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  • Getting started with modern software architecture and design using a book

    - by bitbonk
    I am a rather oldschool developer with some basic knowledge of software design principles and a good background on classic (gof) design patterns. While I continue my life as such I see lots of strange buzzwords emerge: Aspectoriented Design, Componentoriented Design, Domain Driven Design, Domain Specific Languages, Serviceoriented (SOA) Design, Test Driven Design, Extreme Programming, Agile Development, Continuous Integration, Dependency Injection, Software Factories ... Is there good book around that I can take with me on a roadtrip while it is taking me on a trip through all (most) of the above, delivering an 10,000 foot view on modern software archiceture and desing principles and approaches.

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  • Is there a language or design pattern that allows the *removal* of object behavior or properties in a class hierarchy?

    - by Sebastien Diot
    A well-know shortcoming of traditional class hierarchies is that they are bad when it comes to model the real world. As an example, trying to represent animals species with classes. There are actually several problems when doing that, but one that I never saw a solution to is when a sub-class "looses" a behavior or properties that was defined in a super-class, like a penguin not being able to fly (there are probably better examples, but that's the first one that comes to my mind, having seen "Madagascar 2" recently). On the one hand, you don't want to define for every property and behavior some flag that specifies if it is at all present, and check it every time before accessing that behavior or property. You would just like to say that birds can fly, simply and clearly, in the Bird class. But then it would be nice if one could define "exceptions" afterward, without having to use some horrible hacks everywhere. This often happens when a system has been productive for a while. You suddenly find an "exception" that doesn't fit in the original design at all, and you don't want to change a large portion of your code to accommodate it. So, is there some language or design patterns that can cleanly handle this problem, without requiring major changes to the "super-class", and all the code that uses it? Even if a solution only handle a specific case, several solutions might together form a complete strategy. [EDIT] Forgot about the Liskov Substitution Principle. That is why you can't do it. Assuming you define "traits/interfaces" for all major "feature groups", you can freely implement traits in different branches of the hierarchy, like the Flying trait could be implemented by Birds, and some special kind of squirrels and fish. So my question could amount to "How could I un-implement a trait?" If your super-class is a Java Serializable, you have to be one too, even if there is no way for you to serialize your state, for example if you contained a "Socket". So one way to do it is to always define all your traits in pair from the start: Flying and NotFlying (which would throw UnsupportedOperationExceiption, if not checked against). The Not-trait would not define any new interface, and could be simply checked for. Sounds like a "cheap" solution, in particular if used from the start.

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  • Design Patterns: What's the antithesis of Front Controller?

    - by Brian Lacy
    I'm familiar with the Front Controller pattern, in which all events/requests are processed through a single centralized controller. But what would you call it when you wish to keep the various parts of an application separate at the presentation layer as well? My first thought was "Facade" but it turns out that's something entirely different. In my particular case, I'm converting an application from a sprawling procedural mess to a clean MVC architecture, but it's a long-term process -- we need to keep things separated as much as possible to facilitate a slow integration with the rest of the system. Our application is web-based, built in PHP, so for instance, we have an "index.php" and an IndexController, a "account.php" and an AccountController, a "dashboard.php" and DashboardController, and so on.

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  • Session Report - Modern Software Development Anti-Patterns

    - by Janice J. Heiss
    In this standing-room-only session, building upon his 2011 JavaOne Rock Star “Diabolical Developer” session, Martijn Verburg, this time along with Ben Evans, identified and explored common “anti-patterns” – ways of doing things that keep developers from doing their best work. They emphasized the importance of social interaction and team communication, along with identifying certain psychological pitfalls that lead developers astray. Their emphasis was less on technical coding errors and more how to function well and to keep one’s focus on what really matters. They are the authors of the highly regarded The Well-Grounded Java Developer and are both movers and shakers in the London JUG community and on the Java Community Process. The large room was packed as they gave a fast-moving, witty presentation with lots of laughs and personal anecdotes. Below are a few of the anti-patterns they discussed.Anti-Pattern One: Conference-Driven DeliveryThe theme here is the belief that “Real pros hack code and write their slides minutes before their talks.” Their response to this anti-pattern is an expression popular in the military – PPPPPP, which stands for, “Proper preparation prevents piss-poor performance.”“Communication is very important – probably more important than the code you write,” claimed Verburg. “The more you speak in front of large groups of people the easier it gets, but it’s always important to do dry runs, to present to smaller groups. And important to be members of user groups where you can give presentations. It’s a great place to practice speaking skills; to gain new skills; get new contacts, to network.”They encouraged attendees to record themselves and listen to themselves giving a presentation. They advised them to start with a spouse or friends if need be. Learning to communicate to a group, they argued, is essential to being a successful developer. The emphasis here is that software development is a team activity and good, clear, accessible communication is essential to the functioning of software teams. Anti-Pattern Two: Mortgage-Driven Development The main theme here was that, in a period of worldwide recession and economic stagnation, people are concerned about keeping their jobs. So there is a tendency for developers to treat knowledge as power and not share what they know about their systems with their colleagues, so when it comes time to fix a problem in production, they will be the only one who knows how to fix it – and will have made themselves an indispensable cog in a machine so you cannot be fired. So developers avoid documentation at all costs, or if documentation is required, put it on a USB chip and lock it in a lock box. As in the first anti-pattern, the idea here is that communicating well with your colleagues is essential and documentation is a key part of this. Social interactions are essential. Both Verburg and Evans insisted that increasingly, year by year, successful software development is more about communication than the technical aspects of the craft. Developers who understand this are the ones who will have the most success. Anti-Pattern Three: Distracted by Shiny – Always Use the Latest Technology to Stay AheadThe temptation here is to pick out some obscure framework, try a bit of Scala, HTML5, and Clojure, and always use the latest technology and upgrade to the latest point release of everything. Don’t worry if something works poorly because you are ahead of the curve. Verburg and Evans insisted that there need to be sound reasons for everything a developer does. Developers should not bring in something simply because for some reason they just feel like it or because it’s new. They recommended a site run by a developer named Matt Raible with excellent comparison spread sheets regarding Web frameworks and other apps. They praised it as a useful tool to help developers in their decision-making processes. They pointed out that good developers sometimes make bad choices out of boredom, to add shiny things to their CV, out of frustration with existing processes, or just from a lack of understanding. They pointed out that some code may stay in a business system for 15 or 20 years, but not all code is created equal and some may change after 3 or 6 months. Developers need to know where the code they are contributing fits in. What is its likely lifespan? Anti-Pattern Four: Design-Driven Design The anti-pattern: If you want to impress your colleagues and bosses, use design patents left, right, and center – MVC, Session Facades, SOA, etc. Or the UML modeling suite from IBM, back in the day… Generate super fast code. And the more jargon you can talk when in the vicinity of the manager the better.Verburg shared a true story about a time when he was interviewing a guy for a job and asked him what his previous work was. The interviewee said that he essentially took patterns and uses an approved book of Enterprise Architecture Patterns and applied them. Verburg was dumbstruck that someone could have a job in which they took patterns from a book and applied them. He pointed out that the idea that design is a separate activity is simply wrong. He repeated a saying that he uses, “You should pay your junior developers for the lines of code they write and the things they add; you should pay your senior developers for what they take away.”He explained that by encouraging people to take things away, the code base gets simpler and reflects the actual business use cases developers are trying to solve, as opposed to the framework that is being imposed. He told another true story about a project to decommission a very long system. 98% of the code was decommissioned and people got a nice bonus. But the 2% remained on the mainframe so the 98% reduction in code resulted in zero reduction in costs, because the entire mainframe was needed to run the 2% that was left. There is an incentive to get rid of source code and subsystems when they are no longer needed. The session continued with several more anti-patterns that were equally insightful.

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  • Patterns to implement this grammar into C# code

    - by MexicanHacker
    Hey guys, I'm creating this little BNF grammar and I wanted to <template>::= <types><editors> <types>::= <type>+ <type>::= <property>+ <property>::= <name><type> <editors>::= <editor>+ <editor>::= <name><type>(<textfield>|<form>|<list>|<pulldown>)+ <textfield>::= <label><property>[<editable>] <form>::= <label><property><editor> <list>::= <label><property><item-editor> <pulldown>::= <label><property><option>+ <option>::= <value> One possible solution we have in mind is to create POCO's that have annotations of the XMLSerialization namespace, like this, for example: [XMLRoot("template")] public class Template{ [XMLElement("types")] public Types types{ } } However I want to explore more solutions, what do you guys think?

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  • C# Design Layout/Patterns

    - by wpfwannabe
    I am still fairly new to C# and I am trying to decide the best way to structure a new program. Here is what I want to do and I would like feed back on my idea. Presentation Layer Business Layer (Separate Class Library) Data Layer (Separate Class Library) Model Layer (Separate Class Library) What I am struggling with is if it is ok to have the classes in the Data Layer and Business Layer inherit from the types I define in Model Layer. This way I can extended the types as needed in my Business Layer with any new properties I see fit. I might not use every property from the Model type in my Business Layer class but is that really a big deal? If this isn't clear enough I can try and put together an example.

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  • How to refactor my design, if it seems to require multiple inheritance?

    - by Omega
    Recently I made a question about Java classes implementing methods from two sources (kinda like multiple inheritance). However, it was pointed out that this sort of need may be a sign of a design flaw. Hence, it is probably better to address my current design rather than trying to simulate multiple inheritance. Before tackling the actual problem, some background info about a particular mechanic in this framework: It is a simple game development framework. Several components allocate some memory (like pixel data), and it is necessary to get rid of it as soon as you don't need it. Sprites are an example of this. Anyway, I decided to implement something ala Manual-Reference-Counting from Objective-C. Certain classes, like Sprites, contain an internal counter, which is increased when you call retain(), and decreased on release(). Thus the Resource abstract class was created. Any subclass of this will obtain the retain() and release() implementations for free. When its count hits 0 (nobody is using this class), it will call the destroy() method. The subclass needs only to implement destroy(). This is because I don't want to rely on the Garbage Collector to get rid of unused pixel data. Game objects are all subclasses of the Node class - which is the main construction block, as it provides info such as position, size, rotation, etc. See, two classes are used often in my game. Sprites and Labels. Ah... but wait. Sprites contain pixel data, remember? And as such, they need to extend Resource. But this, of course, can't be done. Sprites ARE nodes, hence they must subclass Node. But heck, they are resources too. Why not making Resource an interface? Because I'd have to re-implement retain() and release(). I am avoiding this in virtue of not writing the same code over and over (remember that there are multiple classes that need this memory-management system). Why not composition? Because I'd still have to implement methods in Sprite (and similar classes) that essentially call the methods of Resource. I'd still be writing the same code over and over! What is your advice in this situation, then?

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  • Design pattern for adding / removing elements

    - by de3
    Wikipedia's definition for Iterator pattern design: the Iterator pattern is a design pattern in which iterators are used to access the elements of an aggregate object sequentially without exposing its underlying implementation. Iterator interface in java provides the following methods hasNext() next() remove() Is there a pattern design, or a java interface for inserting / deleting elements, and getting length of the aggregate object, in addition to iterating them? I know remove() is an optional method that can be used once per call to next(), but I am implementing a circular FIFO array and need a method delete() independent of iterator's next().

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  • iPhone development - app design patterns

    - by occulus
    There are tons of resources concerning coding on the iPhone. Most of them concern "how do I do X", e.g. "setup a navigation controller", or "download text from a URL". All good and fine. What I'm more interested in now are the questions that follow the simpler stuff - how to best structure your complex UI, or your app, or the common problems that arise. To illustrate: a book like "Beginning iPhone 3 Development" tells you how to set up a multi viewcontroller app with an top 'switcher' viewcontroller that switches between views owned by other view controllers. Fine, but you're only told how to do that, and nothing about the problems that can follow: for example, if I use their paradigm to switch to a UINavigationViewController, the Navigation bar ends up too low on the screen, because UINavigationViewController expects to be the topmost UIViewController (apparently). Also, delegate methods (e.g. relating to orientation changes) go to the top switcher view controller, not the actual controller responsible for the current view. I have fixes for these things but they feel like hacks which makes me unhappy and makes me feel like I'm missing something. One productive thing might be to look at some open source iPhone projects (see this question). But aside from that?

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  • What are the common patterns in web programming?

    - by lankerisms
    I have been trying to write my first big web app (more than one cgi file) and as I kept moving forward with the rough prototype, paralelly trying to predict more tasks, this is the todo that got accumulated (In no particular order). * Validations and input sanitizations * Object versioning (to avoid edit conflicts. I dont want hard locks) * Exception handling * memcache * xss and injection protections * javascript * html * ACLs * phonetics in search, match and find duplicates (for form validation) * Ajaxify!!! (I have snipped off the project specific items.) I know that each todo will be quite tied up to its project and technologies used. What I am wondering though, is if there is a pattern in your todo items as well as the sequence in which you experienced guys have come across them.

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  • What Design Pattern is this?

    - by 01
    I know that everything we do in programming can be described as design pattern(even abstract method has design pattern called template method) public class Guicer extends AbstractModule { private static Injector injector = Guice.createInjector(new Guicer()); public static void setInjector(Injector injector) { Guicer.injector = injector; } public static T getInstance(Class c) { return injector.getInstance(c); } @Override protected void configure() { } } What design patterns are used in this code?

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  • Is this a well known design pattern? what is it's name

    - by GenEric35
    Hi I have seen this often in code, but when I speak of it i don't know the name of such 'pattern' I have a method with 2 arguments that calls an overloaded method that has 3 arguments and intentionality sets the 3rd one to empty string. public DoWork(string name, string phoneNumber) { CreateContact(name, phoneNumber, string.Empty) } public DoWork(string name, string phoneNumber, string emailAddress) { //do the work } The reason I'm doing this is I to not duplicate code, and allow the existing callers to still call the method that has only 2 parameters. I have associate a few tags to this question, but it probably fit in more categories of questions. Is this a pattern, and does it have a name?

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  • MCV/MVP Patterns and Applications that interface with Hardware (DAQ/PLC/etc)

    - by Ryan
    I've been reading a lot about the MCV and MVP patterns for use with UI and it seems like a really nice powerful way to handle user interfaces. I am - however - having a difficult time deciding how this could integrate into a system where data in the model is created from a Data Acquisition System or Serial/Ethernet devices. There is also the added step that 70% of application interaction is performed by a PLC instead of a live user. It seems that for apps that just read/write & manipulate information from a database this works great, but how does does hardware and automation fit into these patterns? Is it as simple as another controller (for lack of a better term) that interacts with hardware that manipulates data and writes to a model? Maybe I am over thinking this or thinking too simply, so any advice would be great. I'm not quite sure where I'm going with this, so if something doesn't make sense or I was too vague leave me a comment. Thanks!

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  • Finding shapes in 2D Array, then optimising

    - by assemblism
    I'm new so I can't do an image, but below is a diagram for a game I am working on, moving bricks into patterns, and I currently have my code checking for rotated instances of a "T" shape of any colour. The X and O blocks would be the same colour, and my last batch of code would find the "T" shape where the X's are, but what I wanted was more like the second diagram, with two "T"s Current result      Desired Result [X][O][O]                [1][1][1] [X][X][_]                [2][1][_] [X][O][_]                [2][2][_] [O][_][_]                [2][_][_] My code loops through x/y, marks blocks as used, rotates the shape, repeats, changes colour, repeats. I have started trying to fix this checking with great trepidation. The current idea is to: loop through the grid and make note of all pattern occurrences (NOT marking blocks as used), and putting these to an array loop through the grid again, this time noting which blocks are occupied by which patterns, and therefore which are occupied by multiple patterns. looping through the grid again, this time noting which patterns obstruct which patterns That much feels right... What do I do now? I think I would have to try various combinations of conflicting shapes, starting with those that obstruct the most other patterns first.How do I approach this one? use the rational that says I have 3 conflicting shapes occupying 8 blocks, and the shapes are 4 blocks each, therefore I can only have a maximum of two shapes. (I also intend to incorporate other shapes, and there will probably be score weighting which will need to be considered when going through the conflicting shapes, but that can be another day) I don't think it's a bin packing problem, but I'm not sure what to look for. Hope that makes sense, thanks for your help

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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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  • Should we write detailed architecture design or just an outline when designing a program?

    - by EpsilonVector
    When I'm doing design for a task, I keep fighting this nagging feeling that aside from being a general outline it's going to be more or less ignored in the end. I'll give you an example: I was writing a frontend for a device that has read/write operations. It made perfect sense in the class diagram to give it a read and a write function. Yet when it came down to actually writing them I realized they were literally the same function with just one line of code changed (read vs write function call), so to avoid code duplication I ended up implementing a do_io function with a parameter that distinguishes between operations. Goodbye original design. This is not a terribly disruptive change, but it happens often and can happen in more critical parts of the program as well, so I can't help but wondering if there's a point to design more detail than a general outline, at least when it comes to the program's architecture (obviously when you are specifying an API you have to spell everything out). This might be just the result of my inexperience in doing design, but on the other hand we have agile methodologies which sort of say "we give up on planning far ahead, everything is going to change in a few days anyway", which is often how I feel. So, how exactly should I "use" design?

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  • How do game programmers design their classes to reuse in AI, network and play and pass mode?

    - by Amogh Talpallikar
    For a two player game where, your opponent could be on the network, CPU itself or near you where you would play turn by turn on the same machine. How do people design classes for re-use ? I am in a similar situation and have no experience in making such complex games. But here is what I have thought, If I am a player object , I should only be interacting with the GameManager or GameEngine Singleton , from which I will get various notifications about the game status. I dont care where and who my opponent is, this GameManager depending upon the game mode, will interact with gameNetworkManager , or AI tell me what the opponent played. I am not sure about the scenario where we play and pass [turn by turn on same machine]. Hoping for a brief but clear explanation or at least a link to a similar resource.:)

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  • As an indie game dev, what processes are the best for soliciting feedback on my design/spec/idea? [closed]

    - by Jess Telford
    Background I have worked in a professional environment where the process usually goes like the following: Brain storm idea Solidify the game mechanics / design Iterate on design/idea to create a more solid experience Spec out the details of the design/idea Build it Step 3. is generally done with the stakeholders of the game (developers, designers, investors, publishers, etc) to reach an 'agreement' which meets the goals of all involved. Due to this process involving a series of often opposing and unique view points, creative solutions can surface through discussion / iteration. This is backed up by a process for collating the changes / new ideas, as well as structured time for discussion. As a (now) indie developer, I have to play the role of all the stakeholders (developers, designers, investors, publishers, etc), and often find myself too close to the idea / design to do more than minor changes, which I feel to be local maxima when it comes to the best result (I'm looking for the global maxima, of course). I have read that ideas / game designs / unique mechanics are merely multipliers of execution, and that keeping them secret is just silly. In sharing the idea with others outside the realm of my own thinking, I hope to replicate the influence other stakeholders have. I am struggling with the collation of changes / new ideas, and any kind of structured method of receiving feedback. My question: As an indie game developer, how and where can I share my ideas/designs to receive meaningful / constructive feedback? How can I successfully collate the feedback into a new iteration of the design? Are there any specialized websites, etc?

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  • Is there a good design pattern for this messaging class?

    - by salonMonsters
    Is there a good design pattern for this? I want to create a messaging class. The class will be passed: the type of message (eg. signup, signup confirmation, password reminder etc) the client's id The class needs to then look up the client's messaging preferences in the db (whether they want communication by email, sms or both) Then depending on the client's preference it will format the message for the medium (short version for sms, long form for email) and send it through our mail or sms provider's API. Because the fact that we want to be able to change out email and sms providers if need be I wondered if the Command Pattern would be a good choice.

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  • Where can I find design exercises to work on?

    - by Oak
    I feel it's important to continue practicing my problem-solving skills. Writing my own mini-projects is one way, but another is to try and solve problems posted online. It's easy to find interesting programming quizzes online that require applying clever algorithms to solve - Project Euler is one well-known example. However, in a lot of real-life projects the design of the software - especially in the initial phases - has a large impact and at later stages it cannot be tweaked as easily as plain algorithms. In order to improve these skills, I'm looking for any collection of design problems. When I say "design", I mean the abstract design of a software solution - for example what modules will there be and what are the dependencies between them, how data will flow in the program, what sort of data needs to be saved in the database, etc. Design problems are those problems that are critical to solve in the early stages of any project, but their solution is a whiteboard diagram without a single line of code. Of course these sort of problems do not have a single correct solution, but I'll be especially happy with any place that also displays pros and cons of the typical solutions that might be used to approach the problem.

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  • What modelling technique do you use for your continuous design?

    - by d3prok
    Together with my teammates, I'm trying to self-learn XP and apply its principles. We're successfully working in TDD and happily refactoring our code and design. However we're having problems with the overall view of the design of the project. Lately we were wondering what would be the "good" practices for an effective continuous design of the code. We're not strictly seeking the right model, like CRC cards, communication diagrams, etc., instead we're looking for a technique to constantly collaborate on the high level view of the system (not too high though). I'll try to explain myself better: I'm actually interested in the way CRC cards are used to brainstorm a model and I would mix them with some very rough UML diagrams (that we already use). However, what we're looking for are some principles for deciding when, how and how much to model during our iterations. Have you any suggestion on this matter? For example, when your teammates and you know you need a design session and how your meetings work?

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