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  • How to export data which are mapped to enumerations

    - by Joshua
    I have a set of data which needs to be imported from a excel sheet, lets take the simplest example. Note: the data might eventually support uploading any locale. e.g. assuming one of the fields denoting a user is gender mapped to an enumeration and stored in the database as 0 for male and 1 for female. 0 and 1 being short values. If I have to import the values I cannot expect the user to punch in numbers (since they are not intuitive and is cumbersome when the enumerations are bigger), what would be the correct way to map to enumerations. Should we ask them to provide a string value in these cases (e.g. male or female) and provide the transformation to a enum in our code by wring a method public static Gender Gender.fromString(String value)

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  • What technologies/tools do people use to implement live websites ?

    - by MadSeb
    Hi, I have the following situation: -I have a server A hooked up to a piece of hardware that sends values and information out of every second. Programs on the server machine can read these values. This server A is in a very remote location so Internet connection is very slow and not reliable but the connection does exist. Let's say it's a weather station in the Arctic. -Users from the home location want to monitorize the weather values somehow. Well, the users can use a remote desktop connection the server A but that would be too too slow. My idea is somehow to have a website on a web server (let's call the webserver - B and B is in a home location ) and make the server A connect to the server B and somehow send values and the web application reads the values and displays them....... but how to do such a system ?? I know I can use MySQL and have the server A connect to a SQL server on server B and send INSERT queries and have the web application running on server B constantly read from the SQL server but I think that would be way way too slow and I think there has to be a better solution. Any ideas ? BTW. The users should be able to send information to the weather station from the website as well ( so an ADMIN user should be allowed to shut down the weather station from the website or whatever) Best regards, MadSeb

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  • Are bad data issues that common?

    - by Water Cooler v2
    I've worked for clients that had a large number of distinct, small to mid-sized projects, each interacting with each other via properly defined interfaces to share data, but not reading and writing to the same database. Each had their own separate database, their own cache, their own file servers/system that they had dedicated access to, and so they never caused any problems. One of these clients is a mobile content vendor, so they're lucky in a way that they do not have to face the same problems that everyday business applications do. They can create all those separate compartments where their components happily live in isolation of the others. However, for many business applications, this is not possible. I've worked with a few clients, one of whose applications I am doing the production support for, where there are "bad data issues" on an hourly basis. Yeah, it's that crazy. Some data records from one of the instances (lower than production, of course) would have been run a couple of weeks ago, and caused some other user's data to get corrupted. And then, a data script will have to be written to fix this issue. And I've seen this happening so much with this client that I have to ask. I've seen this happening at a moderate rate with other clients, but this one just seems to be out of order. If you're working with business applications that share a large amount of data by reading and writing to/from the same database, are "bad data issues" that common in your environment?

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  • Correct model for a database with a table for each user.

    - by BAH
    Kinda stuck here... I have an application with lets say 5000 rows of data per user and was wondering if it was right or wrong to do it this way: On user account creation a new table is created (UserData_[UserID]) or should I just have 1 table for userdata and have everything in there with a column for userid? The reason I am stuck at the moment is that it seems NHibernate isn't able to be mapped to dynamic table names without creating another ISessionFactory which has alot of overhead AFAIK. Any help would be greatly appreciated. Thanks.

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  • What are the differences between enterprise software/architecture patterns and open source software?

    - by Jeffrey
    I am mainly a business app developer and I hear terms like CQRS, ServiceBus, SOA, DDD, BDD, AOP a lot. My question is that do these patterns/practices exist only in the "enterprise" world? In contract to the enterprise world is the open source community. Highly trafficked sites like Digg, LiveJournal whenever there is an article mentioning about how they built/scaled their sites all I am hearing is what open source software (Memcached, NoSQL) they used in order to scale/simplify the way they tackle software problems and they rarely mention those above terms. Is it because they are not as sophisticated as those of enterprise level software (I doubt it)? Or are people just making up those terms/practices/patterns in order to keep them jobs? Or am I confusing myself with differences between software development and internet website scaling?

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  • How to use Unique Composite Key

    - by LifeH2O
    I have a table Item(ItemName*, ItemSize*, Price, Notes) I was making composite key of (ItemName,ItemSize) to uniquely identify item. And now after reading some answers on stackoverflow suggesting the use of UNIQUE i revised it as Item(ItemID*, ItemName, ItemSize, Price, Notes) But How to apply UNIQUE constraint on ItemName and ItemSize please correct if there is something wrong in question

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  • Implementing the procducer-consumer pattern with .NET 4.0

    - by bitbonk
    With alle the new paralell programming features in .NET 4.0, what would be a a simple and fast way to implement the producer-consumer pattern (where at least one thread is producing/enqueuing task items and another thread executes/dequeues these tasks). Can we benfit from all these new APIs? What is your preferred implementation of this pattern?

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  • What is so bad about Singletons

    - by Ewan Makepeace
    The Singleton pattern is a fully paid up member of the GoF Patterns Book but lately seems rather orphaned by the developer world. I still use quite a lot of singletons, especially for Factory classes, and while you have to be a bit careful about multithreading issues (like any class actually) fail to see why they are so awful. This site especially seems to assume that everyone agrees that Singletons are evil. Why?

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  • How best can I extract a logical model from a physical DB model

    - by Dean
    We have made substantial changes to our physical DB, now as it is the ne dof the project I would like to abstract a logical model from this, to allow me to generate schemas for both Oracle and SQL Server. Can anyone guide me as to the best way to achieve this. I was hoping TOAD data modeller would help but I can't seem to see any options to do what I require?

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  • Delivering activity feed items in a moderately scalable way

    - by sotangochips
    The application I'm working on has an activity feed where each user can see their friends' activity (much like Facebook). I'm looking for a moderately scalable way to show a given users' activity stream on the fly. I say 'moderately' because I'm looking to do this with just a database (Postgresql) and maybe memcached. For instance, I want this solution to scale to 200k users each with 100 friends. Currently, there is a master activity table that stores the rendered html for the given activity (Jim added a friend, George installed an application, etc.). This master activity table keeps the source user, the html, and a timestamp. Then, there's a separate ('join') table that simply keeps a pointer to the person who should see this activity in their friend feed, and a pointer to the object in the main activity table. So, if I have 100 friends, and I do 3 activities, then the join table will then grow to 300 items. Clearly this table will grow very quickly. It has the nice property, though, that fetching activity to show to a user takes a single (relatively) inexpensive query. The other option is to just keep the main activity table and query it by saying something like: select * from activity where source_user in (1, 2, 44, 2423, ... my friend list) This has the disadvantage that you're querying for users who may never be active, and as your friend list grows, this query can get slower and slower. I see the pros and the cons of both sides, but I'm wondering if some SO folks might help me weigh the options and suggest one way or they other. I'm also open to other solutions, though I'd like to keep it simple and not install something like CouchDB, etc. Many thanks!

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  • Process a batch of items, return an object to report on status

    - by Naeem Sarfraz
    I'm looking for a pattern (or good practice) for the following scenario: My function List<BatchItemResponse> Process(List<BatchItem> Data) {..} will process a list of data, and return info on where each item in the batch could be processed. struct BatchItemResponse { int BatchItemID; bool Processed; string Description; } Any thoughts? Is what I've proposed as good as it gets?

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  • Routing redirection decision

    - by programming late night
    I have really no idea why I'm asking this as this a really completely irrelevant question for which I should have figured out an answer within milliseconds, yet I'm doing it. So in my project I have a Router class which splits up the request and selects the right page to be loaded. Fine so far. Now I have a page displayed when the user requests a page that doesn't exist, you know, 404. So theoretically, if the user entered mydomain.com/404 (I use mod_rewrite with a requests collector via index.php?req=*) the 404 error would be shown to him, but in fact there was no error - the 404 page would be displayed as a perfectly normal page. So if someone would try out requesting the 404 page via /404, he would be shown the page but he can't tell if the 404 page he requested doesn't exist and he is actually getting a, you guessed it, 404 error or if he actually found some flaw in the system that makes him able to see an error page when there is no error. I don't know how dumb this whole thing here is but I'm sure some of you have in fact ran into this problem already. Short version: If the user enters mydomain.com/404 the 404 page is shown even though there is no 404 error. I know this is a completely irrelevant question, please don't tell me, but I just spontaneously wanted to hear your thoughts on it. Strange eh? Should I redirect direct access to my 404-page to the home page? Should I do nothing? Should I just go to bed and stop asking irrelevant stuff?

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  • Java - Calling all methods of a class

    - by Thomas Eschemann
    I'm currently working on an application that has to render several Freemarker templates. So far I have a Generator class that handles the rendering. The class looks more or less like this: public class Generator { public static void generate(…) { renderTemplate1(); renderTemplate2(); renderTemplate3(); } private static void render(…) { // renders the template } private static void renderTemplate1() { // Create config object for the rendering // and calls render(); }; private static void renderTemplate1() { // Create config object for the rendering // and calls render(); }; … } This works, but it doesn't really feel right. What I would like to do is create a class that holds all the renderTemplate...() methods and then call them dynamically from my Generator class. This would make it cleaner and easier to extend. I was thinking about using something like reflection, but it doesn't really feel like a good solution either. Any idea on how to implement this properly ?

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  • Am I trying to Implement Multiple Inheritance. How can I do this.

    - by Shantanu Gupta
    I have created a class say A which has some functions defined as protected. Now Class B inherits A and class C inherits B. Class A has private default constructor and protected parameterized constructor. I want Class B to be able to access all the protected functions defined in Class A but class C can have access on some of the functions only not all the functions and class C is inheriting class B. How can I restrict access to some of the functions of Class A from Class C ? EDIT: namespace Db { public Class A { private A(){} protected A(string con){assign this value} protected DataTable getTable(){return Table;} protected Sqlparameters setParameters(){return parameter;} } } namespace Data { public Class B:A { protected B():base("constring"){} protected DataTable output(){return getTable();} protected sqlparameter values(param IDataParameter[] parameter){} } } namespace Bsns { public Class C:B { protected C():base(){} protected DataTable show() {return values(setparameter());} } } EDIT I think what I am trying to do here is Multiple inheritance. Please check. Class A { //suppose 10 functions are declared } Class B:A { //5 functions declared which are using A's function in internal body } Class C:B { //using all functions of B but require only 4 functions of A to be accessible by C. }

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  • Visitor Pattern can be replaced with Callback functions?

    - by getit
    Is there any significant benefit to using either technique? In case there are variations, the Visitor Pattern I mean is this: http://en.wikipedia.org/wiki/Visitor_pattern And below is an example of using a delegate to achieve the same effect (at least I think it is the same) Say there is a collection of nested elements: Schools contain Departments which contain Students Instead of using the Visitor pattern to perform something on each collection item, why not use a simple callback (Action delegate in C#) Say something like this class Department { List Students; } class School { List Departments; VisitStudents(Action<Student> actionDelegate) { foreach(var dep in this.Departments) { foreach(var stu in dep.Students) { actionDelegate(stu); } } } } School A = new School(); ...//populate collections A.Visit((student)=> { ...Do Something with student... }); *EDIT Example with delegate accepting multiple params Say I wanted to pass both the student and department, I could modify the Action definition like so: Action class School { List Departments; VisitStudents(Action<Student, Department> actionDelegate, Action<Department> d2) { foreach(var dep in this.Departments) { d2(dep); //This performs a different process. //Using Visitor pattern would avoid having to keep adding new delegates. //This looks like the main benefit so far foreach(var stu in dep.Students) { actionDelegate(stu, dep); } } } }

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  • Undo/Redo using Memento: Stack, Queue or just LinkedList?

    - by serhio
    What is the best having when implementing Memento pattern (for Undo/Redo) in witch collection to Keep Mementos? Basically, I need this(c = change, u = undo, r = redo): 0 *c -1 0 *c -2 -1 0 *c -3 -2 -1 0 <u -2 -1 0 1 *c -3 -2 -1 0 Variants: LinkedList - possible in principle, maybe not optimized. Queue - not adapted for this task, IMO. Stack - not adapted for undo AND redo; Double Stack - maybe optimal, but can't control the undo maximum size.

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  • .Net - Whats the difference between a Session Facade and Business Delegate?

    - by KP65
    What I understand so far: Business Delegate - In the presentation tier, as an ASP component, provides an interface for ASP views to access business components without exposing their API, therefore reducing coupling between the two. Session Facade - In the business tier, as a com+ component, encapsulates business objects, provides a course grain interface for views to access business components. Reduces coupling, hides complex business component interaction from views. So what is the actual difference? They seem pretty similar to me..

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  • @media queries - one rule overrides another?

    - by John
    I have multiple @media queries all working fine but as soon as i put in a higher max screen-width than 1024px the rules for the higher width gets applied to everything. @media screen and (max-width: 1400px) { #wrap { width: 72%; } } @media screen and (max-width: 1024px) { #slider h2 { width: 100%; } #slider img { margin: 60px 0.83333333333333% 0 2.08333333333333%; } .recent { width: 45.82%; margin: 10px 2.08333333333334% 0 1.875%; } } as you can see 1024px (and also the 800px max-width query) do not change the #wrap width and work fine. As soon as i add the 1400px max-width query it changes them to 72% for ALL sizes and does the same for any element - for instance if i set #slider img to have a margin of 40px it will show at ALL sizes even though it is only in the max-width of 1400px. Am i missing something really obvious? Been trying to work this out for the past 2 days! Thanks, John

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  • Explain "Leader/Follower" Pattern

    - by Alex B
    I can't seem to find a good explanation of "Leader/Follower" pattern. All explanations either simply refer to it in the context of some problem, or are completely meaningless. Can anyone explain to the the mechanics of how this pattern works, and why and how it improves performance over more traditional asynchronous IO models? Examples and links to diagrams are appreciated too.

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  • Need a good way to store data in a DB from a table on a webpage that can have N columns.

    - by Abe Miessler
    Users need to be able to add a specific type of column to an otherwise static table on my web page and then save the information they enter in there to the database. I've been told that in reality they will almost never go over 5 columns but I would rather support N. The columns will all be of the same datatype. My first thought was to have an XML column with the values from all added columns in there but I was curious if anyone else had come up with a better solution. Suggestions?

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