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  • What are the common patterns in web programming?

    - by lankerisms
    I have been trying to write my first big web app (more than one cgi file) and as I kept moving forward with the rough prototype, paralelly trying to predict more tasks, this is the todo that got accumulated (In no particular order). * Validations and input sanitizations * Object versioning (to avoid edit conflicts. I dont want hard locks) * Exception handling * memcache * xss and injection protections * javascript * html * ACLs * phonetics in search, match and find duplicates (for form validation) * Ajaxify!!! (I have snipped off the project specific items.) I know that each todo will be quite tied up to its project and technologies used. What I am wondering though, is if there is a pattern in your todo items as well as the sequence in which you experienced guys have come across them.

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  • Better alternative to autonumber primary keys

    - by Comrad_Durandal
    I am looking for a better primary key than the autonumber data type, namely for the reason that it's limited to a long integer, when I really just need the field to reflect a number or text string that will never ever repeat, no matter HOW many records are added or deleted from the table. The problem is I am not sure how to implement something like turning the current date and time into a hexadecimal string and using that as a unique field I can use as a primary key. Am I just being too paranoid about running out of space?

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  • Pattern for version-specific implementations of a Java class

    - by Mike Monkiewicz
    So here's my conundrum. I am programming a tool that needs to work on old versions of our application. I have the code to the application, but can not alter any of the classes. To pull information out of our database, I have a DTO of sorts that is populated by Hibernate. It consumes a data object for version 1.0 of our app, cleverly named DataObject. Below is the DTO class. public class MyDTO { private MyWrapperClass wrapper; public MyDTO(DataObject data) { wrapper = new MyWrapperClass(data); } } The DTO is instantiated through a Hibernate query as follows: select new com.foo.bar.MyDTO(t1.data) from mytable t1 Now, a little logic is needed on top of the data object, so I made a wrapper class for it. Note the DTO stores an instance of the wrapper class, not the original data object. public class MyWrapperClass { private DataObject data; public MyWrapperClass(DataObject data) { this.data = data; } public String doSomethingImportant() { ... version-specific logic ... } } This works well until I need to work on version 2.0 of our application. Now DataObject in the two versions are very similar, but not the same. This resulted in different sub classes of MyWrapperClass, which implement their own version-specific doSomethingImportant(). Still doing okay. But how does myDTO instantiate the appropriate version-specific MyWrapperClass? Hibernate is in turn instantiating MyDTO, so it's not like I can @Autowire a dependency in Spring. I would love to reuse MyDTO (and my dozens of other DTOs) for both versions of the tool, without having to duplicate the class. Don't repeat yourself, and all that. I'm sure there's a very simple pattern I'm missing that would help this. Any suggestions?

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  • application specific seed data population

    - by user339108
    Env: JBoss, (h2, MySQl, postgres), JPA, Hibernate 3.3.x @Id @GeneratedValue(strategy = IDENTITY) private Integer key; Currently our primary keys are created using the above annotation. We expect to support a large number of users (~million users), what key should be used. Should it be Integer or Long or should I use the unsigned versions of the above declarations. We have a j2ee application which needs to be populated with some seed data on installation. On purchase, the customer creates his own data on top of the application. We just want to make sure that there is enough room to ship, modify or add data for future releases. What would be the best mechanism to support this, we had looked at starting all table identifiers from a certain id (say 1000) but this mandates modifying primary key generation to have table or sequence based generators and we have around ~100 tables. We are not sure if this is the right strategy for this. If we use a signed integer approach for the key, would it make sense to have the seed data as everything starting from 0 and below (i.e -ve numbers), so that all customer specific data will be available on 0 and above (i.e. +ve numbers)

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  • Table with unequal rows in XUL layout

    - by Michael
    Trying to get something similar for Firefox extension using XUL. The most difficult part is the grid with unequal number of rows. I tried <grid> but it didn't work well. Also don't want to use HTML inside of XUL. Any ideas how to build such table?

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  • When to define SDD operations System->Actor?

    - by devoured elysium
    I am having some trouble understanding how to make SDDs, as I don't fully grasp why in some cases one should define operations for System - Actor and in others don't. Here is an example: 1) The User tells the System that wants to buy some tickets, stating his client number. 2) The System confirms that the given client number is valid. 3) The User tells the System the movie that wants to see. 4) The System shows the set of available sessions and seats for that movie. 5) The System asks the user which session/seat he wants. 6) The user tells the System the chosen session/seat. This would be converted to: a) -----> tellClientNumber(clientNumber) b) <----- validClientNumber c) -----> tellMovieToSee(movie) d) <----- showsAvailableSeatsHours e) -----> tellSystemChosenSessionSeat(session, seat) I know that when we are dealing with SDD's we are still far away from coding. But I can't help trying to imagine how it how it would have been had I to convert it right away to code: I can understand 1) and 2). It's like if it was a C#/Java method with the following signature: boolean tellClientNumber(clientNumber) so I put both on the SDD. Then, we have the pair 3) 4). I can imagine that as something as: SomeDataStructureThatHoldsAvailableSessionsSeats tellSystemMovieToSee(movie) Now, the problem: From what I've come to understand, my lecturer says that we shouldn't make an operation on the SDD for 5) as we should only show operations from the Actor to the System and when the System is either presenting us data (as in c)) or validating sent data (such as in b)). I find this odd, as if I try to imagine this like a DOS app where you have to put your input sequencially, it makes sense to make an arrow even for 5). Why is this wrong? How should I try to visualize this? Thanks

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  • database modeling for google app engine for multiple revison of entity.

    - by iamgopal
    hi, in my application ( kind of wiki clone ) - an article is frequently changing. and i need to track all changes that are done on that article. { text only. } one crude way i have done it, is to add a datetime property and create a new entity everytime something change. which is too much database wasting. { and also un-necessary index waste too. } and also need to re-create parent-child and entity relationships. i also have log which can show changes -- but i want some thing easier , so that jumping from one version to another version could be easier. ideas ? thanks.

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  • ASP.NET MVC Filters: How to set Viewdata for Dropdown based on action parameter

    - by CRice
    Hi, Im loading an entity 'Member' from its id in route data. [ListItemsForMembershipType(true)] public ActionResult Edit(Member someMember) {...} The attribute on the action loads the membership type list items for a dropdown box and sticks it in viewdata. This is fine for add forms, and search forms (it gets all active items) but I need the attribute to execute BASED ON THE VALUE someMember.MembershipTypeId, because its current value must always be present when loading the item (i.e. all active items, plus the one from the loaded record). So the question is, what is the standard pattern for this? How can my attribute accept the value or should I be loading the viewdata for the drop down in a controller supertype or during model binding or something else? It is in an attribute now because the code to set the viewdata would otherwise be duplicated in each usage in each action.

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  • Why doesn't Java Map extends Collection?

    - by polygenelubricants
    I was surprised by the fact that Map<?,?> is not a Collection<?>. I thought it'd make a LOT of sense if it was declared as such: public interface Map<K,V> extends Collection<Map.Entry<K,V>> After all, a Map<K,V> is a collection of Map.Entry<K,V>, isn't it? So is there a good reason why it's not implemented as such?

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  • Re-usable Obj-C classes with custom values: The right way

    - by Prairiedogg
    I'm trying to reuse a group of Obj-C clases between iPhone applications. The values that differ from app to app have been isolated and I'm trying to figure out the best way to apply these custom values to the classes on an app-to-app basis. Should I hold them in code? // I might have 10 customizable values for each class, that's a long signature! CarController *controller = [[CarController alloc] initWithFontName:@"Vroom" engine:@"Diesel" color:@"Red" number:11]; Should I store them in a big settings.plist? // Wasteful! I sometimes only use 2-3 of 50 settings! AllMyAppSettings *settings = [[AllMyAppSettings alloc] initFromDisk:@"settings.plist"]; MyCustomController *controller = [[MyCustomController alloc] initWithSettings:settings]; [settings release]; Should I have little, optional n_settings.plists for each class? // Sometimes I customize CarControllerSettings *carSettings = [[CarControllerSettings alloc] initFromDisk:@"car_settings.plist"]; CarController *controller = [[CarController alloc] initWithSettings:carSettings]; [carSettings release]; // Sometimes I don't, and CarController falls back to internally stored, reasonable defaults. CarController *controller = [[CarController alloc] initWithSettings:nil]; Or is there an OO solution that I'm not thinking of at all that would be better?

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  • What strategies are efficient to handle concurrent reads on heterogeneous multi-core architectures?

    - by fabrizioM
    I am tackling the challenge of using both the capabilities of a 8 core machine and a high-end GPU (Tesla 10). I have one big input file, one thread for each core, and one for the the GPU handling. The Gpu thread, to be efficient, needs a big number of lines from the input, while the Cpu thread needs only one line to proceed (storing multiple lines in a temp buffer was slower). The file doesn't need to be read sequentially. I am using boost. My strategy is to have a mutex on the input stream and each thread locks - unlocks it. This is not optimal because the gpu thread should have a higher precedence when locking the mutex, being the fastest and the most demanding one. I can come up with different solutions but before rush into implementation I would like to have some guidelines. What approach do you use / recommend ?

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  • New or not so well-known paradigms, syntax features and behaviours of programming languages?

    - by George B
    I've designed some educational programming languages and interpreters for them, but my problem always was that they ended up "normal" and "boring", mostly similar to some kind of existing language (ASM and BASIC). I find it really hard to come up with new ideas for syntax features, "neat things" and new or very modified programming paradigms for it. I always thought that it was hard to come up with good new things not fun/useless new things for this case. I wondered if you could help me out with your creativity: What features in terms of language syntax and built-in functions as well as maybe even new paradigms can I work into my language to keep it useless but more fun, enjoyable, interesting and/or different to program in?

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  • Multiple values in a column

    - by Adnan
    Hi I need some advice regarding multiple records. I have a table with fields username,*message* and message_to. the scenario could be of sending same message to multiple users in a go. What do you suggest? will it be efficient to save all recipients in a single column with comma separated values or I add multiple entries ? Thanks /A

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  • Define "Validation in the Model"

    - by sunwukung
    There have been a couple of discussions regarding the location of user input validation: http://stackoverflow.com/questions/659950/should-validation-be-done-in-form-objects-or-the-model http://stackoverflow.com/questions/134388/where-do-you-do-your-validation-model-controller-or-view These discussions were quite old, so I wanted to ask the question again to see if anyone had any fresh input. If not, I apologise in advance. If you come from the Validation in the Model camp - does Model mean OOP representation of data (i.e. Active Record/Data Mapper) as "Entity" (to borrow the DDD terminology) - in which case you would, I assume, want all Model classes to inherit common validation constraints. Or can these rules simply be part of a Service in the Model - i.e. a Validation service? For example, could you consider Zend_Form and it's validation classes part of the Model? The concept of a Domain Model does not appear to be limited to Entities, and so validation may not necessarily need to be confined to this Entities. It seems that you would require a lot of potentially superfluous handing of values and responses back and forth between forms and "Entities" - and in some instances you may not persist the data recieved from user input, or recieve it from user input at all.

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  • Unique constraint on more than 10 columns

    - by tk
    I have a time-series simulation model which has more than 10 input variables. The number of distinct simulation instances would be more than 1 million, and each simulation instance generates a few output rows every day. To save the simulation result in a relational database, i designed tables like this. Table SimulationModel { simul_id : integer (primary key), input0 : string or numeric, input1 : string or numeric, ...} Table SimulationOutput { dt : DateTime (primary key), simul_id : integer (primary key), output0 : numeric, ...} My question is, is it fine to put an unique constraint on all of the input columns of SimulationModel table? If it is not a good idea, then what kind of other options do i have to make sure each model is unique?

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  • Recommendation for tool/framework that follows the naked objects pattern?

    - by Marcus Munzert
    I am searching for a tool/framework that follows the naked objects pattern and is written in Java. I know about tools like for instance JMatter, Naked Objects and Domain Object Explorer. That's not exactly what I am searching for, though. Open source would be great, but doesn't need to be. My intention is to use that tool/framework for the purpose of model-driven software development to do the modeling part. Ideally, such a tool/framework would provide the option to use JPA to store/load objects.

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  • Pattern for iPhone background loading during init?

    - by Rob S.
    Hi everyone, I'm currently kicking off a background thread to do some REST queries in my app delegate's didFinishLaunchingWithOptions. This thread creates some objects and populates the model as the rest of the app continues to load (because I don't block, and didFinishLaunchingWithOptions returns YES). I also put up a loading UIViewController 'on top' of the main view that I tear down after the background initialization is complete. My problem is that I need to notify the first view (call it the Home view) that the model is ready, and that it should populate itself. The trick is that the background download could have finished before Home.viewDidAppear is called, or any of the other Home.initX methods. I'm having difficulty synchronizing all of this and I've thought about it long enough that it feels like I'm barking up the wrong tree. Are there any patterns here for this sort of thing? I'm sure other apps start by performing lengthy operations with loading screens :) Thanks!

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  • How do you unit test new code that uses a bunch of classes that cannot be instantiated in a test har

    - by trendl
    I'm writing a messaging layer that should handle communication with a third party API. The API has a bunch of classes that cannot be easily (if at all) instantiated in a test harness. I decided to wrap each class that I need in my unit tests with an adapter/wrapper and expose the members I need through this adapter class. Often I need to expose the wrapped type as well which I do by exposing it as an object. I have also provided an interface for for each or the adapter classes to be able to use them with a mocking framework. This way I can substitute the classes in test for whatever I need. The downside is that I have a bunch of adapter classes that so far server no other reason but testing. For me this is a good reason by itself but others may find this not enough. Possibly, when I write an implementation for another third party vendor's API, I may be able to reuse much of my code and only provide the adapters specific to the vendor's API. However, this is a bit of a long shot and I'm not actually sure it will work. What do you think? Is this approach viable or am I writing unnecessary code that serves no real purpose? Let me say that I do want to write unit tests for my messaging layer and I do now know how to do it otherwise.

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  • Responsive logo (image replacement) in html5boilerplate

    - by Barbara
    I'm using the responsive version of html5 boilerplate via initializr.com. My site uses a custom logo so i added the .ir class to h1 .ir { background-color: transparent; border: 0; overflow: hidden; *text-indent: -9999px; } like this <h1 class="title ir">h1.title</h1> The documentation says Add the .ir class to any element you are applying image-replacement to. When replacing an element's content with an image, make sure to also set a specific background-image: url(pathtoimage.png);, width, and height so that your replacement image appears. So I added to the code these lines .ir { background-image: url(http://i.imgur.com/yYnyJ.jpg); background-size: 100% auto; width:450px; height:450px } The problem are the specific width and height. I can't get rid of them but the logo is not responsive this way. Ideas? Here's the fiddle. http://jsfiddle.net/qeW3e/

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  • What is a good architecture for a Lift-JPA application?

    - by egervari
    I was wondering what is the best practice for a JPA model in Lift? I noticed that in the jpa demo application, there is just a Model object that is like a super object that does everything. I don't think this can be the most scalable approach, no? Is it is wise to still do the DAO pattern in Lift? For example, there's some code that looks a tad bloated and could be simplified across all model objects: Model.remove(Model.getReference(classOf[Author], someId)) Could be: AuthorDao.remove(someId) I'd appreciate any tips for setting up something that will work with the way Lift wants to work and is also easy to organize and maintain. Preferably from someone who has actually used JPA on a medium to large Lift site rather than just postulating what Spring does (we know how to do that) ;) The first phase of development will be around 30-40 tables, and will eventually get to over 100... we need a scalable, neat approach.

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  • Why Do Programmers Get So Invested in their Favorite Technologies?

    - by Pierreten
    I've noticed this culture surrounding Ruby where developers truly believe that they are somehow more gifted than developers of other languages, regardless of experience and talent (even when that isn't the case, I've met some extremely junior Ruby developers come up with some pretty basic constructs, and pass them off as some sort of revolutionary idea). The derision of strongly typed languages seems to be a common theme as well; regardless of its merits. Is there something particular to the Ruby syntax in general that is to account for this? Is there a sociological component to it?

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