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  • Relationship between SOA and OOA

    - by TheSilverBullet
    Thomas Erl defines SOA as follows in his site: Service-oriented computing represents a new generation distributed computing platform. As such, it encompasses many things, including its own design paradigm and design principles, design pattern catalogs, pattern languages, a distinct architectural model, and related concepts, technologies, and frameworks. This definitely sounds like a whole new category which is parallel to object orientation. Almost one in which you would expect an entirely new language to exist for. Like procedural C and object oriented C#. Here is my understanding: In real life, we don't have entirely new language for SOA. And most application which have SOA architecture have an object oriented design underneath it. SOA is a "strategy" to make the entire application/service distributed and reliable. SOA needs OOPS working underneath it. Is this correct? Where does SOA (if at all it does) fit in with object oriented programming practices? Edit: I have learnt through answers that OOA and SOA work with each other and cannot be compared (in a "which is better" way). I have changed the title to "Relationship between SOA and OOA" rather than "comparison".

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  • Must all AI states be able to react to any event?

    - by Prog
    FSMs implemented with the State design pattern are a common way to design AI agents. I am familiar with the State design pattern and know how to implement it. How is this used in games to design AI agents? Consider a simplified class Monster, representing an AI agent: class Monster { State state; // other fields omitted public void update(){ // called every game-loop cycle state.execute(this); } public void setState(State state){ this.state = state; } // irrelevant stuff omitted } There are several State subclasses implementing execute() differently. So far, classic State pattern. AI agents are subject to environmental effects and other objects communicating with them. For example, an AI agent might tell another AI agent to attack (i.e. agent.attack()). Or a fireball might tell an AI agent to fall down. This means that the agent must have methods such as attack() and fallDown(), or commonly some message receiving mechanism to understand such messages. With an FSM, the current State of the agent should be the one taking care of such method calls - i.e. the agent delegates to the current state upon every event. Is this correct? If correct, how is this done? Are all states obligated by their superclass to implement methods such as attack(), fallDown() etc., so the agent can always delegate to them on almost every event? Or is it done in some other way?

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  • How to learn to deliver quality software designs when working on a tight deadline?

    - by chester89
    I read many books about how to design great software, but I kind of struggle to come up with a good design decisions when it comes to business apps, especially when the timeframe is tough. In the company I currently work for, the following situation happen all the time: my teamlead tells me that there's a task to do, I call some guy or a girl from business who tells me exactly what is it they want, and then I start coding. The task always fits in some existing application (we do only web apps or web services), usually it's purpose is to pull data from one datasource and put into the other one, with some business logic attached in the process. I start coding and then, after spending some time on a problem, my code didn't work as expected - either because of technical mistake or my lack of knowledge of the domain. The business is ringing me 2-3 times a day to hurry me up. I ask my team lead to help, he comes up, sees my code and goes like 'What's this?'. Then he throws away about half of my code, including all the design decisions I made, writes 2-3 methods that does the job (each of them usually 200-300 lines long or more, by the way), and task is complete, code works as it should have. The guy is smarter than me, obviously, and I'm aware of that. My goal is to be better software developer, that means write better code, not finish the job quicker with some crappy code. And the thing is, when I have enough time to tackle a problem, I can come up with a design that is good (in my opinion, of course), but I fall short to do so when I'm on a tight deadline. What should I do? I am fully aware that it's rather vague explanation, but please bear with me

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  • How useful are design patterns when it comes to web programming?

    - by Raja
    Background: My organization uses Microsoft .Net (3.5) with SQL Server 2005 as back end. With RAD being the norm and Agile being the widely used process. I have always found using design patterns difficult since it involves a bit more understanding and bit more training. Can you give me some examples where design patterns have solved real time problems in Web programming? What is the criteria for using any design pattern? What is the benefit reaped from it. I know it is a general question but this would help me a bunch.

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  • How can I unit test rendering output?

    - by stephelton
    I've been embracing Test-Driven Development (TDD) recently and it's had wonderful impacts on my development output and the resiliency of my codebase. I would like to extend this approach to some of the rendering work that I do in OpenGL, but I've been unable to find any good approaches to this. I'll start with a concrete example so we know what kinds of things I want to test; lets say I want to create a unit cube that rotates about some axis, and that I want to ensure that, for some number of frames, each frame is rendered correctly. How can I create an automated test case for this? Preferably, I'd even be able to write a test case before writing any code to render the cube (per usual TDD practices.) Among many other things, I'd want to make sure that the cube's size, location, and orientation are correct in each rendered frame. I may even want to make sure that the lighting equations in my shaders are correct in each frame. The only remotely useful approach to this that I've come across involves comparing rendered output to a reference output, which generally precludes TDD practice, and is very cumbersome. I could go on about other desired requirements, but I'm afraid the ones I've listed already are out of reach.

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  • Are DDD Aggregates really a good idea in a Web Application?

    - by Mystere Man
    I'm diving in to Domain Driven Design and some of the concepts i'm coming across make a lot of sense on the surface, but when I think about them more I have to wonder if that's really a good idea. The concept of Aggregates, for instance makes sense. You create small domains of ownership so that you don't have to deal with the entire domain model. However, when I think about this in the context of a web app, we're frequently hitting the database to pull back small subsets of data. For instance, a page may only list the number of orders, with links to click on to open the order and see its order id's. If i'm understanding Aggregates right, I would typically use the repository pattern to return an OrderAggregate that would contain the members GetAll, GetByID, Delete, and Save. Ok, that sounds good. But... If I call GetAll to list all my order's, it would seem to me that this pattern would require the entire list of aggregate information to be returned, complete orders, order lines, etc... When I only need a small subset of that information (just header information). Am I missing something? Or is there some level of optimization you would use here? I can't imagine that anyone would advocate returning entire aggregates of information when you don't need it. Certainly, one could create methods on your repository like GetOrderHeaders, but that seems to defeat the purpose of using a pattern like repository in the first place. Can anyone clarify this for me?

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  • Keeping a domain model consistent with actual data

    - by fstuijt
    Recently domain driven design got my attention, and while thinking about how this approach could help us I came across the following problem. In DDD the common approach is to retrieve entities (or better, aggregate roots) from a repository which acts as a in-memory collection of these entities. After these entities have been retrieved, they can be updated or deleted by the user, however after retrieval they are essentially disconnected from the data source and one must actively inform the repository to update the data source and make is consistent again with our in-memory representation. What is the DDD approach to retrieving entities that should remain connected to the data source? For example, in our situation we retrieve a series of sensors that have a specific measurement during retrieval. Over time, these measurement values may change and our business logic in the domain model should respond to these changes properly. E.g., domain events may be raised if a sensor value exceeds a predefined threshold. However, using the repository approach, these sensor values are just snapshots, and are disconnected from the data source. Does any of you have an idea on how to solve this following the DDD approach?

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  • Repository query conditions, dependencies and DRY

    - by vFragosop
    To keep it simple, let's suppose an application which has Accounts and Users. Each account may have any number of users. There's also 3 consumers of UserRepository: An admin interface which may list all users Public front-end which may list all users An account authenticated API which should only list it's own users Assuming UserRepository is something like this: class UsersRepository extends DatabaseAbstraction { private function query() { return $this->database()->select('users.*'); } public function getAll() { return $this->query()->exec(); } // IMPORTANT: // Tons of other methods for searching, filtering, // joining of other tables, ordering and such... } Keeping in mind the comment above, and the necessity to abstract user querying conditions, How should I handle querying of users filtering by account_id? I can picture three possible roads: 1. Should I create an AccountUsersRepository? class AccountUsersRepository extends UserRepository { public function __construct(Account $account) { $this->account = $account; } private function query() { return parent::query() ->where('account_id', '=', $this->account->id); } } This has the advantage of reducing the duplication of UsersRepository methods, but doesn't quite fit into anything I've read about DDD so far (I'm rookie by the way) 2. Should I put it as a method on AccountsRepository? class AccountsRepository extends DatabaseAbstraction { public function getAccountUsers(Account $account) { return $this->database() ->select('users.*') ->where('account_id', '=', $account->id) ->exec(); } } This requires the duplication of all UserRepository methods and may need another UserQuery layer, that implements those querying logic on chainable way. 3. Should I query UserRepository from within my account entity? class Account extends Entity { public function getUsers() { return UserRepository::findByAccountId($this->id); } } This feels more like an aggregate root for me, but introduces dependency of UserRepository on Account entity, which may violate a few principles. 4. Or am I missing the point completely? Maybe there's an even better solution? Footnotes: Besides permissions being a Service concern, in my understanding, they shouldn't implement SQL query but leave that to repositories since those may not even be SQL driven.

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  • Flash Web Design with the Help of Flash Professionals

    Flash has often been criticized by web specialists for its relatively slow loading time. It?s also been targeted by many people who have experienced loading problem of a Flash site on the web. But no... [Author: David Jackson - Web Design and Development - August 31, 2009]

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  • 24 Hours of PASS – Database Design Fundamentals

    - by drsql
    Well, I have to admit when I got the invite to speak during this event, I was honored (and still am for that matter). But I have to admit, I hope people don’t come in with any belief that I will be Celebrating SQL Server 2008 R2.  Most of what I will present could have been celebrated with SQL Server 6.5, as I will be doing my bread and butter Database Design Fundamentals session that I have done multiple times over the past few years. Ironically, had the people that you and I work with/for...(read more)

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  • Professional Custom Logo Design vs. Mr. Right

    John is an ex-marine and ex-employee of general motors. He recently lost his job working as a welder on the assembly lines of one of GM manufacturing plants. John has traveled a lot and knows a lot a... [Author: Emily Matthew - Web Design and Development - March 31, 2010]

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  • Design Book– Third Section (Implementing the Database)

    - by drsql
    The third section is the primary section that a person who has some decent knowledge and experience doing design will likely really find exciting. Whereas the first half of the book is there for fundamentals, this section is more skills based, and unless you are a walking encyclopedia of SQL Server syntax (and I am not), you have to use some form of reference to discover how to implement different sorts of problems using DDL, including Triggers, Constraints, etc;  Security; Source Control, etc....(read more)

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  • Website Design Versus Website Development

    Even though website design and website development is treated as one and the same thing, one should not confuse the differences between the two. To make a website complete, both a website designer and developers contribution is important as without either one we would not be able to view the websites on the world wide web.

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  • Google I/O 2011: Smart App Design

    Google I/O 2011: Smart App Design Travis Green, Max Lin, Robert Kaplow, Jóhannes Kristinsson, Ryan McGee Learn how to recommend the unexpected, automate the repetitive, and distill the essential using machine learning. This session will show you how you can easily add smarts to your apps with the Prediction API, and how to create apps that rapidly adapt to new data. From: GoogleDevelopers Views: 10078 47 ratings Time: 01:01:04 More in Science & Technology

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  • Using Flash in Your Website Design

    Many people like a wow factor in their website design and something that gives that is flash. Flash is used to created rich internet applications such as animation, video, audio and the interactivity of images.

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  • Responsive Web design d'Ethan Marcotte, critique par Ihèb BEN ROMDHANE

    Bonjour, Je vous propose la critique du Livre Responsive Web design de Ethan Marcotte. Citation: Encore un très bon ouvrage dans l'excellente collection A book Apart, dans lequel Ethan Marcotte aborde, de manière très claire et argumentée, les différents aspects qui mènent à la création d'une mise en page fluide et responsive. Les exemples présentés s'appuient sur le principe des grilles de m...

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  • BAM design pointers

    - by Kavitha Srinivasan
    In working recently with a large Oracle customer on SOA and BAM, I discovered that some BAM best practices are not quite well known as I had always assumed ! There is a doc bug out to formally incorporate those learnings but here are a few notes..  EMS-DO parity When using EMS (Enterprise Message Source) as a BAM feed, the best practice is to use one EMS to write to one Data Object. There is a possibility of collisions and duplicates when multiple EMS write to the same row of a DO at the same time. This customer had 17 EMS writing to one DO at the same time. Every sensor in their BPEL process writes to one topic but the Topic was read by 1 EMS corresponding to one sensor. They then used XSL within BAM to transform the payload into the BAM DO format. And hence for a given BPEL instance, 17 sensors fired, populated 1 JMS topic, was consumed by 17 EMS which in turn wrote to 1 DataObject.(You can image what would happen for later versions of the application that needs to send more information to BAM !).  We modified their design to use one Master XSL based on sensorname for all sensors relating to a DO- say Data Object 'Orders' and were able to thus reduce the 17 EMS to 1 with a master XSL. For those of you wondering about how squeaky clean this design is, you are right ! This is indeed not squeaky clean and that brings us to yet another 'inferred' best practice. (I try very hard not to state the obvious in my blogs with the hope that everytime I blog, it is very useful but this one is an exception.) Transformations and Calculations It is optimal to do transformations within an engine like BPEL. Not only does this provide modelling ease with a nice GUI XSL mapper in JDeveloper, the XSL engine in BPEL is quite efficient at runtime as well. And so, doing XSL transformations in BAM is not quite prudent.  The same is true for any non-trivial calculations as well. It is best to do all transformations,calcuations and sanitize the data in a BPEL or like layer and then send this to BAM (via JMS, WS etc.) This then delegates simply the function of report rendering and mechanics of real-time reporting to the Oracle BAM reporting tool which it is most suited to do. All nulls are not created equal Here is yet another possibly known fact but reiterated here. For an EMS with an Upsert operation: a) If Empty tags or tags with no value are sent like <Tag1/> or <Tag1></Tag1>, the DO will be overwritten with --null-- b) If Empty tags are suppressed ie not generated at all, the corresponding DO field will NOT be overwritten. The field will have whatever value existed previously.  For an EMS with an Insert operation, both tags with an empty value and no tags result in –null-- being written to the DO. Hope this helps .. Happy 4th!

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  • Google Chrome Extensions: UI Design

    Google Chrome Extensions: UI Design Erik Kay, an engineer at Google, provides more information about the UI of Google Chrome's extension system. For more information visit code.google.com/chrome/extensions. From: GoogleDevelopers Views: 10120 57 ratings Time: 03:49 More in Science & Technology

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  • Simple tips to design a Customer Journey Map

    - by Isabel F. Peñuelas
    “A model can abstract to a level that is comprehensible to humans, without getting lost in details.” -The Unified Modeling Language Reference Manual. Inception using Post-it, StoryBoards, Lego or Mindmaping Techniques The first step in a Customer Experience project is to describe customer interactions creating a customer journey map. Modeling is never easy, so to succeed on this effort, it is very convenient that your CX´s team have some “abstract thinking” skills. Besides is very helpful to consult a Business Service Design offered by an Interactive Agency to lead your inception process. Initially, you may start by a free discussion using post-it cards; storyboards; even lego or any other brainstorming technique you like. This will help you to get your mind into the path followed by the customer to purchase your product or to consume any business service you actually offer to your customers, or plan to offer in the near future. (from www.servicedesigntools.org) Colorful Mind Maps are very useful to document and share meeting ideas. Some Mind Maps software providers as ThinkBuzzan provide trial versions, and you will find more mindmapping options on this post by Mashable. Finally to produce a quick one, I do recommend Wise, an entirely online mindmaping service. On my view the best results in terms of communication will always come for an artistic hand-made drawing. Customer Experience Mind Map Example Making your first Customer Journey Map To add some more formalization to your thoughts, there is a wide offering for designing Customer Journey Maps. A Customer Map can be represented as an oriented graph in which another follows each step. The one below is the most simple Customer Journey you can draw. Nothing more than a couple of pictures, numbers and lines to design the customer steps sequence in the purchase process. Very simple Customer Journey for Social Mobile Shopping There are a lot of Customer Journey templates much more sophisticated available  in the Web using a variety of styles, as per example this one with a focus on underlining emotional experience, or this other worksheet template. Representing different interaction devices on the vertical axis, and touchpoints / requirements and existing gaps horizontally  is today´s most common format for Customer Journeys. From Customer Journey Maps to CX Technology Adoption Plans Once you have your map ready, you can start to identify the IT infrastructure requirements for your CXProject. By analyzing customer problems and improvement opportunities with maps, you will then identify the technology gaps and the new investment requirements in your IT infrastructure. Deeping step by step from the more abstract to the more concrete is the best guarantee to take the right IT investment decisions.  ¡Remember to keep your initial customer journey safe on your pocket in every one of your CX´s project meetings- that´s you map to success!

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  • Task Flow Design Paper Revised

    - by Duncan Mills
    Thanks to some discussion over at the ADF Methodology Group and contributions from Simon Lessard and Jan Vervecken I have been able to make some refinements to the Task Flow Design Fundamentals paper on OTN.As a bonus, whilst I was making some edits anyway I've included some of Frank Nimphius's memory scope diagrams which are a really useful tool for understanding how request, view, backingBean and pageFlow scopes all fit together.

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