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  • Database Design Question

    - by deniz
    Hi, I am designing a database for a project. I have a table that has 10 columns, most of them are used whenever the table is accessed, and I need to add 3 more rows; View Count Thumbs Up (count) Thumbs Down (Count) which will be used on %90 of the queries when the table is accessed. So, my question is that whether it is better to break the table up and create new table which will have these 3 columns + Foreign ID, or just make it 13 columns and use no joins? Since these columns will be used frequently, I guess adding 3 more columns is better, but if I need to create 10 more columns which will be used %90 of the time, should I add them as well, or create a new table and use joins? I am not sure when to break the table if the columns are used very frequently. Do you have any suggestions? Thanks in advance,

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  • Open source libraries to design directed graphs

    - by Benjamin
    Hi all, I'm going to need to write a software that takes a list of persons and connects them together in a directed-graph-like manner. The GUI aspect of the whole project is very important. The graph must allow a lot of interaction. Such as selecting several people and hiding the others, moving them around. Additionally, the software will need to be able to provide other kind of GUI-features such as several tabs, text boxes etc. The application must be quite performant. As in, it must be able to handle hundreds if not thousands of widgets. Hence, I would like to know which open source libraries (at this point the programming language they are written in does not matter - I just want an overview of everything good that is out there) would allow me to develop such piece of software? What would you recommend? Thanks for that. Edit: Could you please also link to tutorials explaining how I could program a GUI that can interact with the generated graph? For example mouse events.

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  • Comparing two Objects which implement the same interface for equality / equivalence - Design help

    - by gav
    Hi All, I have an interface and two objects implementing that interface, massively simplied; public interface MyInterface { public int getId(); public int getName(); ... } public class A implements MyInterface { ... } public class B implements MyInterface { ... } We are migrating from using one implementation to the other but I need to check that the objects of type B that are generated are equivalent to those of type A. Specifically I mean that for all of the interface methods an object of Type A and Type B will return the same value (I'm just checking my code for generating this objects is correct). How would you go about this? Map<String, MyInterface> oldGeneratedObjects = getOldGeneratedObjects(); Map<String, MyInterface> newGeneratedObjects = getNewGeneratedObjects(); // TODO: Establish that for each Key the Values in the two maps return equivalent values. I'm looking for good coding practices and style here. I appreciate that I could just iterate through one key set pulling out both objects which should be equivalent and then just call all the methods and compare, I'm just thinking there may be a cleaner, more extensible way and I'm interested to learn what options there might be. Would it be appropriate / possible / advised to override equals or implement Comparable? Thanks in advance, Gavin

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  • GUI design techniques to enhance user experience

    - by aku
    What techniques do you know\use to create user-friendly GUI ? I can name following techniques that I find especially useful: Non-blocking notifications (floating dialogs like in Firefox3 or Vista's pop-up messages in tray area) Absence of "Save" button MS OneNote as an example. IM clients can save conversation history automatically Integrated search Search not only through help files but rather make UI elements searchable. Vista made a good step toward such GUI. Scout addin Microsoft Office was a really great idea. Context oriented UI (Ribbon bar in MS Office 2007) Do you implement something like listed techniques in your software? Edit: As Ryan P mentioned, one of the best way to create usable app is to put yourself in user's place. I totally agree with it, but what I want to see in this topic is specific techniques (like those I mentioned above) rather than general recommendations.

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  • How to design websites for all display sizes

    - by katie bekell
    I like to use a lot of unique graphics on my pages, which often results in making different page sizes depending on available screen width/height. Here are two examples: http://www.uvm.edu/~areid/homesite/ - the image floats at the bottom of my screen but on a larger browser, the image floats near the middle making it look off. It looks best when the bottom of the window aligns with the bottom of the image www.stevenlebel.com - it loads two different pages depending on what monitor size is detected. This seems like a lot of redundant coding. My question is, how can I make sliced/Photoshop images transition well to different screen sizes. Does Photoshop allow you to make DIVS instead of tables? Can i make each of the slices created by Photoshop grow/shrink when the browser window size changes? If anyone has any input on creating websites like this I would be very interested to hear what they have to say. Thanks Katie

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  • CLI design and implementation?

    - by Majid
    I am developing a time management tool for my personal use. I prefer using keyboard over mouse, and on the interface have a general purpose text box which will act like a command line. I have just started thinking about what commands I need, what to use for the command names, how to pass in switches and parameters, and so forth. I wonder if some of you have come across a good read along these lines; something that describes the choices you have for designing a cli, and how those affect the complexity of the interpreter, and extendability of the commands. It makes no difference if the descriptions are language-specific or in general terms. However, my implementation will be with javascript. Thank you.

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  • Database Table design for Weekdays and Values

    - by Ved
    Guys, I would love to here your ideas on this. I am creating a table which will store weekly shift hours for employees. for example: Jon works 9:00am tp 9:00pm Monday , 10:00 AM to 5:00PM on Tuseday etc.... How should i go on designing this table. I thought of 2 options. (1) For every record I can have two lines for AM and PM and have columns for Monday to Sunday ID | ParentID | Type | Monday | Tuseday ......Sunday 1 | 1 | AM | 9:00 | 9:00 12:00 2 | 1 | PM | 9:00 | 5:00 02:00 3 | 2 | AM | 10:00 | 4 | 2 | PM | 10:00 | (2) I can save Preference in XML format in one column ID | Info 1 | |Hours|Monday|9:00 AM - 9:00PM|Monday|Tuseday........|Hours Any better ideas ? Thanks

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  • Effecient data structure design

    - by Sway
    Hi there, I need to match a series of user inputed words against a large dictionary of words (to ensure the entered value exists). So if the user entered: "orange" it should match an entry "orange' in the dictionary. Now the catch is that the user can also enter a wildcard or series of wildcard characters like say "or__ge" which would also match "orange" The key requirements are: * this should be as fast as possible. * use the smallest amount of memory to achieve it. If the size of the word list was small I could use a string containing all the words and use regular expressions. however given that the word list could contain potentially hundreds of thousands of enteries I'm assuming this wouldn't work. So is some sort of 'tree' be the way to go for this...? Any thoughts or suggestions on this would be totally appreciated! Thanks in advance, Matt

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  • Dependency Injection & Singleton Design pattern

    - by SysAdmin
    How do we identify when to use dependency injection or singleton pattern. I have read in lot of websites where they say "Use Dependency injection over singleton pattern". But I am not sure if I totally agree with them. For my small or medium scale projects I definitely see the use of singleton pattern straightforward. For example Logger. I could use Logger.GetInstance().Log(...) But, instead of this, why do I need to inject every class I create, with the logger's instance?.

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  • java api design - NULL or Exception

    - by srini.venigalla
    Is it better to return a null value or throw an exception from an API method? Returning a null requires ugly null checks all over, and cause a major quality problem if the return is not checked. Throwing an exception forces the user to code for the faulty condition, but since Java exceptions bubble up and force the caller code to handle them, in general, using custom exceptions may be a bad idea (specifically in java). Any sound and practical advice?

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  • Useful design patterns when dealing with spring 3 controllers

    - by Mat Banik
    Recently I was overlooking my controllers and they are bit of mess. I'd like to organize they way I set returning views Do more elegant mesageSource massaging back to the users and account for i18n Security checking, what user can access an what they can't Consistent way of calling the service layer And somehow bring consistency to the debugging lines. Do better job with error handling and serving it to the user. I'm already on mission to do security logging with AOP :) I'm just looking for patterns I could implement to help me to do all of the above. Or just some general advice in case no patterns apply, or advice on something I didn't mention but is common practice.

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  • MVC & Design patterns in C++

    - by theunanonim
    I have an assignment (university level) in C++ The application that was done so far: - MVC agenda - the views are command-line - Agenda contains a list of contacts - a contact may be a friend or an acquiantance - Agenda may contain also a Company that is a contact and may contain other contacts (sorry the code is already too big as I tried to keep the MVC aspect of the application, and I can't post it here or request your time to study it..) To do: - implement factory method pattern - implement observer pattern - implement strategy pattern - implement visitor pattern The evaluation will depend on the number of added patterns and places they have been added. Am I an idiot or this is the stupidies possible assignement ? If not, please help me with some basic tips.. which one where ? Best Regards. P.S. Sorry for my English

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  • SQL Server many-to-many design recommendation

    - by Jean-Philippe Brabant
    I have a SQL Server database with two table : Users and Achievements. My users can have multiple achievements so it a many-to-many relation. At school we learned to create an associative table for that sort of relation. That mean creating a table with a UserID and an AchivementID. But if I have 500 users and 50 achievements that could lead to 25 000 row. As an alternative, I could add a binary field to my Users table. For example, if that field contained 10010 that would mean that this user unlocked the first and the fourth achievements. Is their other way ? And which one should I use.

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  • Database design: objects with different attributes

    - by Álvaro G. Vicario
    I'm designing a product database where products can have very different attributes depending on their type, but attributes are fixed for each type and types are not manageable at all. E.g.: magazine: title, issue_number, pages, copies, close_date, release_date web_site: name, bandwidth, hits, date_from, date_to I want to use InnoDB and enforce database integrity as much as the engine allows. What's the recommended way to handle this? I hate those designs where tables have 100 columns and most of the values are NULL so I thought about something like this: product_type ============ product_type_id INT product_type_name VARCHAR product ======= product_id INT product_name VARCHAR product_type_id INT -> Foreign key to product_type.product_type_id valid_since DATETIME valid_to DATETIME magazine ======== magazine_id INT title VARCHAR product_id INT -> Foreign key to product.product_id issue_number INT pages INT copies INT close_date DATETIME release_date DATETIME web_site ======== web_site_id INT name VARCHAR product_id INT -> Foreign key to product.product_id bandwidth INT hits INT date_from DATETIME date_to DATETIME This can handle cascaded product deletion but... Well, I'm not fully convinced...

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  • Request for advice about class design, inheritance/aggregation

    - by Lasse V. Karlsen
    I have started writing my own WebDAV server class in .NET, and the first class I'm starting with is a WebDAVListener class, modelled after how the HttpListener class works. Since I don't want to reimplement the core http protocol handling, I will use HttpListener for all its worth, and thus I have a question. What would the suggested way be to handle this: Implement all the methods and properties found inside HttpListener, just changing the class types where it matters (ie. the GetContext + EndGetContext methods would return a different class for WebDAV contexts), and storing and using a HttpListener object internally Construct WebDAVListener by passing it a HttpListener class to use? Create a wrapper for HttpListener with an interface, and constrct WebDAVListener by passing it an object implementing this interface? If going the route of passing a HttpListener (disguised or otherwise) to the WebDAVListener, would you expose the underlying listener object through a property, or would you expect the program that used the class to keep a reference to the underlying HttpListener? Also, in this case, would you expose some of the methods of HttpListener through the WebDAVListener, like Start and Stop, or would you again expect the program that used it to keep the HttpListener reference around for all those things? My initial reaction tells me that I want a combination. For one thing, I would like my WebDAVListener class to look like a complete implementation, hiding the fact that there is a HttpListener object beneath it. On the other hand, I would like to build unit-tests without actually spinning up a networked server, so some kind of mocking ability would be nice to have as well, which suggests I would like the interface-wrapper way. One way I could solve this would be this: public WebDAVListener() : WebDAVListener(new HttpListenerWrapper()) { } public WebDAVListener(IHttpListenerWrapper listener) { } And then I would implement all the methods of HttpListener (at least all those that makes sense) in my own class, by mostly just chaining the call to the underlying HttpListener object. What do you think? Final question: If I go the way of the interface, assuming the interface maps 1-to-1 onto the HttpListener class, and written just to add support for mocking, is such an interface called a wrapper or an adapter?

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  • Design pattern: polymorphisim for list of objects

    - by ziang
    Suppose I have a class A, and A1, A2 inherits from A. There are 2 functions: List<A1> getListA1(){...} List<A2> getListA2(){...} Now I want to do something similar to both A1 and A2 in another function public void process(List<A>){...} If I want to pass the instance of either ListA1 or ListA2, of course the types doesn't match because the compiler doesn't allow the coercion from List< A1 to List< A. I can't do something like this: List<A1> listA1 = getListA1(); List<A> newList = (List<A>)listA1; //this is not allowed. So what is the best approach to the process()? Is there any way to do it in a universal way rather than write the similar code to both List and List?

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  • Web Applications Development: Security practices for Application design

    - by Shyam
    Hi, As I am creating more web applications that are targeted for multiple users, I figured out that I have to start thinking about user management and security. At a glance and in my ideal world, all users belong to a group. Permissions and access is thus defined per group (and inherited by the users of that group). Logically, I have my group of administrators, which are identified with a level "7" (integer) clearance. A group of webusers have for example level "1". This in generally all works great for me, but I need some kind of list that I have to keep in mind how I secure my system, and some general practices. I am not looking for a specific environment; I want to learn the why's and how's. An example is privilege escalation. If someone would be able to "push" themselves inside a group with higher privileges, for example the Administration, how can I prevent this, or what measures should I take to have some sort of precaution? I don't like in that case to walk into a caveat. My question is basically: where can I find a good resource, list, policy, book that explains the security of web applications, the why's, the how's and readable if you don't have any experience in the realm of advanced security? I prefer a free resource, as I believe I couldn't be the first one who thought about this. Thank you for your answers, comments and feedback.

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  • What is this Design Pattern?

    - by Can't Tell
    I read the Wikipedia articles on FactoryMethod and AbstractFactory but the following code doesn't seem to fit anywhere. Can someone explain to me what the following pattern is or if it is an anti-pattern? interace PaymentGateway{ void makePayment(); } class PaypalPaymentGateway implements PaymentGateway { public void makePayment() { //some implementation } } class AuthorizeNetPaymentGateway implements PaymentGateway { public void makePayment() { //some implementation } } class PaymentGatewayFacotry{ PaymentGateway createPaymentGateway(int gatewayId) { if(gatewayId == 1) return PaypalPaymentGateway(); else if(gatewayId == 2) return AuthorizeNetPaymentGateway(); } } Let's say the user selects the payment method using a radio button on an html page and the gatewayId is derived from the radio button value. I have seen code like this and thought it was the AbstractFactory pattern but after reading the Wikipedia article, I'm having doubts.

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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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  • pattern to transfer search model to dao

    - by zeroed
    We have a dao as a project (jar file). Clients use its interfaces and factories to operate with database. Using standard CRUD operations, dao allows you to search an entity by some search criteria. What is the best way to represent this criteria? Is transfer object appropriate pattern in this situation? How should client create SearchModel instance? Please, share. Regards.

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  • Table index design

    - by Swoosh
    I would like to add index(s) to my table. I am looking for general ideas how to add more indexes to a table. Other than the PK clustered. I would like to know what to look for when I am doing this. So, my example: This table (let's call it TASK table) is going to be the biggest table of the whole application. Expecting millions records. IMPORTANT: massive bulk-insert is adding data in this table table has 27 columns: (so far, and counting :D ) int x 9 columns = id-s varchar x 10 columns bit x 2 columns datetime x 5 columns INT COLUMNS all of these are INT ID-s but from tables that are usually smaller than Task table (10-50 records max), example: Status table (with values like "open", "closed") or Priority table (with values like "important", "not so important", "normal") there is also a column like "parent-ID" (self - ID) join: all the "small" tables have PK, the usual way ... clustered STRING COLUMNS there is a (Company) column (string!) that is something like "5 characters long all the time" and every user will be restricted using this one. If in Task there are 15 different "Companies" the logged in user would only see one. So there's always a filter on this one. Might be a good idea to add an index to this column? DATE COLUMNS I think they don't index these ... right? Or can / should be?

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  • Help needed in database design for application of Timetable Generation

    - by Himadri
    I am planning for an application of time-table generation. I wanted the data such as standardname, teachername, standard wise subjects and also relate the corresponding teacher with the subject and standard. I had think like, StandardMaster(stdid,stdname) TeacherMaster(teacherid,teachername) SubjectMaster(subid,subname,stdid) What more I need? Any corrections needed in these three tables?

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  • Design pattern to encapsulate common funtionality among UI controls

    - by Dan
    I'm brainstorming some ideas around a pattern to use for the following scenario. I have some 3rd party controls that I want to add common functionality to. Functionality is added by handling several of the the events and doing certain things when the events fire along with adding some private variables to hold some state info between events. I want to reuse the code and functionality so this is what I'd typically do. Create a class for this functionality and pass in the instance of the control that I want to add the functionality to in the constructor. Then I can add event handlers to the control in the instance of the class. Can anyone think of alternative patterns to use in order to create this kind of reusable functionality.

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  • Database design for a Fantasy league

    - by Samidh T
    Here's the basic schema for my database Table user{ userid numeber primary key, count number } Table player{ pid number primary key, } Table user-player{ userid number primary key foreign key(user), pid number primary key foreign key(player) } Table temp{ pid number primary key, points number } Here's what I intend to do... After every match the temp table is updated which holds the id of players that played the last match and the points they earned. Next run a procedure that will match the pid from temp table with every uid of user-player table having the same pid. add the points from temp table to the count of user table for every matching uid. empty temp table. My questions is considering 200 players and 10000 users,Will this method be efficient? I am going to be using mysql for this.

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