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  • Questions about identifying the components in MVC

    - by luiscubal
    I'm currently developing an client-server application in node.js, Express, mustache and MySQL. However, I believe this question should be mostly language and framework agnostic. This is the first time I'm doing a real MVC application and I'm having trouble deciding exactly what means each component. (I've done web applications that could perhaps be called MVC before, but I wouldn't confidently refer to them as such) I have a server.js that ties the whole application together. It does initialization of all other components (including the database connection, and what I think are the "models" and the "views"), receiving HTTP requests and deciding which "views" to use. Does this mean that my server.js file is the controller? Or am I mixing code that doesn't belong there? What components should I break the server.js file into? Some examples of code that's in the server.js file: var connection = mysql.createConnection({ host : 'localhost', user : 'root', password : 'sqlrevenge', database : 'blog' }); //... app.get("/login", function (req, res) { //Function handles a GET request for login forms if (process.env.NODE_ENV == 'DEVELOPMENT') { mu.clearCache(); } session.session_from_request(connection, req, function (err, session) { if (err) { console.log('index.js session error', err); session = null; } login_view.html(res, user_model, post_model, session, mu); //I named my view functions "html" for the case I might want to add other output types (such as a JSON API), or should I opt for completely separate views then? }); }); I have another file that belongs named session.js. It receives a cookies object, reads the stored data to decide if it's a valid user session or not. It also includes a function named login that does change the value of cookies. First, I thought it would be part of the controller, since it kind of dealt with user input and supplied data to the models. Then, I thought that maybe it was a model since it dealt with the application data/database and the data it supplies is used by views. Now, I'm even wondering if it could be considered a View, since it outputs data (cookies are part of HTTP headers, which are output)

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  • JavaDay Taipei 2014 Trip Report

    - by reza_rahman
    JavaDay Taipei 2014 was held at the Taipei International Convention Center on August 1st. Organized by Oracle University, it is one of the largest Java developer events in Taiwan. This was another successful year for JavaDay Taipei with a fully sold out venue packed with youthful, energetic developers (this was my second time at the event and I have already been invited to speak again next year!). In addition to Oracle speakers like me, Steve Chin and Naveen Asrani, the event also featured a bevy of local speakers including Taipei Java community leaders. Topics included Java SE, Java EE, JavaFX, cloud and Big Data. It was my pleasure and privilege to present one of the opening keynotes for the event. I presented my session on Java EE titled "JavaEE.Next(): Java EE 7, 8, and Beyond". I covered the changes in Java EE 7 as well as what's coming in Java EE 8. I demoed the Cargo Tracker Java EE BluePrints. I also briefly talked about Adopt-a-JSR for Java EE 8. The slides for the keynote are below (click here to download and view the actual PDF): It appears your Web browser is not configured to display PDF files. No worries, just click here to download the PDF file. In the afternoon I did my JavaScript + Java EE 7 talk titled "Using JavaScript/HTML5 Rich Clients with Java EE 7". This talk is basically about aligning EE 7 with the emerging JavaScript ecosystem (specifically AngularJS). The talk was completely packed. The slide deck for the talk is here: JavaScript/HTML5 Rich Clients Using Java EE 7 from Reza Rahman The demo application code is posted on GitHub. The code should be a helpful resource if this development model is something that interests you. Do let me know if you need help with it but the instructions should be fairly self-explanatory. I am delivering this material at JavaOne 2014 as a two-hour tutorial. This should give me a little more bandwidth to dig a little deeper, especially on the JavaScript end. I finished off Java Day Taipei with my talk titled "Using NoSQL with ~JPA, EclipseLink and Java EE" (this was the last session of the conference). The talk covers an interesting gap that there is surprisingly little material on out there. The talk has three parts -- a birds-eye view of the NoSQL landscape, how to use NoSQL via a JPA centric facade using EclipseLink NoSQL, Hibernate OGM, DataNucleus, Kundera, Easy-Cassandra, etc and how to use NoSQL native APIs in Java EE via CDI. The slides for the talk are here: Using NoSQL with ~JPA, EclipseLink and Java EE from Reza Rahman The JPA based demo is available here, while the CDI based demo is available here. Both demos use MongoDB as the data store. Do let me know if you need help getting the demos up and running. After the event the Oracle University folks hosted a reception in the evening which was very well attended by organizers, speakers and local Java community leaders. I am extremely saddened by the fact that this otherwise excellent trip was scarred by terrible tragedy. After the conference I joined a few folks for a hike on the Maokong Mountain on Saturday. The group included friends in the Taiwanese Java community including Ian and Robbie Cheng. Without warning, fatal tragedy struck on a remote part of the trail. Despite best efforts by us, the excellent Taiwanese Emergency Rescue Team and World class Taiwanese physicians we were unable to save our friend Robbie Cheng's life. Robbie was just thirty-four years old and is survived by his younger brother, mother and father. Being the father of a young child myself, I can only imagine the deep sorrow that this senseless loss unleashes. Robbie was a key member of the Taiwanese Java community and a Java Evangelist at Sun at one point. Ironically the only picture I was able to take of the trail was mere moments before tragedy. I thought I should place him in that picture in profoundly respectful memoriam: Perhaps there is some solace in the fact that there is something inherently honorable in living a bright life, dying young and meeting one's end on a beautiful remote mountain trail few venture to behold let alone attempt to ascend in a long and tired lifetime. Perhaps I'd even say it's a fate I would not entirely regret facing if it were my own. With that thought in mind it seems appropriate to me to quote some lyrics from the song "Runes to My Memory" by legendary Swedish heavy metal band Amon Amarth idealizing a fallen Viking warrior cut down in his prime: "Here I lie on wet sand I will not make it home I clench my sword in my hand Say farewell to those I love When I am dead Lay me in a mound Place my weapons by my side For the journey to Hall up high When I am dead Lay me in a mound Raise a stone for all to see Runes carved to my memory" I submit my deepest condolences to Robbie's family and hope my next trip to Taiwan ends in a less somber note.

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  • I'm a C Programmer, but I can't find a comfortable environment to work in

    - by Jesse Brands
    Hello everyone, Last time I asked a question, I was having issues dealing with Java which I had to do for a course work. I generally use C for my development work - especially personal projects - and I've grown up in what is pretty much a Linux/UNIX world. In this world, it was easy to use C, you had your C compiler (GCC is excellent in that regard) and a wealth of tools such as the command line and vi/emacs/whatever-you-got. However, that was all that I really liked about Linux/UNIX. It really fitted well with the C language; nowadays, I'm somewhat forced into Windows/Mac OS X for most of my work. C seems poorly supported on a mac for starters, there's no GUI API to use and pretty much you get forced into Obj-C. This is not a problem, I like Objective-C, but it's another language I have to learn. Now coming to Windows. Why does everything about Windows Development try to scare me away? It's basically come down to: USE C# AND .NET OR DIE. I don't like C#, I like C, they are fundamentally different. Yet when I make a Windows Forms application in MSVC++ (I know that's not C), I get a main function riddled with weird things I've never heard of before, along with a poor, barely-compliant C/C++ compiler. What am I to do when I just want to program in C, make applications that look and feel like native Windows applications (I am a sucker for aesthetics, and I'm not looking to make something cross-platform. I just want it to work on Windows, and look as native as possible.). C++ is a fine alternative, but it really looks like the only way to make a decent, native feeling Windows application, is to use C#. Am I missing something here? I'd rather not use CYGWIN. Like I said, I want people to install the program, and it should just work out of the box on Windows 7. Program in question involves a Media Player, if anyone is curious what I'm targetting at. Anyone who had the same experiences who can help me out? How can I code something in ANSI C and still have a native feel?

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  • Java EE 8 update

    - by delabassee
    Planning for Java EE 8 is now well underway. As you know, a few weeks ago, we conducted a three part Java EE 8 Community Survey (you can find the final summary here). The data gathered have been very influential for the next steps. You can now expect over the coming weeks and months to see updates on the various specifications that compose the Java EE platform. Some Specification Leads are busy gathering additional feedback regarding what they should focus their efforts on (e.g. CDI 2 survey). Other Specification Leads have already publicly exposed what they think should be one of the focus for the evolution of the specification they lead.  For example, adding Server-Senet Events (SSE) support in JAX-RS is being discussed here and adding MVC support is being discussed here. Please remember that the fact we are now discussing any feature does not insure that it will be included in the proposal, nor in any particular update to Java EE. We can expect additional enhancements, changes and evolutions as we get closer to the finalisation of the different specifications... and there is still a long way to go with these specification proposals! Linda DeMichiel, Java EE Co-Specification Lead, has recently posted a draft proposal for the Java EE 8 Platform specification. Linda's goal is to recruit people and companies supporting this proposal before submitting it to the JCP.  This draft proposal is very interesting reading as it contains relevant information on the plans for Java EE 8 such as : The themes: Support for the latest web standards (eg. HTTP 2.0)  Continue to work on ease of development Improve the infrastructure for cloud support Alignment with Java SE 8 New JSRs to be added to the platform: J-Cache Java API for JSON Binding Java Configuration Plans for the Web Profile Plans on technologies to prune in Java EE 8, ... So if you haven't done it yet, I really encourage you to read the Java EE 8 draft proposal! Our goal for the Java EE 8 specification is for it to be finalized in the second half of 2016. It is important to note that we are in the early days of Java EE 8 and at this stage everything (themes, content, timing, etc.) is preliminary. Everything still needs to be discussed, challenged and agreed within the different Java Community Process (JCP) Experts Groups (EGs). Some EGs that still need to be formed! It could also means that the roadmap will have to be adjusted to follow the progress being made in the different EGs. This is also a good occasion to remind you that participation within those upcoming JCP Experts Groups is encouraged. Contributing in an EG is an effective lever to influence what Java EE 8 will become! Finally, as things get more concrete, we will share details on how to engage in the different Java EE 8 related Adopt-a-JSR initiatives, another way to contribute. You can also read other posts related to Java EE 8, here at The Aquarium blog. Just look for articles with the 'javaee8' tag.

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  • Making A Photo-Sharing App For Android In Eclipse [on hold]

    - by user3694394
    I've only just started developing mobile apps, which is something that I've been wanting to learn for a while now. I'm from an indie games studio, making PC games for around the last 3 years, and I finally decided to move into android app development. The only problem I'm having is that I don't know where to start. The project which I'm aiming to create will be something similar to Instagram, basically a photo-sharing app which allows users to take new photos, or pull them from their device, and add filters to them, before posting them. I have a rough idea of how I could go about doing this, but I need pointing towards any tutorials available for each specific step. So, here's my idea: Create a UI in eclipse (this wont be a problem for me, I should be able to do this fine through xml files) Setup a server-side database to store all user info and uploaded images (the images will need to be converted into byte arrays, and I have no idea how to do this through a database). My best idea would be to use a MySQL database to do this. Add user interactions (likes, favourites, reposts, etc.). This would, again, have to be stored in the database (or, at least, i think it would). Add the ability to take new photos using the phone's camera (I can probably do this anyway, using the Camera API). Add the ability to pull existing photos from the device (again, pretty simple to do). Add the ability to add filters to any photos (I had a look around, and there are some repos and resources which allow you to do this, but they're mainly for iOS development). Add facebook/twitter integration (possibly) to allow phots to be shared to other social networks. Create a news feed which shows users all of the latest photos from their friends, and allows them to post their own images to it. Give all registered users their own wall/page which has their latest posts/images displayed on it. Add the ability to allow users to follow other users, and display their followed users posts on their news feed. Yep. It's not going to be easy, and I don't even know if it's possible for me to do alone in Eclipse. However, this is the plan, and I'm going to do my best to learn everything I need to know to do this successfully. My actual question would be how should I start doing this- where do I begin learning how to do all of this? I've had a look at snapify, which can be edited via Parse, but I won't be spending hundreds of dollars (since I'm 15 and just don't have the available funds) on software. I have extensive knowledge of Java (again, I've been making games for around 3 years, mainly in Java), and various scripting languages. So, hopefully, this will be of some use here. Thanks in advance, Josh.

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  • cloud programming for OpenStack in C / C++

    - by Basile Starynkevitch
    (Sorry for such a fuzzy question, I am very newbie to cloud programming) I am interested in designing (and developing) a (free software) program in C or C++ (probably, most of it being meta-programmed, i.e. part of the C code code being generated). I am still in the thinking / designing phase. And I might perhaps give up. For reference, I am the main architect and implementor of GCC MELT, a domain specific language to extend the GCC compiler (the MELT language is translated to C/C++ and is bootstrapped: the MELT to C/C++ translator being written in MELT). And I am dreaming of extending it with some cloud computing abilities. But I am a newbie in cloud computing. (I am only interested in free-software, GPLv3 friendly, based cloud computing, which probably means openstack). I believe that "compiling on the cloud with some enhanced GCC" could make sense (for super-optimizations or static analysis of e.g. an entire Linux distribution, or at least a massive GCC compiled free software like Qt, GCC itself, or the Linux kernel). I'm dreaming of a MELT specific monitoring program which would store, communicate, and and enhance GCC compilation (extended by MELT). So the picture would be that each GCC process (actually the cc1 or cc1plus started by the gcc driver, suitably extended by some MELT extension) would communicate with some monitor. That "monitoring/persisting" program would run "on the cloud" (and probably manage some information produced by GCC e.g. on NoSQL bases). So, how should some (yet to be written) C program (some Linux daemon) be designed to be cloud-friendly? So far, I understood that it should provide some Web service, probably thru a RESTful service, so should use an HTTP server library like onion. And that OpenStack is able to start (e.g. a dozen of) such services. But I don't have a clear picture of what OpenStack brings. So far, I noticed the ability to manage (and distribute) virtual machines (with some Python API). It is less clear how can it distribute some ELF executable, how can it start it, etc. Do you have any references or examples of C / C++ programming on the cloud? How should a "cloud-friendly" (actually, OpenStack friendly) C/C++ server application be designed?

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  • What's the best way to create a static utility class in python? Is using metaclasses code smell?

    - by rsimp
    Ok so I need to create a bunch of utility classes in python. Normally I would just use a simple module for this but I need to be able to inherit in order to share common code between them. The common code needs to reference the state of the module using it so simple imports wouldn't work well. I don't like singletons, and classes that use the classmethod decorator do not have proper support for python properties. One pattern I see used a lot is creating an internal python class prefixed with an underscore and creating a single instance which is then explicitly imported or set as the module itself. This is also used by fabric to create a common environment object (fabric.api.env). I've realized another way to accomplish this would be with metaclasses. For example: #util.py class MetaFooBase(type): @property def file_path(cls): raise NotImplementedError def inherited_method(cls): print cls.file_path #foo.py from util import * import env class MetaFoo(MetaFooBase): @property def file_path(cls): return env.base_path + "relative/path" def another_class_method(cls): pass class Foo(object): __metaclass__ = MetaFoo #client.py from foo import Foo file_path = Foo.file_path I like this approach better than the first pattern for a few reasons: First, instantiating Foo would be meaningless as it has no attributes or methods, which insures this class acts like a true single interface utility, unlike the first pattern which relies on the underscore convention to dissuade client code from creating more instances of the internal class. Second, sub-classing MetaFoo in a different module wouldn't be as awkward because I wouldn't be importing a class with an underscore which is inherently going against its private naming convention. Third, this seems to be the closest approximation to a static class that exists in python, as all the meta code applies only to the class and not to its instances. This is shown by the common convention of using cls instead of self in the class methods. As well, the base class inherits from type instead of object which would prevent users from trying to use it as a base for other non-static classes. It's implementation as a static class is also apparent when using it by the naming convention Foo, as opposed to foo, which denotes a static class method is being used. As much as I think this is a good fit, I feel that others might feel its not pythonic because its not a sanctioned use for metaclasses which should be avoided 99% of the time. I also find most python devs tend to shy away from metaclasses which might affect code reuse/maintainability. Is this code considered code smell in the python community? I ask because I'm creating a pypi package, and would like to do everything I can to increase adoption.

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  • Oracle At QCon SF 2012

    - by Cassandra Clark - OTN
    Oracle Technology Network is a Platinum sponsor at QCon San Francisco.  (qconsf.com).  Don’t miss these great developer focused sessions: Shay ShmeltzerHow we simplified Web, Mobile and Cloud development for our own developers? - the Oracle StoryOver the past several years, Oracle has beendeveloping a new set of enterprise applications in what is probably one of thelargest Java based development project in the world. How do you take 3000 developers and make them productive? How do you insure the delivery of cutting edge UIs for both Mobile and Web channels? How do you enable Cloud baseddevelopment and deployment?  Come and learn how we did it at Oracle, and see how the same technologies and methodologies can apply to your development efforts. Dan SmithProject Lambda in Java 8Java SE 8 will include major enhancements to the Java Programming Language and its core libraries.  This suite of new features, known as Project Lambda in the OpenJDK community, includes lambda expressions, default methods, and parallel collections (and much more!).  The result will be a next-generation Java programming experience with more flexibility and better abstractions.   This talk will introduce the new Java features and offer a behind-the-scenes view of how they evolved and why they work the way that they do. Arun GuptaJSR 356: Building HTML5 WebSocket Applications in JavaThe family of HTML5 technologies has pushed the pendulum away from rich client technologies and toward ever-more-capable Web clients running on today’s browsers. In particular, WebSocket brings new opportunities for efficient peer-to-peer communication, providing the basis for a new generation of interactive and “live” Web applications. This session examines the efforts under way to support WebSocket in the Java programming model, from its base-level integration in the Java Servlet and Java EE containers to a new, easy-to-use API and toolset that are destined to become part of the standard Java platform. The full conference schedule is here: http://qconsf.com/sf2012/schedule/wednesday.jsp But wait, there’s more!  At the Oracle booth, we’ll also be covering: ·         Oracle ADF Mobile·         Oracle Developer Cloud Service·         Oracle ADF Essentials·         NetBeans Project Easel Lastly we’ll share the results of a short cloud survey at QConSF ater this week.  If you attended this year's Oracle OpenWorld and JavaOne conferences, it would be hard not to notice that Oracle is clearly "all-in" when it comes to the Cloud.  With Cloud computing being such a hot topic on many OTN members' minds, we'd like to know what you're doing in the cloud and invite you to take this short cloud survey.

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  • Should a server "be lenient" in what it accepts and "discard faulty input silently"?

    - by romkyns
    I was under the impression that by now everyone agrees this maxim was a mistake. But I recently saw this answer which has a "be lenient" comment upvoted 137 times (as of today). In my opinion, the leniency in what browsers accept was the direct cause of the utter mess that HTML and some other web standards were a few years ago, and have only recently begun to properly crystallize out of that mess. The way I see it, being lenient in what you accept will lead to this. The second part of the maxim is "discard faulty input silently, without returning an error message unless this is required by the specification", and this feels borderline offensive. Any programmer who has banged their head on the wall when something fails silently will know what I mean. So, am I completely wrong about this? Should my program be lenient in what it accepts and swallow errors silently? Or am I mis-interpreting what this is supposed to mean? The original question said "program", and I take everyone's point about that. It can make sense for programs to be lenient. What I really meant, however, is APIs: interfaces exposed to other programs, rather than people. HTTP is an example. The protocol is an interface that only other programs use. People never directly provide the dates that go into headers like "If-Modified-Since". So, the question is: should the server implementing a standard be lenient and allow dates in several other formats, in addition to the one that's actually required by the standard? I believe the "be lenient" is supposed to apply to this situation, rather than human interfaces. If the server is lenient, it might seem like an overall improvement, but I think in practice it only leads to client implementations that end up relying on the leniency and thus failing to work with another server that's lenient in slightly different ways. So, should a server exposing some API be lenient or is that a very bad idea? Now onto lenient handling of user input. Consider YouTrack (a bug tracking software). It uses a language for text entry that is reminiscent of Markdown. Except that it's "lenient". For example, writing - foo - bar - baz is not a documented way of creating a bulleted list, and yet it worked. Consequently, it ended up being used a lot throughout our internal bugtracker. Next version comes out, and this lenient feature starts working slightly differently, breaking a bunch of lists that (mis)used this (non)feature. The documented way to create bulleted lists still works, of course. So, should my software be lenient in what user inputs it accepts?

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  • Java: How to manage UDP client-server state

    - by user92947
    I am trying to write a Java application that works similar to MapReduce. There is a server and several workers. Workers may come and go as they please and the membership to the group has a soft-state. To become a part of the group, the worker must send a UDP datagram to the server, but to continue to be part of the group, the worker must send the UDP datagram to the server every 5 minutes. In order to accommodate temporary errors, a worker is allowed to miss as many as two consecutive periodic UDP datagrams. So, the server must keep track of the current set of workers as well as the last time each worker had sent a UDP datagram. I've implemented a class called WorkerListener that implements Runnable and listens to UDP datagrams on a particular UDP port. Now, to keep track of active workers, this class may maintain a HashSet (or HashMap). When a datagram is received, the server may query the HashSet to check if it is a new member. If so, it can add the new worker to the group by adding an entry into the HashSet. If not, it must reset a "timer" for the worker, noting that it has just heard from the corresponding worker. I'm using the word timer in a generic sense. It doesn't have to be a clock of sorts. Perhaps this could also be implemented using int or long variables. Also, the server must run a thread that continuously monitors the timers for the workers to see that a client that times out on two consecutive datagram intervals, it is removed from the HashSet. I don't want to do this in the WorkerListener thread because it would be blocking on the UDP datagram receive() function. If I create a separate thread to monitor the worker HashSet, it would need to be a different class, perhaps WorkerRegistrar. I must share the HashSet with that thread. Mutual exclusion must also be implemented, then. My question is, what is the best way to do this? Pointers to some sample implementation would be great. I want to use the barebones JDK implementation, and not some fancy state maintenance API that takes care of everything, because I want this to be a useful demonstration for a class that I am teaching. Thanks

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  • .Net Application & Database Modularity/Reuse

    - by Martaver
    I'm looking for some guidance on how to architect an app with regards to modularity, separation of concerns and re-usability. I'm working on an application (ASP.Net, C#) that has distinctly generic chunks of functionality, that I'd love to be able to lift out, all layers, into re-usable components. This means the module handles the database schema, data access, API, everything so that the next time I want to use it I can just register the module and hook into it. Developing modules of re-usable functionality is a no-brainer, but what is really confusing me is what to do when it comes to handling a core re-usable database schema that serves the module's functionality. In an ideal world, I would register a module and it would ensure that the associated database schema exists in the DB. I would code on the assumption that the tables exist, calling the module's functionality through the DLL, agnostic of the database layer. Kind of like Enterprise Library's Caching/Logging Application Block, which can create a DB schema in the target DB to use as a data store. My Questions is: What do you think is the best way to achieve this, firstly, in terms design architecture, and secondly solution structure. What patterns/frameworks do you know that exist & support this kind of thing? My thoughts so far: I mostly use Entity Framework and SQL Server DB Projects. I thought about a 'black box' approach to modules of functionality. I could use use a code-first approach in EF4, and use the ObjectContext to create a database when the module is initialized. However this means that all of the entities that my module encapsulates would be disconnected from the rest of the application because they belonged to an abstracted ObjectContext. Further - Creating appropriate indexes and references between domain entities and the module's entities would be impossible to do practically. I've thought of adopting Enterprise Library and creating my own Application Blocks. I'm not sure how this would play nice with Entity Framework (if at all) though. I like the idea of building on proven patterns & practices to encapsulate established, reusable functionality. I thought of abandoning Entity Framework for the Module, and just creating a separate DB schema for the module with its own set of stored procedures & ADO.Net. Then deploying the script at run-time if interrogation shows that it doesn't exist. But once again, for application developing outside of the application, I would want to use Entity Framework and I would have to use the module separately, disconnected from the domain ObjectContext. Has anyone had experience developing these sorts of full-stack modules? What advice can you offer? Am I biting off more than I can chew?

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  • Is code like this a "train wreck" (in violation of Law of Demeter)?

    - by Michael Kjörling
    Browsing through some code I've written, I came across the following construct which got me thinking. At a first glance, it seems clean enough. Yes, in the actual code the getLocation() method has a slightly more specific name which better describes exactly which location it gets. service.setLocation(this.configuration.getLocation().toString()); In this case, service is an instance variable of a known type, declared within the method. this.configuration comes from being passed in to the class constructor, and is an instance of a class implementing a specific interface (which mandates a public getLocation() method). Hence, the return type of the expression this.configuration.getLocation() is known; specifically in this case, it is a java.net.URL, whereas service.setLocation() wants a String. Since the two types String and URL are not directly compatible, some sort of conversion is required to fit the square peg in the round hole. However, according to the Law of Demeter as cited in Clean Code, a method f in class C should only call methods on C, objects created by or passed as arguments to f, and objects held in instance variables of C. Anything beyond that (the final toString() in my particular case above, unless you consider a temporary object created as a result of the method invocation itself, in which case the whole Law seems to be moot) is disallowed. Is there a valid reasoning why a call like the above, given the constraints listed, should be discouraged or even disallowed? Or am I just being overly nitpicky? If I were to implement a method URLToString() which simply calls toString() on a URL object (such as that returned by getLocation()) passed to it as a parameter, and returns the result, I could wrap the getLocation() call in it to achieve exactly the same result; effectively, I would just move the conversion one step outward. Would that somehow make it acceptable? (It seems to me, intuitively, that it should not make any difference either way, since all that does is move things around a little. However, going by the letter of the Law of Demeter as cited, it would be acceptable, since I would then be operating directly on a parameter to a function.) Would it make any difference if this was about something slightly more exotic than calling toString() on a standard type? When answering, do keep in mind that altering the behavior or API of the type that the service variable is of is not practical. Also, for the sake of argument, let's say that altering the return type of getLocation() is also impractical.

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  • Help identify the pattern for reacting on updates

    - by Mike
    There's an entity that gets updated from external sources. Update events are at random intervals. And the entity has to be processed once updated. Multiple updates may be multiplexed. In other words there's a need for the most current state of entity to be processed. There's a point of no-return during processing where the current state (and the state is consistent i.e. no partial update is made) of entity is saved somewhere else and processing goes on independently of any arriving updates. Every consequent set of updates has to trigger processing i.e. system should not forget about updates. And for each entity there should be no more than one running processing (before the point of no-return) i.e. the entity state should not be processed more than once. So what I'm looking for is a pattern to cancel current processing before the point of no return or abandon processing results if an update arrives. The main challenge is to minimize race conditions and maintain integrity. The entity sits mainly in database with some files on disk. And the system is in .NET with web-services and message queues. What comes to my mind is a database queue-like table. An arriving update inserts row in that table and the processing is launched. The processing gathers necessary data before the point of no-return and once it reaches this barrier it looks into the queue table and checks whether there're more recent updates for the entity. If there are new updates the processing simply shuts down and its data is discarded. Otherwise the processing data is persisted and it goes beyond the point of no-return. Though it looks like a solution to me it is not quite elegant and I believe this scenario may be supported by some sort of middleware. If I would use message queues for this then there's a need to access the queue API in the point of no-return to check for the existence of new messages. And this approach also lacks elegance. Is there a name for this pattern and an existing solution?

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  • iOS Support with Windows Azure Mobile Services – now with Push Notifications

    - by ScottGu
    A few weeks ago I posted about a number of improvements to Windows Azure Mobile Services. One of these was the addition of an Objective-C client SDK that allows iOS developers to easily use Mobile Services for data and authentication.  Today I'm excited to announce a number of improvement to our iOS SDK and, most significantly, our new support for Push Notifications via APNS (Apple Push Notification Services).  This makes it incredibly easy to fire push notifications to your iOS users from Windows Azure Mobile Service scripts. Push Notifications via APNS We've provided two complete tutorials that take you step-by-step through the provisioning and setup process to enable your Windows Azure Mobile Service application with APNS (Apple Push Notification Services), including all of the steps required to configure your application for push in the Apple iOS provisioning portal: Getting started with Push Notifications - iOS Push notifications to users by using Mobile Services - iOS Once you've configured your application in the Apple iOS provisioning portal and uploaded the APNS push certificate to the Apple provisioning portal, it's just a matter of uploading your APNS push certificate to Mobile Services using the Windows Azure admin portal: Clicking the “upload” within the “Push” tab of your Mobile Service allows you to browse your local file-system and locate/upload your exported certificate.  As part of this you can also select whether you want to use the sandbox (dev) or production (prod) Apple service: Now, the code to send a push notification to your clients from within a Windows Azure Mobile Service is as easy as the code below: push.apns.send(deviceToken, {      alert: 'Toast: A new Mobile Services task.',      sound: 'default' }); This will cause Windows Azure Mobile Services to connect to APNS (Apple Push Notification Service) and send a notification to the iOS device you specified via the deviceToken: Check out our reference documentation for full details on how to use the new Windows Azure Mobile Services apns object to send your push notifications. Feedback Scripts An important part of working with any PNS (Push Notification Service) is handling feedback for expired device tokens and channels. This typically happens when your application is uninstalled from a particular device and can no longer receive your notifications. With Windows Notification Services you get an instant response from the HTTP server.  Apple’s Notification Services works in a slightly different way and provides an additional endpoint you can connect to poll for a list of expired tokens. As with all of the capabilities we integrate with Mobile Services, our goal is to allow developers to focus more on building their app and less on building infrastructure to support their ideas. Therefore we knew we had to provide a simple way for developers to integrate feedback from APNS on a regular basis.  This week’s update now includes a new screen in the portal that allows you to optionally provide a script to process your APNS feedback – and it will be executed by Mobile Services on an ongoing basis: This script is invoked periodically while your service is active. To poll the feedback endpoint you can simply call the apns object's getFeedback method from within this script: push.apns.getFeedback({       success: function(results) {           // results is an array of objects with a deviceToken and time properties      } }); This returns you a list of invalid tokens that can now be removed from your database. iOS Client SDK improvements Over the last month we've continued to work with a number of iOS advisors to make improvements to our Objective-C SDK. The SDK is being developed under an open source license (Apache 2.0) and is available on github. Many of the improvements are behind the scenes to improve performance and memory usage. However, one of the biggest improvements to our iOS Client API is the addition of an even easier login method.  Below is the Objective-C code you can now write to invoke it: [client loginWithProvider:@"twitter"                     onController:self                        animated:YES                      completion:^(MSUser *user, NSError *error) {      // if no error, you are now logged in via twitter }]; This code will automatically present and dismiss our login view controller as a modal dialog on the specified controller.  This does all the hard work for you and makes login via Twitter, Google, Facebook and Microsoft Account identities just a single line of code. My colleague Josh just posted a short video demonstrating these new features which I'd recommend checking out: Summary The above features are all now live in production and are available to use immediately.  If you don’t already have a Windows Azure account, you can sign-up for a free trial and start using Mobile Services today. Visit the Windows Azure Mobile Developer Center to learn more about how to build apps with Mobile Services. Hope this helps, Scott P.S. In addition to blogging, I am also now using Twitter for quick updates and to share links. Follow me at: twitter.com/scottgu

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  • What arguments can I use to "sell" the BDD concept to a team reluctant to adopt it?

    - by S.Robins
    I am a bit of a vocal proponent of the BDD methodology. I've been applying BDD for a couple of years now, and have adopted StoryQ as my framework of choice when developing DotNet applications. Even though I have been unit testing for many years, and had previously shifted to a test-first approach, I've found that I get much more value out of using a BDD framework, because my tests capture the intent of the requirements in relatively clear English within my code, and because my tests can execute multiple assertions without ending the test halfway through - meaning I can see which specific assertions pass/fail at a glance without debugging to prove it. This has really been the tip of the iceberg for me, as I've also noticed that I am able to debug both test and implementation code in a more targeted manner, with the result that my productivity has grown significantly, and that I can more easily determine where a failure occurs if a problem happens to make it all the way to the integration build due to the output that makes its way into the build logs. Further, the StoryQ api has a lovely fluent syntax that is easy to learn and which can be applied in an extraordinary number of ways, requiring no external dependencies in order to use it. So with all of these benefits, you would think it an easy to introduce the concept to the rest of the team. Unfortunately, the other team members are reluctant to even look at StoryQ to evaluate it properly (let alone entertain the idea of applying BDD), and have convinced each other to try and remove a number of StoryQ elements from our own core testing framework, even though they originally supported the use of StoryQ, and that it doesn't impact on any other part of our testing system. Doing so would end up increasing my workload significantly overall and really goes against the grain, as I am convinced through practical experience that it is a better way to work in a test-first manner in our particular working environment, and can only lead to greater improvements in the quality of our software, given I've found it easier to stick with test first using BDD. So the question really comes down to the following: What arguments can I use to really drive the point home that it would be better to use StoryQ, or at the very least apply the BDD methodology? Can you point me to any anecdotal evidence that I can use to support my argument to adopt BDD as our standard method of choice? What counter arguments can you think of that could suggest that my wish to convert the team efforts to BDD might be in error? Yes, I'm happy to be proven wrong provided the argument is a sound one. NOTE: I am not advocating that we rewrite our tests in their entirety, but rather to simply start working in a different manner for all future testing work.

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  • LINQ and ArcObjects

    - by Marko Apfel
    Motivation LINQ (language integrated query) is a component of the Microsoft. NET Framework since version 3.5. It allows a SQL-like query to various data sources such as SQL, XML etc. Like SQL also LINQ to SQL provides a declarative notation of problem solving – i.e. you don’t need describe in detail how a task could be solved, you describe what to be solved at all. This frees the developer from error-prone iterator constructs. Ideally, of course, would be to access features with this way. Then this construct is conceivable: var largeFeatures = from feature in features where (feature.GetValue("SHAPE_Area").ToDouble() > 3000) select feature; or its equivalent as a lambda expression: var largeFeatures = features.Where(feature => (feature.GetValue("SHAPE_Area").ToDouble() > 3000)); This requires an appropriate provider, which manages the corresponding iterator logic. This is easier than you might think at first sight - you have to deliver only the desired entities as IEnumerable<IFeature>. LINQ automatically establishes a state machine in the background, whose execution is delayed (deferred execution) - when you are really request entities (foreach, Count (), ToList (), ..) an instantiation processing takes place, although it was already created at a completely different place. Especially in multiple iteration through entities in the first debuggings you are rubbing your eyes when the execution pointer jumps magically back in the iterator logic. Realization A very concise logic for constructing IEnumerable<IFeature> can be achieved by running through a IFeatureCursor. You return each feature via yield. For an easier usage I have put the logic in an extension method Getfeatures() for IFeatureClass: public static IEnumerable<IFeature> GetFeatures(this IFeatureClass featureClass, IQueryFilter queryFilter, RecyclingPolicy policy) { IFeatureCursor featureCursor = featureClass.Search(queryFilter, RecyclingPolicy.Recycle == policy); IFeature feature; while (null != (feature = featureCursor.NextFeature())) { yield return feature; } //this is skipped in unit tests with cursor-mock if (Marshal.IsComObject(featureCursor)) { Marshal.ReleaseComObject(featureCursor); } } So you can now easily generate the IEnumerable<IFeature>: IEnumerable<IFeature> features = _featureClass.GetFeatures(RecyclingPolicy.DoNotRecycle); You have to be careful with the recycling cursor. After a delayed execution in the same context it is not a good idea to re-iterated on the features. In this case only the content of the last (recycled) features is provided and all the features are the same in the second set. Therefore, this expression would be critical: largeFeatures.ToList(). ForEach(feature => Debug.WriteLine(feature.OID)); because ToList() iterates once through the list and so the the cursor was once moved through the features. So the extension method ForEach() always delivers the same feature. In such situations, you must not use a recycling cursor. Repeated executions of ForEach() is not a problem, because for every time the state machine is re-instantiated and thus the cursor runs again - that's the magic already mentioned above. Perspective Now you can also go one step further and realize your own implementation for the interface IEnumerable<IFeature>. This requires that only the method and property to access the enumerator have to be programmed. In the enumerator himself in the Reset() method you organize the re-executing of the search. This could be archived with an appropriate delegate in the constructor: new FeatureEnumerator<IFeatureclass>(_featureClass, featureClass => featureClass.Search(_filter, isRecyclingCursor)); which is called in Reset(): public void Reset() { _featureCursor = _resetCursor(_t); } In this manner, enumerators for completely different scenarios could be implemented, which are used on the client side completely identical like described above. Thus cursors, selection sets, etc. merge into a single matter and the reusability of code is increasing immensely. On top of that in automated unit tests an IEnumerable could be mocked very easily - a major step towards better software quality. Conclusion Nevertheless, caution should be exercised with these constructs in performance-relevant queries. Because of managing a state machine in the background, a lot of overhead is created. The processing costs additional time - about 20 to 100 percent. In addition, working without a recycling cursor is fast a performance gap. However declarative LINQ code is much more elegant, flawless and easy to maintain than manually iterating, compare and establish a list of results. The code size is reduced according to experience an average of 75 to 90 percent! So I like to wait a few milliseconds longer. As so often it has to be balanced between maintainability and performance - which for me is gaining in priority maintainability. In times of multi-core processors, the processing time of most business processes is anyway not dominated by code execution but by waiting for user input. Demo source code The source code for this prototype with several unit tests, you can download here: https://github.com/esride-apf/Linq2ArcObjects. .

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  • Defining a service layer: the text-based adventure

    - by Stacy Vicknair
    Applications these days have more options than ever for a user interface, and it’s only going to grow. A successful product might require native applications for mobile devices, a regular web implementation, or even a gaming console. These systems often will be centralized and data driven. The solution is one that’s fairly solitary, a service layer! Simply put, take what’s shared and put it behind a physical or abstract layer that defines the boundary between the specific user interface and the shared content.   I know, I know, none of this is complicated. But some times it can be difficult to discern what belongs on which side of the line. For instance, say we’re creating a service that will provide content for both an ASP.NET MVC application and a WP7 application. Although the content served to each application is the same, there are different paradigms and patterns for displaying that data in the different environments. In ASP.NET MVC, you may create a model specific to a page that combines necessary information. In the WP7 application you might require different sets of data that you will connect via MVVM with the view. The general rule of thumb is that any shared content, business rules, or data should exist separately. Any element that is specific to the current UI implementation should be included in a separate library or with the UI implementation itself. The WP7 application doesn’t need my MVC specific model classes. My MVC application doesn’t require those INotifyPropertyChanged viewmodels that the WP7 application depends on. In both cases, there should be additional processing done above the service layer to massage the data to the application’s specific needs.   Service-ocalypse: the text based adventure What helps me the most about deciding whether or not something belongs coupled to the UI implementation or in the shared implementation is thinking of the simplest implementation you could have: a console application. You might have played a game like Peasant’s Quest: The console app is the text based adventure game version of your application. If you’re service was consumed in its simplest form, you would simply have a console based API for it that issues requests. Maybe those requests aren’t SWIM TO BOAT, but they might be CREATE USER JOHN. If I issue a request, I expect that request to be issued to the service. If the service has any exceptions or issues with my input, that business logic should be encapsulated in that service, not implemented in the UI. The service layer should be your functional application in its entirety, and anything above that layer should only assist with the display of that information.

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  • Should accessible members of an internal class be internal too?

    - by Jeff Mercado
    I'm designing a set of APIs for some applications I'm working on. I want to keep the code style consistent in all the classes I write but I've found that there are a few inconsistencies that I'm introducing and I don't know what the best way to resolve them is. My example here is specific to C# but this would apply to any language with similar mechanisms. There are a few classes that I need for implementation purposes that I don't necessarily want to expose in the API so I make them internal whereever needed. Generally what I would do is design the class as I normally would (e.g., make members public/protected/private where necessary) and change the visibility level of the class itself to internal. So I might have a few classes that look like this: internal interface IMyItem { ItemSet AddTo(ItemSet set); } internal class _SmallItem : IMyItem { private readonly /* parameters */; public _SmallItem(/* small item parameters */) { /* ... */ } public ItemSet AddTo(ItemSet set) { /* ... */ } } internal abstract class _CompositeItem: IMyItem { private readonly /* parameters */; public _CompositeItem(/* composite item parameters */) { /* ... */ } public abstract object UsefulInformation { get; } protected void HelperMethod(/* parameters */) { /* ... */ } } internal class _BigItem : _CompositeItem { private readonly /* parameters */; public _BigItem(/* big item parameters */) { /* ... */ } public override object UsefulInformation { get { /* ... */ } } public ItemSet AddTo(ItemSet set) { /* ... */ } } In another generated class (part of a parser/scanner), there is a structure that contains fields for all possible values it can represent. The class generated is internal too but I have control over the visibility of the members and decided to make them internal as well. internal partial struct ValueType { internal string String; internal ItemSet ItemSet; internal IMyItem MyItem; } internal class TokenValue { internal static int EQ(ItemSetScanner scanner) { /* ... */ } internal static int NAME(ItemSetScanner scanner, string value) { /* ... */ } internal static int VALUE(ItemSetScanner scanner, string value) { /* ... */ } //... } To me, this feels odd because the first set of classes, I didn't necessarily have to make some members public, they very well could have been made internal. internal members of an internal type can only be accessed internally anyway so why make them public? I just don't like the idea that the way I write my classes has to change drastically (i.e., change all uses of public to internal) just because the class is internal. Any thoughts on what I should do here? It makes sense to me that I might want to make some members of a class declared public, internal. But it's less clear to me when the class is declared internal.

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  • LINQ to Twitter v2.1.09 Released

    - by Joe Mayo
    Originally posted on: http://geekswithblogs.net/WinAZ/archive/2013/10/15/linq-to-twitter-v2.1.09-released.aspxToday, I released LINQ to Twitter v2.1.09. Here are important new changes. Bug Fixes This is primarily a bug fix release. Most notably, there were authentication problems in WinRT apps. This is now fixed. New Features One new feature is the addition of ApplicationOnlyAuthentication for WinRT. It is fully async.  Here’s how it works: var auth = new WinRtApplicationOnlyAuthorizer { Credentials = new InMemoryCredentials { ConsumerKey = "", ConsumerSecret = "" } }; if (auth == null || !auth.IsAuthorized) { await auth.AuthorizeAsync(); } var twitterCtx = new TwitterContext(auth); (from search in twitterCtx.Search where search.Type == SearchType.Search && search.Query == SearchTextBox.Text select search) .MaterializedAsyncCallback( async response => await Dispatcher.RunAsync( CoreDispatcherPriority.Normal, async () => { Search searchResponse = response.State.Single(); string message = string.Format( "Search returned {0} statuses", searchResponse.Statuses.Count); await new MessageDialog(message, "Search Complete").ShowAsync(); })); It’s called the WinRtApplicationOnlyAuthorizer. You only need two tokens, ConsumerKey and ConsumerSecret, which come from your Twitter API application settings page. Note: You need a Twitter Application, which you can create at https://dev.twitter.com/. The MaterializedAsyncCallback materializes your query and handles the response. I put everything together in a lambda for demonstration purposes, but you can always replace the callback with a handler of type Action<TwitterAsyncResponse<IEnumerable<T>>>, where T is Search for this example. On the Horizon The next version of LINQ to Twitter is in development. I discussed it at LINQ to Twitter Async. This isn’t complete, but you can download the source code at the LINQ to Twitter site on CodePlex. I’ve competed all the spikes for what I thought would be the hard parts and now have prototypes of queries and commands working. This would be a good time to provide feedback if there are features in the current version that you think could be improved. The current driving forces for the next version will be async and PCL.   @JoeMayo

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  • How to snap a 2D Quad to the mouse cursor using OpenGL 3.0/WIN32?

    - by NoobScratcher
    I've been having issues trying to snap a 2D Quad to the mouse cursor position I'm able : 1.) To get values into posX, posY, posZ 2.) Translate with the values from those 3 variables But the quad positioning I'm not able to do correctly in such a way that the 2D Quad is near the mouse cursor using those values from those 3 variables eg."posX, posY, posZ" I need the mouse cursor in the center of the 2D Quad. I'm hoping someone can help me achieve this. I've tried searching around with no avail. Heres the function that is ment to do the snapping but instead creates weird flicker or shows nothing at all only the 3d models show up : void display() { glClearColor(0.0,0.0,0.0,1.0); glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT); for(std::vector<GLuint>::iterator I = cube.begin(); I != cube.end(); ++I) { glCallList(*I); } if(DrawArea == true) { glReadPixels(winX, winY, 1, 1, GL_DEPTH_COMPONENT, GL_FLOAT, &winZ); cerr << winZ << endl; glGetDoublev(GL_MODELVIEW_MATRIX, modelview); glGetDoublev(GL_PROJECTION_MATRIX, projection); glGetIntegerv(GL_VIEWPORT, viewport); gluUnProject(winX, winY, winZ , modelview, projection, viewport, &posX, &posY, & posZ); glBindTexture(GL_TEXTURE_2D, DrawAreaTexture); glPixelStorei(GL_UNPACK_ALIGNMENT, 1); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL); glTexImage2D (GL_TEXTURE_2D, 0, GL_RGB, DrawAreaSurface->w, DrawAreaSurface->h, 0, GL_RGBA, GL_UNSIGNED_BYTE, DrawAreaSurface->pixels); glEnable(GL_TEXTURE_2D); glBindTexture(GL_TEXTURE_2D, DrawAreaTexture); glTranslatef(posX , posY, posZ); glBegin(GL_QUADS); glTexCoord2f (0.0, 0.0); glVertex3f(0.5, 0.5, 0); glTexCoord2f (1.0, 0.0); glVertex3f(0, 0.5, 0); glTexCoord2f (1.0, 1.0); glVertex3f(0, 0, 0); glTexCoord2f (0.0, 1.0); glVertex3f(0.5, 0, 0); glEnd(); } SwapBuffers(hDC); } I'm using : OpenGL 3.0 WIN32 API C++ GLSL if you really want the full source here it is - http://pastebin.com/1Ncm9HNf , Its pretty messy.

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  • Understanding exceptional cases

    - by Justin
    I've been studying the use of exceptions in various php projects (such as Doctrine and Zend Framework). Exceptions seem to be thrown when unordinary input/state occurs. A perfect example is Doctrine throwing an exception when you try to use a invalid query string. I think the creators of the doctrine api understood that first, you can't query data by using an invalid DQL statement, and a developer should immediately be warned that an error has occurred, rather then letting execution continue with the possibility of an error code going un-checked. I also bet that this simplifies reading the code. I can't think of a situation where you would want to use an invalid DQL statement, except unit testing. Since this is true, it's better to avoid plaguing a bunch of code with null/error checks and use exceptions. I've read in books that exceptions shouldn't be thrown when validating dating user input. I've seen examples where of where the guideline is broken. One example is the Zend framework. If supplying an invalid controller or action name, an exception is thrown. Unlike doctrine, the user has more direct control over this sort of input. I know you can configure an error controller and set up a 404 message or what have you, but I'm curious why they have used an exception in this scenario? I guess you can argue the Zend Framework does not know how to continue processing the quest. One last example Is I wrote a function to return some html based on a given resource type. This resource type is hard-coded and sent when a user interacts with a web site (such as clicking a button to display the form to input data). I don't expect users to be mucking around with the request type. Under normal operating conditions, the resource type should be valid. To clean up some logic, I was going to throw an exception if a particular form wasn't found. This is mainly to find the correct form associated with a resource type so proper validation can occur. Does this sound like a valid use case for an exception? Right now it's pretty trivial, but I do plan to implement a restful consumer and re-using a function to map resources to their validation services would be very useful. I can then catch the exception and based on the consumer, return an error message suitable for the request type...

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  • What will be the better way for data retrieval on application that needs to handle limited amount of data.?

    - by Milanix
    This is not really a coding question since, I am not adding any code in here. Since, adding my code snippets itself would make this question really long. Instead, I am pretty interested in knowing a better ways for data retrieval on application that needs to handle limited amount of data which isn't updated regularly. Let's take this example: I am writing an application which gets a schedule as an XML from server. I have written a logic in order to parse XML version and update database only if the version is newer than the local version. Although the update is checked automatically/manually on daily basis based on user preference, the actual version update happens only once per few months or so. Since, this is done by some other authority which doesn't provide API but, rather inform publicly on their changes. The actual XML contains a "(n number of groups)(days in a week) (n number of schedule)" . The group is usually 6 and the number of schedule is usually 2. So basically there would usually be only around 100 strings. Now although I have used SQLite at the moment. I want to know how to make update on database. Should I show progress dialog that the application is updating and exit the app when it's done? Since, my updates are infrequent i don't think this will really harm user experience but, is there any better ways to do it? Because I don't want update to be made when user is searching which is done using database. This will cause an database already open exception. Atleast I have faced this problem before. Is it better to rather parse XML every time when user wants to view certain things or to use SQLite? Since, I make lots of use of adapter in my app to create lists, will that degrade the performance? It would really be a great help if anyone can give me better overview about it. Or may be counter argument against each. Many thanks!

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  • How best to look up objects by label?

    - by dsollen
    I am writing the server backed by a pre-written API. I'm going to get a number of strings representing ports, signals, paths, etc etc etc. I need to look up the object associated with a given label, these objects are all in memory (no sql magic to do this for me). My question is, how best do I associate a given unique label with the mutable object it represents? I have enough objects that looking through every signal or every port to find the one that matches is possible, but may be slightly too slow. To be honest the direct 'look at every object' method is probably good enough for so small a body of objects and anything else is premature optimization, but I still am curious what the proper solution would be if I thought my signals were going to grow a bit larger. As I see it there are two options available. First would be to to create a 'store' that is a simple map between object and label. I could have it so that every time I call addObject the object is automatically saved into a hashmap or the like. This works, but relies on my properly adding and deleting each object so the map doesn't grow indefinitely. The biggest issue to me is that this involves having some hidden static map in my ModelObject class that just feels...wrong somehow. The other option is to have some method that can interpret the labels. All of these labels are derived from the underlying objects. So I can look at the signal label, for instance, and say "these 20 characters are the port" to figure out what port I need. This would allow me to quickly figure out what I need. However, if the label method is changed the translateLabelToObject method needs to be updated as well or everything breaks. Which solution is cleaner, or possibly a cleaner solution than either of above? For the record I'm working with sufficient number of variables to make direct comparison a little slow, but not enough to be concerned about memory overhead, written in java. All objects that have labels I need to look up extend the same parent class.

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  • How to snap a 2D Quad to the mouse cursor using OpenGL 3.0?

    - by NoobScratcher
    I've been having issues trying to snap a 2D Quad to the mouse cursor position I'm able : 1.) To get values into posX, posY, posZ 2.) Translate with the values from those 3 variables But the quad positioning I'm not able to do correctly in such a way that the 2D Quad is near the mouse cursor using those values from those 3 variables eg."posX, posY, posZ" I need the mouse cursor in the center of the 2D Quad. I'm hoping someone can help me achieve this. I've tried searching around with no avail. Heres the function that is ment to do the snapping but instead creates weird flicker or shows nothing at all only the 3d models show up : void display() { glClearColor(0.0,0.0,0.0,1.0); glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT); for(std::vector<GLuint>::iterator I = cube.begin(); I != cube.end(); ++I) { glCallList(*I); } if(DrawArea == true) { glReadPixels(winX, winY, 1, 1, GL_DEPTH_COMPONENT, GL_FLOAT, &winZ); cerr << winZ << endl; glGetDoublev(GL_MODELVIEW_MATRIX, modelview); glGetDoublev(GL_PROJECTION_MATRIX, projection); glGetIntegerv(GL_VIEWPORT, viewport); gluUnProject(winX, winY, winZ , modelview, projection, viewport, &posX, &posY, & posZ); glBindTexture(GL_TEXTURE_2D, DrawAreaTexture); glPixelStorei(GL_UNPACK_ALIGNMENT, 1); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL); glTexImage2D (GL_TEXTURE_2D, 0, GL_RGB, DrawAreaSurface->w, DrawAreaSurface->h, 0, GL_RGBA, GL_UNSIGNED_BYTE, DrawAreaSurface->pixels); glEnable(GL_TEXTURE_2D); glBindTexture(GL_TEXTURE_2D, DrawAreaTexture); glTranslatef(posX , posY, posZ); glBegin(GL_QUADS); glTexCoord2f (0.0, 0.0); glVertex3f(0.5, 0.5, 0); glTexCoord2f (1.0, 0.0); glVertex3f(0, 0.5, 0); glTexCoord2f (1.0, 1.0); glVertex3f(0, 0, 0); glTexCoord2f (0.0, 1.0); glVertex3f(0.5, 0, 0); glEnd(); } SwapBuffers(hDC); } I'm using : OpenGL 3.0 WIN32 API C++ GLSL if you really want the full source here it is - http://pastebin.com/1Ncm9HNf , Its pretty messy.

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  • Development Approach: User Interface In or Domain Model Out?

    - by Berin Loritsch
    While I've never delivered anything using Smalltalk, my brief time playing with it has definitely left its mark. The only way to describe the experience is MVC the way it was meant to be. Essentially, all the heavy lifting for your application is done in the business objects (or domain model if you are so inclined). The standard controls are bound to the business objects in some way. For example, a text box is mapped to an object's field (the field itself is an object so it's easy to do). A button would mapped to a method. This is all done with a very simple and natural API. We don't have to think about binding objects, etc. It just works. Yet, in many newer languages and APIs you are forced to think from the outside in. First with C++ and MFC, and now with C# and WPF, Microsoft has gotten it's developer world hooked on GUI builders where you build your application by implementing event handlers. Java Swing development isn't so different, only you are writing the code to instantiate the controls on the form yourself. For some projects, there may never even be a domain model--just event handlers. I've been in and around this model for most of my carreer. Each way forces you to think differently. With the Smalltalk approach, your domain is smart while your GUI is dumb. With the default VisualStudio approach, your GUI is smart while your domain model (if it exists) is rather anemic. Many developers that I work with see value in the Smalltalk approach, and try to shoehorn that approach into the VisualStudio environment. WPF has some dynamic binding features that makes it possible; but there are limitations. Inevitably some code that belongs in the domain model ends up in the GUI classes. So, which way do you design/develop your code? Why? GUI first. User interaction is paramount. Domain first. I need to make sure the system is correct before we put a UI on it. There's pros and cons for either approach. Domain model fits in there with crystal cathedrals and pie in the sky. GUI fits in there with quick and dirty (sometimes really dirty). And for an added bonus: How do you make sure the code is maintainable?

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