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  • UML Class Diagram for User Login

    - by 01010011
    Hi, The diagram below is my very first attempt at creating a UML class diagram describing a user login into a website. I'm sure its a poor design and full of flaws, but I'm hoping to learn from you guys how you would design a simple login like this. I'm particularly interested in your use of design patterns and which patterns you would use, how you would implement it in the design, and why. Any advise, criticisms, comments and suggestions will be really appreciated. Thanks in advance.

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  • Design Patters in Rails

    - by Winston
    I remember, I have a GoF book back in college about design patterns which helped me a lot with my C and C++ programming, since my jump ship to Rails I was trying to use those design patterns I learned previously, Rails is a relatively new paradigm to me, plurals, verbs, REST, DRY.. Can you give me a recommended book for Rails that I can easily understand what I previously learned back in College. P.S. I suspect Matz knew about the GoF book, and applied it on Ruby... :-)

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  • What are MVP and MVC and what is the difference?

    - by Wolfbyte
    When looking beyond the RAD (drag-drop and configure) way of building User Interfaces that many tools encourage you are likely to come across 2 design patterns called Model-View-Controller and Model-View-Presenter. My question has two parts to it: What issues do these patterns address? How are they similar? How are they different?

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  • "Agile Principles, Patterns, and Practices in C#": Is this just a .NET-translation of the popular Uncle Bob book?

    - by Louis Rhys
    I found this book sold on Amazon Agile Principles, Patterns, and Practices in C#, written by Robert C Martin and Micah Martin. Is it merely a .NET port of the older, more popular Agile Software Development, Principles, Patterns, and Practices? Or is it just a new book trying to take advantage of the other book's popularity? If I am a .NET developer who hasn't read either book, which one would you recommend?

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  • Join the Authors of SSIS Design Patterns at the PASS Summit 2012!

    - by andyleonard
    My fellow authors and I will be presenting a day-long pre-conference session titled SSIS Design Patterns at the PASS Summit 2012 in Seattle Monday 5 Nov 2012! Register to learn patterns for: Package execution Package logging Loading flat file sources Loading XML sources Loading the cloud Dynamic package generation SSIS Frameworks Data warehouse ETL Data flow performance   Presenting this session: Matt Masson Tim Mitchell Jessica Moss Michelle Ufford Andy Leonard I hope to see you in Seattle!...(read more)

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  • Learn SSIS from the Authors of SSIS Design Patterns at the PASS Summit 2012!

    - by andyleonard
    Jessica Moss ( blog | @jessicammoss ), Michelle Ufford ( blog | @sqlfool ), Tim Mitchell ( blog | @tim_mitchell ), Matt Masson ( blog | @mattmasson ), and me – we are all presenting the SSIS Design Patterns pre-conference session at the PASS Summit 2012 ! We will be covering material from, and based upon, the book. We will describe and demonstrate patterns for package execution, package logging, loading flat file and XML sources, loading the cloud, dynamic package generation, SSIS Frameworks, data...(read more)

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  • Azure Design Patterms

    - by kaleidoscope
    Design patterns are represented as relationships between classes and objects with defined responsibilities that act in concert to carry out the solution. Azure Design Pattern : Design Pattern on the Azure platform. · Cloud Hosting Patterns · Cloud Data Patterns · Cloud Communication & Sync Patterns · Cloud Security Patterns · Application Patterns More Information: http://azuredesignpatterns.com/   Ram, P

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  • Service Oriented Architecture & Domain-Driven Design

    - by Michael
    I've always developed code in a SOA type of way. This year I've been trying to do more DDD but I keep getting the feeling that I'm not getting it. At work our systems are load balanced and designed not to have state. The architecture is: Website ===Physical Layer== Main Service ==Physical Layer== Server 1/Service 2/Service 3/Service 4 Only Server 1,Service 2,Service 3 and Service 4 can talk to the database and the Main Service calls the correct service based on products ordered. Every physical layer is load balanced too. Now when I develop a new service, I try to think DDD in that service even though it doesn't really feel like it fits. I use good DDD principles like entities, value types, repositories, aggregates, factories and etc. I've even tried using ORM's but they just don't seem like they fit in a stateless architecture. I know there are ways around it, for example use IStatelessSession instead of ISession with NHibernate. However, ORM just feel like they don't fit in a stateless architecture. I've noticed I really only use some of the concepts and patterns DDD has taught me but the overall architecture is still SOA. I am starting to think DDD doesn't fit in large systems but I do think some of the patterns and concepts do fit in large systems. Like I said, maybe I'm just not grasping DDD or maybe I'm over analyzing my designs? Maybe by using the patterns and concepts DDD has taught me I am using DDD? Not sure if there is really a question to this post but more of thoughts I've had when trying to figure out where DDD fits in overall systems and how scalable it truly is. The truth is, I don't think I really even know what DDD is?

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  • Is MVVM killing silverlight development?

    - by DeanMc
    This is a question I have had rattling around in my head for some time. I had a chat with a guy the other night who told me he would not be using the navigational framework because he could not figure out how it works with MVVM. As much as I tried to explain that patterns should be taken with a pinch of salt he would not listen. My point is this, patterns are great when they solve some problem. Sometimes only part of the pattern solves a particular problem while the other parts of it cause different problems. The goal of any developer is to build a solid application using a combination of patterns know how and foresight. I feel MVVM is becoming the one pattern to rule them all. As it is not directly supported by .Net some fancy business is needed to make it work. I feel that people are missing the point of the pattern, which is loosely coupled, testable code and instead jumping through hoops and missing out on great experiences trying to follow MVVM to the letter. MVVM is great but I wish it came with a warning or disclaimer for newbies as my fear is people will shy away from silverlight development for fear of being smacked with the mvvm stick. EDIT: Can I just add as an edit, I use and agree with MVVM as a pattern I know when it is and isn't feasible in my projects. My issue is with the encompassing nature it is taking, as if it HAS to be used as part of development. It is being used as an integral feature and not a pattern, which it is.

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  • design an extendable database model

    - by wishi_
    Hi! Currently I'm doing a project whose specifications are unclear - well who doesn't. I wonder what's the best development strategy to design a DB, that's going to be extended sooner or later with additional tables and relations. I want to include "changeability". My main concern is that I want to apply design patterns (it's a university project) and I want to separate the constant factors from those, that change by choosing appropriate design patterns - in my case MVC and a set of sub-patterns at model level. When it comes to the DB however, I may have to resdesign my model in my MVC approach, because my domain model at a later stage my require a different set of classes representing the DB tables. I use Hibernate as an abstraction layer between DB and application. Would you start with a very minimal DB, just a few tables and relations? And what if I want an efficient DB, too? I wonder what strategies are applied in the real world. Stakeholder analysis for example isn't a sufficient planing solution when it comes to changing requirements. I think - at a DB level - my design pattern ends. So there's breach whose impact I'd like to minimize with a smart strategy.

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  • Replace conditional with polymorphism refactoring or similar?

    - by Anders Svensson
    Hi, I have tried to ask a variant of this question before. I got some helpful answers, but still nothing that felt quite right to me. It seems to me this shouldn't really be that hard a nut to crack, but I'm not able to find an elegant simple solution. (Here's my previous post, but please try to look at the problem stated here as procedural code first so as not to be influenced by the earlier explanation which seemed to lead to very complicated solutions: http://stackoverflow.com/questions/2772858/design-pattern-for-cost-calculator-app ) Basically, the problem is to create a calculator for hours needed for projects that can contain a number of services. In this case "writing" and "analysis". The hours are calculated differently for the different services: writing is calculated by multiplying a "per product" hour rate with the number of products, and the more products are included in the project, the lower the hour rate is, but the total number of hours is accumulated progressively (i.e. for a medium-sized project you take both the small range pricing and then add the medium range pricing up to the number of actual products). Whereas for analysis it's much simpler, it is just a bulk rate for each size range. How would you be able to refactor this into an elegant and preferably simple object-oriented version (please note that I would never write it like this in a purely procedural manner, this is just to show the problem in another way succinctly). I have been thinking in terms of factory, strategy and decorator patterns, but can't get any to work well. (I read Head First Design Patterns a while back, and both the decorator and factory patterns described have some similarities to this problem, but I have trouble seeing them as good solutions as stated there. The decorator example seems very complicated for just adding condiments, but maybe it could work better here, I don't know. And the factory pattern example with the pizza factory...well it just seems to create such a ridiculous explosion of classes, at least in their example. I have found good use for factory patterns before, but I can't see how I could use it here without getting a really complicated set of classes) The main goal would be to only have to change in one place (loose coupling etc) if I were to add a new parameter (say another size, like XSMALL, and/or another service, like "Administration"). Here's the procedural code example: public class Conditional { private int _numberOfManuals; private string _serviceType; private const int SMALL = 2; private const int MEDIUM = 8; public int GetHours() { if (_numberOfManuals <= SMALL) { if (_serviceType == "writing") return 30 * _numberOfManuals; if (_serviceType == "analysis") return 10; } else if (_numberOfManuals <= MEDIUM) { if (_serviceType == "writing") return (SMALL * 30) + (20 * _numberOfManuals - SMALL); if (_serviceType == "analysis") return 20; } else //i.e. LARGE { if (_serviceType == "writing") return (SMALL * 30) + (20 * (MEDIUM - SMALL)) + (10 * _numberOfManuals - MEDIUM); if (_serviceType == "analysis") return 30; } return 0; //Just a default fallback for this contrived example } } All replies are appreciated! I hope someone has a really elegant solution to this problem that I actually thought from the beginning would be really simple... Regards, Anders

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  • How to use regex to extract nested patterns

    - by Rob Romanek
    Hi I'm struggling with some regex I've got a string like this: a:b||c:{d:e||f:g}||h:i basically name value pairings. I want to be able to parse out the pairings so I get: a:b c:{d:e||f:g} h:i then I can further parse the pairings contained in { } if required It is the nesting that is making me scratch my head. Any regex experts out there that can give me a hand? thanks, Rob

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  • Looking for efficient scaling patterns for Silverlight application with distributed text-file data s

    - by Edward Tanguay
    I'm designing a Silverlight software solution for students and teachers to record flashcards, e.g. words and phrases that students find while reading and errors that teachers notice while teaching. Requirements are: each person publishes his own flashcards in a file on a web server, e.g. http://:www.mywebserver.com/flashcards.txt other people subscribe to that person's flashcards by using a Silverlight flashcard reader that I have developed and entering the URLs of flashcard files they want to subscribe to, URLs and imported flashcards being saved in IsolatedStorage the flashcards.txt file has the following simple format: title, then blocks of question/answers: Jim Smith's flashcards from English class 53-222, winter semester 2009 ==fla Das kann nicht sein. That can't be. ==fla Es sei denn, er kommt nicht. Unless he doesn't come. The user then makes public the URL to his flashcard file and other readers begin reading in his flashcards. In order to lower the bar for non-technical users to contribute, it will even be possible for them to save this text in a Google Document, which they publish and distribute the URL. The flashcard readers will then recognize it is a google document and perform the necessary screen scraping to get at the raw text. I have two technical questions about this approach: What is a best way to plan now for scalability issues: e.g. if your reader is subscribed to 10 flashcard files that are each 200K, it will have to download 2MB of text just to find out if any new flashcards are available. Or can I somehow accurately and consistently get at the last update date/time of text files on servers and published google docs? Each reader will have the ability to allow the person to test himself on imported flashcards and add meta information to them, e.g. categorize them, edit them, etc. This information will be stored in IsolatedStorage along with the important flashcards themselves. What is a good pattern to allow these readers to share and synchronize this meta data, e.g. so when you are looking at a flashcard you can see that 5 other people have made corrections to it. The best solution I can think of now is that the Silverlight readers will have to republish their data to a central database, but then there is the problem of uniquely identifying each flashcard, the best approach seems to be URL + position-in-file, or even better URL + original text of both question and answer fields, but both of these have their obvious drawbacks. The main requirement is that the bar for participation is kept as low as possible, i.e. type text in a google document, publish it, distribute the URL, and you're publishing within the flashcard community. So I want to come up with the most efficient technical solutions in order to compensate for the lack of database, lack of unique ids, etc. For those who have designed or developed similar non-traditional, distributed database projects like this, what advice, experience or best-practice tips you can share on the above two points?

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  • c# memory allocation and deallocation patterns

    - by Neal
    Since C# uses Garbage Collection. When is it necessary to use .Dispose to free the memory? I realize there are a few situations so I'll try to list the ones I can think of. If I close a Form that contains GUI type object, are those objects dereferenced and therefore will be collected? If I create a local object using new should I .Dispose of it before the method exits or just let the GC take care of it? What is good practice in this case? Are there any times in which forcing a GC is understandable? Are events collected by the GC when it's object is collected?

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  • Facade Design Patterns and Subclassing

    - by Code Sherpa
    Hi. I am using a facade design pattern for a C# program. The program basically looks like this... public class Api { #region Constants private const int version = 1; #endregion #region Private Data private XProfile _profile; private XMembership _membership; private XRoles _role; #endregion Private Data public Api() { _membership = new XMembership(); _profile = new XProfile(); _role = new XRoles(); } public int GetUserId(string name) { return _membership.GetIdByName(name); } } Now, as I would like subclass my methods into three categories: Role, Profile, and Member. This will be easier on the developers eye because both Profile and Membership expose a lot of methods that look similar (and a few by Role). For example, getting a user's ID would look like: int _id = Namespace.Api.Member.GetUserId("Henry222"); Can somebody "illustrate" how subclassing should work in this case to achieve the effect I am looking for? Thanks in advance.

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  • Good patterns for loose coupling in Java?

    - by Eye of Hell
    Hello. I'm new to java, and while reading documentation so far i can't find any good ways for programming with loose coupling between objects. For majority of languages i know (C++, C#, python, javascript) i can manage objects as having 'signals' (notification about something happens/something needed) and 'slots' (method that can be connected to signal and process notification/do some work). In all mentioned languages i can write something like this: Object1 = new Object1Class(); Object2 = new Object2Class(); Connect( Object1.ItemAdded, Object2.OnItemAdded ); Now if object1 calls/emits ItemAdded, the OnItemAdded method of Object2 will be called. Such loose coupling technique is often referred as 'delegates', 'signal-slot' or 'inversion of control'. Compared to interface pattern, technique mentioned don't need to group signals into some interfaces. Any object's methods can be connected to any delegate as long as signatures match ( C++Qt even extends this by allowing only partial signature match ). So i don't need to write additional interface code for each methods / groups of methods, provide default implementation for interface methods not used etc. And i can't see anything like this in Java :(. Maybe i'm looking a wrong way?

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  • Patterns for simulating optional "out" parameters in C#?

    - by Jesse McGrew
    I'm translating an API from C to C#, and one of the functions allocates a number of related objects, some of which are optional. The C version accepts several pointer parameters which are used to return integer handles to the objects, and the caller can pass NULL for some of the pointers to avoid allocating those objects: void initialize(int *mainObjPtr, int *subObjPtr, int *anotherSubObjPtr); initialize(&mainObj, &subObj, NULL); For the C# version, the obvious translation would use out parameters instead of pointers: public static void Initialize(out int mainObj, out int subObj, out int anotherSubObj); ... but this leaves no way to indicate which objects are unwanted. Are there any well-known examples of C# APIs doing something similar that I could imitate? If not, any suggestions?

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  • Servlet mapping url patterns

    - by Scobal
    I have the following urls that need mapping to two different servlets. Can anyone suggest a working url-pattern please? vehlocsearch-ws: /ws/vehlocsearch/vehlocsearch /ws/vehavailrate/vehavailratevehlocsearch /ws/vehavailrate/vehavailratevehlocsearch.wsdl vehavailrate-ws: /ws/vehavailrate/vehavailrate /ws/vehavailrate/vehavailratevehavailrate /ws/vehavailrate/vehavailratevehavailrate.wsdl So far I have this, which feels right, but isn't: <servlet-mapping> <servlet-name>vehlocsearch-ws</servlet-name> <url-pattern>*.vehlocsearch*</url-pattern> </servlet-mapping> <servlet-mapping> <servlet-name>vehavailrate-ws</servlet-name> <url-pattern>*.vehavailrate*</url-pattern> </servlet-mapping> Note: I have no control over the incoming urls

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  • Best Practices / Patterns for Enterprise Protection/Remediation of SSNs (Social Security Numbers)

    - by Erik Neu
    I am interested in hearing about enterprise solutions for SSN handling. (I looked pretty hard for any pre-existing post on SO, including reviewing the terriffic SO automated "Related Questions" list, and did not find anything, so hopefully this is not a repeat.) First, I think it is important to enumerate the reasons systems/databases use SSNs: (note—these are reasons for de facto current state—I understand that many of them are not good reasons) Required for Interaction with External Entities. This is the most valid case—where external entities your system interfaces with require an SSN. This would typically be government, tax and financial. SSN is used to ensure system-wide uniqueness. SSN has become the default foreign key used internally within the enterprise, to perform cross-system joins. SSN is used for user authentication (e.g., log-on) The enterprise solution that seems optimum to me is to create a single SSN repository that is accessed by all applications needing to look up SSN info. This repository substitutes a globally unique, random 9-digit number (ASN) for the true SSN. I see many benefits to this approach. First of all, it is obviously highly backwards-compatible—all your systems "just" have to go through a major, synchronized, one-time data-cleansing exercise, where they replace the real SSN with the alternate ASN. Also, it is centralized, so it minimizes the scope for inspection and compliance. (Obviously, as a negative, it also creates a single point of failure.) This approach would solve issues 2 and 3, without ever requiring lookups to get the real SSN. For issue #1, authorized systems could provide an ASN, and be returned the real SSN. This would of course be done over secure connections, and the requesting systems would never persist the full SSN. Also, if the requesting system only needs the last 4 digits of the SSN, then that is all that would ever be passed. Issue #4 could be handled the same way as issue #1, though obviously the best thing would be to move away from having users supply an SSN for log-on. There are a couple of papers on this: UC Berkely: http://bit.ly/bdZPjQ Oracle Vault: bit.ly/cikbi1

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  • What design pattern do you use the most?

    - by spoon16
    I'm interested in understanding what design patterns people find themselves using often. Hopefully this list will help other recognize common scenarios and the associated design pattern that can be used to solve them. Please describe a common problem you find yourself solving and the design pattern(s) you use to solve it. Links to blogs or documentation describing the pattern are also appreciated. Edit: Please expand on your answers a bit, I would like this to be a useful reference for someone who wants to learn more about design patterns and is curious on what situations a specific design pattern might be used. Nobody has linked to any "more learning" resources.

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  • MVC Paging and Sorting Patterns: How to Page or Sort Re-Using Form Criteria

    - by CRice
    What is the best ASP.NET MVC pattern for paging data when the data is filtered by form criteria? This question is similar to: http://stackoverflow.com/questions/1425000/preserve-data-in-net-mvc but surely there is a better answer? Currently, when I click the search button this action is called: [AcceptVerbs(HttpVerbs.Post)] public ActionResult Search(MemberSearchForm formSp, int? pageIndex, string sortExpression) {} That is perfect for the initial display of the results in the table. But I want to have page number links or sort expression links re-post the current form data (the user entered it the first time - persisted because it is returned as viewdata), along with extra route params 'pageIndex' or 'sortExpression', Can an ActionLink or RouteLink (which I would use for page numbers) post the form to the url they specify? <%= Html.RouteLink("page 2", "MemberSearch", new { pageIndex = 1 })%> At the moment they just do a basic redirect and do not post the form values so the search page loads fresh. In regular old web forms I used to persist the search params (MemberSearchForm) in the ViewState and have a GridView paging or sorting event reuse it.

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