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  • Are certain problems solved more elegantly with AOP?

    - by Winston Ewert
    I've come across the idea of Aspect Oriented Programming, and I have some concerns with it. The basic idea seems to be that we want to take cross-cutting concerns which aren't well modularized using object and modularize them. That is all very fine and well. But the implementation of AOP seems to be that of modifying code from outside of the module. So, for example, an aspect could be written that changes what happens when a particular object is passed as a parameter in a function. This seems to go directly against the idea of modules. I should not be able to modify a module's behavior from outside of that module, otherwise the whole point of modules are overturned. But aspects seem to be doing exactly that! Basically, aspects seems to be a form of code patching. It may useful for some quick hacks; but, as a general principle perhaps its not something you want to do. Aspect Oriented Programming seems to me taking a bad practice and raising to a general design principle. Is AOP a good practice? Are certain programming problems solved more elegantly with AOP?

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  • What is logical cohesion, and why is it bad or undesirable?

    - by Matt Fenwick
    From the c2wiki page on coupling & cohesion: Cohesion (interdependency within module) strength/level names : (from worse to better, high cohesion is good) Coincidental Cohesion : (Worst) Module elements are unrelated Logical Cohesion : Elements perform similar activities as selected from outside module, i.e. by a flag that selects operation to perform (see also CommandObject). i.e. body of function is one huge if-else/switch on operation flag Temporal Cohesion : operations related only by general time performed (i.e. initialization() or FatalErrorShutdown?()) Procedural Cohesion : Elements involved in different but sequential activities, each on different data (usually could be trivially split into multiple modules along linear sequence boundaries) Communicational Cohesion : unrelated operations except need same data or input Sequential Cohesion : operations on same data in significant order; output from one function is input to next (pipeline) Informational Cohesion: a module performs a number of actions, each with its own entry point, with independent code for each action, all performed on the same data structure. Essentially an implementation of an abstract data type. i.e. define structure of sales_region_table and its operators: init_table(), update_table(), print_table() Functional Cohesion : all elements contribute to a single, well-defined task, i.e. a function that performs exactly one operation get_engine_temperature(), add_sales_tax() (emphasis mine). I don't fully understand the definition of logical cohesion. My questions are: what is logical cohesion? Why does it get such a bad rap (2nd worst kind of cohesion)?

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  • BPM Solution Catalogue–promote your process templates

    - by JuergenKress
    Oracle’s BPM Solution Catalogue showcasing our solutions with partners is now live. Take a look at the initial entries here. We are planning to use this catalogue not only to publish and highlight successful BPM implementations but also will be running campaigns in industry verticals with your solutions. If you have delivered a successful implementation in BPM and think it could be reused and applied again in a similar scenario in the same industry or in a similar environment, then we are keen to know about it and will add it to the solution catalogue. The solution catalogue will showcase successful BPM solutions both inside and outside Oracle. Be in touch with us on this via this e-mail id and we will make sure to add your solution. For more information you can also read the article “Leading-Edge BPM Benefits Without Bleeding-Edge Pain” SOA & BPM Partner Community For regular information on Oracle SOA Suite become a member in the SOA & BPM Partner Community for registration please visit  www.oracle.com/goto/emea/soa (OPN account required) If you need support with your account please contact the Oracle Partner Business Center. Blog Twitter LinkedIn Mix Forum Technorati Tags: BPM,Solution Catalogue,process templates,BPM Suite,SOA Community,Oracle SOA,Oracle BPM,Community,OPN,Jürgen Kress

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  • Website Ethics / legal issues, image copyrights

    - by RailsN00b
    Ignoring the technical implementation of a website for a second, assume a website that is similar to twitter but with pictures. A user say something and puts a picture of whatever they said. As the nature of the internet, the images will most likely not be his/hers image. There are 2 options that I see for dealing with this: 1. The user will post a URL of the picture and the website will pull the picture from that URL everytime someone enters that page 2. The website will save the image in its own database of images and display the image to the visitors 'locally' The problem with option #1, while it saved storage, I see an issue with 'stealing' other websites bandwidth and if my website has many many visitors it could cost the image-hosting websites a lot and possible even crash it if the server can't handle the load. The problem with opion #2, while it saves the load to other websites, it practically takes pictures that could have copyright on them. Which option is better to implement in terms of legal issues and ethics? When do I need to contact another website to request permission to use the images from that site? Does anyone really care about that anymore. Where can I read about this?

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  • Should I use an interface when methods are only similar?

    - by Joshua Harris
    I was posed with the idea of creating an object that checks if a point will collide with a line: public class PointAndLineSegmentCollisionDetector { public void Collides(Point p, LineSegment s) { // ... } } This made me think that if I decided to create a Box object, then I would need a PointAndBoxCollisionDetector and a LineSegmentAndBoxCollisionDetector. I might even realize that I should have a BoxAndBoxCollisionDetector and a LineSegmentAndLineSegmentCollisionDetector. And, when I add new objects that can collide I would need to add even more of these. But, they all have a Collides method, so everything I learned about abstraction is telling me, "Make an interface." public interface CollisionDetector { public void Collides(Spatial s1, Spatial s2); } But now I have a function that only detects some abstract class or interface that is used by Point, LineSegment, Box, etc.. So if I did this then each implementation would have to to a type check to make sure that the types are the appropriate type because the collision algorithm is different for each different type match up. Another solution could be this: public class CollisionDetector { public void Collides(Point p, LineSegment s) { ... } public void Collides(LineSegment s, Box b) { ... } public void Collides(Point p, Box b) { ... } // ... } But, this could end up being a huge class that seems unwieldy, although it would have simplicity in that it is only a bunch of Collide methods. This is similar to C#'s Convert class. Which is nice because it is large, but it is simple to understand how it works. This seems to be the better solution, but I thought I should open it for discussion as a wiki to get other opinions.

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  • Choosing open source vs. proprietary CMS

    - by jkneip
    Hi- I've been tasked with redesigning a website for a small academic library. While only in charge of the site for 6 months, we've been maintaining static html pages edited in Dreamweaver for years. Last count of our total pages is around 400. Our university is going with an enterprise level solution called Sitefinity, although we maintain our own domain and are responsible to maintain our own presense. Some background-my library has a couple Microsoft IIS servers on which this static html site has been running. I'm advocating for the implementation of a CMS while doing this redesign. The problem is I'm basically the lone webmaster so I have no one to agree or disagree with my choice. There are also only 1-2 content editors right know for the site but a CMS could change that factor. I would like to use the functionality of having servers that run .NET and MS SQL but am more experience setting up and maintaining open source software like Wordpress or Drupal on web hosts. My main concern is choosing a CMS that will be easy to update / maintain / deal with upgrades (i.e., support) in case I'm not there in the future. So I'm wondering how to factor in the open source CMS vs. a relatively inexpensive commercial CMS decision and whether choosing PHP/MySQL vs. ASP.net framework for development environment will play into my decision. Thanks for any input that can be offered based on the details I've given. Thanks, Jason

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  • Software Installation Failure!

    - by NIKOS ANTONIOU
    I get the same error whenever I try to install software on my laptop, for example: I want to install Pavucontrol. So, I open the terminal and I type sudo apt-get install pavucontrol and my terminal output is: Reading package lists... Done Building dependency tree Reading state information... Done The following extra packages will be installed: libgconfmm-2.6-1c2 libglademm-2.4-1c2a libpulse-mainloop-glib0 padevchooser paman paprefs pavumeter pulseaudio-module-zeroconf The following NEW packages will be installed: libgconfmm-2.6-1c2 libglademm-2.4-1c2a libpulse-mainloop-glib0 padevchooser paman paprefs pavucontrol pavumeter pulseaudio-module-zeroconf 0 upgraded, 9 newly installed, 0 to remove and 172 not upgraded. 1 not fully installed or removed. Need to get 0B/345kB of archives. After this operation, 2044kB of additional disk space will be used. Do you want to continue [Y/n]? Y perl: warning: Setting locale failed. perl: warning: Please check that your locale settings: LANGUAGE = (unset), LC_ALL = (unset), LANG = "el_GR.UTF-8" are supported and installed on your system. perl: warning: Falling back to the standard locale ("C"). Can't exec "locale": No such file or directory at /usr/share/perl5/Debconf/Encoding.pm line 16. Use of uninitialized value $Debconf::Encoding::charmap in scalar chomp at /usr/share/perl5/Debconf/Encoding.pm line 17. dpkg: `ldconfig' not found on PATH. dpkg: 1 expected program(s) not found on PATH. NB: root's PATH should usually contain /usr/local/sbin, /usr/sbin and /sbin. E: Sub-process /usr/bin/dpkg returned an error code (2) What is the problem and how do I fix it?

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  • Java's Object.wait method with nanoseconds: Is this a joke or am I missing something

    - by Krumia
    I was checking out the Java API source code (Java 8) just out of curiosity. And I found this in java/lang/Object.java. There are three methods named wait: public final native void wait(long timeout): This is the core of all wait methods, which has a native implementation. public final void wait(): Just calls wait(0). And then there is public final void wait(long timeout, int nanos). The JavaDoc for the particular method tells me that, This method is similar to the wait method of one argument, but it allows finer control over the amount of time to wait for a notification before giving up. The amount of real time, measured in nanoseconds, is given by: 1000000*timeout+nanos But this is how the methods achieves "finer control over the amount of time to wait": if (nanos >= 500000 || (nanos != 0 && timeout == 0)) { timeout++; } wait(timeout); So this method basically does a crude rounding up of nanoseconds to milliseconds. Not to mention that anything below 500000ns/0.5ms will be ignored. Is this piece of code bad/unnecessary code, or am I missing some unseen virtue of declaring this method, and it's no argument cousin as the way they are?

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  • From Oracle PL/SQL Developer to Java programmer - Is it a good decision? [on hold]

    - by user3554231
    I will explain my question in simple words. I have little over 1 year experience in Oracle. My dream is to be "called" as a 'Developer', be it database developer if not software developer. But right now I don't develop anything neither I am in good touch with PL/SQL and other Oracle Utilites like SQL*LOADER, shell scripting and stuff like that as I am only a System Analyst where I analyze and configure database using SQL queries. To be honest, I know very basic PL/SQL and good knowledge in SQL but that won't ever give me a chance to be a developer as I am lagging way behind the "real" developers knowledge. Now I feel I should learn JAVA as well so that I can cope up with the competition. But I am too scared to learn new things as it will take much more time which will indirectly increase my useless work experince(just analyzing) which values nothing in todays market. Moreover that, I am too lazy to work hard i.e. to study and not to work during office hours. To sum it up I am lazy and confused and scared but I want to learn things as well but don't know if I am intelligent enough to learn whole of PL/SQL or to master any other language. Is there any other way from which I can feel confident? Actually I even feel sometimes that after 2-3 years if I still don't achieve my goal, I won't ever be able to reach my destination. I just want to live my dream of being a developer. Give me some tips and hopes but not false hopes.

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  • ArchBeat Link-o-Rama for December 4, 2012

    - by Bob Rhubart
    Exalogic 2.0.1 Tea Break Snippets - Creating and using Distribution Groups | The Old Toxophilist "Although in many cases we, as Cloud Users, may not be to worried how the Virtualisation Algorithm decides where to place our vServers," says The Old Toxopholist, "there are cases where it is extremely important that vServers run on distinct physical compute nodes." There's plenty more on the subject in his blog post. Oracle Endeca (2.3) Record Level Security | Adam Seed Adam Sneed's blog post covers "the basics of security within Endeca Information Discovery, as these basic security objects are required in order to explain the implementation of record level security." ODI Handling DQ | Gurcan Orhan Oracle ACE Director Gurcan Orhan suggests you have fun with these scripts for Oracle Data Integrator. Parleys Testimonial at GlassFish Community Event - JavaOne 2012 Video of Parley's webmaster Stephan Janssen's presentation at the GlassFish Community Event at JavaOne 2012, in which he explains why Parley's moved from Tomcat to GlassFish. Java Spotlight Episode 109: Pete Muir on CDI 1.1 This edition of Roger Brinkley's Java Spotlight Podcast features an interview with CDI 1.1 spec lead Pete Muir of JBoss/Red Hat. Muir talks about the features in CDI 1.1 and what to expect in the future. Webcast: Java Management Extensions with Oracle WebLogic Server 12c Dr. Frank Munz and Dave Cabelus do the talking in this on-demand webcast focused on Oracle WebLogic Server 12c with Java Management Extensions (JMX). Using the Coherence API to get Portable Object Format bytes | Bruno Borges Bruno Borges shares a code snippet that illustrates how easy it is to use the Coherence API. Thought for the Day "Experience is something you don't get until just after you need it." — Anonymous Source: SoftwareQuotes.com

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  • Square game map rendered as sphere with OpenGL

    - by Roflha
    Okay so I have been trying to find a good way to do this for a while now and so far I have nothing. For a hobby project of mine I have created a finite voxel world (similar to minecraft), but as I said, mine is finite. When you reach the edge of it, you are sent to the other side. That is all working fine along with rendering the far side of the map, but I want to be able to render this grid as a sphere. Looking down from above, the world is a square. I basically want to be able to represent a portion of that square as a sphere, as if you were looking at a planet. Right now I am experimenting with taking a circular section of the map, and rendering that, but it look to flat (no curvature around the edges). My question then, is what would be the best way to add some curvature to the edges of a 2d circle to make it look like a hemisphere. However, I am not overly attached to this implementation so if somebody has some other idea for representing the square as a planet, I am all ears.

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  • Synchronous vs. asynchronous for publish subscribe communication between JavaScript objects

    - by natlee75
    I implemented the publish subscribe pattern in a JavaScript module to be used by entirely client-side oriented JavaScript objects. This module has nothing to do with client-server communications in any way, shape or form. My question is whether it's better for the publish method in such a module to be synchronous or asynchronous, and why. As a very simplified example let's say I'm building a custom UI for an HTML5 video player widget: One of my modules is the "video" module that contains the VIDEO element and handles the various features and events associated with that element. This would probably have a namespace something like "widgets.player.video." Another is the "controls" module that has the various buttons - play, pause, volume, scrub, fullscreen, etc. This might have a namespace along the lines of "widgets.player.controls." These two modules are children of a parent "player" module ("widgets.player" ??), and as such would have no inherent knowledge of each other when instantiated as children of the "player" object. The "controls" elements would obviously need to be able to effect some changes on the video (click "Play" and the video should play), and vice versa (video's "timeUpdate" event fires and the visual display of the current time in the controls should update). I could tightly couple these modules and pass references to each other, but I'd rather take a more loosely coupled approach by setting up a pubsub type module that both can subscribe to and publish from. SO (thanks for bearing with me) in this kind of a scenario is there an advantage one way or another for synchronous publication versus asynchronous publication? I've seen some solutions posted online that allow for either/or with a boolean flag whereas others automatically do it asynchronously. I haven't personally seen an implementation that just automatically goes with synchronous publication... is this because there's no advantage to it? I know that I can accomplish this with features provided by jQuery, but it seems that there may be too much overhead involved here. The publish subscribe pattern can be implemented with relatively lightweight code designed specifically for this particular purpose so I'd rather go with that then a more general purpose eventing system like jQuery's (which I'll use for more general eventing needs :-).

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  • Canonical representation of a class object containing a list element in XML

    - by dendini
    I see that most implementations of JAX-RS represent a class object containing a list of elements as follows (assume a class House containing a list of People) <houses> <house> <person> <name>Adam</name> </person> <person> <name>Blake</name> </person> </house> <house> </house> </houses> The result above is obtained for instance from Jersey 2 JAX-RS implementation, notice Jersey creates a wrapper class "houses" around each house, however strangely it doesn't create a wrapper class around each person! I don't feel this is a correct mapping of a list, in other words I'd feel more confortable with something like this: <houses> <house> <persons> <person> <name>Adam</name> </person> <person> <name>Blake</name> </person> </persons> </house> <house> </house> </houses> Is there any document explaining how an object should be correctly mapped apart from any opninion?

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  • How to effectively design a piece of software

    - by ti83plus
    Im a compsci student and ive got some experience in various languages and paradigms c/java/python/ruby/html/css/scheme/sql/asp(classic). I realise that i want to have some software in my portfolio for future job hunting even tho i still have 2 years left of my education. Ive got a pretty good idea of what i want to make, its a webapp. Most shops around here are either .net or java and since i know java best and dont have access to ms developer tools im thinking i should go with java. Even tho i feel i know the principles of OOP pretty good ive got no clue how to go from my idea to a working solution. Where can i access information about designing the underlying architechture of my solution? Also i would like to know what other technologies i should train on, my current list includes javascript(and possibly a javascript library) some sort of java web framework tips are appreciated. I would like to add support for android/iphone apps in the future and this is something i have to take into account when designing the app. I have done a course on software engineering but i found this to be more centered around project management ideas then the actual design and implementation. So i would like tips on technologies i should focus on to get the most out of my time without the massive overhead of huge config processes but at the same time keep my project viable in a business sense, so that i use technologies that are relevant for business (java developer jobs). And i would also like tips on where i can learn more about the design process around a software project, i will be working mostly alone. But i find the approach ive used up until now (start coding and figure it out as you go) wont suffice.

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  • Web development and tips for building a website and the advantages of using HTML 5 in the site

    - by Siddarth
    I am trying to make a website for my college, and the program starts from jan 13 and we get 15 days of time to develop a running site. The best site will become the college site. I am participating, for all these days i used to participate in C and C++ contests and also won a few contests, now i am really into web dev for the last 2 months. I knew HTML long ago recently i brushed up on it and learnt javascript from "javascript and jquery the missing manual"(sorry for not adding the link) and recently bought "PHP and MySQL web development" and I am going on fine with it, but still a lot of pages to cover in that book. After this what do i need to know ajax is one language to concentrate on, what else do i need to do to make this project up and running. Can someone let me know the tricks of this trade and complete information to build a site like this. Right now i am good with javascript HTML and CSS and thats it, what else I am studying HTML5 and CSS3 its pretty fast and neat. The info on site is a college website which includes students profiles where the have to register their info with college id number and pretty much thats it. Think of it as a college site + a social networking site for students, where they can upload there pics and videos pdf books etc.

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  • I want to be a programmer, work in corporate environment, earn well, learn fast and eventually become a great programmer [on hold]

    - by Shin San
    I'll try to keep this simple: I'm 29, been dabbling with computers for the past 10 years, had entry level jobs in tech support for different apps, been fixing computers for a while and now want to specialize in something. I'm not 100% stranger to programming but haven't gone past if/then/else with anything. A bit of JavaScript, PHP, Python and currently checking out the "SELECT" statement in SQL :)) I'm curious about programming, I enjoy it and I'm thinking of making a living out of it. So, while I'm at it, why not earn a bit more than the average Joe? So, that's why I'm checking what the best solution, the best learning path and the most useful languages are considering: a) how easy/fast can you find a job by knowing it b) how much would I be able to earn c) how fast can I learn it By reading 10-20 articles online I've come up with an example, but I'm here for some expert advice. Example: * ratings from a) and b) point of view #1 sql ; #2 java ; #3 html (please don't start the markup language debate) ; #4 javascript From this ratings, I'd say a good way to go is learn html/css/(javascript or php) for the web part of apps, some SQL/MySQL/whateverSQL for holding data and loads of Java for the program itself. Please let me know if this is a good idea and if so, what should be the order for learning all of the above. Else, please let me know a better way and why it would be better. Many thanks for taking the time to read my question. Best wishes to you guys Edit: if I think Java + SQL + HTML&JavaScript is the way to go, does the order I'm learning them in matter? Or can I try to learn them all at once?

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  • Do you think Scala will be the dominant JVM langauge, ie be the next Java? [on hold]

    - by user1037729
    From what I've read about Scala do far I think it has some nice features but I do not think it should be "the next Java". It might however end up being the next Java (due to fashion rather than fact) but lets not hope it does not... To me adds a lot of complexity over Java which is a simple and scalable language. Scala Pattern matching allows you to perform some type/value checking in a more concise way, this is possible in Java, Scala's pattern matching has a limit to it, you cannot continuously match deeper and deeper down the object graph, so why not just stick to Java and use decent invariants? Scala provides tuples, easy enough to make in Java, create a static factory method and it all reads nicely too. Scala provides mixins, why not just use composition? I believe Scala implicit's are bad, they can lead to code becoming complex and hard to maintain, explicitness is good. Scala provides closures, well they will be in Java 8 too. Scala has lazy keyword for lazy instantiation, this is easy enough to do in Java by calling a getter which creates the instance when needed, no hidden magic here. Scala can be used with AKKA, well so can Java, there is an Java AKKA implementation. Scala offers addition functional features but these can all be created in Java, there are many frameworks with have implemented functional features in Java. All in all Scala seems to offer is addition complexity and thats it...

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  • Stuff you learned in school, that you have never used again?

    - by Mercfh
    Obviously we learn plenty of things in our University/College/Whatever that probably don't apply to everyday use, but is there anything that stands out particularly? Maybe something that was concentrated ALOT on? For me it was def. 2 things: OO Concepts and Pointers I still use OO, but not nearly to the amount people made it out to be, i can see where it'd be useful but in my line of work we don't have huge amounts of classes, maybe a couple at most. And there certainly isn't much OO reuse (i finally figured out what that means lol) Pointers are another thing, again I can see where they'd be useful...however I barely barely ever touch them, nor do the others I work with. I guess language choice has alot to do with that but still. What about you guys? edit: For those who are asking I work for a Large Printer company, and most of the Applications we work on are Java+XML and Actionscript for "Printer Apps". But we are moving towards other languages (think like webkits and stuff). So the Code amounts per parts are quite small. I never say OO wasn't useful I just said I personally havent seen it used in my workplace much.

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  • Static DataTable or DataSet in a class - bad idea?

    - by Superbest
    I have several instances of a class. Each instance stores data in a common database. So, I thought "I'll make the DataTable table field static, that way every instance can just add/modify rows to its own table field, but all the data will actually be in one place!" However, apparently it's a bad idea to do use static fields, especially if it's databases: Don't Use "Static" in C#? Is this a bad idea? Will I run into problems later on if I use it? This is a small project so I can accept no testing as a compromise if that is the only drawback. The benefit of using a static database is that there can be many objects of type MyClass, but only one table they all talk to, so a static field seems to be an implementation of exactly this, while keeping syntax concise. I don't see why I shouldn't use a static field (although I wouldn't really know) but if I had to, the best alternative I can think of is creating one DataTable, and passing a reference to it when creating each instance of MyClass, perhaps as a constructor parameter. But is this really an improvement? It seems less intuitive than a static field.

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  • Do we have enough time to build an electric car future?

    - by julien.groues
    A recent article from Greenbang has posed the question 'Do we have enough time to build an electric car future?'. The writer discusses that, although the future of transport might lie with electric cars, there is concern regarding whether we'll be able to build the market and infrastructure required to support them, before carbon and oil constraints create difficulties in powering the vehicles. Of course, the increasing use of Electric vehicles (EVs) is going to put excessive pressure on energy grids, as large volumes of electricity will need to be directed to charging points, which in turn must handle fluctuating demand at peak times. EVs are increasing in popularity as a sustainable method of transport to reduce carbon consumption, and electric utilities will have the opportunity, and the challenge, to quickly determine the best methods to fuel these vehicles and accommodate the associated increases in demand for energy. Critically, efficient software is required to provide diagnostic and predictive capabilities related to EV refuelling - for example, anticipated electricity flow will need to be addressed as the number of EVs on the road increases, and electricity will need to be directed to specific areas on-demand as vehicles attempt to recharge en-mass. But a smart grid infrastructure can meet these demands, intelligently. The implementation of a smart grid is not in the distant future, it is an achievable reality for utilities via simple installation of new software and technologies, which can be done incrementally for those facing existing legacy systems or concerned with upfront costs. The smart grid is integral to the monitoring and control of energy use as well as the future-proofing of the energy grid. A smart grid will be critical to meeting the electricity requirements of new EVs and will ensure their successful deployment by providing a reliable foundation for the data handling required to record and manage electricity distribution - from recording and assessing energy usage, to analysing data and sharing information with consumers via green billing. http://www.greenbang.com/do-we-have-enough-time-to-build-an-electric-car-future_14248.html

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  • Everything has an Interface [closed]

    - by Shane
    Possible Duplicate: Do I need to use an interface when only one class will ever implement it? I am taking over a project where every single real class is implementing an Interface. The vast majority of these interfaces are implemented by a single class that share a similar name and the exact same methods (ex: MyCar and MyCarImpl). Almost no 2 classes in the project implement more than the interface that shares its name. I know the general recommendation is to code to an interface rather than an implementation, but isn't this taking it a bit too far? The system might be more flexible in that it is easier to add a new class that behaves very much like an existing class. However, it is significantly harder to parse through the code and method changes now require 2 edits instead of 1. Personally, I normally only create interfaces when there is a need for multiple classes to have the same behavior. I subscribe to YAGNI, so I don't create something unless I see a real need for it. Am I doing it all wrong or is this project going way overboard?

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  • How to Implement Project Type "Copy", "Move", "Rename", and "Delete"

    - by Geertjan
    You've followed the NetBeans Project Type Tutorial and now you'd like to let the user copy, move, rename, and delete the projects conforming to your project type. When they right-click a project, they should see the relevant menu items and those menu items should provide dialogs for user interaction, followed by event handling code to deal with the current operation. Right now, at the end of the tutorial, the "Copy" and "Delete" menu items are present but disabled, while the "Move" and "Rename" menu items are absent: The NetBeans Project API provides a built-in mechanism out of the box that you can leverage for project-level "Copy", "Move", "Rename", and "Delete" actions. All the functionality is there for you to use, while all that you need to do is a bit of enablement and configuration, which is described below. To get started, read the following from the NetBeans Project API: http://bits.netbeans.org/dev/javadoc/org-netbeans-modules-projectapi/org/netbeans/spi/project/ActionProvider.html http://bits.netbeans.org/dev/javadoc/org-netbeans-modules-projectapi/org/netbeans/spi/project/CopyOperationImplementation.html http://bits.netbeans.org/dev/javadoc/org-netbeans-modules-projectapi/org/netbeans/spi/project/MoveOrRenameOperationImplementation.html http://bits.netbeans.org/dev/javadoc/org-netbeans-modules-projectapi/org/netbeans/spi/project/DeleteOperationImplementation.html Now, let's do some work. For each of the menu items we're interested in, we need to do the following: Provide enablement and invocation handling in an ActionProvider implementation. Provide appropriate OperationImplementation classes. Add the new classes to the Project Lookup. Make the Actions visible on the Project Node. Run the application and verify the Actions work as you'd like. Here we go: Create an ActionProvider. Here you specify the Actions that should be supported, the conditions under which they should be enabled, and what should happen when they're invoked, using lots of default code that lets you reuse the functionality provided by the NetBeans Project API: class CustomerActionProvider implements ActionProvider { @Override public String[] getSupportedActions() { return new String[]{ ActionProvider.COMMAND_RENAME, ActionProvider.COMMAND_MOVE, ActionProvider.COMMAND_COPY, ActionProvider.COMMAND_DELETE }; } @Override public void invokeAction(String string, Lookup lkp) throws IllegalArgumentException { if (string.equalsIgnoreCase(ActionProvider.COMMAND_RENAME)) { DefaultProjectOperations.performDefaultRenameOperation( CustomerProject.this, ""); } if (string.equalsIgnoreCase(ActionProvider.COMMAND_MOVE)) { DefaultProjectOperations.performDefaultMoveOperation( CustomerProject.this); } if (string.equalsIgnoreCase(ActionProvider.COMMAND_COPY)) { DefaultProjectOperations.performDefaultCopyOperation( CustomerProject.this); } if (string.equalsIgnoreCase(ActionProvider.COMMAND_DELETE)) { DefaultProjectOperations.performDefaultDeleteOperation( CustomerProject.this); } } @Override public boolean isActionEnabled(String command, Lookup lookup) throws IllegalArgumentException { if ((command.equals(ActionProvider.COMMAND_RENAME))) { return true; } else if ((command.equals(ActionProvider.COMMAND_MOVE))) { return true; } else if ((command.equals(ActionProvider.COMMAND_COPY))) { return true; } else if ((command.equals(ActionProvider.COMMAND_DELETE))) { return true; } return false; } } Importantly, to round off this step, add "new CustomerActionProvider()" to the "getLookup" method of the project. If you were to run the application right now, all the Actions we're interested in would be enabled (if they are visible, as described in step 4 below) but when you invoke any of them you'd get an error message because each of the DefaultProjectOperations above looks in the Lookup of the Project for the presence of an implementation of a class for handling the operation. That's what we're going to do in the next step. Provide Implementations of Project Operations. For each of our operations, the NetBeans Project API lets you implement classes to handle the operation. The dialogs for interacting with the project are provided by the NetBeans project system, but what happens with the folders and files during the operation can be influenced via the operations. Below are the simplest possible implementations, i.e., here we assume we want nothing special to happen. Each of the below needs to be in the Lookup of the Project in order for the operation invocation to succeed. private final class CustomerProjectMoveOrRenameOperation implements MoveOrRenameOperationImplementation { @Override public List<FileObject> getMetadataFiles() { return new ArrayList<FileObject>(); } @Override public List<FileObject> getDataFiles() { return new ArrayList<FileObject>(); } @Override public void notifyRenaming() throws IOException { } @Override public void notifyRenamed(String nueName) throws IOException { } @Override public void notifyMoving() throws IOException { } @Override public void notifyMoved(Project original, File originalPath, String nueName) throws IOException { } } private final class CustomerProjectCopyOperation implements CopyOperationImplementation { @Override public List<FileObject> getMetadataFiles() { return new ArrayList<FileObject>(); } @Override public List<FileObject> getDataFiles() { return new ArrayList<FileObject>(); } @Override public void notifyCopying() throws IOException { } @Override public void notifyCopied(Project prjct, File file, String string) throws IOException { } } private final class CustomerProjectDeleteOperation implements DeleteOperationImplementation { @Override public List<FileObject> getMetadataFiles() { return new ArrayList<FileObject>(); } @Override public List<FileObject> getDataFiles() { return new ArrayList<FileObject>(); } @Override public void notifyDeleting() throws IOException { } @Override public void notifyDeleted() throws IOException { } } Also make sure to put the above methods into the Project Lookup. Check the Lookup of the Project. The "getLookup()" method of the project should now include the classes you created above, as shown in bold below: @Override public Lookup getLookup() { if (lkp == null) { lkp = Lookups.fixed(new Object[]{ this, new Info(), new CustomerProjectLogicalView(this), new CustomerCustomizerProvider(this), new CustomerActionProvider(), new CustomerProjectMoveOrRenameOperation(), new CustomerProjectCopyOperation(), new CustomerProjectDeleteOperation(), new ReportsSubprojectProvider(this), }); } return lkp; } Make Actions Visible on the Project Node. The NetBeans Project API gives you a number of CommonProjectActions, including for the actions we're dealing with. Make sure the items in bold below are in the "getActions" method of the project node: @Override public Action[] getActions(boolean arg0) { return new Action[]{ CommonProjectActions.newFileAction(), CommonProjectActions.copyProjectAction(), CommonProjectActions.moveProjectAction(), CommonProjectActions.renameProjectAction(), CommonProjectActions.deleteProjectAction(), CommonProjectActions.customizeProjectAction(), CommonProjectActions.closeProjectAction() }; } Run the Application. When you run the application, you should see this: Let's now try out the various actions: Copy. When you invoke the Copy action, you'll see the dialog below. Provide a new project name and location and then the copy action is performed when the Copy button is clicked below: The message you see above, in red, might not be relevant to your project type. When you right-click the application and choose Branding, you can find the string in the Resource Bundles tab, as shown below: However, note that the message will be shown in red, no matter what the text is, hence you can really only put something like a warning message there. If you have no text at all, it will also look odd.If the project has subprojects, the copy operation will not automatically copy the subprojects. Take a look here and here for similar more complex scenarios. Move. When you invoke the Move action, the dialog below is shown: Rename. The Rename Project dialog below is shown when you invoke the Rename action: I tried it and both the display name and the folder on disk are changed. Delete. When you invoke the Delete action, you'll see this dialog: The checkbox is not checkable, in the default scenario, and when the dialog above is confirmed, the project is simply closed, i.e., the node hierarchy is removed from the application. However, if you truly want to let the user delete the project on disk, pass the Project to the DeleteOperationImplementation and then add the children of the Project you want to delete to the getDataFiles method: private final class CustomerProjectDeleteOperation implements DeleteOperationImplementation { private final CustomerProject project; private CustomerProjectDeleteOperation(CustomerProject project) { this.project = project; } @Override public List<FileObject> getDataFiles() { List<FileObject> files = new ArrayList<FileObject>(); FileObject[] projectChildren = project.getProjectDirectory().getChildren(); for (FileObject fileObject : projectChildren) { addFile(project.getProjectDirectory(), fileObject.getNameExt(), files); } return files; } private void addFile(FileObject projectDirectory, String fileName, List<FileObject> result) { FileObject file = projectDirectory.getFileObject(fileName); if (file != null) { result.add(file); } } @Override public List<FileObject> getMetadataFiles() { return new ArrayList<FileObject>(); } @Override public void notifyDeleting() throws IOException { } @Override public void notifyDeleted() throws IOException { } } Now the user will be able to check the checkbox, causing the method above to be called in the DeleteOperationImplementation: Hope this answers some questions or at least gets the discussion started. Before asking questions about this topic, please take the steps above and only then attempt to apply them to your own scenario. Useful implementations to look at: http://kickjava.com/src/org/netbeans/modules/j2ee/clientproject/AppClientProjectOperations.java.htm https://kenai.com/projects/nbandroid/sources/mercurial/content/project/src/org/netbeans/modules/android/project/AndroidProjectOperations.java

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  • Is an event loop just a for/while loop with optimized polling?

    - by Alan
    I'm trying to understand what an event loop is. Often the explanation is that in the event loop, you do something until you're notified that an event occurred. You than handle the event and continue doing what you did before. To map the above definition with an example. I have a server which 'listens' in a event loop, and when a socket connection is detected, the data from it gets read and displayed, after which the server goes to the listening it did before. However, this event happening and us getting notified 'just like that' are to much for me to handle. You can say: "It's not 'just like that' you have to register an event listener". But what's an event listener but a function which for some reason isn't returning. Is it in it's own loop, waiting to be notified when an event happens? Should the event listener also register an event listener? Where does it end? Events are a nice abstraction to work with, however just an abstraction. I believe that in the end, polling is unavoidable. Perhaps we are not doing it in our code, but the lower levels (the programming language implementation or the OS) are doing it for us. It basically comes down to the following pseudo code which is running somewhere low enough so it doesn't result in busy waiting: while(True): do stuff check if event has happened (poll) do other stuff This is my understanding of the whole idea, and i would like to hear if this is correct. I am open in accepting that the whole idea is fundamentally wrong, in which case I would like the correct explanation. Best regards

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  • MapReduce

    - by kaleidoscope
    MapReduce is a programming model and an associated implementation for processing and generating large data sets. Users specify a map function that processes a key/value pair to generate a set of  intermediate key/value pairs, and a reduce function that merges all intermediate values associated with the same intermediate key. Many real world tasks are expressible in this model, as shown in the paper. Programs written in this functional style are automatically parallelized and executed on a large cluster of commodity machines. The run-time system takes care of the details of partitioning the input data,  scheduling the program's execution across a set of machines, handling machine failures, and managing the required inter-machine communication. This allows programmers without any experience with parallel and distributed systems to easily utilize the resources of a large distributed system. Example: A process to count the appearances of each different word in a set of documents void map(String name, String document):   // name: document name   // document: document contents   for each word w in document:     EmitIntermediate(w, 1); void reduce(String word, Iterator partialCounts):   // word: a word   // partialCounts: a list of aggregated partial counts   int result = 0;   for each pc in partialCounts:     result += ParseInt(pc);   Emit(result); Here, each document is split in words, and each word is counted initially with a "1" value by the Map function, using the word as the result key. The framework puts together all the pairs with the same key and feeds them to the same call to Reduce, thus this function just needs to sum all of its input values to find the total appearances of that word.   Sarang, K

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  • EMEA OTN Virtual Technology Summit - Hands-On Learning

    - by Thanos Terentes Printzios
    The Oracle Technology Network (OTN) is excited to invite you to our first Virtual Technology Summit. EMEA – Thursday July 10th / 9am to 1pm BST / 10am – 2pm CET / 12pm to 4pm MSK / GST - Register Now Learn first hand from Oracle ACEs, Java Champions, and Oracle product experts, as they share their insight and expertise on using Oracle technologies to meet today’s IT challenges. This interactive, online event offers four technical tracks, each with a unique focus on specific tools, technologies, and tips in these focus areas. Java – Big Trends and Technologies – Java lets you mine Big Data, build robust apps with HTML5, JavaScript and Java EE, and expand into the Internet of Things. Experts will present and you’ll be able to chat with them live online. Don’t miss out on this great opportunity to learn from some of the best minds in the Java community. Systems – OS Tips and Tricks for Sysadmins – Learn first hand how to configure Oracle Linux to run Oracle Database 11g and 12c, how to use the latest networking capabilities in Oracle Solaris 11, and how to troubleshoot networking problems in Unix and Linux systems. Database – Mastering Oracle Database Management & Development Techniques – Experts will present advanced features and management methods that will help you master your Oracle Database capabilities and drive greater performance, agility and manageability of your IT implementation. This track will build upon your skills with data management, migration, and performance. Middleware – The Architecture of Analytics: Big Time Big Data and Business Intelligence – This track will present a solution architect’s perspective on how business intelligence products in Oracle’s Fusion Middleware family and beyond fit into an effective big data architecture, and present insight and expertise from Oracle ACEs specializing in business Intelligence to help you meet your big data business intelligence challenges. This same content is being offered at 3 different dates listed below, at times convenient for all regions Americas - Wednesday July 9th EMEA – Thursday July 10th APAC English - July 16th 9am to 1pm PST12pm to 4pm  EST1 to 5 pm BRTRegister 9am to 1pm BST10am – 2pm CET12pm to 4pm MSK / GSTRegister IST – 10:00amSG – 12:30pmAEST – 2:30pmRegister The full event agenda is available at https://wikis.oracle.com/display/OTNVirtualTechSummit/Home

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