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  • Building Enterprise Smartphone App &ndash; Part 4: Application Development Considerations

    - by Tim Murphy
    This is the final part in a series of posts based on a talk I gave recently at the Chicago Information Technology Architects Group.  Feel free to leave feedback. Application Development Considerations Now we get to the actual building of your solutions.  What are the skills and resources that will be needed in order to develop a smartphone application in the enterprise? Language Knowledge One of the first things you need to consider when you are deciding which platform language do you either have the most in house skill base or can you easily acquire.  If you already have developers who know Java or C# you may want to use either Android or Windows Phone.  You should also take into consideration the market availability of developers.  If your key developer leaves how easy is it to find a knowledgeable replacement? A second consideration when it comes to programming languages is the qualities exposed by the languages of a particular platform.  How well does that development language and its associated frameworks support things like security and access to the features of the smartphone hardware?  This will play into your overall cost of ownership if you have to create this infrastructure on your own. Manage Limited Resources Everything is limited on a smartphone: battery, memory, processing power, network bandwidth.  When developing your applications you will have to keep your footprint as small as possible in every way.  This means not running unnecessary processes in the background that will drain the battery or pulling more data over the airwaves than you have to.  You also want to keep your on device in as compact a format as possible. Mobile Design Patterns There are a number of design patterns that have either come to life because of smartphone development or have been adapted for this use.  The main pattern in the Windows Phone environment is the MVVM (Model-View-View-Model).  This is great for overall application structure and separation of concerns.  The fun part is trying to keep that separation as pure as possible.  Many of the other patterns may or may not have strict definitions, but some that you need to be concerned with are push notification, asynchronous communication and offline data storage. Real estate is limited on smartphones and even tablets. You are also limited in the type of controls that can be represented in the UI. This means rethinking how you modularize your application. Typing is also much harder to do so you want to reduce this as much as possible.  This leads to UI patterns.  While not what we would traditionally think of as design patterns the guidance each platform has for UI design is critical to the success of your application.  If user find the application difficult navigate they will not use it. Development Process Because of the differences in development tools required, test devices and certification and deployment processes your teams will need to learn new way of working together.  This will include the need to integrate service contracts of back-end systems with mobile applications.  You will also want to make sure that you present consistency across different access points to corporate data.  Your web site may have more functionality than your smartphone application, but it should have a consistent core set of functionality.  This all requires greater communication between sub-teams of your developers. Testing Process Testing of smartphone apps has a lot more to do with what happens when you lose connectivity or if the user navigates away from your application. There are a lot more opportunities for the user or the device to perform disruptive acts.  This should be your main testing concentration aside from the main business requirements.  You will need to do things like setting the phone to airplane mode and seeing what the application does in order to weed out any gaps in your handling communication interruptions. Need For Outside Experts Since this is a development area that is new to most companies the need for experts is a lot greater. Whether these are consultants, vendor representatives or just development community forums you will need to establish expert contacts. Nothing is more dangerous for your project timelines than a lack of knowledge.  Make sure you know who to call to avoid lengthy delays in your project because of knowledge gaps. Security Security has to be a major concern for enterprise applications. You aren't dealing with just someone's game standings. You are dealing with a companies intellectual property and competitive advantage. As such you need to start by limiting access to the application itself.  Once the user is in the app you need to ensure that the data is secure at all times.  This includes both local storage and across the wire.  This means if a platform doesn’t natively support encryption for these functions you will need to find alternatives to secure your data.  You also need to keep secret (encryption) keys obfuscated or locked away outside of the application. People can disassemble the code otherwise and break your encryption. Offline Capabilities As we discussed earlier one your biggest concerns is not having connectivity.  Because of this a good portion of your code may be dedicated to handling loss of connection and reconnection situations.  What do you do if you lose the network?  Back up all your transactions and store of any supporting data so that operations can continue off line. In order to support this you will need to determine the available flat file or local data base capabilities of the platform.  Any failed transactions will need to support a retry mechanism whether it is automatic or user initiated.  This also includes your services since they will need to be able to roll back partially completed transactions.  What ever you do, don’t ignore this area when you are designing your system. Deployment Each platform has different deployment capabilities. Some are more suited to enterprise situations than others. Apple's approach is probably the most mature at the moment. Prior to the current generation of smartphone platforms it would have been Windows CE. Windows Phone 7 has the limitation that the app has to be distributed through the same network as public facing applications. You mark them as private which means that they are only accessible by a direct URL. Unfortunately this does not make them undiscoverable (although it is very difficult). This will change with Windows Phone 8 where companies will be able to certify their own applications and distribute them.  Given this Windows Phone applications need to be more diligent with application access in order to keep them restricted to the company's employees. My understanding of the Android deployment schemes is that it is much less standardized then either iOS or Windows Phone. Someone would have to confirm or deny that for me though since I have not yet put the time into researching this platform further. Given my limited exposure to the iOS and Android platforms I have not been able to confirm this, but there are varying degrees of user involvement to install and keep applications updated. At one extreme the user just goes to a website to do the install and in other case they may need to download files and perform steps to install them. Future Bluetooth Today we use Bluetooth for keyboards, mice and headsets.  In the future it could be used to interrogate car computers or manufacturing systems or possibly retail machines by service techs.  This would open smartphones to greater use as a almost a Star Trek Tricorder.  You would get you all your data as well as being able to use it as a universal remote for just about any device or machine. Better corporation controlled deployment At least in the Windows Phone world the upcoming release of Windows Phone 8 will include a private certification and deployment option that is currently not available with Windows Phone 7 (Mango). We currently have to run the apps through the Marketplace certification process and use a targeted distribution method. Platform independent approaches HTML5 and JavaScript with Web Service has become a popular topic lately for not only creating flexible web site, but also creating cross platform mobile applications.  I’m not yet convinced that this lowest common denominator approach is viable in most cases, but it does have it’s place and seems to be growing.  Be sure to keep an eye on it. Summary From my perspective enterprise smartphone applications can offer a great competitive advantage to many companies.  They are not cheap to build and should be approached cautiously.  Understand the factors I have outlined in this series, do you due diligence and see if there is a portion of your business that can benefit from the mobile experience. del.icio.us Tags: Architecture,Smartphones,Windows Phone,iOS,Android

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  • Build an ASP.NET 3.5 Guestbook using MS SQL Server and VB.NET

    One of the most important website features is a guest book. This is particularly useful if you need to know the responses and reactions of your website s visitors. With the release of ASP.NET 3.5 and Visual Web Developer Express 2 8 several web controls make it possible to create an ASP.NET application without the need to hard manually code everything including database scripts server side scripts etc. You can see how that would be helpful to writing a guest book. This is the first part of a multi-part series.... SW Deployment Automation Best Practices Free Guide for IT Leaders: Overcoming Software Distribution & Mgmt Challenges.

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  • Silverlight 4 Training Course

    - by guybarrette
    A Silverlight 4 training course is now available on Channel 9.  Here’s the course description: The Silverlight 4 Training Course includes a whitepaper explaining all of the new Silverlight 4 RC features, several hands-on-labs that explain the features, and a 8 unit course for building business applications with Silverlight 4. The business applications course includes 8 modules with extensive hands on labs as well as 25 accompanying videos that walk you through key aspects of building a business application with Silverlight. Key aspects in this course are working with numerous sandboxed and elevated out of browser features, the new RichTextBox control, implicit styling, webcam, drag and drop, multi touch, validation, authentication, MEF, WCF RIA Services, right mouse click, and much more! You can download it here var addthis_pub="guybarrette";

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  • What are the different ways to texture a terrain?

    - by ApocKalipsS
    I'm working with XNA on a 3D Game, and I'm trying to have a proper and nice environnement. I actually followed a tutorial to create a terrain from a Heightmap, and to texture it, I just apply a grass texture on it and tile it a number of times. But what I want to do is to have a really realistic texturing, but also generate it automatically (for example if I want to use a perlin noise to generate a terrain and then texture it). I already learnt about multi-texturing, loading a map file with different colors for different textures, but I don't think this is really efficient, for instance for cliffs or very steep areas it will tile a texture badly as it's a view from the top. Also I don't know how i'll draw roads or dirt paths with that. I hope you understood me despite my english! If you don't, basically, here what I want to do: How do I texture a randomly generated terrain? :) Thank you for your answers!

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  • Windows Azure : J-2 avant le dev camp en direct sur Developpez.com, réservez votre mercredi

    Le 20 juin aura lieu la journée Dev Camp consacrée à Azure. [IMG]http://i.msdn.microsoft.com/hh868108.azure-camps(fr-fr,MSDN.10).png[/IMG] Cette journée est l'occasion de découvrir tous les services Cloud d'Azure (SQL Azure, Stockage avec Windows Azure Storage, Back-end, etc.), d'apprendre comment réaliser des projets et héberger des applications ? ou des sites webs - sur la plateforme. L'Azure Dev Camp abordera également les applications multi-tiers et la manière de « migrer, intégrer et étendre votre code et vos applications existantes grâce à Windows Azure ». Cette journée abordera aussi la construction d'APIs Web pour enrichir des applications mobiles iOS, Android et bien sûr Windows Phone. Enfin, le rendez-vous...

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  • Project Jigsaw: Late for the train: The Q&A

    - by Mark Reinhold
    I recently proposed, to the Java community in general and to the SE 8 (JSR 337) Expert Group in particular, to defer Project Jigsaw from Java 8 to Java 9. I also proposed to aim explicitly for a regular two-year release cycle going forward. Herewith a summary of the key questions I’ve seen in reaction to these proposals, along with answers. Making the decision Q Has the Java SE 8 Expert Group decided whether to defer the addition of a module system and the modularization of the Platform to Java SE 9? A No, it has not yet decided. Q By when do you expect the EG to make this decision? A In the next month or so. Q How can I make sure my voice is heard? A The EG will consider all relevant input from the wider community. If you have a prominent blog, column, or other communication channel then there’s a good chance that we’ve already seen your opinion. If not, you’re welcome to send it to the Java SE 8 Comments List, which is the EG’s official feedback channel. Q What’s the overall tone of the feedback you’ve received? A The feedback has been about evenly divided as to whether Java 8 should be delayed for Jigsaw, Jigsaw should be deferred to Java 9, or some other, usually less-realistic, option should be taken. Project Jigsaw Q Why is Project Jigsaw taking so long? A Project Jigsaw started at Sun, way back in August 2008. Like many efforts during the final years of Sun, it was not well staffed. Jigsaw initially ran on a shoestring, with just a handful of mostly part-time engineers, so progress was slow. During the integration of Sun into Oracle all work on Jigsaw was halted for a time, but it was eventually resumed after a thorough consideration of the alternatives. Project Jigsaw was really only fully staffed about a year ago, around the time that Java 7 shipped. We’ve added a few more engineers to the team since then, but that can’t make up for the inadequate initial staffing and the time lost during the transition. Q So it’s really just a matter of staffing limitations and corporate-integration distractions? A Aside from these difficulties, the other main factor in the duration of the project is the sheer technical difficulty of modularizing the JDK. Q Why is modularizing the JDK so hard? A There are two main reasons. The first is that the JDK code base is deeply interconnected at both the API and the implementation levels, having been built over many years primarily in the style of a monolithic software system. We’ve spent considerable effort eliminating or at least simplifying as many API and implementation dependences as possible, so that both the Platform and its implementations can be presented as a coherent set of interdependent modules, but some particularly thorny cases remain. Q What’s the second reason? A We want to maintain as much compatibility with prior releases as possible, most especially for existing classpath-based applications but also, to the extent feasible, for applications composed of modules. Q Is modularizing the JDK even necessary? Can’t you just put it in one big module? A Modularizing the JDK, and more specifically modularizing the Java SE Platform, will enable standard yet flexible Java runtime configurations scaling from large servers down to small embedded devices. In the long term it will enable the convergence of Java SE with the higher-end Java ME Platforms. Q Is Project Jigsaw just about modularizing the JDK? A As originally conceived, Project Jigsaw was indeed focused primarily upon modularizing the JDK. The growing demand for a truly standard module system for the Java Platform, which could be used not just for the Platform itself but also for libraries and applications built on top of it, later motivated expanding the scope of the effort. Q As a developer, why should I care about Project Jigsaw? A The introduction of a modular Java Platform will, in the long term, fundamentally change the way that Java implementations, libraries, frameworks, tools, and applications are designed, built, and deployed. Q How much progress has Project Jigsaw made? A We’ve actually made a lot of progress. Much of the core functionality of the module system has been prototyped and works at both compile time and run time. We’ve extended the Java programming language with module declarations, worked out a structure for modular source trees and corresponding compiled-class trees, and implemented these features in javac. We’ve defined an efficient module-file format, extended the JVM to bootstrap a modular JRE, and designed and implemented a preliminary API. We’ve used the module system to make a good first cut at dividing the JDK and the Java SE API into a coherent set of modules. Among other things, we’re currently working to retrofit the java.util.ServiceLoader API to support modular services. Q I want to help! How can I get involved? A Check out the project page, read the draft requirements and design overview documents, download the latest prototype build, and play with it. You can tell us what you think, and follow the rest of our work in real time, on the jigsaw-dev list. The Java Platform Module System JSR Q What’s the relationship between Project Jigsaw and the eventual Java Platform Module System JSR? A At a high level, Project Jigsaw has two phases. In the first phase we’re exploring an approach to modularity that’s markedly different from that of existing Java modularity solutions. We’ve assumed that we can change the Java programming language, the virtual machine, and the APIs. Doing so enables a design which can strongly enforce module boundaries in all program phases, from compilation to deployment to execution. That, in turn, leads to better usability, diagnosability, security, and performance. The ultimate goal of the first phase is produce a working prototype which can inform the work of the Module-System JSR EG. Q What will happen in the second phase of Project Jigsaw? A The second phase will produce the reference implementation of the specification created by the Module-System JSR EG. The EG might ultimately choose an entirely different approach than the one we’re exploring now. If and when that happens then Project Jigsaw will change course as necessary, but either way I think that the end result will be better for having been informed by our current work. Maven & OSGi Q Why not just use Maven? A Maven is a software project management and comprehension tool. As such it can be seen as a kind of build-time module system but, by its nature, it does nothing to support modularity at run time. Q Why not just adopt OSGi? A OSGi is a rich dynamic component system which includes not just a module system but also a life-cycle model and a dynamic service registry. The latter two facilities are useful to some kinds of sophisticated applications, but I don’t think they’re of wide enough interest to be standardized as part of the Java SE Platform. Q Okay, then why not just adopt the module layer of OSGi? A The OSGi module layer is not operative at compile time; it only addresses modularity during packaging, deployment, and execution. As it stands, moreover, it’s useful for library and application modules but, since it’s built strictly on top of the Java SE Platform, it can’t be used to modularize the Platform itself. Q If Maven addresses modularity at build time, and the OSGi module layer addresses modularity during deployment and at run time, then why not just use the two together, as many developers already do? A The combination of Maven and OSGi is certainly very useful in practice today. These systems have, however, been built on top of the existing Java platform; they have not been able to change the platform itself. This means, among other things, that module boundaries are weakly enforced, if at all, which makes it difficult to diagnose configuration errors and impossible to run untrusted code securely. The prototype Jigsaw module system, by contrast, aims to define a platform-level solution which extends both the language and the JVM in order to enforce module boundaries strongly and uniformly in all program phases. Q If the EG chooses an approach like the one currently being taken in the Jigsaw prototype, will Maven and OSGi be made obsolete? A No, not at all! No matter what approach is taken, to ensure wide adoption it’s essential that the standard Java Platform Module System interact well with Maven. Applications that depend upon the sophisticated features of OSGi will no doubt continue to use OSGi, so it’s critical that implementations of OSGi be able to run on top of the Java module system and, if suitably modified, support OSGi bundles that depend upon Java modules. Ideas for how to do that are currently being explored in Project Penrose. Java 8 & Java 9 Q Without Jigsaw, won’t Java 8 be a pretty boring release? A No, far from it! It’s still slated to include the widely-anticipated Project Lambda (JSR 335), work on which has been going very well, along with the new Date/Time API (JSR 310), Type Annotations (JSR 308), and a set of smaller features already in progress. Q Won’t deferring Jigsaw to Java 9 delay the eventual convergence of the higher-end Java ME Platforms with Java SE? A It will slow that transition, but it will not stop it. To allow progress toward that convergence to be made with Java 8 I’ve suggested to the Java SE 8 EG that we consider specifying a small number of Profiles which would allow compact configurations of the SE Platform to be built and deployed. Q If Jigsaw is deferred to Java 9, would the Oracle engineers currently working on it be reassigned to other Java 8 features and then return to working on Jigsaw again after Java 8 ships? A No, these engineers would continue to work primarily on Jigsaw from now until Java 9 ships. Q Why not drop Lambda and finish Jigsaw instead? A Even if the engineers currently working on Lambda could instantly switch over to Jigsaw and immediately become productive—which of course they can’t—there are less than nine months remaining in the Java 8 schedule for work on major features. That’s just not enough time for the broad review, testing, and feedback which such a fundamental change to the Java Platform requires. Q Why not ship the module system in Java 8, and then modularize the platform in Java 9? A If we deliver a module system in one release but don’t use it to modularize the JDK until some later release then we run a big risk of getting something fundamentally wrong. If that happens then we’d have to fix it in the later release, and fixing fundamental design flaws after the fact almost always leads to a poor end result. Q Why not ship Jigsaw in an 8.5 release, less than two years after 8? Or why not just ship a new release every year, rather than every other year? A Many more developers work on the JDK today than a couple of years ago, both because Oracle has dramatically increased its own investment and because other organizations and individuals have joined the OpenJDK Community. Collectively we don’t, however, have the bandwidth required to ship and then provide long-term support for a big JDK release more frequently than about every other year. Q What’s the feedback been on the two-year release-cycle proposal? A For just about every comment that we should release more frequently, so that new features are available sooner, there’s been another asking for an even slower release cycle so that large teams of enterprise developers who ship mission-critical applications have a chance to migrate at a comfortable pace.

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  • File system layout for multiple build targets

    - by Yttrill
    I am seeking some ideas for how to build and install software with some parameters. These including target OS, target platform CPU details, debugging variant, etc. Some parts of the install are shared, such as documentation and many platform independent files, others are not, such as 64 and 32 bit libraries when these are separated and not together in a multi-arch library. On big networked platforms one often has multiple computers sharing some large server space, so there is actually cause to have even Windows and Unix binaries on the same disk. My product has already fixed an install philosophy of $INSTALL_ROOT/genericname/version/ so that multiple versions can coexist. The question is: how to manage the layout of all the other stuff?

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  • Java ME Tech Holiday Gift Idea #3: Kindle Touch Wi-Fi

    - by hinkmond
    Here's a Java ME tech-enabled device holiday gift idea: The venerable Amazon Kindle Touch with built-in Wi-Fi. Niiiice! See: Java ME Tech Gift Idea #3 Here's a quote: + Most-advanced E Ink display, now with multi-touch + New sleek design - 8% lighter, 11% smaller, holds 3,000 books + Only e-reader with text-to-speech, audiobooks and mp3 support + Built in Wi-Fi - Get books in 60 seconds If you want to give someone special a cool device, you want to give something with Java ME technology. Give only the best this holiday season! Hinkmond

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  • Google déploie Android 4.2 et publie son code source ainsi que son SDK

    Fuite des fonctionnalités d'Android 4.2 : nouveau Google Play, gestion du multi-utilisateur et contrôle parental Google a récemment envoyé des invitations à la presse pour un évènement Android le 29 octobre prochain à New York. Au cours de cet évènement, l'éditeur pourrait dévoiler Android 4.2, une mise à jour mineure de la version 4.1, Jelly Bean. Cette nouvelle a laissé place à des rumeurs qui viennent dévoiler quelques-unes des nouvelles fonctionnalités et améliorations qu'apportera cette version d'Android. Selon le site spécialisé Android Police, la prochaine mise à jour de l'OS mobile de Google apportera une nouvelle version de la galerie d'applications...

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  • Online architecture guide

    - by hunterman
    I am a newbie in gamedev, and I don't know about programmer's problems that can appear during development. So can you advice me some best practice for starting build new online multi-player game backend? I just saw reddraft server, and I think Spring library can also do some of its features. What is big difference? Do I need learn more spring or I have to use servers like reddraft or write these tools myself? I know that I need to learn hard and many - and the question is - what I should to learn now at the beginning? Thanks.

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  • unzip error "End-of-central-directory signature not found"

    - by Tim
    I try to unzip a zip file, but got an error: $ unzip COCR2_100.zip Archive: COCR2_100.zip End-of-central-directory signature not found. Either this file is not a zipfile, or it constitutes one disk of a multi-part archive. In the latter case the central directory and zipfile comment will be found on the last disk(s) of this archive. note: COCR2_100.zip may be a plain executable, not an archive unzip: cannot find zipfile directory in one of COCR2_100.zip or COCR2_100.zip.zip, and cannot find COCR2_100.zip.ZIP, period. I googled but didn't find a solution. I was wondering why it is and how I should fix it? Thanks! The zip file can be downloaded from COCR2_100. It is an application, and here is its website http://users.belgacom.net/chardic/cocr2.html. My OS is 10.10.

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  • Google I/O 2012 - Fast UIs for the Cross-Device Web

    Google I/O 2012 - Fast UIs for the Cross-Device Web Boris Smus One of the great features of the modern web is that sites work on any device with a browser. This session will focus on creating UIs for the cross-device web. We will cover building web sites that support multiple device form factors (responsive and non-responsive approaches), discuss single page sites and some of the layout features in modern mobile browsers, and do a deep dive into multi-touch input on the web. Finally, we'll show some of the awesome new mobile debugging tools in Chrome and Chrome for Android. For all I/O 2012 sessions, go to developers.google.com From: GoogleDevelopers Views: 105 3 ratings Time: 49:31 More in Science & Technology

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  • Implementation of a Rules Engine in Your Business Applicaitons

    - by enonu
    I'm for an experience driven answer from a few software engineers who have implemented a rules engine in their internal business applications. How has it affected your business in the following ways: Ability to launch and iterate over business driven logic Ability to have "business users" perform the actual modification of those rules rather than developers. Ability to comprehend the business rules in general. Quality of the software releases. More or less bugs from the end-user's POV? Speed of the applications. If you had to do it all over again, what would you do differently? Lastly, I'm looking for a qualification of your answer w/ respect to the architecture. Would you do the same thing if you were deploying to a 1-machine setup vs. your architecture vs. a multi-tier cloud-based distributed architecture using 1000s of machines? How would it be different? Thanks!

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  • Coherence Data Guarantees for Data Reads - Basic Terminology

    - by jpurdy
    When integrating Coherence into applications, each application has its own set of requirements with respect to data integrity guarantees. Developers often describe these requirements using expressions like "avoiding dirty reads" or "making sure that updates are transactional", but we often find that even in a small group of people, there may be a wide range of opinions as to what these terms mean. This may simply be due to a lack of familiarity, but given that Coherence sits at an intersection of several (mostly) unrelated fields, it may be a matter of conflicting vocabularies (e.g. "consistency" is similar but different in transaction processing versus multi-threaded programming). Since almost all data read consistency issues are related to the concept of concurrency, it is helpful to start with a definition of that, or rather what it means for two operations to be concurrent. Rather than implying that they occur "at the same time", concurrency is a slightly weaker statement -- it simply means that it can't be proven that one event precedes (or follows) the other. As an example, in a Coherence application, if two client members mutate two different cache entries sitting on two different cache servers at roughly the same time, it is likely that one update will precede the other by a significant amount of time (say 0.1ms). However, since there is no guarantee that all four members have their clocks perfectly synchronized, and there is no way to precisely measure the time it takes to send a given message between any two members (that have differing clocks), we consider these to be concurrent operations since we can not (easily) prove otherwise. So this leads to a question that we hear quite frequently: "Are the contents of the near cache always synchronized with the underlying distributed cache?". It's easy to see that if an update on a cache server results in a message being sent to each near cache, and then that near cache being updated that there is a window where the contents are different. However, this is irrelevant, since even if the application reads directly from the distributed cache, another thread update the cache before the read is returned to the application. Even if no other member modifies a cache entry prior to the local near cache entry being updated (and subsequently read), the purpose of reading a cache entry is to do something with the result, usually either displaying for consumption by a human, or by updating the entry based on the current state of the entry. In the former case, it's clear that if the data is updated faster than a human can perceive, then there is no problem (and in many cases this can be relaxed even further). For the latter case, the application must assume that the value might potentially be updated before it has a chance to update it. This almost aways the case with read-only caches, and the solution is the traditional optimistic transaction pattern, which requires the application to explicitly state what assumptions it made about the old value of the cache entry. If the application doesn't want to bother stating those assumptions, it is free to lock the cache entry prior to reading it, ensuring that no other threads will mutate the entry, a pessimistic approach. The optimistic approach relies on what is sometimes called a "fuzzy read". In other words, the application assumes that the read should be correct, but it also acknowledges that it might not be. (I use the qualifier "sometimes" because in some writings, "fuzzy read" indicates the situation where the application actually sees an original value and then later sees an updated value within the same transaction -- however, both definitions are roughly equivalent from an application design perspective). If the read is not correct it is called a "stale read". Going back to the definition of concurrency, it may seem difficult to precisely define a stale read, but the practical way of detecting a stale read is that is will cause the encompassing transaction to roll back if it tries to update that value. The pessimistic approach relies on a "coherent read", a guarantee that the value returned is not only the same as the primary copy of that value, but also that it will remain that way. In most cases this can be used interchangeably with "repeatable read" (though that term has additional implications when used in the context of a database system). In none of cases above is it possible for the application to perform a "dirty read". A dirty read occurs when the application reads a piece of data that was never committed. In practice the only way this can occur is with multi-phase updates such as transactions, where a value may be temporarily update but then withdrawn when a transaction is rolled back. If another thread sees that value prior to the rollback, it is a dirty read. If an application uses optimistic transactions, dirty reads will merely result in a lack of forward progress (this is actually one of the main risks of dirty reads -- they can be chained and potentially cause cascading rollbacks). The concepts of dirty reads, fuzzy reads, stale reads and coherent reads are able to describe the vast majority of requirements that we see in the field. However, the important thing is to define the terms used to define requirements. A quick web search for each of the terms in this article will show multiple meanings, so I've selected what are generally the most common variations, but it never hurts to state each definition explicitly if they are critical to the success of a project (many applications have sufficiently loose requirements that precise terminology can be avoided).

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  • Le HTML5, 6 à 10 fois moins rapide sur smartphone, d'après une étude : le standard est-il vraiment adapté pour les jeux mobiles ?

    Le HTML5, entre 6 et 10 fois moins rapide sur smartphones que sur bureau Le standard est-il vraiment adapté pour des jeux mobiles ? Le HTML5 sur mobile n'est pas encore tout à fait adapté pour les applications multi-plateformes complexes. C'est en résumé la conclusion d'une étude menée par la société spaceport.io qui souligne par exemple que le rendu des animations en HTML5 sur Smartphones et tablettes est très largement inférieur à celui sur PC de Bureau. Voilà qui a de quoi faire réfléchir sur la dimension "développer une fois, fonctionne partout" semblable à celle de Java et tant vantée pour la technologie Web comme alternative à des développements natifs. D'après cett...

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  • Add Custom Color Changing RGB LED Lighting to Your Next Project

    - by Jason Fitzpatrick
    While this specific project is a really neat back-lit bookcase with customizable LED lights galore, you could easily add the exact same setup to just about anything you wanted to give some LED love. The core of the project is a set of addressable LED modules, an Arduino board, and a simple bit of code. You could use it to make a 70s style mood lighting box, add color changing accents to your media room, or any other number of fun projects just by cloning this project and extending/shortening the wires where appropriate. The control module allows for solid colors, multi-colors, and animations. Hit up the link below for more information including the source code. ExpeditInvaders [via IKEAHacker] HTG Explains: What The Windows Event Viewer Is and How You Can Use It HTG Explains: How Windows Uses The Task Scheduler for System Tasks HTG Explains: Why Do Hard Drives Show the Wrong Capacity in Windows?

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  • Les grandes nouveautés de l'iPhone OS 4.0

    Comme on vous l'avait annoncé précédemment, Apple avait invité certains journalistes pour leur présenter certaines nouveautés de l'iPhone OS 4.0. Voici un tout petit résumé des nouveautés introduites dans iPhone OS 4.0 : 1500 nouvelles API à disposition des développeurs 100 nouvelles fonctionnalités proposées aux utilisateurs Parmi les nouvelles fonctionnalités proposées aux utilisateurs, Apple a mis l'accent sur 7 nouvelles fonctionnalités : Le multi-tache, mais de façon limitée (on reviendra là dessus plus tard) Les dossiers : vous pouvez maintenant avoir plus de 2000 applications réparties dans les dossiers. Au lieu de 180 auparavant. iBooks disponible également sur l'iPhone. Messagerie un...

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  • I'm trying to install Bruteforce Savedata from the archiver

    - by Jonathan
    I've just installed UBUNTU 12.04 for curiosity purposes. I'm a gamer and I wanted to install Brute force Save data on my comp. So i download it and it open in the Archive manager i go to run the ".exe" but encounter this message Archive: /home/c4/Desktop/Bruteforce_Save_Data_installer.exe [/home/c4/Desktop/Bruteforce_Save_Data_installer.exe] End-of-central-directory signature not found. Either this file is not a zipfile, or it constitutes one disk of a multi-part archive. In the latter case the central directory and zipfile comment will be found on the last disk(s) of this archive. zipinfo: cannot find zipfile directory in one of /home/c4/Desktop/Bruteforce_Save_Data_installer.exe or /home/c4/Desktop/Bruteforce_Save_Data_installer.exe.zip, and cannot find /home/c4/Desktop/Bruteforce_Save_Data_installer.exe.ZIP, period. Please help!

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  • Android performance/issues with Corona SDK?

    - by B5Fan74
    I know this is a fairly broad question. We are looking to develop a mobile game and want to use a multi-platform engine/SDK. We like what we see with Corona but in doing some reading, we are seeing a lot of references to poor performance on the 'droid platforms. I am unsure how much of this is still relevant? Many of the articles/posts/references/discussions vary in date from 18 months ago to earlier this year. Is there a reason we should not pursue Corona if Android support is important to us? The game is going to be 2D isometric view. Thanks!

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  • Do you want to learn about developing Web, Mobile and beyond Oracle based applications? Join our online virtual event on November 26th

    - by JuergenKress
    Learn about the latest innovations in Oracle ADF. Our virtual event provides sessions that range from introductory to deep dive, covering Oracle’s strategic framework for developing multi-channel enterprise applications for the Oracle platforms. Multiple tracks cover every interest and every level and include live online Q&A chats with Oracle’s technical staff. For details please visit our registration page. WebLogic Partner Community For regular information become a member in the WebLogic Partner Community please visit: http://www.oracle.com/partners/goto/wls-emea ( OPN account required). If you need support with your account please contact the Oracle Partner Business Center. Blog Twitter LinkedIn Mix Forum Wiki Technorati Tags: ADF,ADF mobile,education,training,Oracle OpenWorld,WebLogic,WebLogic Community,Oracle,OPN,Jürgen Kress

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  • NeoAxis 3D disponible en version 1.3, le moteur de jeu ajoute le SSAO et une meilleure gestion du terrain

    NeoAxis 3D et maintenant disponible en version 1.3 La nouvelle version du moteur de jeu apporte le SSAO, des améliorations sur le terrain et plein d'autres surprises C'est en cette période de Noël que NeoAxis 3D, le moteur de jeu multi-plateforme revient avec une hotte fournit en cadeau pour nous, les développeurs. Tout d'abord, cette version estampillée 1.3 apporte le Screen Space Ambient Occlusion (SSAO). Une technique de rendu temps réel qui est grandement utilisée dans l'industrie pour permettre une approximation efficace de l'ambient occlusion (des ombres sont rajoutés selon le buffer de profondeur).. Celui-ci est implémenté tel un effet après rendu (post processing) afin de garder une bonne synergi...

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  • The resulting .iso doesn't work - MultiCD

    - by Ravi
    Burning a separate CD for each distribution (Ubuntu, Kubuntu etc.) is cumbersome. I found MultiCD which promises me to have a single DVD which can hold several distributions. It is very great tool. Main Problem : The resulting .iso created from multicd doesn't work in a USB pen drive through I haven't tested it in a DVD. Running the .iso through pen drive (I mean booting from pen drive) doesn't work. I cannot even run it in live mode or can install it. Concern : I think if I burn the .iso to a DVD then might it will work. But considering it doesn't work in the pen drive, Will it work on the DVD? So how to fix it? If you know other method to make a multi CD/DVD then please tell me.

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  • Restoring Virtualbox machine images from old hard drive

    - by memilanuk
    I recently replaced the HDD in my laptop, and re-installed Windows & Ubuntu. Now I want to restore the various virtual machines I had set up on the old HDD, which is mounted in an external USB enclosure. I can read the HDD okay, and the 'bad' spots seemed to be in the Windows partition... but whenever I try to restore the VDI files the copy errors out. I've tried drag-n-drop in Nautilus, I've tried grsync, etc. Always bombs out on the VDI files. I've copied over multi-GB dvd iso images with no problem, but the VDI files always fail the checksums. Any ideas? TIA, Monte

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  • How can I spawn a sprite based on a condition after the game starts?

    - by teddyweedy
    How do I spawn a sprite anytime later in the game when the game starts? I'm using FlashDevelop with Flixel. I did try it in override public function create(): void. It works only in the beginning. I try it using if (FlxG.score == 1) but it doesn't work. I also tried it in override public function update(): void. It works and it is moving but it leaves a sprite making it a multi-sprite. I also did try FlxGroup but to no avail.

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  • Colour scheme for editor - guidelines or medical reccomendations

    - by Kevin D
    Is anyone aware of any studies on what colour scheme is best for use in multi-coloured text based computer work? Specifically in terms of reducing eye strain. For instance is a black back ground and light text best? Should it be a dark colour rather than going all the way to black? I've seen the questions on this site about "which is your favourite" that is not what I am after. I also aware that my question may be to specific asking for a colour scheme, if anyone could link me to some guidelines instead that would be appreciated as well. I'm concious of the fact that anyone using a computer is really using it for text based work but with the multitude of colours used to convey information within our modern IDEs I feel this is a good StackExchange site for this question.

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