebird Project's Firebird Relational Database
- SUSE LLC's SUSE Manager
- Murat Yener and Onur Dundar's Expert Android Studio (Wrox)
- Managing Linux Using Puppet
- My +1 Sword of Productivity
- Non-Linux FOSS: Caffeine!
- Google's SwiftShader Released
- SuperTuxKart 0.9.2 Released
- Doing for User Space What We Did for Kernel Space
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