Search Results

Search found 22098 results on 884 pages for 'service oriented architec'.

Page 39/884 | < Previous Page | 35 36 37 38 39 40 41 42 43 44 45 46  | Next Page >

• How to design a scalable notification system?

  - by Trent

  I need to write a notification system manager. Here is my requirements: I need to be able to send a Notification on different platforms, which may be totally different (for exemple, I need to be able to send either an SMS or an E-mail). Sometimes the notification may be the same for all recipients for a given platform, but sometimes it may be a notification per recipients (or several) per platform. Each notification can contain platform specific payload (for exemple an MMS can contains a sound or an image). The system need to be scalable, I need to be able to send a very large amount of notification without crashing either the application or the server. It is a two step process, first a customer may type a message and choose a platform to send to, and the notification(s) should be created to be processed either real-time either later. Then the system needs to send the notification to the platform provider. For now, I end up with some though but I don't know how scalable it will be or if it is a good design. I've though of the following objects (in a pseudo language): a generic Notification object: class Notification { String $message; Payload $payload; Collection<Recipient> $recipients; } The problem with the following objects is what if I've 1.000.000 recipients ? Even if the Recipient object is very small, it'll take too much memory. I could also create one Notification per recipient, but some platform providers requires me to send it in batch, meaning I need to define one Notification with several Recipients. Each created notification could be stored in a persistent storage like a DB or Redis. Would it be a good it to aggregate this later to make sure it is scalable? On the second step, I need to process this notification. But how could I distinguish the notification to the right platform provider? Should I use an object like MMSNotification extending an abstract Notification? or something like Notification.setType('MMS')? To allow to process a lot of notification at the same time, I think a messaging queue system like RabbitMQ may be the right tool. Is it? It would allow me to queue a lot of notification and have several worker to pop notification and process them. But what if I need to batch the recipients as seen above? Then I imagine a NotificationProcessor object for which I could I add NotificationHandler each NotificationHandler would be in charge to connect the platform provider and perform notification. I can also use an EventManager to allow pluggable behavior. Any feedbacks or ideas? Thanks for giving your time. Note: I'm used to work in PHP and it is likely the language of my choice.

  Read the article

• How do you educate your teammates without seeming condescending or superior?

  - by Dan Tao

  I work with three other guys; I'll call them Adam, Brian, and Chris. Adam and Brian are bright guys. Give them a problem; they will figure out a way to solve it. When it comes to OOP, though, they know very little about it and aren't particularly interested in learning. Pure procedural code is their MO. Chris, on the other hand, is an OOP guy all the way -- and a cocky, condescending one at that. He is constantly criticizing the work Adam and Brian do and talking to me as if I must share his disdain for the two of them. When I say that Adam and Brian aren't interested in learning about OOP, I suspect Chris is the primary reason. This hasn't bothered me too much for the most part, but there have been times when, looking at some code Adam or Brian wrote, it has pained me to think about how a problem could have been solved so simply using inheritance or some other OOP concept instead of the unmaintainable mess of 1,000 lines of code that ended up being written instead. And now that the company is starting a rather ambitious new project, with Adam assigned to the task of getting the core functionality in place, I fear the result. Really, I just want to help these guys out. But I know that if I come across as just another holier-than-thou developer like Chris, it's going to be massively counterproductive. I've considered: Team code reviews -- everybody reviews everybody's code. This way no one person is really in a position to look down on anyone else; besides, I know I could learn plenty from the other members on the team as well. But this would be time-consuming, and with such a small team, I have trouble picturing it gaining much traction as a team practice. Periodic e-mails to the team -- this would entail me sending out an e-mail every now and then discussing some concept that, based on my observation, at least one team member would benefit from learning about. The downside to this approach is I do think it could easily make me come across as a self-appointed expert. Keeping a blog -- I already do this, actually; but so far my blog has been more about esoteric little programming tidbits than straightforward practical advice. And anyway, I suspect it would get old pretty fast if I were constantly telling my coworkers, "Hey guys, remember to check out my new blog post!" This question doesn't need to be specifically about OOP or any particular programming paradigm or technology. I just want to know: how have you found success in teaching new concepts to your coworkers without seeming like a condescending know-it-all? It's pretty clear to me there isn't going to be a sure-fire answer, but any helpful advice (including methods that have worked as well as those that have proved ineffective or even backfired) would be greatly appreciated. UPDATE: I am not the Team Lead on this team. Chris is. UPDATE 2: Made community wiki to accord with the general sentiment of the community (fancy that).

  Read the article

• Test interface implementation

  - by Michael

  I have a interface in our code base that I would like to be able to mock out for unit testing. I am writing a test implementation to allow the individual tests to be able to override the specific methods they are concerned with rather than implementing every method. I've run into a quandary over how the test implementation should behave if the test fails to override a method used by the method under test. Should I return a "non-value" (0, null) in the test implementation or throw a UnsupportedOperationException to explicitly fail the test?

  Read the article

• Need advice on design in Ruby On Rails

  - by Elad

  For personal educational purposes I am making a site for a conference. One of the object that exist in a conference is a session, which has different states and in each state it has slightly different attributes: When submitted it has a speaker (User in the system), Title and abstract. When under review it has reviews and comments (in addition to the basic data) When accepted it has a defined time-slot but no reviewers anymore. I feel that it is not the best thing to add a "status" attributes and start adding many if statements... So I thought it would be better to have different classes for each state each with it's own validations and behaviors. What do you think about this design? Do you have a better idea? *I must add this out of frustration: I had several edits of the question, including one major change but no one actually gave any hint or clue on which direction should i take or where is a better place to ask this... Hardly helpful.

  Read the article

• Is there any reason to use "plain old data" classes?

  - by Michael

  In legacy code I occasionally see classes that are nothing but wrappers for data. something like: class Bottle { int height; int diameter; Cap capType; getters/setters, maybe a constructor } My understanding of OO is that classes are structures for data and the methods of operating on that data. This seems to preclude objects of this type. To me they are nothing more than structs and kind of defeat the purpose of OO. I don't think it's necessarily evil, though it may be a code smell. Is there a case where such objects would be necessary? If this is used often, does it make the design suspect?

  Read the article

• How can we protect the namespace of an object in Javascript?

  - by Eduard Florinescu

  Continuing from my previous question: Javascript simple code to understand prototype-based OOP basics Let's say we run into console this two separate objects(even if they are called child and parent there is no inheritance between them): var parent = { name: "parent", print: function(){ console.log("Hello, "+this.name); } }; var child = { name: "child", print: function(){ console.log("Hi, "+this.name); } }; parent.print() // This will print: Hello, parent child.print() // This will print: Hi, child temp =parent; parent = child; child = temp; parent.print() // This will now print: Hi, child child.print() // This will now print: Hello, parent Now suppose that parent is a library, as a HTML5 application in a browser this cannot do much harm because is practically running sandboxed, but now with the advent of the ChromeOS, FirefoxOS and other [Browser] OS they will also be linked to a native API, that would be a head out of the „sandbox”. Now if someone changes the namespace it would be harder for a code reviewer (either automated or not ) to spot an incorrect use if the namespaces changes. My question would be: Are there many ways in which the above situation can be done and what can be done to protect this namespaces? (Either in the javascript itself or by some static code analysis tool)

  Read the article

• Advice on designing a robust program to handle a large library of meta-information & programs

  - by Sam Bryant

  So this might be overly vague, but here it is anyway I'm not really looking for a specific answer, but rather general design principles or direction towards resources that deal with problems like this. It's one of my first large-scale applications, and I would like to do it right. Brief Explanation My basic problem is that I have to write an application that handles a large library of meta-data, can easily modify the meta-data on-the-fly, is robust with respect to crashing, and is very efficient. (Sorta like the design parameters of iTunes, although sometimes iTunes performs more poorly than I would like). If you don't want to read the details, you can skip the rest Long Explanation Specifically I am writing a program that creates a library of image files and meta-data about these files. There is a list of tags that may or may not apply to each image. The program needs to be able to add new images, new tags, assign tags to images, and detect duplicate images, all while operating. The program contains an image Viewer which has tagging operations. The idea is that if a given image A is viewed while the library has tags T1, T2, and T3, then that image will have boolean flags for each of those tags (depending on whether the user tagged that image while it was open in the Viewer). However, prior to being viewed in the Viewer, image A would have no value for tags T1, T2, and T3. Instead it would have a "dirty" flag indicating that it is unknown whether or not A has these tags or not. The program can introduce new tags at any time (which would automatically set all images to "dirty" with respect to this new tag) This program must be fast. It must be easily able to pull up a list of images with or without a certain tag as well as images which are "dirty" with respect to a tag. It has to be crash-safe, in that if it suddenly crashes, all of the tagging information done in that session is not lost (though perhaps it's okay to loose some of it) Finally, it has to work with a lot of images (10,000) I am a fairly experienced programmer, but I have never tried to write a program with such demanding needs and I have never worked with databases. With respect to the meta-data storage, there seem to be a few design choices: Choice 1: Invidual meta-data vs centralized meta-data Individual Meta-Data: have a separate meta-data file for each image. This way, as soon as you change the meta-data for an image, it can be written to the hard disk, without having to rewrite the information for all of the other images. Centralized Meta-Data: Have a single file to hold the meta-data for every file. This would probably require meta-data writes in intervals as opposed to after every change. The benefit here is that you could keep a centralized list of all images with a given tag, ect, making the task of pulling up all images with a given tag very efficient

  Read the article

• Web Developer interview questions

  - by Baba

  I read an article today that listed some basic questions about web development: Describe how POST data was submitted to a server by a browser. Explain a number of HTTP status codes (except maybe 404 and 500). Explain SOLID or name a design pattern. Explain ways to improve a page load speed or user experience. The author says "if you can’t answer the questions above there are a lot of people who wouldn’t think of you as a Senior Web Developer." My questions are: How relevant are these questions in respect to real life web programming and scalability? How true is that statement? In other words, do you consider this knowledge a requirement to be considered a Senior Web Developer? I was able to answer all the questions, too easily it seemed, so I'm wondering whether it is effective to use these or similar questions to screen developers rather than asking them to write sample code.

  Read the article

• If I define a property to prototype appears in the constructor of object, why?

  - by Eduard Florinescu

  I took the example from this question modified a bit: What is the point of the prototype method? function employee(name,jobtitle,born) { this.name=name; this.jobtitle=jobtitle; this.born=born; this.status="single" } employee.prototype.salary=10000000; var fred=new employee("Fred Flintstone","Caveman",1970); console.log(fred.salary); fred.salary=20000; console.log(fred.salary) And the output in console is this: What is the difference salary is in constructor but I still can access it with fred.salary, how can I see if is in constructor from code, status is still employee property how can I tell for example if name is the one of employee or has been touch by initialization? Why is salary in constructor, when name,jobtitle,born where "touched" by employee("Fred Flintstone","Caveman",1970); «constructor»?

  Read the article

• Can't I just use all static methods?

  - by Reddy S R

  What's the difference between the two UpdateSubject methods below? I felt using static methods is better if you just want to operate on the entities. In which situations should I go with non-static methods? public class Subject { public int Id {get; set;} public string Name { get; set; } public static bool UpdateSubject(Subject subject) { //Do something and return result return true; } public bool UpdateSubject() { //Do something on 'this' and return result return true; } } I know I will be getting many kicks from the community for this really annoying question but I could not stop myself asking it. Does this become impractical when dealing with inheritance?

  Read the article

• Naming a class that decides to retrieve things from cache or a service + architecture evaluation

  - by Thomas Stock

  Hi, I'm a junior developer and I'm working on a pet project that I want to learn as much as possible from. I have the following scenario: There's a WCF service that I use to retrieve and update data, lets say Cars. So it's called CarWCFService and has a GetCars(), SaveCar(), ... . It implements interface ICarService. This isn't the Actual WCF service but more like a wrapper around it. Upon retrieving data from the service, I want to store them in local memory, as cache. I have made a class for this called CarCacheService which also implements interface ICarService. (I will explain later why it implements ICarService) I don't want client code to be calling these implementations. Instead, I want to create a third implementation for ICarService that tries to read from the CarCacheService before calling the WCFCarService, stores retrieved data in the CarCacheService, etc. 3 questions: How do I name this third class? I was thinking about something as simple as CarService. This does not really says what the service does exactly, tho. Is the naming for the other classes good? Would this naming and architecture be obvious for future programmers? This is my biggest concern. Does this architecture make sense? The reason that I implement ICarService on the CarCacheService is mainly because it allows me to fake the WCFService while debugging. I can store dummy data in a CarCacheService instance and pass it to the CarService, together with an(other) empty CarCacheService. If I made CacheCarService and WCFService public I could let client code decide if they want to drop the caching and just work directly on the WCFService.

  Read the article

• Is it a good practice to wrap all primitives and Strings?

  - by Amogh Talpallikar

  According to Jeff Bay's Essay on Object Callisthenics, One of the practices is set to be "Wrap all primitives and Strings" Can anyone elaborate on this ? In languages where we already have wrappers for primitives like C# and Java. and In languages where Collections can have generics where you are sure of what type goes into the collection, do we need to wrap string's inside their own classes ? Does it have any other advantage ?

  Read the article

• Manager/Container class vs static class methods

  - by Ben

  Suppose I a have a Widget class that is part of a framework used independently by many applications. I create Widget instances in many situations and their lifetimes vary. In addition to Widget's instance specified methods, I would like to be able to perform the follow class wide operations: Find a single Widget instance based on a unique id Iterate over the list of all Widgets Remove a widget from the set of all widgets In order support these operations, I have been considering two approaches: Container class - Create some container or manager class, WidgetContainer, which holds a list of all Widget instances, support iteration and provides methods for Widget addition, removal and lookup. For example in C#: public class WidgetContainer : IEnumerable<Widget { public void AddWidget(Widget); public Widget GetWidget(WidgetId id); public void RemoveWidget(WidgetId id); } Static class methods - Add static class methods to Widget. For example: public class Widget { public Widget(WidgetId id); public static Widget GetWidget(WidgetId id); public static void RemoveWidget(WidgetId id); public static IEnumerable<Widget AllWidgets(); } Using a container class has the added problem of how to access the container class. Make it a singleton?..yuck! Create some World object that provides access to all such container classes? I have seen many frameworks that use the container class approach, so what is the general consensus?

  Read the article

• When are Getters and Setters Justified

  - by Winston Ewert

  Getters and setters are often criticized as being not proper OO. On the other hand most OO code I've seen has extensive getters and setters. When are getters and setters justified? Do you try to avoid using them? Are they overused in general? If your favorite language has properties (mine does) then such things are also considered getters and setters for this question. They are same thing from an OO methodology perspective. They just have nicer syntax. Sources for Getter/Setter Criticism (some taken from comments to give them better visibility): http://www.javaworld.com/javaworld/jw-09-2003/jw-0905-toolbox.html http://typicalprogrammer.com/?p=23 http://c2.com/cgi/wiki?AccessorsAreEvil http://www.darronschall.com/weblog/2005/03/no-brain-getter-and-setters.cfm http://www.adam-bien.com/roller/abien/entry/encapsulation_violation_with_getters_and To state the criticism simply: Getters and Setters allow you to manipulate the internal state of objects from outside of the object. This violates encapsulation. Only the object itself should care about its internal state. And an example Procedural version of code. struct Fridge { int cheese; } void go_shopping(Fridge fridge) { fridge.cheese += 5; } Mutator version of code: class Fridge { int cheese; void set_cheese(int _cheese) { cheese = _cheese; } int get_cheese() { return cheese; } } void go_shopping(Fridge fridge) { fridge.set_cheese(fridge.get_cheese() + 5); } The getters and setters made the code much more complicated without affording proper encapsulation. Because the internal state is accessible to other objects we don't gain a whole lot by adding these getters and setters. The question has been previously discussed on Stack Overflow: http://stackoverflow.com/questions/565095/java-are-getters-and-setters-evil http://stackoverflow.com/questions/996179

  Read the article

• When should a method of a class return the same instance after modifying itself?

  - by modiX

  I have a class that has three methods A(), B() and C(). Those methods modify the own instance. While the methods have to return an instance when the instance is a separate copy (just as Clone()), I got a free choice to return void or the same instance (return this;) when modifying the same instance in the method and not returning any other value. When deciding for returning the same modified instance, I can do neat method chains like obj.A().B().C();. Would this be the only reason for doing so? Is it even okay to modify the own instance and return it, too? Or should it only return a copy and leave the original object as before? Because when returning the same modified instance the user would maybe admit the returned value is a copy, otherwise it would not be returned? If it's okay, what's the best way to clarify such things on the method?

  Read the article

• OO Design, how to model Tonal Harmony?

  - by David

  I have started to write a program in C++ 11 that would analyse chords, scales, and harmony. The biggest problem I am having in my design phase, is that the note 'C' is a note, a type of chord (Cmaj, Cmin, C7, etc), and a type of key (the key of Cmajor, Cminor). The same issue arises with intervals (minor 3rd, major 3rd). I am using a base class, Token, that is the base class for all 'symbols' in the program. so for example: class Token { public: typedef shared_ptr<Token> pointer_type; Token() {} virtual ~Token() {} }; class Command : public Token { public: Command() {} pointer_type execute(); } class Note : public Token; class Triad : public Token; class MajorTriad : public Triad; // CMajorTriad, etc class Key : public Token; class MinorKey : public Key; // Natural Minor, Harmonic minor,etc class Scale : public Token; As you can see, to create all the derived classes (CMajorTriad, C, CMajorScale, CMajorKey, etc) would quickly become ridiculously complex including all the other notes, as well as enharmonics. multiple inheritance would not work, ie: class C : public Note, Triad, Key, Scale class C, cannot be all of these things at the same time. It is contextual, also polymorphing with this will not work (how to determine which super methods to perform? calling every super class constructors should not happen here) Are there any design ideas or suggestions that people have to offer? I have not been able to find anything on google in regards to modelling tonal harmony from an OO perspective. There are just far too many relationships between all the concepts here.

  Read the article

• LSP vs OCP / Liskov Substitution VS Open Close

  - by Kolyunya

  I am trying to understand the SOLID principles of OOP and I've come to the conclusion that LSP and OCP have some similarities (if not to say more). the open/closed principle states "software entities (classes, modules, functions, etc.) should be open for extension, but closed for modification". LSP in simple words states that any instance of Foo can be replaced with any instance of Bar which is derived from Foo and the program will work the same very way. I'm not a pro OOP programmer, but it seems to me that LSP is only possible if Bar, derived from Foo does not change anything in it but only extends it. That means that in particular program LSP is true only when OCP is true and OCP is true only if LSP is true. That means that they are equal. Correct me if I'm wrong. I really want to understand these ideas. Great thanks for an answer.

  Read the article

• Communication between WCF service [library] and Self-host [Winform]

  - by Mur Haf Soz

  Introduction: I have a WCF service library and a self-host Winform. Service features is File explorer including (copy, move, delete, new folder, delete... etc) and Task Manager (run, kill, update list). Then now I want to add other features like chatting between self-host and client, send an image from client to self-host so when it received, it is shown in a pictureBox in a new form. Till now I have two endpoints for (Task Manager, File Manager) that runs under one service "MainService". And I set up all the connections using DotNet 4.0 WCF Configuration and Wizards, and I'm using netTcpBinding. Problem: I need to know how to communicate with between WCF service lib and self-host, so I can append a received chat from client on self-host form's textbox TextBoxChat. And also call a client callback from self-host when Send button clicked, to send the message from self-host textbox TextBoxMessage. Let's say this's self-host ChatForm So is it possible to do that in WCF? I would prefer to run ChatEndpoint under MainService, so all Endpoints use one port.

  Read the article

• Which topics should be covered in a basic undergraduate C++ course?

  - by Gulshan

  I have a young lecturer friend who is going to teach the undergraduate C++ course in CS. He asked me for some suggestions regarding how the course should be organized. Now I am asking you. I have seen many trends in universities which leads to a nasty experience of C++. So, please suggest from a professional programmer's point of view. For your information, the students going to take the course, have taken course like "Introduction to programming with C" in previous semester.

  Read the article

• Looking for some OO design advice

  - by Andrew Stephens

  I'm developing an app that will be used to open and close valves in an industrial environment, and was thinking of something simple like this:- public static void ValveController { public static void OpenValve(string valveName) { // Implementation to open the valve } public static void CloseValve(string valveName) { // Implementation to close the valve } } (The implementation would write a few bytes of data to the serial port to control the valve - an "address" derived from the valve name, and either a "1" or "0" to open or close the valve). Another dev asked whether we should instead create a separate class for each physical valve, of which there are dozens. I agree it would be nicer to write code like PlasmaValve.Open() rather than ValveController.OpenValve("plasma"), but is this overkill? Also, I was wondering how best to tackle the design with a couple of hypothetical future requirements in mind:- We are asked to support a new type of valve requiring different values to open and close it (not 0 and 1). We are asked to support a valve that can be set to any position from 0-100, rather than simply "open" or "closed". Normally I would use inheritance for this kind of thing, but I've recently started to get my head around "composition over inheritance" and wonder if there is a slicker solution to be had using composition?

  Read the article

• Design patterns and multiple programming languages

  - by Eduard Florinescu

  I am referring here to the design patterns found in the GOF book. First, how I see it, there are a few peculiarities to design pattern and knowing multiple languages, for example in Java you really need a singleton but in Python you can do without it you write a module, I saw somewhere a wiki trying to write all GOF patterns for JavaScript and all the entries were empty, I guess because it might be a daunting task to do that adaptation. If there is someone who is using design patterns and is programming multiple languages supporting the OOP paradigm and can give me a hint on how should I approach design patterns. An approach that might help me in all languages I use(Java, JavaScript, Python, Ruby): Can I write good application without knowing exactly the GOF design patterns or I might need just some of them which might be crucial and if yes which one, are there alternatives to GOF for specific languages, and should a programmer or a team make their own design patterns set?

  Read the article

• Which open source PHP project has the 'perfect' OOP design I can learn from?

  - by aditya menon

  I am a newbie to OOP, and I learn best by example. You could say this question is similar to Which Scala open source projects should I study to learn best coding practices - but in PHP. I have heard-tell that Symfony has the best 'architecture' (I will not pretend I know what that exactly means), as well as Doctrine ORM. Is it worth it to spend many months reading the source code of these projects, trying to deduce the patterns used and learning new tricks? I have seen equal number of web pages dissing and liking Zend's codebase (will provide links if deemed necessary). Do you know of any other project that would make any veteran OOP developer shed tears of joy? Please let me add that practicality and scope of use is not a concern at all here - I just want to do: Pick a project that has a codebase deemed awesome by devs way better and greater than me. Write code that achieves what the project does. Compare results and try to learn what I don't know. Basically, an academic interest codebase. Any recommendations please?

  Read the article

• Dependency injection in constructor, method or just use a static class instead?

  - by gaetanm

  What is the best between: $dispatcher = new Dispatcher($request); $dispatcher->dispatch(); and $dispatcher = new Dispatcher(); $dispatcher->dispatch($request); or even Dispatcher::dispatch($request); Knowing that only one method of this class uses the $request instance. I naturally tend to the last solution because the class have no other states, but by I feel that it may not be the best OOP solution.

  Read the article

• how do you read from system.out in Java [closed]

  - by Dan

  I'm trying to create a word scramble game and so far I have taken a vector of randomly assorted strings that contains both words and hints and split them into two vectors. I have randomly scrambled the word and set this all up in text boxes. Right now I'm stuck because I have a text box that takes input but I'm not sure how to read that in? I want the user to type the unscrambled word into the text box and have it calculate as correct and move on to the next word immediately. I also don't know how to get the keys working. I want the "?" character to be the hint button that shows the hint. At the moment the hint box works if I type the question mark in using the System.in but it doesn't work if I type it directly in to the text box. The characters are showing up in the text box but nothing is working after that.

  Read the article

• What simple game is good to learn OO principles?

  - by Bogdan Gavril

  I have to come up with a project propsal for my students, here are some details: The design should be gove over OO concepts: encapsulation, interfaces, inheritance, abstract classes Idealy a game, to keep interest high No GUI, just the console Effective time to finish this: ~ 6 days (1 person per proj) I have found one nice example of a game with carnivore and herbivore cells in a drop of water (array), it's a game of life twist. It is a bit too simple. Any ideeas? Aditional info: - language is C#

  Read the article

< Previous Page | 35 36 37 38 39 40 41 42 43 44 45 46  | Next Page >