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• Subscribe/Publish Model in Web-based Application (c#) - Best Practices for Event Handlers

  - by KingOfHypocrites

  I was recently exposed to a desktop application that uses an publish/subscribe model to handle commands, events, etc. I can't seem to find any good examples of using this in a web application, so I wonder if I am off base in trying to use this for web based development (on the server side)? I'm using asp.net c#. My main question in regards to the design is: When using a publish/subscribe model, is it better to have generic commands/events that pass no parameters and then have the subscribers look at static context objects that contain the data relevant to the event? Or is it better to create custom arguments for every event that contain data related to the event? The whole concept of a global container seems so convenient but at the same time seems to break encapsulation. Any thoughts or best practices from anyone who has implemented this type of model in a web based application? Even suggestions on this model out of the scope of my question are appreciated.

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• How to change the state of a singleton in runtime

  - by user34401

  Consider I am going to write a simple file based logger AppLogger to be used in my apps, ideally it should be a singleton so I can call it via public class AppLogger { public static String file = ".."; public void logToFile() { // Write to file } public static log(String s) { AppLogger.getInstance().logToFile(s); } } And to use it AppLogger::log("This is a log statement"); The problem is, what is the best time I should provide the value of file since it is a just a singleton? Or how to refactor the above code (or skip using singleton) so I can customize the log file path? (Assume I don't need to write to multiple at the same time) p.s. I know I can use library e.g. log4j, but consider it is just a design question, how to refactor the code above?

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• Learning to program in the modern era?

  - by BBHorus

  At this time, lets say in the modern era, in which order do you organize a programing course for teaching and/or learning, what should be learned first, what should emphasize: Databases Data structures Design patterns Programing paradigms(Procedural, functional, OOP, ...etc ) Operating System Some specific programing language What about English if you are not native speaker or doesn't know English AI Anything else... I ask this because in the university that I went, the programing course was awful it was not focus on what you were going to see out when you work what you were supposed to learn. PS: Again sorry about my English is not my main language. ...Experts and gurus please share

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• Event Aggregator.. not getting a response, how to determine completion?

  - by Duncan_m

  I'm rewriting a vehicle tracking application, a google maps based thing.. The users are able to search for a vehicle by typing a few characters of the vehicles "callsign". My application is based around a sort of "event bus" within Backbone.. when a search occurs I send a message on the bus saying something like "does anyone match this?".. If a marker matches the search term it responds with a sort of "yes, I match!".. My challenge arises when no-one matches, I get no response.. it feels a little hacky to "wait a little while" and check if a response has been recieved.. The application is based around Backbone.js and using the Event Aggregator pattern described in the answer to this question on Stack Overflow: http://stackoverflow.com/questions/7708195/access-function-in-one-view-from-another-in-backbone-js Is there a well defined design pattern that might assist me here? Sending a request for a response and not getting any responses?

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• is it allowed to create a app with overscroll feature?

  - by user61664

  As Apple wo lawsuits against Motorola and Samsung with the so called overscroll patent, i am asking myself what the legal consequences of releasing a APP with such a feature are. I think if one releases the APP in IOS it would be okay, but what happens in android or Windows? Am i getting sued ? What happens if i am writing an APP for the Browser? Isn`t this overscroll patent a design patent? It this is true, all apps hat usw overscrolling and not written by apple , would be illegal. Very confusing. Can anyone explain is?

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

  - by ericgorr

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

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• Distinguishing between sets of status reports

  - by user1769486

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

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• Recommended Win2k8 Server software to fix my RAID-0 issue

  - by Jason Kealey

  I'm running an Asus P6T V2 Deluxe. It has six SATA ports and supports onboard RAID. I am using two of those ports for a RAID0 array of 1.5TB Seagate drives using the onboard RAID controller. One of them is giving me SMART warnings and I want to preemptively replace it. I pulled out two other 1.5TB drives from another computer and am ready to use one or both, if necessary. I can't run any SMART diagnostic software from within Windows because it only sees the hardware RAID-0 array, not each individual drive. The first thing I tried was a slow sector-by-sector copy using a free tool called EASEUS Disk Copy. Used the bootdisk, copied (took like 16 hours), unplugged the defective drive and plugged the new one in its place. The motherboard didn't recognize the new drive as being part of the known setup, so it did not want to boot. The second thing I tried was using other software (I forget the name) to copy the partition from within Windows. The first software failed because I had a server operating system. I found another software (I forget the name) which supported a server OS and did a partition copy onto the new drive. This seemed to work and the OS started to boot, but blue screened and started a reboot cycle. I'm assuming the software I was using was no good as it was trying to copy the boot disk while it was in use. I am looking for recommendations on what software to use to fix my problem without doing a re-install. Everything is backed up but my computer works fine and I'd like to avoid re-installation when possible. However, my system would be back up now if I had just started over on a second RAID array. :)

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• Flowcharting tool/add-in for Visual Studio

  - by Rajah

  A 2 part question: Are flow-charts, as tool to analyze source-code, no longer considered useful? The reason I ask this question is that if you Google for source-code to flowchart tools for Visual Studio, there are no relevant results. Also, Microsoft does not seem to have a tool for this purpose. Are people just not using flowcharts that much any more? (I find them to be a great way to document complex logic in my code). Are there any VS tools that can take .Net (C#, VB.Net) code and convert it to a flowchart? (The only tool that I found is Aviosto's Visustin, which does not provide VS integration). Any other tools that you can recommend for this purpose?

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• Sequence diagram to state diagram

  - by kingh

  Can we make state diagram from sequence diagram....Is there any tool for the same... plz reply ASP thnx in advance...........

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

  - by Robert Fraser

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

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• Empty data problem - data layer or DAL?

  - by luckyluke

  I designing the new App now and giving the following question a lot of thought. I consume a lot of data from the warehouse, and the entities have a lot of dictionary based values (currency, country, tax-whatever data) - dimensions. I cannot be assured though that there won't be nulls. So I am thinking: create an empty value in each of teh dictionaries with special keyID - ie. -1 do the ETL (ssis) do the correct stuff and insert -1 where it needs to let the DAL know that -1 is special (Static const whatever thing) don't care in the code to check for nullness of dictionary entries because THEY will always have a value But maybe I should be thinking: import data AS IS let the DAL do the thinking using empty record Pattern still don't care in the code because business layer will have what it needs from DAL. I think is more of a approach thing but maybe i am missing something important here... What do You think? Am i clear? Please don't confuse it with empty record problem. I do use emptyCustomer think all the time and other defaults too.

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• dynamic behavior of factory class

  - by manu1001

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

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• QuestionOrAnswer model?

  - by Mark

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

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• Recommendation on an esoteric programming language?

  - by Arpan

  Hello Everyone, If there is one esoteric programming language that you'd recommend someone to pick up (assume a C++/Perl background), which one would it be? Arpan

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

  - by devoured elysium

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

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• having problems with update manager

  - by Howie Lynch

  I'm trying to update my Ubuntu system, but cannot do anything with the Update Manager. It loads up 3/4 of the way and then says: Could not initialize the package information An unresolvable problem occurred while initializing the package information. Please report this bug against the 'update-manager' package and include the following error message: 'E:The package google-chrome-stable:i386 needs to be reinstalled, but I can't find an archive for it.' Also ubuntu software center will not open and keeps crashing. This is very annoying as I can't install or update anything.

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• Can you be a web and desktop developer at the same time?

  - by Charmop

  In my environment, I found web programmers, desktop programmers and both web and desktop programmers. About myself I started my career with desktop development using C and then Java, did couple of simple level projects. Then at the final graduating year, my project was a web one, so I turned to web development until this moment. But, when I meet people having chosen to be web or software developers from the beginning, I figure out that they have more knowledge/experience than I have. So I get kind of regret why didn't I specialize my self from the first day? The question is: Is it a good habit to work at two, more or less, different fields: web and desktop? Or we must specialize ourselves?

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• Is loose coupling w/o use cases an anti-pattern?

  - by dsimcha

  Loose coupling is, to some developers, the holy grail of well-engineered software. It's certainly a good thing when it makes code more flexible in the face of changes that are likely to occur in the foreseeable future, or avoids code duplication. On the other hand, efforts to loosely couple components increase the amount of indirection in a program, thus increasing its complexity, often making it more difficult to understand and often making it less efficient. Do you consider a focus on loose coupling without any use cases for the loose coupling (such as avoiding code duplication or planning for changes that are likely to occur in the foreseeable future) to be an anti-pattern? Can loose coupling fall under the umbrella of YAGNI?

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• Ubuntu gone out of order - Wont install any packages. What do I do?

  - by Aborted

  Lately, I've been getting some strange behaviour from Ubuntu. First and the most important is that it wont install updates. It gives a package installation error and it simply wont work. Earlier I tried to install TeamViewer via the Software Center, but got the same package error. I also feel like the connection speed is going slower than it should - don't know if this one is relevant to this case. What's wrong with my installation? How do I fix these package installation errors?

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• Looking for personal scheduling software / todo list with rather particular requirements

  - by Cthulhu

  I've been scouring the web for a couple of (my boss') hours, looking for a piece of software that can organize my tasks in two ways. First, I have a list of bullet points / todo items I can do at any given time. Think of stuff like solve issue X, ask X about Y, write documentation about Z, etcetera. Second, I have a number of running projects I'd like to organize better, as in schedule for a certain part of a day of the week. Ideally (I think), my day would be organized as 50% spent on projects and 50% on the other small things. Now, I don't like most calendar applications (such as Outlook & friends), their UI is too 'official', not really easy to move stuff around (in my experience). I don't like most todo lists either, too static and things. I like new, fast and hip software. I've looked at GTD versions of Tiddlywiki, and I like mGSD for one particular feature. You can make lists of tasks and basically give them one of three statusses - Now (nothing required, you can do it right away), Waiting (you need someone or something before you can work on this), or the most gratifying of all, Done. I like that feature because it's a simple todo list, but indicates more accurately the things you can do right now and the things you depend on someone else for to do. Anyways, that's just a small aspect of that program - most of the other things in there I can't find a particularly good use for. If there's something like that (maybe something that works even snappier, cleaner UI), combined with an easy to use bit of scheduling software (optionally separated into two applications, but preferrably not), I think I'd like that. (Besides something like that, I also use several instances of Trac to monitor tasks and bugs and things for the various clients and projects I have to serve, and TaskCoach to monitor the amount of time I spend on each task / each client. An easy / low-maintenance time tracking software would be neat too) Of course, the software has to be free to use. I don't like shareware, trials, limited software and the like. I could develop my own too, but I'm lazy like that and there's a dozen other projects I'd like to do in my free time (neither of which I actually do). Edit: I like David Seah's printable CEO stuff, if something like that (with some video game / instant achievement / gratification) exists in software, it'd be awesome.

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• Push The Pebble

  - by andyleonard

  Introduction This post is the fifty-fifth part of a ramble-rant about the software business. The current posts in this series can be found on the series landing page . This post is about starting something. Today is the First Day… … of something. Somewhere, someone is starting something shat will become big. It will impact lives. It will change things, forever. Somewhere else, someone is improving the thing they started recently. They are tweaking, tinkering, thinking, and doing. Is either of these...(read more)

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• Minimize useless tweaking of a numeric app

  - by Potatoswatter

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

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

  - by Mahdi

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

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• Struggling with the Single Responsibility Principle

  - by AngryBird

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

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