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  • When designing an application around Model-View-Controller (MVC), what is in your toolbox?

    - by ericgorr
    There are a lot of great explanations for what the Model-View-Controller design pattern is, but I am having trouble finding good resources showing how to use it in practice. So, when you are starting a new application (doesn't matter what it is), what is in your toolbox? For example, it was suggested that using UML collaboration diagrams ( http://www.objectmentor.com/resources/articles/umlCollaborationDiagrams.pdf ) can be useful when designing an application around MVC, although, I am not certain exactly how or why this might be the case...? So, what is in your toolbox for MVC?

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  • Distinguishing between sets of status reports

    - by user1769486
    I am working on an internal database monitoring system and am at a point where I sort of hit the wall in terms of application design. Basically I have an extensible plugin architecture where I shall have an OK, a warning or an error upon running a db verification. My first question whether it is sufficient to have only one status reported with an optional status message or provide the ability to have more than one returned (with attached messages) and then calculate an aggregated overall status. In particular in the latter case my second issue would be how to distinguish between two verification reports with the same status code (as it can come from different triggers). I would need to do this to see whether some change happened between the current and last verification. I could simply have string comparisons of the attached status messages mentioned above but that does not seem very reliable.

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  • Glassfish alive or dead? WebLogic SE cost is less than Glassfish!

    - by JuergenKress
    Is a hot discussion in the community in the last few days! Send us your opinion on tiwtter @wlscommunity #Glassfish #WebLogicCommunity We posted theGlassFishStrategy.pptx at our WebLogic Community Workspace (WebLogic Community membership required). Please read also the Java EE and GlassFish Server Roadmap Update Bruno Borges ?Another great article covering story about #GlassFish. Comments starting to be reasonable ;-) 6 facts helped a lot http://adtmag.com/articles/2013/11/08/oracle-drops-glassfish.aspx … Adam Bien ?What Oracle Could Do For GlassFish Now: Move the sources to GitHub (GitHub is the most popular collaboration p... http://bit.ly/1d1uo24 JAXenter.com ?Oracle evangelist: “GlassFish Open Source Edition is not dead” http://jaxenter.com/oracle-evangelist-glassfish-open-source-edition-is-not-dead-48830.html … GlassFish 6 Facts About #GlassFish Announcement and the Future of #JavaEE http://bit.ly/1bbSVPf via @brunoborges David Blevins ?In support of our #GlassFish friends and open source in general: Feed the Fish http://www.tomitribe.com/blog/2013/11/feed-the-fish/ … #JavaEE #opensource #manifesto GlassFish ?GlassFish Server Open Source Edition 4.1 is scheduled for 2014. Version 5.0 as impl for #JavaEE8 https://blogs.oracle.com/theaquarium/entry/java_ee_and_glassfish_server … #Community focused C2B2 Consulting ?C2B2 continues to offer support for your operational #JEE applications running on #GlassFish http://blog.c2b2.co.uk/2013/11/oracle-dropping-commercial-support-of.html … #Java Markus Eisele ?RT @InfoQ: #GlassFish Commercial Edition is Dead http://bit.ly/17eFB0Z < at least they agree to my points... Adam Bien suggests: Move the sources to GitHub (GitHub is the most popular collaboration platform). It is more likely for an individual to contribute via GitHub, than the current infrastructure. Introduce a business friendlier license like e.g. the Apache license. Companies interesting in providing added value (and commercial support) on top of existing sources would appreciate it. Implement GitHub-based, open source, CI system with nightly builds. Introduce a transparent voting process / pull-request acceptance process. Release more frequently. Keep https://glassfish.java.net as the main hub. C2B2 offers Glassfish support by Steve Millidge Oracle have just announced that commercial support for GlassFish 4 will not be available from Oracle. In light of this announcement I thought I would put together some thoughts about how I see this development. I think the key word in this announcement is "commercial", nowhere does Oracle announce the "death of GlassFish" in contrary Oracle reaffirm; GlassFish Server Open Source Edition continues to be the strategic foundation for Java EE reference implementation going forward. And for developers, updates will be delivered as needed to continue to deliver a great developer experience for GlassFish Server Open Source Edition so GlassFish is not about to go away soon. In a similar fashion RedHat do not provide commercial support for WildFly and only provide commercial support for JBoss EAP. Admittedly JBoss EAP and WildFly are much closer together than GlassFish and WebLogic but WildFly and JBoss EAP are absolutely NOT the same thing. The key going forward to the viability of GlassFish as a production platform is how the GlassFish community develops; How often does the community release binary builds? How open is the community to bug fixes? How much engineering resource does Oracle commit to GlassFish? At this stage we just don't know the answers to these questions. If the GlassFish open source project continues on it's current trajectory without a commercial support offering then I don't see much of a problem. Oracle just have to work harder to sell migration paths to WebLogic in the same way as RedHat have to sell migration paths from WildFly to JBoss EAP. In the meantime C2B2 continues to offer support for your operational JEE applications running on GlassFish and we will endeavour to work with the community to get any bugs fixed. The key difference is we can no longer back our Expert Support with a support contract from Oracle for patches and fixes for any release greater than 3.x. Read the complete article here. 6 Facts About GlassFish Announcement By Bruno.Borges Fact #1 - GlassFish Open Source Edition is not dead GlassFish Server Open Source Edition will remain the reference implementation of Java EE. The current trunk is where an implementation for Java EE 8 will flourish, and this will become the future GlassFish 5.0. Calling "GlassFish is dead" does no good to the Java EE ecosystem. The GlassFish Community will remain strong towards the future of Java EE. Without revenue-focused mind, this might actually help the GlassFish community to shape the next version, and set free from any ties with commercial decisions. Fact #2 - OGS support is not over As I said before, GlassFish Server Open Source Edition will continue. Main change is that there will be no more future commercial releases of Oracle GlassFish Server. New and existing OGS 2.1.x and 3.1.x commercial customers will continue to be supported according to the Oracle Lifetime Support Policy. In parallel, I believe there's no other company in the Java EE business that offers commercial support to more than one build of a Java EE application server. This new direction can actually help customers and partners, simplifying decision through commercial negotiations. Fact #3 - WebLogic is not always more expensive than OGS Oracle GlassFish Server ("OGS") is a build of GlassFish Server Open Source Edition bundled with a set of commercial features called GlassFish Server Control and license bundles such as Java SE Support. OGS has at the moment of this writing the pricelist of U$ 5,000 / processor. One information that some bloggers are mentioning is that WebLogic is more expensive than this. Fact 3.1: it is not necessarily the case. The initial edition of WebLogic is called "Standard Edition" and falls into a policy where some “Standard Edition” products are licensed on a per socket basis. As of current pricelist, US$ 10,000 / socket. If you do the math, you will realize that WebLogic SE can actually be significantly more cost effective than OGS, and a customer can save money if running on a CPU with 4 cores or more for example. Quote from the price list: “When licensing Oracle programs with Standard Edition One or Standard Edition in the product name (with the exception of Java SE Support, Java SE Advanced, and Java SE Suite), a processor is counted equivalent to an occupied socket; however, in the case of multi-chip modules, each chip in the multi-chip module is counted as one occupied socket.” For more details speak to your Oracle sales representative - this is clearly at list price and every customer typically has a relationship with Oracle (like they do with other vendors) and different contractual details may apply. And although OGS has always been production-ready for Java EE applications, it is no secret that WebLogic has always been more enterprise, mission critical application server than OGS since BEA. Different editions of WLS provide features and upgrade irons like the WebLogic Diagnostic Framework, Work Managers, Side by Side Deployment, ADF and TopLink bundled license, Web Tier (Oracle HTTP Server) bundled licensed, Fusion Middleware stack support, Oracle DB integration features, Oracle RAC features (such as GridLink), Coherence Management capabilities, Advanced HA (Whole Service Migration and Server Migration), Java Mission Control, Flight Recorder, Oracle JDK support, etc. Fact #4 - There’s no major vendor supporting community builds of Java EE app servers There are no major vendors providing support for community builds of any Open Source application server. For example, IBM used to provide community support for builds of Apache Geronimo, not anymore. Red Hat does not commercially support builds of WildFly and if I remember correctly, never supported community builds of former JBoss AS. Oracle has never commercially supported GlassFish Server Open Source Edition builds. Tomitribe appears to be the exception to the rule, offering commercial support for Apache TomEE. Fact #5 - WebLogic and GlassFish share several Java EE implementations It has been no secret that although GlassFish and WebLogic share some JSR implementations (as stated in the The Aquarium announcement: JPA, JSF, WebSockets, CDI, Bean Validation, JAX-WS, JAXB, and WS-AT) and WebLogic understands GlassFish deployment descriptors, they are not from the same codebase. Fact #6 - WebLogic is not for GlassFish what JBoss EAP is for WildFly WebLogic is closed-source offering. It is commercialized through a license-based plus support fee model. OGS although from an Open Source code, has had the same commercial model as WebLogic. Still, one cannot compare GlassFish/WebLogic to WildFly/JBoss EAP. It is simply not the same case, since Oracle has had two different products from different codebases. The comparison should be limited to GlassFish Open Source / Oracle GlassFish Server versus WildFly / JBoss EAP. Read the complete article here 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: Glassfish,training,WebLogic,WebLogic Community,Oracle,OPN,Jürgen Kress

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  • Announcing the MOS WCI "Community"

    - by brian.harrison
    The WCI Technical Support team are please to announce the launch of the long awaited WCI Support Community on My Oracle Support (MOS) "Community". Users can navigate to this "first stop" for WebCenter Interaction information by logging on to following this link: WCI Community (Note that this requires a valid login credential to the My Oracle Support tool). In this community you'll find a product related discussion forum moderated by Oracle WebCenter Interaction support engineers, recommended tips and tricks, links to knowledge base articles and best practices for setting up and administering up your environment. We hope you'll take a minute to have a look through the community. If you have a question about WebCenter Interaction, a comment or a suggestion regarding the content, please feel free to post it to the forum and someone will respond to your request. Think of the forum here as another method to communicate directly with the WCI Technical Support team for questions and answers to simple WCI support topics. The forum is moderated by WCI Technical Support engineers directly and we hope it will help you avoid the need to log support incidents for less complex support related questions. We encourage all of our customers, both internal and external, to participate in the forums discussions, sharing information, knowledge, best practices and in the effort to help us build a vital and vibrant "home base" for WCI users on the My Oracle Support tool. Thank you for visiting! The WebCenter Interaction Support Community Moderator Team

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  • NINE Great Reasons to Attend the GlassFish Community Event at JavaOne 2012

    - by Alexandra Huff
    Are you coming to the annual GlassFish Community Event at JavaOne this year? Here are nine great reasons not to miss it! Great company Meet and mingle with community leaders and luminaries, the GlassFish engineering team, and Oracle executives! Learn from others How are your peers using GlassFish in creative ways? A few community members will share their challenges and creative solutions. Ask tough questions Meet Oracle GlassFish and Middleware executives; the panel discussion will be moderated by one of our stellar community leaders! Shirts! Be sure to get this year's GlassFish T-shirt, designed by and voted on by YOU, our community members! Don't miss it - they go fast. Share your story Give us a two minute update on why you love GlassFish and how you are using it! We will immortalize you in a very brief video and post it to our GlassFish Stories page! Find out... about the new book, hot off the press, authored by our very own Arun Gupta: "Java EE 6 Pocket Guide: A Quick Reference for Simplified Enterprise Java Development" If you share... your story, you will win a copy of Arun's new book as our thank you gift! Suggest... some ideas on how to make GlassFish even better! Have fun Lively discussion, news and updates, excellent company -- this is THE place to be on Sunday at JavaOne! Convinced? Excellent! Then please register here! A JavaOne Pass is required to enter Moscone Center. All passes accepted, including Discover, Exhibitor, Press, Blogger, etc. Agenda 11:00 - 11:05: Introduction 11:05 - 11:30: Roadmap and Community Updates 11:30 - 12:15: Q&A with Executive Speaker Panel from Oracle and the GlassFish Team 12:15 - 01:00: Customer Testimonials Location: Moscone West, Room 2005 Add sessions UGF10359 and UGF10360 to Schedule Builder

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  • Procurement Community Live Chat December 13th on Implementing AME with Purchase Orders

    - by LuciaC
    Do you still have questions on setting up the Approval Management Engine (AME) for Purchase Orders after attending the AME Webcast? Or maybe you are new to this topic and need more information?  Don’t miss our Procurement Community Live Chat on December 13th from 7:00 am to 11:00 am EST. Proactive Support and Development will be available to answer questions.You can access the main Oracle Communities page at http://communities.oracle.com (If you are enrolled, the Procurement community will be listed on your left.   If you're not already enrolled in the Procurement community, you can do so by clicking on the link Edit Subscriptions). OR you can use these alternative steps:From "My Oracle Support" as follows:    Log into My Oracle Support.    Click on the 'Community' link at the top of the page.    Click in 'Find a Community' field and enter Procurement.    Double click on Procurement in the list.    Click on the 'Create a Community Post' button and submit your question.Then in the ‘Procurement Featured Discussions’ section, drill down on the following thread and post your question.  We are looking forward to hearing from you!

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  • Wrappers/law of demeter seems to be an anti-pattern...

    - by Robert Fraser
    I've been reading up on this "Law of Demeter" thing, and it (and pure "wrapper" classes in general) seem to generally be anti patterns. Consider an implementation class: class Foo { void doSomething() { /* whatever */ } } Now consider two different implementations of another class: class Bar1 { private static Foo _foo = new Foo(); public static Foo getFoo() { return _foo; } } class Bar2 { private static Foo _foo = new Foo(); public static void doSomething() { _foo.doSomething(); } } And the ways to call said methods: callingMethod() { Bar1.getFoo().doSomething(); // Version 1 Bar2.doSomething(); // Version 2 } At first blush, version 1 seems a bit simpler, and follows the "rule of Demeter", hide Foo's implementation, etc, etc. But this ties any changes in Foo to Bar. For example, if a parameter is added to doSomething, then we have: class Foo { void doSomething(int x) { /* whatever */ } } class Bar1 { private static Foo _foo = new Foo(); public static Foo getFoo() { return _foo; } } class Bar2 { private static Foo _foo = new Foo(); public static void doSomething(int x) { _foo.doSomething(x); } } callingMethod() { Bar1.getFoo().doSomething(5); // Version 1 Bar2.doSomething(5); // Version 2 } In both versions, Foo and callingMethod need to be changed, but in Version 2, Bar also needs to be changed. Can someone explain the advantage of having a wrapper/facade (with the exception of adapters or wrapping an external API or exposing an internal one).

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  • dynamic behavior of factory class

    - by manu1001
    I have a factory class that serves out a bunch of properties. Now, the properties might come either from a database or from a properties file. This is what I've come up with. public class Factory { private static final INSTANCE = new Factory(source); private Factory(DbSource source) { // read from db, save properties } private Factory(FileSource source) { // read from file, save properties } // getInstance() and getProperties() here } What's a clean way of switching between these behaviors based on the environment. I want to avoid having to recompile the class each time.

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  • QuestionOrAnswer model?

    - by Mark
    My site has Listings. Users can ask Questions about listings, and the author of the listing can respond with an Answer. However, the Answer might need clarification, so I've made them recursive (you can "answer" an answer). So how do I set up the database? The way I have it now looks like this (in Django-style models): class QuestionOrAnswer(Model): user = ForeignKey(User, related_name='questions') listing = ForeignKey(Listing, related_name='questions') parent = models.ForeignKey('self', null=True, blank=True, related_name='children') message = TextField() But what bugs me is that listing is now an attribute of the answers as well (it doesn't need to be). What happens if the database gets mangled and an answer belongs to a different listing than its parent question? That just doesn't make any sense. We can separate it with polymorphism: QuestionOrAnswer user message created updated Question(QuestionOrAnswer) shipment Answer(QuestionOrAnswer) parent = ForeignKey(QuestionOrAnswer) And that ought to work, but now ever question and answer is split into 2 tables. Is it worth this overhead for clearly defined models?

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  • Help naming a class that has a single public method called Execute()

    - by devoured elysium
    I have designed the following class that should work kind of like a method (usually the user will just run Execute()): public abstract class ??? { protected bool hasFailed = false; protected bool hasRun = false; public bool HasFailed { get { return hasFailed; } } public bool HasRun { get { return hasRun; } } private void Restart() { hasFailed = false; hasRun = false; } public bool Execute() { ExecuteImplementation(); bool returnValue = hasFailed; Restart(); return returnValue; } protected abstract void ExecuteImplementation(); } My question is: how should I name this class? Runnable? Method(sounds awkward)?

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  • Ways to use your skills as a developer to give back to the community/charities.

    - by Ryan Hayes
    Recently I came upon a community event called GiveCamp. GiveCamp is a weekend-long event where technology professionals from designers, developers and database administrators to marketers and web strategists donate their time to provide solutions for non-profit organizations. Since its inception in 2007, the GiveCamp program has provided benefits to over 150 charities, with a value of developer and designer time exceeding $1,000,000 in services! Coming from a very rural part of the country where there is a huge opportunity for charity events like this, it got me wondering. Are there other large movements like GiveCamp that are out there? GiveCamp is sponsored by Microsoft, so of course most are run through .NET user groups. Are there other flavors of it? Different types? Java/Python/other open source charity movements? If not, how do you give back?

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  • Is there a real name policy in the Ubuntu community?

    - by martin001
    I'm not ashamed to be a part of Ubuntu, but I'm trying to keep the number of web search hits for my real name low, which is kinda impossible if you use a Launchpad account. So, I'm wondering if there is a real name policy in the Ubuntu community, or if it's okay to use a pseudonym/nick name/fake name? While it might be okay to use nick names on IRC and in forums, how about these topics: Adding an OpenPGP key to Launchpad. Signing the Ubuntu Code of Conduct. Becoming an Ubuntu member. Code contributions (e.g., signing the Canonical CLA). Thanks in advance for your answers!

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  • How can I motivate the community to use boinc?

    - by user49523
    boinc is a really nice application to use on background of a computer that can help science projects and humanity as a all. I would like somehow to encourage people use boinc with their preferences on boinc like projects choice, cpu from 10 to 100 ,.. with their computer that will help science to move more quickly and help humanity There are 20 million users of ubuntu if most of use boinc , this will increase the speed of science projets .. and if other people from other operating systems use as also like mac,windows,.. and other open source like debian,.. this would even speed more science and now anyone can win also a prize , joining a project management like http://boincstats.com/ and there is more 2 How can i get ubuntu users and ubuntu community to know and use boinc application?

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  • Minimize useless tweaking of a numeric app

    - by Potatoswatter
    I'm developing a numeric application (nonlinear optimizer), with a zillion knobs to tweak and rising. It's not my first foray into this domain, but this time there are even more variables in the code and I'm on a tight schedule. Don't want to waste time fiddling. Days or even months can potentially be wasted adjusting variables, recompiling, and reprocessing benchmark datasets. The resulting data is viewed and trouble spots are checked. The overall quality of the solution is reported by the program but the meaning of the report could change over time. (Numeric units for the report are one thing I'm trying to nail down.) One main problem is organizing result files to identify each with specific code changes. Note taking can be a pain, is there software to help with this? Are there agreed best practices to making this kind of development cycle reliably move forward? The solver package converges to its optimal solution with mechanical determination, but I'm all too familiar with the way an excess of design decisions can mire development.

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  • Prioritize compiler functionality/tasks, when designing a new language

    - by Mahdi
    Well, the question should be so hard to ask and I expect couple of down votes, however, I'm really interested to have your ideas and recommendations. :) I've already made a very simple compiler, with a few and limited functionality. Now I'm getting more on it to make it more like a real-world compiler. I definitely need to start over 'cause I've much more experience and ideas in this area rather a few years ago. So, I want to know, right now, from the very first step again, which tasks/features for the new compiler should implement first and which tasks has lower priority rather than others? For example, I'd say, first I'd go to decide about the object-oriented structure for the new language, but you might say, hey, just go for a compiler that could define a variable, when you finished that, then start thinking about OOP designs ... I prefer to hear the pros and cons for your suggestions also. Actually I like to start from Bottom to Top, where I could add simplest tasks first, and later adding more complex ones, but I'm totally open for any new ideas, and really appreciate that. Also please consider that I'm thinking about the design concepts. Actually I expect answers like: Priority from Highest to Lowest: variables, because .... functions, because .... loops, because .... ... Not: define a syntax for your new language, and start parsing your source code ...

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  • Struggling with the Single Responsibility Principle

    - by AngryBird
    Consider this example: I have a website. It allows users to make posts (can be anything) and add tags that describe the post. In the code, I have two classes that represent the post and tags. Lets call these classes Post and Tag. Post takes care of creating posts, deleting posts, updating posts, etc. Tag takes care of creating tags, deleting tags, updating tags, etc. There is one operation that is missing. The linking of tags to posts. I am struggling with who should do this operation. It could fit equally well in either class. On one hand, the Post class could have a function that takes a Tag as a parameter, and then stores it in a list of tags. On the other hand, the Tag class could have a function that takes a Post as a parameter and links the Tag to the Post. The above is just an example of my problem. I am actually running into this with multiple classes that are all similar. It could fit equally well in both. Short of actually putting the functionality in both classes, what conventions or design styles exist to help me solve this problem. I am assuming there has to be something short of just picking one? Maybe putting it in both classes is the correct answer?

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  • From a DDD perspective is a report generating service a domain service or an infrastructure service?

    - by Songo
    Let assume we have the following service whose responsibility is to generate Excel reports: class ExcelReportService{ public String generateReport(String fileFormatFilePath, ResultSet data){ ReportFormat reportFormat = new ReportFormat(fileFormatFilePath); ExcelDataFormatterService excelDataFormatterService = new ExcelDataFormatterService(); FormattedData formattedData = excelDataFormatterService.format(data); ExcelFileService excelFileService = new ExcelFileService(); String reportPath= excelFileService.generateReport(reportFormat,formattedData); return reportPath; } } This is pseudo code for the service I want to design where: fileFormatFilePath: path to a configuration file where I'll keep the format of my excel file (headers, column widths, number of columns,..etc) data: the actual records returned from the database. This data can't be used directly coz I might need to make further calculations to the data before inserting them to the excel file. ReportFormat: Value object to hold the report format, has methods like getHeaders(), getColumnWidth(),...etc. ExcelDataFormatterService: a service to hold any logic that need to be applied to the data returned from the database before inserting it to the file. FormattedData: Value object the represents the formatted data to be inserted. ExcelFileService: a wrapper top the 3rd party library that generates the excel file. Now how do you determine whether a service is an infrastructure or domain service? I have the following 3 services here: ExcelReportService, ExcelDataFormatterService and ExcelFileService?

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  • Implementing a ILogger interface to log data

    - by Jon
    I have a need to write data to file in one of my classes. Obviously I will pass an interface into my class to decouple it. I was thinking this interface will be used for testing and also in other projects. This is my interface: //This could be used by filesystem, webservice public interface ILogger { List<string> PreviousLogRecords {get;set;} void Log(string Data); } public interface IFileLogger : ILogger { string FilePath; bool ValidFileName; } public class MyClassUnderTest { public MyClassUnderTest(IFileLogger logger) {....} } [Test] public void TestLogger() { var mock = new Mock<IFileLogger>(); mock.Setup(x => x.Log(Is.Any<string>).AddsDataToList()); //Is this possible?? var myClass = new MyClassUnderTest(mock.Object); myClass.DoSomethingThatWillSplitThisAndLog3Times("1,2,3"); Assert.AreEqual(3,mock.PreviousLogRecords.Count); } This won't work I don't believe as nothing is storing the items so is this possible using Moq and also what do you think of the design of the interface?

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  • Handling Types for Real and Complex Matrices in a BLAS Wrapper

    - by mga
    I come from a C background and I'm now learning OOP with C++. As an exercise (so please don't just say "this already exists"), I want to implement a wrapper for BLAS that will let the user write matrix algebra in an intuitive way (e.g. similar to MATLAB) e.g.: A = B*C*D.Inverse() + E.Transpose(); My problem is how to go about dealing with real (R) and complex (C) matrices, because of C++'s "curse" of letting you do the same thing in N different ways. I do have a clear idea of what it should look like to the user: s/he should be able to define the two separately, but operations would return a type depending on the types of the operands (R*R = R, C*C = C, R*C = C*R = C). Additionally R can be cast into C and vice versa (just by setting the imaginary parts to 0). I have considered the following options: As a real number is a special case of a complex number, inherit CMatrix from RMatrix. I quickly dismissed this as the two would have to return different types for the same getter function. Inherit RMatrix and CMatrix from Matrix. However, I can't really think of any common code that would go into Matrix (because of the different return types). Templates. Declare Matrix<T> and declare the getter function as T Get(int i, int j), and operator functions as Matrix *(Matrix RHS). Then specialize Matrix<double> and Matrix<complex>, and overload the functions. Then I couldn't really see what I would gain with templates, so why not just define RMatrix and CMatrix separately from each other, and then overload functions as necessary? Although this last option makes sense to me, there's an annoying voice inside my head saying this is not elegant, because the two are clearly related. Perhaps I'm missing an appropriate design pattern? So I guess what I'm looking for is either absolution for doing this, or advice on how to do better.

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  • Parameterized Django models

    - by mgibsonbr
    In principle, a single Django application can be reused in two or more projects, providing functionality relevent to both. That implies that the same database structure (tables and relations) will be re-created identically in different databases, and most times this is not a problem (assuming the projects/databases are unrelated - for instance when someone downloads a complete app to use in their own projects). Sometimes, however, the models must be "tweaked" a little to better fit the problem needs. This can be accomplished by forking the app, but I wondered if there wouldn't be a better option in cases where the app designer can anticipate the most common customizations. For instance, if I have a model that could relate to another as one-to-one or one-to-many, I could specify the unique property as a parameter, that can be specified in the project's settings: class This(models.Model): other = models.ForeignKey(Other, unique=settings.OTHER_TO_THIS) Or if a model can relate to many others, I could create an intermediate table for each of them (thus enforcing referential integrity) instead of using generic fks: for related in settings.MODELS_RELATED_TO_OTHER: model_name = '%s_Other' % related globals()[model_name] = type(model_name, (models.Model,) { me:models.ForeignKey(find_model_class(related)), other:models.ForeignKey(Other), # Some other properties all intersection tables must have }) Etc. Let me stress out that I'm not proposing to change the models at runtime nor anything like that; once the parameters were defined and syncdb called for the first time, those parameters are not to be changed again (unless you're doing a schema migration). Is this a good design? Are there better ways to accomplish the same thing, or maybe drawbacks I coulnd't anticipate? This technique is meant to be used sparingly (only on apps meant to be reused in wildly different contexts, and only when a specific need of customization can be detected while the app model is being designed).

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  • Best practice to collect information from child objects

    - by Markus
    I'm regularly seeing the following pattern: public abstract class BaseItem { BaseItem[] children; // ... public void DoSomethingWithStuff() { StuffCollection collection = new StuffCollection(); foreach(child c : children) c.AddRequiredStuff(collection); // do something with the collection ... } public abstract void AddRequiredStuff(StuffCollection collection); } public class ConcreteItem : BaseItem { // ... public override void AddRequiredStuff(StuffCollection collection) { Stuff stuff; // ... collection.Add(stuff); } } Where I would use something like this, for better information hiding: public abstract class BaseItem { BaseItem[] children; // ... public void DoSomethingWithStuff() { StuffCollection collection = new StuffCollection(); foreach(child c : children) collection.AddRange(c.RequiredStuff()); // do something with the collection ... } public abstract StuffCollection RequiredStuff(); } public class ConcreteItem : BaseItem { // ... public override StuffCollection RequiredStuff() { StuffCollection stuffCollection; Stuff stuff; // ... stuffCollection.Add(stuff); return stuffCollection; } } What are pros and cons of each solution? For me, giving the implementation access to parent's information is some how disconcerting. On the other hand, initializing a new list, just to collect the items is a useless overhead ... What is the better design? How would it change, if DoSomethingWithStuff wouldn't be part of BaseItem but a third class? PS: there might be missing semicolons, or typos; sorry for that! The above code is not meant to be executed, but just for illustration.

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  • Classes as a compilation unit

    - by Yannbane
    If "compilation unit" is unclear, please refer to this. However, what I mean by it will be clear from the context. Edit: my language allows for multiple inheritance, unlike Java. I've started designing+developing my own programming language for educational, recreational, and potentially useful purposes. At first, I've decided to base it off Java. This implied that I would have all the code be written inside classes, and that code compiles to classes, which are loaded by the VM. However, I've excluded features such as interfaces and abstract classes, because I found no need for them. They seemed to be enforcing a paradigm, and I'd like my language not to do that. I wanted to keep the classes as the compilation unit though, because it seemed convenient to implement, familiar, and I just liked the idea. Then I noticed that I'm basically left with a glorified module system, where classes could be used either as "namespaces", providing constants and functions using the static directive, or as templates for objects that need to be instantiated ("actual" purpose of classes in other languages). Now I'm left wondering: what are the benefits of having classes as compilation units? (Also, any general commentary on my design would be much appreciated.)

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  • DB Object passing between classes singleton, static or other?

    - by Stephen
    So I'm designing a reporting system at work it's my first project written OOP and I'm stuck on the design choice for the DB class. Obviously I only want to create one instance of the DB class per-session/user and then pass it to each of the classes that need it. What I don't know it what's best practice for implementing this. Currently I have code like the following:- class db { private $user = 'USER'; private $pass = 'PASS'; private $tables = array( 'user','report', 'etc...'); function __construct(){ //SET UP CONNECTION AND TABLES } }; class report{ function __construct ($params = array(), $db, $user) { //Error checking/handling trimed //$db is the database object we created $this->db = $db; //$this->user is the user object for the logged in user $this->user = $user; $this->reportCreate(); } public function setPermission($permissionId = 1) { //Note the $this->db is this the best practise solution? $this->db->permission->find($permissionId) //Note the $this->user is this the best practise solution? $this->user->checkPermission(1) $data=array(); $this->db->reportpermission->insert($data) } };//end report I've been reading about using static classes and have just come across Singletons (though these appear to be passé already?) so what's current best practice for doing this?

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  • Tips for Making this Code Testable [migrated]

    - by Jesse Bunch
    So I'm writing an abstraction layer that wraps a telephony RESTful service for sending text messages and making phone calls. I should build this in such a way that the low-level provider, in this case Twilio, can be easily swapped without having to re-code the higher level interactions. I'm using a package that is pre-built for Twilio and so I'm thinking that I need to create a wrapper interface to standardize the interaction between the Twilio service package and my application. Let us pretend that I cannot modify this pre-built package. Here is what I have so far (in PHP): <?php namespace Telephony; class Provider_Twilio implements Provider_Interface { public function send_sms(Provider_Request_SMS $request) { if (!$request->is_valid()) throw new Provider_Exception_InvalidRequest(); $sms = \Twilio\Twilio::request('SmsMessage'); $response = $sms->create(array( 'To' => $request->to, 'From' => $request->from, 'Body' => $request->body )); if ($this->_did_request_fail($response)) { throw new Provider_Exception_RequestFailed($response->message); } $response = new Provider_Response_SMS(TRUE); return $response; } private function _did_request_fail($api_response) { return isset($api_response->status); } } So the idea is that I can write another file like this for any other telephony service provided that it implements Provider_Interface making them swappable. Here are my questions: First off, do you think this is a good design? How could it be improved? Second, I'm having a hard time testing this because I need to mock out the Twilio package so that I'm not actually depending on Twilio's API for my tests to pass or fail. Do you see any strategy for mocking this out? Thanks in advance for any advice!

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  • Java Cloud and Developer Service

    - by JuergenKress
    At our WebLogic Community Workspace (WebLogic Community membership required) you can find the latest Java and Developer Cloud presentations and demos: General+Session-+Building+and+Managing+a+Private+Oracle+Java Experiences-building-JavaEE-based-PaaS-Platform_Compressed.ppt Oracle Enterprise Manager 12c Cloud Control Demo.zip 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. BlogTwitterLinkedInMixForumWiki Technorati Tags: Oracle cloud,Cloud,Java Cloud,Oracle developer cloud,Java as a service,Oracle PAAS,WebLogic Community,Oracle,OPN,Jürgen Kress

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