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• Has the emerging generation of programmers got the wrong idea about design patterns? [closed]

  - by MattDavey

  Over the years I've noticed a shift in attitude towards design patterns, particularly amongst the emerging generation of developers. There seems to be a notion these days that design patterns are silver bullets that instantly cure any problem, a proliferating idea that advancing as a software engineer simply means learning and applying more and more patterns. When confronted with a problem, developers no longer strive to truly understand the issue and design a solution - instead they simply pick a design pattern which seems to be a close fit, and try to brute-force it. You can see evidence of this by the many, many questions on Stack Overflow that begin with the phrase "what pattern should I use to...". I fall into a slightly more mature category of developers (5-10 years experience) and I have a very different viewpoint on patterns - simply as a communication tool to enhance clarity. I find this perspective of design patterns being lego bricks (collected like pokemon cards) a little disconcerting. Will developers lose this attitude as they gain more experience in software engineering? Or could these notions perhaps steer the direction of our craft in years to come? Did the older generation of developers have any similar concerns about us? (perhaps about OO design or similar...). if so, how did we turn out?

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• The data reader returned by the store data provider does not have enough columns

  - by molgan

  Hello I get the following error when I try to execute a stored procedure: "The data reader returned by the store data provider does not have enough columns" When I in the sql-manager execute it like this: DECLARE @return_value int, @EndDate datetime EXEC @return_value = [dbo].[GetSomeDate] @SomeID = 91, @EndDate = @EndDate OUTPUT SELECT @EndDate as N'@EndDate' SELECT 'Return Value' = @return_value GO It returns the value properly.... @SomeDate = '2010-03-24 09:00' And in my app I have: if (_entities.Connection.State == System.Data.ConnectionState.Closed) _entities.Connection.Open(); using (EntityCommand c = new EntityCommand("MyAppEntities.GetSomeDate", (EntityConnection)this._entities.Connection)) { c.CommandType = System.Data.CommandType.StoredProcedure; EntityParameter paramSomeID = new EntityParameter("SomeID", System.Data.DbType.Int32); paramSomeID.Direction = System.Data.ParameterDirection.Input; paramSomeID.Value = someID; c.Parameters.Add(paramSomeID); EntityParameter paramSomeDate = new EntityParameter("SomeDate", System.Data.DbType.DateTime); SomeDate.Direction = System.Data.ParameterDirection.Output; c.Parameters.Add(paramSomeDate); int retval = c.ExecuteNonQuery(); return (DateTime?)c.Parameters["SomeDate"].Value; Why does it complain about columns? I googled on error and someone said something about removing RETURN in sp, but I dont have any RETURN there. last like is like SELECT @SomeDate = D.SomeDate FROM .... /M

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• Passing data structures to different threads

  - by Robb

  I have an application that will be spawning multiple threads. However, I feel there might be an issue with threads accessing data that they shouldn't be. I'm relatively new to threading so bare with me. Here is the structure of the threaded application (sorry for the crudeness): MainThread / \ / \ / \ Thread A Thread B / \ / \ / \ / \ / \ / \ Thread A_1 Thread A_2 Thread B_1 Thread B_2 Under each lettered thread (which could be many), there will only be two threads and they are fired of sequentially. The issue i'm having is I'm not entirely sure how to pass in a datastructure into these threads. So, the datastructure is created in MainThread, will be modified in the lettered thread (Thread A, etc) specific to that thread and then a member variable from that datastructure is sent to Letter_Numbered threads. Currently, the lettered thread class has a member variable and when the class is constructed, the datastructure from mainthread is passed in by reference, invoking the copy constructor so the lettered thread has it's own copy to play with. The lettered_numbered thread simply takes in a string variable from the data structure within the lettered thread. My question is, is this accceptable? Is there a much better way to ensure each lettered thread gets its own data structure to play with? Sorry for the somewhat poor explanation, please leave comments and i'll try to clarify.

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• ASP.NET server data persistence

  - by Wayne Werner

  Hi, I'm not really sure exactly how the question should be phrased, so please be patient if I ask the wrong thing. I'm writing an ASP.NET application using VB as the code behind language. I have a data access class that connects to the DB to run the query (parameterized, of course), and another class to perform the validation tasks - I access this class from my aspx page. What I would like is to be able to store the data server side and wait for the user to choose from a few options based on the validity of the data. But unless my understanding is completely off, having persistent data objects on the server will give problems when multiple users connect? My ultimate goal is that once the data has been validated the end user can't modify it. Currently I'm validating the data, but I still have to retrieve it from the web form AFTER the user says OK, which obviously leaves open the possibility of injecting bad data either accidentally (unlikely) or on purpose (also unlikely for the use, but I'd prefer not to take the chance). So am I completely off in my understanding? If so, can someone point me to a resource that provides some instructions on keeping persistent data on the server, or provide instruction? Thanks!

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• SQLAuthority News – Best Practices for Data Warehousing with SQL Server 2008 R2

  - by pinaldave

  An integral part of any BI system is the data warehouse—a central repository of data that is regularly refreshed from the source systems. The new data is transferred at regular intervals  by extract, transform, and load (ETL) processes. This whitepaper talks about what are best practices for Data Warehousing. This whitepaper discusses ETL, Analysis, Reporting as well relational database. The main focus of this whitepaper is on mainly ‘architecture’ and ‘performance’. Download Best Practices for Data Warehousing with SQL Server 2008 R2 Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Best Practices, Data Warehousing, PostADay, SQL, SQL Authority, SQL Documentation, SQL Download, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• Nagy dobás készül az Oracle adatányászati felületen, Oracle Data Mining

  - by Fekete Zoltán

  Ahogyan már a tavaly oszi Oracle OpenWorld hírekben és eloadásokban is láthattuk a beharangozót, az Oracle nagy dobásra készül az adatbányászati fronton (Oracle Data Mining), mégpedig a remekül használható adatbányászati motor grafikus felületének a kiterjesztésével. Ha jól megfigyeljük ezt az utóbbi linket, az eddigi grafikus felület már Oracle Data Miner Classic néven fut. Hogyan is lehet használni az Oracle Data Mining-ot? - Oracle Data Miner (ingyenesen letöltheto GUI az OTN-rol) - Java-ból és PL/SQL-bol, Oracle Data Mining JDeveloper and SQL Developer Extensions - Excel felületrol, Oracle Spreadsheet Add-In for Predictive Analytics - ODM Connector for mySAP BW Oracle Data Mining technikai információ.

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• Should pathfinder in A* hold closedSet and openedSet or each object should hold its sets?

  - by Patryk

  I am about to implement A* pathfinding algorithm and I wonder how should I implement this - from the point of view of architecture. I have the pathfinder as a class - I think I will instantiate only one object of this class (or maybe make it a Singleton - this is not so important). The hardest part for me is whether the closedSet and openedSet should be attached to objects that can find the path for them or should be stored in pathfinder class ? I am opened to any hints and critique whatsoever. What is the best practice considering pathfinding in terms of design ?

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• Low coupling processing big quantities of data

  - by vitalik

  Usually I achieve low coupling by creating classes that exchange lists, sets, and maps between them. Now I am developing a batch application and I can't put all the data inside a data structure because there isn't enough memory. I have to read and process one chunk of data and then going to the next one. So having low coupling is much more difficult because I have to check somewhere if there is still data to read, etc. What I am using now is: Source - Process - Persist The classes that process have to ask to the Source classes if there are more rows to read. What are the best practices and or useful patterns in such situations? I hope I am explaining myself, if not tell me.

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• What is a best practice tier structure of a Java EE 6/7 application?

  - by James Drinkard

  I was attempting to find a best practice for modeling the tiers in a Java EE application yesterday and couldn't come up with anything current. In the past, say java 1.4, it was four tiers: Presentation Tier Web Tier Business Logic Tier DAL (Data Access Layer ) which I always considered a tier and not a layer. After working with Web Services and SOA I thought to add in a services tier, but that may fall under 3. the business logic tier. I did searches for quite a while and reading articles. It seems like Domain Driven Design is becoming more popular, but I couldn't find a diagram on it's tier structure. Anyone have ideas or diagrams on what the proper tier structure is for newer Java EE applications or is it really the same, but more items are ranked under the four I've mentioned?

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• When should we use weak entities when modelling a database?

  - by Songo

  This is basically a question about what are weak entities? When should we use them? How should they be modeled? What is the main difference between normal entities and weak entities? Does weak entities correspond to value objects when doing Domain Driven Design? To help keep the question on topic here is an example taken from Wikipedia that people can use to answer these question: In this example OrderItem was modeled as a weak entity, but I can't understand why it can't be modeled as a normal entity. Another question is what if I want to track the order history (i.e. the changes in it status) would that be a normal or weak entity?

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• Single database, multiple system dependency

  - by davenewza

  Consider an environment where we have a single, core database, with many separate systems using this one database. This leads to all of these systems have a common dependency, which ultimately introduces coupling between them. This means that we cannot always evolve systems independently of each other. Structural changes to the database (even if only intended for one, particular system), requires a full sweep test of ALL systems, and may require that other systems be 'patched' and subsequently released. This is especially tricky when you want to have separate teams working on different projects. What is a good 'pattern' to help in avoiding such coupling? I would imagine that a database should be exclusively depended on by one system. If other systems require data for whatever reason, they should request such from an API service of some kind. A drawback of this approach which comes to mind is performance: routing data between high-throughput systems through service calls is much slower than through a database connection.

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• What to choose API based server or Socket based server for data driven application

  - by Imdad

  I am working on a project which has a Desktop Application for MAC/COCOA, a native application for iPhone another native application in iPad. All the application do almost same thing. The applications are data driven applications. Every communication to server is made via a restful API developed in PHP. When a user logs in a lot of data is fetched from server. And to remain in sync with server pooling is done. As there are lot of data to pool it makes application slower and un-reliable. A possible solution that comes into my mind is to use Socket based server. My question is that will it reasonably improve the performance? And which technology (of sockets) will be good as a server side solution for data driven application? I have heard a lot about Node.js. Please give your suggestions.

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• Customizing configuration with Dependency Injection

  - by mathieu

  I'm designing a small application infrastructure library, aiming to simplify development of ASP.NET MVC based applications. Main goal is to enforce convention over configuration. Hovewer, I still want to make some parts "configurable" by developpers. I'm leaning towards the following design: public interface IConfiguration { SomeType SomeValue; } // this one won't get registered in container protected class DefaultConfiguration : IConfiguration { public SomeType SomeValue { get { return SomeType.Default; } } } // declared inside 3rd party library, will get registered in container protected class CustomConfiguration : IConfiguration { public SomeType SomeValue { get { return SomeType.Custom; } } } And the "service" class : public class Service { private IConfiguration conf = new DefaultConfiguration(); // optional dependency, if found, will be set to CustomConfiguration by DI container public IConfiguration Conf { get { return conf; } set { conf = value; } } public void Configure() { DoSomethingWith( Conf ); } } There, the "configuration" part is clearly a dependency of the service class, but it this an "overuse" of DI ?

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• Google I/O 2012 - Big Data: Turning Your Data Problem Into a Competitive Advantage

  Google I/O 2012 - Big Data: Turning Your Data Problem Into a Competitive Advantage Ju-kay Kwek, Navneet Joneja Can businesses get practical value from web-scale data without building proprietary web-scale infrastructure? This session will explore how new Google data services can be used to solve key data storage, transformation and analysis challenges. We will look at concrete case studies demonstrating how real life businesses have successfully used these solutions to turn data into a competitive business asset. For all I/O 2012 sessions, go to developers.google.com From: GoogleDevelopers Views: 1 0 ratings Time: 52:39 More in Science & Technology

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• Why is nesting or piggybacking errors within errors bad in general?

  - by dietbuddha

  Why is nesting or piggybacking errors within errors bad in general? To me it seems bad intuitively, but I'm suspicious in that I cannot adequately articulate why it is bad. This may be because it is not in general bad and that it is only bad in specific instances. Why is it detrimental to design error/exception handling in such a way. The specific instance is that of a REST service. There is a desire by some to use http errors (specifically the 500 response) as a way to indicate any problem with specific instances of a resource. An example of an instance resource in this case would be: http://server/ticket/80 # instance http://server/ticket # not an instance So this is the behavior that is being proposed. If ticket 80 does not exist return a http response code of 500. Within the body of the error return the "real" error as an additional error code and description. If the ticket resource doesn't exist return a response code of 404.

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• Is it bad practice to pass instances through several layers?

  - by Puckl

  In my program design, I often come to the point where I have to pass object instances through several classes. For example, if I have a controller that loads an audio file, and then passes it to a player, and the player passes it to the playerRunnable, which passes it again somewhere else etc. It looks kind of bad, but I don´t know how to avoid it. Or is it OK to do this? EDIT: Maybe the player example is not the best because I could load the file later, but in other cases that does not work.

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• Data-Driven SOA with Oracle Data Integrator

  - by Irem Radzik

  v\:* {behavior:url(#default#VML);} o\:* {behavior:url(#default#VML);} w\:* {behavior:url(#default#VML);} .shape {behavior:url(#default#VML);} Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Cambria","serif"; mso-fareast-font-family:"MS Mincho";} By Mike Eisterer, Data integration is more than simply moving data in bulk or in real-time, it is also about unifying information for improved business agility and integrating it in today’s service-oriented architectures. SOA enables organizations to easily define services which may then be discovered and leveraged by varying consumers. These consumers may be applications, customer facing portals, or complex business rules which are assembling services to automate process. Data as a foundational service provider is a key component of today’s successful SOA implementations. Oracle offers the broadest and most integrated portfolio of products to help you define, organize, orchestrate and consume data services. If you are attending Oracle OpenWorld next week, you will have ample opportunity to see the latest Oracle Data Integrator live in action and work with it yourself in two offered Hands-on Labs. Visit the hands-on lab to gain experience firsthand: Oracle Data Integrator and Oracle SOA Suite: Hands-on- Lab (HOL10480) Wed Oct 3rd 11:45AM Marriott Marquis- Salon 1/2 To learn more about Oracle Data Integrator, please visit our Introduction Hands-on LAB: Introduction to Oracle Data Integrator (HOL10481) Mon Oct 1st 3:15PM, Marriott Marquis- Salon 1/2 If you are not able to attend OpenWorld, please check out our latest resources for Data Integration.

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• Passing data between engine layers

  - by spaceOwl

  I am building a software system (game engine with networking support ) that is made up of (roughly) these layers: Game Layer Messaging Layer Networking Layer Game related data is passed to the messaging layer (this could be anything that is game specific), where they are to be converted to network specific messages (which are then serialized to byte arrays). I'm looking for a way to be able to convert "game" data into "network" data, such that no strong coupling between these layers will exist. As it looks now, the Messaging layer sits between both layers (game and network) and "knows" both of them (it contains Converter objects that know how to translate between data objects of both layers back and forth). I am not sure this is the best solution. Is there a good design for passing objects between layers? I'd like to learn more about the different options.

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• Earliest use of Comments as Semantically Meaningful Things in a Program?

  - by Alan Storm

  In certain corners of the PHP meta-programming world, it's become fashionable to use PHPDoc comments as a mechanism for providing semantically meaningful information to a program. That is, other code will parse the doc blocks and do something significant with the information encoded in those comments. Doctrine's annotations and code generation are an example of this. What's the earliest (or some early) use of this technique? I have vague memories of some early java Design by Contract implementations doing similar things, but I'm not sure of those folks were inventing the technique, or if they got it from somewhere. Mainly asking so I can provide some historical context for PHP developers who haven't come across the technique before, and are distrustful of it because it seems a little crazy pants.

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• What is the good way of sharing specific data between ViewModels

  - by voroninp

  We have IAppContext which is injected into ViewModel. This service contains shared data: global filters and other application wide properties. But there are cases when data is very specific. For example one VM implements Master and the second one - Details of selected tree item. Thus DetailsVm must know about the selected item and its changes. We can store this information either in IAppContext or inside each concerned VM. In both cases update notifications are sent via Messenger. I see pros and cons for any of the approaches and can not decide which one is better. 1st: + explicitly exposed shared proerties, easy to follow dependencies - IAppContxt becomes cluttered with very specific data. 2nd: the exact opposite of the first and more memory load due to data duplication. May be someone can offer design alternatives or tell that one of the variants is objectively superior to the other cause I miss something important?

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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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• 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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• Is there a design pattern to cut down on code duplication when subclassing Activities in Android?

  - by Daniel Lew

  I've got a common task that I do with some Activities - downloading data then displaying it. I've got the downloading part down pat; it is, of course, a little tricky due to the possibility of the user changing the orientation or cancelling the Activity before the download is complete, but the code is there. There is enough code handling these cases such that I don't want to have to copy/paste it to each Activity I have, so I thought to create an abstract subclass Activity itself such that it handles a single background download which then launches a method which fills the page with data. This all works. The issue is that, due to single inheritance, I am forced to recreate the exact same class for any other type of Activity - for example, I use Activity, ListActivity and MapActivity. To use the same technique for all three requires three duplicate classes, except each extends a different Activity. Is there a design pattern that can cut down on the code duplication? As it stands, I have saved much duplication already, but it pains me to see the exact same code in three classes just so that they each subclass a different type of Activity.

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• Website for prototyping OO class diagrams

  - by JavaRocky

  Do any web 2.0 like websites exist for prototyping object oriented class diagrams?

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