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  • Any tips of how to handle hierarchical trees in relational model?

    - by George
    Hello all. I have a tree structure that can be n-levels deep, without restriction. That means that each node can have another n nodes. What is the best way to retrieve a tree like that without issuing thousands of queries to the database? I looked at a few other models, like flat table model, Preorder Tree Traversal Algorithm, and so. Do you guys have any tips or suggestions of how to implement a efficient tree model? My objective in the real end is to have one or two queries that would spit the whole tree for me. With enough processing i can display the tree in dot net, but that would be in client machine, so, not much of a big deal. Thanks for the attention

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  • ASP.NET sets of technologies/components

    - by Maxim Gueivandov
    Just a question of pure curiosity. It happens that development teams tend to stick to the same technological set(s) for some time, for various reasons (obviously, the lack of time, money, necessity and/or willingless to adopt new technologies). So, what are your usual sets of technologies/components to build an ASP.NET application (e.g., WebForms / MVC, Automapper, NInject, NHibernate / LinqToSql, JQuery / ASP.NET Ajax, ...) or architectural frameworks (Arch#, Catharsis, ...) and in which context do you use them (site size, speed/availability requirements, etc.)?

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  • Am I abusing Policies?

    - by pmr
    I find myself using policies a lot in my code and usually I'm very happy with that. But from time to time I find myself confronted with using that pattern in situations where the Policies are selected and runtime and I have developed habbits to work around such situations. Usually I start with something like that: class DrawArrays { protected: void sendDraw() const; }; class DrawElements { protected: void sendDraw() const; }; template<class Policy> class Vertices : public Policy { using Policy::sendDraw(); public: void render() const; }; When the policy is picked at runtime I have different choices of working around the situation. Different code paths: if(drawElements) { Vertices<DrawElements> vertices; } else { Vertices<DrawArrays> vertices; } Inheritance and virtual calls: class PureVertices { public: void render()=0; }; template<class Policy> class Vertices : public PureVertices, public Policy { //.. }; Both solutions feel wrong to me. The first creates an umaintainable mess and the second introduces the overhead of virtual calls that I tried to avoid by using policies in the first place. Am I missing the proper solutions or do I use the wrong pattern to solve the problem?

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  • Designing a general database interface in PHP

    - by lamas
    I'm creating a small framework for my web projects in PHP so I don't have to do the basic work over and over again for every new website. It is not my goal to create a second CakePHP or Codeigniter and I'm also not planning to build my websites with any of the available frameworks as I prefer to use things I've created myself in general. I have no problems in designing that framework when it comes to parts like the core structure, request handling, and so on but I'm getting stuck with designing the database interface for my modules. I've already thought about using the MVC pattern but thought that it would be a bit of a overkill. So the exact problem I'm facing is how my frameworks modules (viewCustomers could be a module, for example) should interact with the database. Is it a good idea to write SQL directly in PHP (mysql_query( 'SELECT firstname, lastname(.....))? How could I abstract a query like SELECT firstname, lastname FROM customers WHERE id=X Would MySQL helper functions like $this->db->get( array('firstname', 'lastname'), array('id'=>X) ) be a good idea? I suppose not because they actually make everything more complicated by requiring arrays to be created and passed. Is the Model pattern from MVC my only real option?

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  • PHP: Best solution for links breaking in a mod_rewrite app

    - by psil
    I'm using mod rewrite to redirect all requests targeting non-existent files/directories to index.php?url=* This is surely the most common thing you do with mod_rewrite yet I have a problem: Naturally, if the page url is "mydomain.com/blog/view/1", the browser will look for images, stylesheets and relative links in the "virtual" directory "mydomain.com/blog/view/". Problem 1: Is using the base tag the best solution? I see that none of the PHP frameworks out there use the base tag, though. I'm currently having a regex replace all the relative links to point to the right path before output. Is that "okay"? Problem 2: It is possible that the server doesn't support mod_rewrite. However, all public files like images, stylesheets and the requests collector index.php are located in the directory /myapp/public. Normally mod_rewrite points all request to /public so it seems as if public was actually the root directory too all users. However if there is no mod_rewrite, I then have to point the users to /public from the root directory with a header() call. That means, however that all links are broken again because suddenly all images, etc. have to be called via /public/myimage.jpg Additional info: When there is no mod_rewrite the above request would look like this: mydomain.com/public/index.php/blog/view/1 What would be the best solutions for both problems?

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  • [C++]Advantage of using a static member function instead of an equivalent non-static member function

    - by jonathanasdf
    I was wondering whether there's any advantages to using a static member function when there is a non-static equivalent. Will it result in faster execution (because of not having to care about all of the member variables), or maybe less use of memory (because of not being included in all instances)? Basically, the function I'm looking at is an utility function to rotate an integer array representing pixel colours an arbitrary number of degrees around an arbitrary centre point. It is placed in my abstract Bullet base class, since only the bullets will be using it and I didn't want the overhead of calling it in some utility class. It's a bit too long and used in every single derived bullet class, making it probably not a good idea to inline. How would you suggest I define this function? As a static member function of Bullet, of a non-static member function of Bullet, or maybe not as a member of Bullet but defined outside of the class in Bullet.h? What are the advantages and disadvantages of each?

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  • Returning large collections from WCF Serivce

    - by Nate Bross
    I'm trying to determine the best approach for building a WCF Service, and the area I'm struggling with most is returning lists of objects. The built-in maxMessageSize of 64k seems pretty high, and I really don't want to bump it up (quick googling finds 100s of places bumping the maxMessageSize up to multi-gigabyte range which seems foolish). But, when I'm returning a collection of objects (~150 items) I am exceeding the default 64k. I'm almost to the point of returning my own class which inherits IEnumerable and has properties for hasNext, hasPrevious and PageSize so that I can implement paging on the client side -- this seems like alot of code. The other option is to jackup the maxMessageSize and hope for the best, but that feels wrong. All other aspects of my service are working great, its just returning large collectiosn where I'm having issues. For background, there are two types of consumers of this service, UI applications which will be primarly web and/or wpf applications, and data processing applications, .NET console apps, and maybe some other non-UI apps. For the UI applications, I would like to keep them responsive and keep the messageSize low, on the console apps it doesn't matter as much as they are just pulling data down to do processing and push it back up to the service.

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  • Which system modelling notation for showing interconnections and internal logical structures?

    - by user1043838
    I am trying to model a collection of systems, their various interconnections, as well as their internal logical structures, as a message is passed through them, initiated by an actor. I have been using BPMN 2.0 notation with Yaoqiang Editor. However I'm not sure if I'm doing this right, or even using the right notation. System example Is this correct, if not, can you recommend an alternate notation or method of displaying the systems? Thanks for all suggestions

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  • Natural vs surrogate keys on support tables

    - by Bugeo
    I have read many articles about the battle between natural versus surrogate primary keys. I agree in the use of surrogate keys to identify records of tables whose contents are created by the user. But in the case of supporting tables what should I use? For example, in a hypothetical table "orderStates". If you use a natural key would have the following data: TABLE ORDERSTATES {ID: "NEW", NAME: "New"} {ID: "MANAGEMENT" NAME: "Management"} {ID: "SHIPPED" NAME: "Shipped"} If I use a surrogate key would have the following data: TABLE ORDERSTATES {ID: 1 CODE: "NEW", NAME: "New"} {ID: 2 CODE: "MANAGEMENT" NAME: "Management"} {ID: 3 CODE: "SHIPPED" NAME: "Shipped"} Now let's take an example: a user enters a new order. In the case in which use natural keys, in the code I can write this: newOrder.StateOrderId = "NEW"; With the surrogate keys instead every time I have an additional step. stateOrderId_NEW = .... I retrieve the id corresponding to the recod code "NEW" newOrder.StateOrderId = stateOrderId_NEW; The same will happen every time I have to move the order in a new status. So, in this case, what are the reason to chose one key type vs the other one?

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  • Creating combinations that have no more one intersecting element

    - by khuss
    I am looking to create a special type of combination in which no two sets have more than one intersecting element. Let me explain with an example: Let us say we have 9 letter set that contains A, B, C, D, E, F, G, H, and I If you create the standard non-repeating combinations of three letters you will have 9C3 sets. These will contain sets like ABC, ABD, BCD, etc. I am looking to create sets that have at the most only 1 common letter. So in this example, we will get following sets: ABC, ADG, AEI, AFH, BEH, BFG, BDI, CFI, CDH, CEG, DEF, and GHI - note that if you take any two sets there are no more than 1 repeating letter. What would be a good way to generate such sets? It should be scalable solution so that I can do it for a set of 1000 letters, with sub set size of 4. Any help is highly appreciated. Thanks

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  • index 'enabled' fields good idea?

    - by sibidiba
    Content of a website is stored in a MySQL database. 99% of the content will be enabled, but some (users, posts etc.) will be disabled. Most of the queries end as WHERE (...) AND enabled Is it a good idea to create an index on the field 'enabled'?

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  • Dealing with dependencies between WCF services when using Castle Windsor

    - by Georgia Brown
    I have several WCF services which use castle windsor to resolve their dependencies. Now I need some of these services to talk to each other. The typical structure is service -- Business Logic -- DAL The calls to the other services need to occur at Business Logic level. What is the best approach for implementing this? Should I simply inject a service proxy into the business logic? Is this wasteful if for example, only one of two method from my service need to use this proxy? What if the services need to talk to each other? - Will castle windsor get stuck in a loop trying to resolve each services dependencies?

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  • Are these jobs for developer or designers or for client itself?

    - by jitendra
    Spell checking grammar checking Descriptive alt text for big chart , graph images, technical images To write Table summary and caption Descriptive Link text Color Contrast checking Deciding in content what should be H2 ,H3, H4... and what should be <strong> or <span class="boldtext"> Meta Description and keywords for each pages Image compression To decide Filenames for images,PDf etc To decide Page's <title> for each page

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  • best option to create simple website mockup with navigation

    - by Buzzer
    I'm trying to put together a static html website with full navigation. In other words, I want the user to click some links and images and actually be taken to another page. I'm a developer so I know how to do this in frameworks like ASP.Net MVC and grails. However, for this particular case, I just want to quickly mock up the UI and provide simple navigation so I can do some user testing. Can anyone advice on how to do this? Thanks,

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  • Some questions regarding Flex

    - by Rachel
    For what real time scenarios/use cases one should go to Flex Technology ? What real time problems you have solved using Flex Technology ? What real time problems have you faced because of using Flex Technology and what was your work around for that use case ?

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  • Migration solution for singletons in an OSGI environment

    - by Ido
    I'm working in a JEE Environment in which each application is in a war file of its own. In the WEB-INF/lib of each application war file there is a common jar that is shared by all applications. This common jar contains several Singletons which are accessed from many points in the code. Because of the war-file boundaries each application has its own instances of the Singletons. Which is how we operate today, since we want to configure some of the singletons differently in each application. Now we are moving towards an OSGi environment, where this solution will no longer work since each bundle has its own class loader, so if I try to access MySingleton which resides in bundle "common.jar" from bundle "appA.jar" or from bundle "appB.jar" I will get the same instance. Remember I "want" a different instance of a singleton per bundle. (as ironic as it sounds) Now I realize the ideal solution would be to fix the code to not rely on those singletons, however due to a tight schedule I was wondering if you guys can suggest some sort of a migration solution that would allow me to use bundle-wide singletons so each of them could be configured per bundle.

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  • What to name column in database table that holds versioning number

    - by rwmnau
    I'm trying to figure out what to call the column in my database table that holds an INT to specific "record version". I'm currently using "RecordOrder", but I don't like that, because people think higher=newer, but the way I'm using it, lower=newer (with "1" being the current record, "2" being the second most current, "3" older still, and so on). I've considered "RecordVersion", but I'm afraid that would have the same problem. Any other suggestions? "RecordAge"? I'm doing this because when I insert into the table, instead of having to find out what version is next, then run the risk of having that number stolen from me before I write, I just insert insert with a "RecordOrder" of 0. There's a trigger on the table AFTER INSERT that increments all the "RecordOrder" numbers for that key by 1, so the record I just inserted becomes "1", and all others are increased by 1. That way, you can get a person's current record by selection RecordOrder=1, instead of getting the MAX(RecordOrder) and then selecting that. PS - I'm also open to criticism about why this is a terrible idea and I should be incrementing this index instead. This just seemed to make lookups much easier, but if it's a bad idea, please enlighten me! Some details about the data, as an example: I have the following database table: CREATE TABLE AmountDue ( CustomerNumber INT, AmountDue DECIMAL(14,2), RecordOrder SMALLINT, RecordCreated DATETIME ) A subset of my data looks like this: CustomerNumber Amountdue RecordOrder RecordCreated 100 0 1 2009-12-19 05:10:10.123 100 10.05 2 2009-12-15 06:12:10.123 100 100.00 3 2009-12-14 14:19:10.123 101 5.00 1 2009-11-14 05:16:10.123 In this example, there are three rows for customer 100 - they owed $100, then $10.05, and now they owe nothing. Let me know if I need to clarify it some more. UPDATE: The "RecordOrder" and "RecordCreated" columns are not available to the user - they're only there for internal use, and to help figure out which is the current customer record. Also, I could use it to return an appropriately-ordered customer history, though I could just as easily do that with the date. I can accomplish the same thing as an incrementing "Record Version" with just the RecordCreated date, I suppose, but that removes the convenience of knowing that RecordOrder=1 is the current record, and I'm back to doing a sub-query with MAX or MIN on the DateTime to determine the most recent record.

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  • Storing year/make/model in a database?

    - by Mark
    Here's what I'm thinking (excuse the Django format): class VehicleMake(Model): name = CharField(max_length=50) class VehicleModel(Model): make = ForeignKey(VehicleMake) name = CharField(max_length=50) class VehicleYear(Model): model = ForeignKey(VehicleModel) year = PositiveIntegerField() This is going to be used in those contingent drop-down select boxes, which would visually be laid out like [- Year -][- Make -][- Model -]. So, to query the data I need I would first have to select all distinct years from the years table, sorted descending. Then I'd find all the vehicle makes that have produced a model in that year. And then all the models by that make in that year. Is this a good way to do it, or should I re-arrange the foreign keys somehow? Or use a many-to-many table for the years/models so that no year is repeated?

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  • Pros / Cons displaying list of users at login page

    - by Radu094
    We seem to have a lot of clients asking us to change the login screen in this manner: Display a list of all available users (thumbnail picture + name) User selects a username from the list A password prompt appears near the username User enters password then presses enter This sounds remarcably similar to the Windows XP login, which is probably where they got the ideea in the first place. There are only about 4 - 5 different users that can login at any given station, so implementing that list on one screen is feasable. So I was wondering if there are any usability experts with some word on this method of login. As far as I can tell, MS droped this behaviour in Vista/Win7, didn't they?

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  • What do you choose, protected or internal?

    - by brickner
    If I have a class with a method I want protected and internal. I want that only derived classes in the assembly would be able to call it. Since protected internal means protected or internal, you have to make a choice. What do you choose in this case - protected or internal?

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  • Risking the exception anti-pattern.. with some modifications

    - by Sridhar Iyer
    Lets say that I have a library which runs 24x7 on certain machines. Even if the code is rock solid, a hardware fault can sooner or later trigger an exception. I would like to have some sort of failsafe in position for events like this. One approach would be to write wrapper functions that encapsulate each api a: returnCode=DEFAULT; try { returnCode=libraryAPI1(); } catch(...) { returnCode=BAD; } return returnCode; The caller of the library then restarts the whole thread, reinitializes the module if the returnCode is bad. Things CAN go horribly wrong. E.g. if the try block(or libraryAPI1()) had: func1(); char *x=malloc(1000); func2(); if func2() throws an exception, x will never be freed. On a similar vein, file corruption is a possible outcome. Could you please tell me what other things can possibly go wrong in this scenario?

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  • Saving Abstract and Sub classes to database

    - by bretddog
    Hi, I have an abstract class "StrategyBase", and a set of sub classes, StrategyA/B/C etc. The sub classes use some of the properties of the base class, and have some individual properties. My question is how to save this to a database. I'm currently using SqlCE, and Linq-To-Sql by creating entity classes automatically with SqlMetal.exe. I've seen there are three solutions shown in this question, but I'm not able to see how these solutions will work or not with SqlMetal/entity classes. Though it seems to me the "concrete table inheritance" would probably work without any manual modifying. What about the other two, would they be problematic? For "Single Table Inheritance" wouldn't all classes get all variables, even though they don't need them? And for the "Class table inheritance" solution I can't really see at all how that will map into the entity-classes for a useful purpose. I may note that I extend these partial entity classes for making the classes of my business objects. I may also consider moving to EntityFramework instead of SqlMetal/Linq2Sql, so would be nice also to know if that makes any difference to what schema is easy to implement. One likely important thing to note is that I will constantly be develop new strategies, which makes me have to modify the program code, and probably the database shcema; when adding a new strategy. Sorry the question is a bit "all over the place", but hopefully it's some clear advantages/disadvantages here that you may be able to advice. ? Cheers!

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  • Use of (non) qualified names

    - by AProgrammer
    If I want to use the name baz defined in package foo|bar|quz, I've several choices: provide fbq as a short name for foo|bar|quz and use fbq|baz use foo|bar|quz|baz import baz from foo|bar|quz|baz and then use baz (or an alias given in the import process) import all public symbols from foo|bar|quz|baz and then use baz For the languages I know, my perception is that the best practice is to use the first two ways (I'll use one or the other depending on the specific package full name and the number of symbols I need from it). I'd use the third only in a language which doesn't provide the first and hunt for supporting tools to write the import statements. And in my opinion the fourth should be reserved to package designed with than import in mind, for instance if all exported symbols start with a prefix or contains the name of the package. My questions: what is in your opinion the best practice for your favorite languages? what would you suggest in a new language? what would you suggest in an old language adding such a feature?

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