Plasma Active - a New Approach to Tablet Computing
Adapting to Different Tasks
It is the two tabs on the sides of the screen that are unique to Plasma Active. The tab on the right, when dragged out, reveals a wheel of Activities, each represented by a thumbnail image. A few selections are predefined, including "Introduction" that provides some information on getting started; "Vacation planning", set up for just that; and "My first activity", which invites you to make your own. You can delete, customize or add activities using icons that are visible with the Activity wheel.
Figure 3. You can have an Activity for all the things you need to do—and for the things you want to do.
Selecting an Activity changes the desktop background and desktop widgets to those associated with the Activity. Choose the vacation planning Activity, and you are presented with a picture of a hay field as the desktop background and have the KDE weather forecast widget and bookmarks for OpenStreetMap, Wikitravel and a rail operator on your desktop. You can open a browser and start booking your holiday, but if your child (or you) suddenly has an overpowering urge to play Solitaire, you can just switch to an Activity set up for games. If you check the task bar by pulling down the top panel, you will see that it shows only the applications from the current Activity, so your holiday booking in the vacation planning Activity is safe from little fingers accidentally closing the browser or upgrading you all to first-class transatlantic travel. Once your child (or you) have had your game-playing fix, you can use the Activities wheel to get back to booking your holiday quickly.
Getting Smart with Nepomuk
The tab on the left of the screen reveals Plasma Active's "Recommendations": links to files, widgets and contacts that might be relevant to the current activity. This is based on Nepomuk, KDE's semantic storage technology, which draws links between items based on the context of their use. Marco explains that this enables "the information stored on the device by users to be kept in a central place, allowing them to treat in the same way and display in a coherent way everything, regardless if it is a file, a contact, a bookmark or information about a location, linking them together with semantic information". What this means in practice is that the Recommendations are able to be more than a list of recently used or most-accessed files, suggesting documents that often are used at the same time as those presently open or often used within the current Activity (the recommendations are tailored to each Activity). While writing this article, it suggested some irrelevant items, but the system quickly learned to suggest screenshots I had collected and suggested adding the Linux Journal author guidelines and Plasma Active Wiki pages to my bookmarks. The idea is that the system learns from its user and becomes ever more useful over time, and based on my experience, I give it a cautious thumbs-up.
Figure 4. Plasma Active provides Recommendations of files and actions that are relevant to the task you are working on.
Nepomuk has, since it was first introduced in KDE software in 2008, been the target of many complaints about resource usage, something that is likely to be of even greater concern on a low-powered portable device. Marco, however, points out that "on a mobile device the stored data is very small compared to a desktop, and measurements have shown that with the limited number of items in it, the memory usage stays very small", while, of course, using a central store also "avoids the necessity to build different storage/indexing for every application". Aaron agrees: "the devices we currently target are all in the 600MHz to 1GHz range with 256MB or more of RAM. On these devices, it works acceptably". Nevertheless, the developers have been working on "numerous optimizations and improvements", and Aaron acknowledges there is always the possibility of "stripping out Nepomuk for some very low-end, in terms of hardware and user interaction, scenarios". I did not come across any of the slowness that sometimes accompanies extensive indexing on the desktop.
It's All about the Apps
The basic user interface seems slick and well thought out, and through Activities, it does offer something different from the competition. However, a computer is only as good as its applications, and if Plasma Active is to be a success, KDE must provide a compelling suite of touch-friendly applications.
Figure 5. The applications that already have been adjusted for use with Plasma Active, such as the image viewer, work well.
A few "Active" variants of established KDE applications already are available. These include those that have been largely designed from the ground up for Plasma Active, such as the Web browser and image viewer, both of which were easy to use. Some other applications, such as the media player Bangarang, have received modifications to make them a little more touch-friendly. There are dedicated Active versions of the Kontact suite of groupware applications. Each of these are easy to use with a stubby finger, but their interfaces are so different from their desktop counterparts that even if you are an experienced Kontact user, you will find they take a little getting used to. Calligra, KDE's productivity suite, also is available in an Active version, but it felt slow on the device I used. However, Calligra's underlying technology already has been used in the successful FreOffice viewers for Nokia's mobile phones, so it is likely the performance will improve.
Some other applications, such as Dolphin (the KDE file manager), have not been adapted for touch-friendly use—and it shows. A similar interface is used in the Open and Save dialogs of most applications, but these will all be improved in future versions.
The most essential of applications on a tablet, the on-screen keyboard, works very well with easy-to-touch buttons and a sensible layout. It appears when needed, and it can be switched from the bottom to the top of the screen if desired.
Figure 6. The on-screen keyboard is easy to use and can be moved out of the way when needed.
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