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• Why put a DAO layer over a persistence layer (like JDO or Hibernate)

  - by Todd Owen

  Data Access Objects (DAOs) are a common design pattern, and recommended by Sun. But the earliest examples of Java DAOs interacted directly with relational databases -- they were, in essence, doing object-relational mapping (ORM). Nowadays, I see DAOs on top of mature ORM frameworks like JDO and Hibernate, and I wonder if that is really a good idea. I am developing a web service using JDO as the persistence layer, and am considering whether or not to introduce DAOs. I foresee a problem when dealing with a particular class which contains a map of other objects: public class Book { // Book description in various languages, indexed by ISO language codes private Map<String,BookDescription> descriptions; } JDO is clever enough to map this to a foreign key constraint between the "BOOKS" and "BOOKDESCRIPTIONS" tables. It transparently loads the BookDescription objects (using lazy loading, I believe), and persists them when the Book object is persisted. If I was to introduce a "data access layer" and write a class like BookDao, and encapsulate all the JDO code within this, then wouldn't this JDO's transparent loading of the child objects be circumventing the data access layer? For consistency, shouldn't all the BookDescription objects be loaded and persisted via some BookDescriptionDao object (or BookDao.loadDescription method)? Yet refactoring in that way would make manipulating the model needlessly complicated. So my question is, what's wrong with calling JDO (or Hibernate, or whatever ORM you fancy) directly in the business layer? Its syntax is already quite concise, and it is datastore-agnostic. What is the advantage, if any, of encapsulating it in Data Access Objects?

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• Generate SQL Server Express database from Entity Framework 4 model

  - by Cranialsurge

  I am able to auto-generate a SQL Server CE 4.0 *.sdf file using code-first generation as explained by Scott Guthrie here. The connection string for the same is as follows: <add name="NerdDinners" providerName="System.Data.SqlServerCe.4.0" connectionString="data source=|DataDirectory|NerdDinner.sdf"/> However if I try to generate an mdf instead using the following connection string, it fails to do so with the following error - "The provider did not return a ProviderManifestToken string.". <add name="NerdDinners" providerName="System.Data.SqlClient" connectionString="data source=|DataDirectory|NerdDinner.mdf"/> Even directly hooking into a SQLEXPRESS instance using the following connection string fails <add name="NerdDinners" providerName="System.Data.SqlClient" connectionString="Data Source=.\SQLEXPRESS;Initial Catalog=NerdDinner;Integrated Security=True"/> Does EF 4 only support SQL CE 4.0 for database creation from a model for now or am I doing something wrong here?

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• WPF/MVVM - should we create a different Class for each ViewModel ?

  - by FMFF

  I'm attempting the example from the excellent "How Do I" video for MVVM by Todd Miranda found in MSDN. I'm trying to adapt the example for my learning purpose. In the example, he has a ViewModel called EmployeeListViewModel. Now if I want to include Departments, should I create another ViewModel such as DepartmentListViewModel? The example has EmployeeRepository as the Data Source. In my case, I'm trying to use an Entity object as the datasource (Employees.edmx in Model folder and EmployeeRepository.cs in DataAccess folder). If I want to display the list of Departments, should I create a separate class called DepartmentRepository and put all department related method definitions there? What if I want to retrieve the employee name and their department's name together? Where should I place the methods for this? I'm very new to WPF and MVVM and please let me know if any of the above needs to be re-phrased. Thank you for all the help.

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• To Wrap or Not to Wrap: Wrapping Data Access in a Service Facade

  - by PureCognition

  For a while now, my team and I have been wrapping our data access layer in a web service facade (using WCF) and calling it from the business logic layer. Meanwhile, we could simply use the repository pattern where the business logic layer consumes the data access layer locally through an interface, and at any point in time, we can switch things out for it to hit a service instead (if necessary). The question is: When is it a good time to wrap the data access layer in a service facade and when isn't it? Right now, it seems like the main advantage is that other applications can consume the service, but if they are internal applications written in .NET then they can just consume the .NET assembly instead. Are there other advantages of having the DAL be wrapped in a service that I am unaware of?

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• How can i return abstract class from any factory?

  - by programmerist

  using System; using System.Collections.Generic; using System.Linq; using System.Web; namespace EfTestFactory { public abstract class _Company { public abstract List<Personel> GetPersonel(); public abstract List<Prim> GetPrim(); public abstract List<Finans> GetFinans(); } public abstract class _Radyoloji { public abstract List<string> GetRadyoloji(); } public abstract class _Satis { public abstract List<string> GetSatis(); } public abstract class _Muayene { public abstract List<string> GetMuayene(); } public class Company : _Company { public override List<Personel> GetPersonel() { throw new NotImplementedException(); } public override List<Prim> GetPrim() { throw new NotImplementedException(); } public override List<Finans> GetFinans() { throw new NotImplementedException(); } } public class Radyoloji : _Radyoloji { public override List<string> GetRadyoloji() { throw new NotImplementedException(); } } public class Satis : _Satis { public override List<string> GetSatis() { throw new NotImplementedException(); } } public class Muayene : _Muayene { public override List<string> GetMuayene() { throw new NotImplementedException(); } } public class GenoTipController { public object CreateByEnum(DataModelType modeltype) { string enumText = modeltype.ToString(); // will return for example "Company" Type classType = Type.GetType(enumText); // the Type for Company class object t = Activator.CreateInstance(classType); // create an instance of Company class return t; } } public class AntsController { static Dictionary<DataModelType, Func<object>> s_creators = new Dictionary<DataModelType, Func<object>>() { { DataModelType.Radyoloji, () => new _Radyoloji() }, { DataModelType.Company, () => new _Company() }, { DataModelType.Muayene, () => new _Muayene() }, { DataModelType.Satis, () => new _Satis() }, }; public object CreateByEnum(DataModelType modeltype) { return s_creators[modeltype](); } } public class CompanyView { public static List<Personel> GetPersonel() { GenoTipController controller = new GenoTipController(); _Company company = controller.CreateByEnum(DataModelType.Company) as _Company; return company.GetPersonel(); } } public enum DataModelType { Radyoloji, Satis, Muayene, Company } } if i write above codes i see some error: Cannot create an instance of abstract class or interface 'EfTestFactory_Company'How can i solve it? Look please below pic.

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• SOA design principles with regards to database relationships

  - by Eitan

  If I were to extricate my current membership provider from my solution, i.e. as a dll and expose it as a web service with it's own db, how would I model the relationships with regards to SOA design. For example I have a table: USER id, name, lastname, username, password, role. and table PRODUCT id, name, price, createdate, userid the foreign key being userid to table user. How would I model the relationship and/or query the db. If I wanted to get all products that were uploaded today for example, before I would query: SELECT u.name, u.lastname, u.username, p.* FROM PRODUCT p INNER JOIN USER u ON p.userid = u.id WHERE createdate = '05/05/2010' Now that I don't have the table within the database how would I perform this query? Thanks.

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• Ideal way to deliver large data over Web Services

  - by zengr

  We are trying to design 6 web services, which will serve another client component. The client component requires data from the web service we are implementing. Now, the problem is, there is not 1 WS we are implementing, there is one WS which the client component hits, this initiates a series (5 more) of WSs which gather data from their respective data stores and finally provide the data back to the original WS, which then delivers the data back to the client component. So, if the requested data becomes huge, then, this will be a serious problem for our internal communication channel. So, what do you guys suggest? What can be done to avoid overloading of the communication channel between the internal WS and at the same time, also delivering the data to the client component.

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• Proper way to format date from database using javascript/jquery

  - by Darcy

  Hi all, I am calling my database which contains a datetime datatype. The date looks like this: 2005-05-23 16:06:00.000 I would like to display this in a table when a user selects a certain item from a list. I call my controller action and return Json of all the times and put them in a table. The problem is the date is completely wrong. What is displayed is this: /Date(1255470180000)/ The date that is returned isn't even parsable (which I don't want to do anyway) so I can't even get the data if I wanted to. Any ideas?

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• FluentValidation + s#arp

  - by csetzkorn

  Hi, Did someone implement something like this: http://www.jeremyskinner.co.uk/2010/02/22/using-fluentvalidation-with-an-ioc-container/ in s#arp? Thanks. Christian PS: Hi, I have made a start in using FluentValidation in S#arp. I have implemented a Validator factory: public class ResolveType { private static IWindsorContainer _windsorContainer; public static void Initialize(IWindsorContainer windsorContainer) { _windsorContainer = windsorContainer; } public static object Of(Type type) { return _windsorContainer.Resolve(type); } } public class CastleWindsorValidatorFactory : ValidatorFactoryBase { public override IValidator CreateInstance(Type validatorType) { return ResolveType.Of(validatorType) as IValidator; } } I think I will use services which can be used by the controllers etc.: public class UserValidator : AbstractValidator { private readonly IUserRepository UserRepository; public UserValidator(IUserRepository UserRepository) { Check.Require(UserRepository != null, "UserRepository may not be null"); this.UserRepository = UserRepository; RuleFor(user => user.Email).NotEmpty(); RuleFor(user => user.FirstName).NotEmpty(); RuleFor(user => user.LastName).NotEmpty(); } } public interface IUserService { User CreateUser(User User); } public class UserService : IUserService { private readonly IUserRepository UserRepository; private readonly UserValidator UserValidator; public UserService ( IUserRepository UserRepository ) { Check.Require(UserRepository != null, "UserRepository may not be null"); this.UserRepository = UserRepository; this.UserValidator = new UserValidator(UserRepository); } public User CreateUser(User User) { UserValidator.Validate(User); ... } } Instead of putting concrete validators in the service, I would like to use the above factory somehow. Where do I register it and how in s#arp (Global.asax)? I believe s#arp is geared towards the nhibernator validator. How do I deregister it? Thanks. Best wishes, Christian

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• Book for Anti Design Patterns

  - by Pranali Desai

  I have heard a lot about anti patterns and would like to read a book on this,which book would you suggest for Anti patterns.

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• help finding a hosing company with unixODBC and FreeTDS support

  - by patrick

  I need to find a hosting company that provides a LAMP stack, the P being PHP. Finding that is pretty easy, but I have a further requirement of unixODBC and FreeTDS or some equilant. The project will require a remote connection to a Microsoft SQL 2005 database. Most of the project will use a local MySQL database but it also requires data from a remote MS SQL 2005 database. In my reading it looks like I'll need unixODBC and FreeTDS installed on the server to make that connection. So far I've been unable to find a shared host that provides these. Can anyone suggest or use a host that might work? The project has budget limits so we we're hoping to find a shared host.

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• Voting software with remote units - architectural questions

  - by David Neale

  I'm looking at designing some software that registers live votes (let's say A,B,C or D). The vote needs to be picked up and processed by a .NET engine. The remote voting units should be as small as possible. What form of data transmission should be used for the voting? The data is obviously very simple but there is a need to make sure each unit can only vote once per question. How would the data be received by the computer running the software?

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• If you are forced to use an Anemic domain model, where do you put your business logic and calculated

  - by Jess

  Our current O/RM tool does not really allow for rich domain models, so we are forced to utilize anemic (DTO) entities everywhere. This has worked fine, but I continue to struggle with where to put basic object-based business logic and calculated fields. Current layers: Presentation Service Repository Data/Entity Our repository layer has most of the basic fetch/validate/save logic, although the service layer does a lot of the more complex validation & saving (since save operations also do logging, checking of permissions, etc). The problem is where to put code like this: Decimal CalculateTotal(LineItemEntity li) { return li.Quantity * li.Price; } or Decimal CalculateOrderTotal(OrderEntity order) { Decimal orderTotal = 0; foreach (LineItemEntity li in order.LineItems) { orderTotal += CalculateTotal(li); } return orderTotal; } Any thoughts?

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• Run EJB3Unit against Oracle Database

  - by justastefan

  I want to run EJB3Unit-Test in my oracle 10g Database. Therefore I use this configuration (ejb3unit.properties). ### The ejb3unit configuration file ### ejb3unit.inMemoryTest=false ejb3unit.connection.url=jdbc:oracle:thin:....:1432:SID ejb3unit.connection.driver_class=oracle.jdbc.OracleDriver ejb3unit.connection.username=user ejb3unit.connection.password=name ejb3unit.dialect=org.hibernate.dialect.Oracle10gDialect ejb3unit.show_sql=true ## values are create-drop, create, update ## ejb3unit.schema.update=create I will result in the following error: Caused by: HibernateException: cannot instantiate dialect class ... org.hibernate.dialect.Oracle10gDialect cannot be cast to org.ejb3unit.hibernate.dialect.Dialect How can ejb3unit-testing be done using oracle db?

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• Application Server or Lightweight Container?

  - by Jeff Storey

  Let me preface this by saying this is not an actual situation of mine but I'm asking this question more for my own knowledge and to get other people's inputs here. I've used both Spring and EJB3/JBoss, and for the smaller types of applications I've built, Spring (+Tomcat when needed) has been much simpler to use. However, when scaling up to larger applications that require things like load balancing and clustering, is Spring still a viable solution? Or is it time to turn to a solution like EJB3/JBoss when you start to get big enough to need that? I'm not sure if I've scoped the problem well enough to get a good answer, so please let me know. Thanks, Jeff

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• Subversion (20014)Internal error: database is locked on NFS

  - by Niraj Gurjar

  i have subversion setup using apache and DAV. OS is RHEL 4. Repository is created on NFS server mounted on this machine. when i try to access this repository i get following error in apache logs (20014)Internal error: database is locked Could not fetch resource information. [500, #0] Could not open the requested SVN filesystem [500, #200030] Could not open the requested SVN filesystem [500, #200030] The URI does not contain the name of a repository. [403, #190001] i did 'chmod' on that mounted partition but problem still persists. any help?

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• Strategies for Error Handling in .NET Web Services

  - by Jarrod

  I have a fairly substantial library of web services built in .NET that I use as a data model for our company web sites. In most .NET applications I use the Global ASAX file for profiling, logging, and creating bug reports for all exceptions thrown by the application. Global ASAX isn't available for web services so I'm curious as to what other strategies people have come up with to work around this limitation. Currently I just do something along these lines: <WebMethod()> _ Public Function MyServiceMethod(ByVal code As Integer) As String Try Return processCode(code) Catch ex As Exception CustomExHandler(ex) 'call a custom function every time to log exceptions Return errorObject End Try End Function Anybody have a better way of doing things besides calling a function inside the Catch?

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• Adding data in multiple tables in vb.net

  - by user225269

  This is a winform and I'm using mysql as a database, here is my code: I'm trying to add data into multiple tables. If TextBox14.Text = "" Or TextBox7.Text = "" Or TextBox10.Text = "" Then MsgBox("Please fill up the fields with a labels in bold letters!", MsgBoxStyle.Information) cn = New MySqlConnection("Server=localhost; Database=school;Uid=root;Pwd=nitoryolai123$%^;") 'provider to be used when working with access database cn.Open() cmd = New MySqlCommand("select * from parents, mother, father", cn) cmd.CommandText = "insert into parents values('" + idnum + "','" + p_contact + "','" + p_ad + "')" cmd.CommandText = "insert into mother values('" + idnum + "','" + mother + "','" + mother_occu + "')" cmd.CommandText = "insert into father values('" + idnum + "','" + father + "',''" + father_occu + "')" cmd.ExecuteNonQuery() I get this error, please help: Index and length must refer to a location within the string. Parameter name: length

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• Entity Framework does not display the last change from the database

  - by Jack

  Entity Framework does not display the last change from the database, but after sometime it show the updated content. I don't any special change on the server or on the page. Thank in advance. Jack Here is the code i use to get the list: var m = from r in ett.Article_Relations from i in ett.Article_Articles from a in ett.Article_Contents where r.MenuItemID == id && r.Article_Articles.ArticleID == i.ArticleID && a.LanguageID == LanguageID && i.ArticleID == a.Article_Articles.ArticleID select new ArticleViewModel { ArticleID = i.ArticleID, IsActive = i.IsActive, Author = i.ArticleAuthor, Content = a, DateCreated = i.DateCreated };

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• How to implement ASP.NET membership provider in my domain model

  - by Kjensen

  In a website, I need to integrate membership and authentication. So I want to use the functionality of ASP.NET Membership, but I have other custom stuff, that a "user" has to do. So I am sitting here with my pencil and paper, drawing lines for my domain model... And how can I best utilize the ASP.Net membership, but extend it to fill my needs? Should I create a class that inherits from a MembershipUser and extend it with my own properties and methods (and save this in a seperate table). Or should I let the MembershipUser be a property on my custom User/Client object? What would be a good solid way to do this?

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• Should frontend and backend handled by different controllers?

  - by DR

  In my previous learning projects I always used a single controller, but know I wonder if that is good practice or even always possible. In all RESTful Rails tutorials the controllers have a show, an edit and an index view. If an authorized user is logged on, the edit view becomes available and the index view shows additional data manipulation controls, like a delete button or a link to the edit view. Now I have a Rails application which falls exactly into this pattern, but the index view is not reusable: The normal user sees a flashy index page with lots of pictures, complex layout, no Javascript requirement, ... The Admin user index has a completly different minimalistic design, jQuery table and lots of additional data, ... Now I'm not sure how to handle this case. I can think of the following: Single controller, single view: The view is split into two large blocks/partials using an if statement. Single controller, two views: index and index_admin. Two different controllers: BookController and BookAdminController None of this solutions seems perfect, but for now I'm inclined to use the 3rd option. What's the preferred way to do this?

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• Why don't stacks grow upwards (for security)?

  - by AshleysBrain

  This is related to the question 'Why do stacks typically grow downwards?', but more from a security point of view. I'm generally referring to x86. It strikes me as odd that the stack would grow downwards, when buffers are usually written to upwards in memory. For example a typical C++ string has its end at a higher memory address than the beginning. This means that if there's a buffer overflow you're overwriting further up the call stack, which I understand is a security risk, since it opens the possibility of changing return addresses and local variable contents. If the stack grew upwards in memory, wouldn't buffer overflows simply run in to dead memory? Would this improve security? If so, why hasn't it been done? What about x64, do those stacks grow upwards and if not why not?

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• get Generic CRUD operation in EF

  - by kathy

  Hello, Is there any way or design pattern can I use to get Generic CRUD operations? Because I’m working on n-tire application using EF in the data layer and I don’t want to use CRUD Functions in Every Entities. Your help would be appreciated

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• UML interface: URL iframe integration

  - by Bernd

  I have two applications, A and B, both with a web-based user interface. Both applications are integrated via an URL iframe mechanism. A user can click on a link in application A and then gets the UI of application B as am iframe in application A. Now, since both applications have an interface between each other (do they?): Who provides the interface and who requires the interface, in the UML sense? What is the main information flow on this interface?

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• getting a date array from a mysql database?

  - by user296516

  Hi guys, I have a database with date field is this format "2010.06.11. | 10:26 13" What is need is a php array that would hold all the different dates, .i.e. array[0] = "2010.06.09." array[1] = "2010.06.10." array[2] = "2010.06.11." Currently I am doing it by selecting the whole table, then looping through the result and adding the date substr to an array if it is not already there. But maybe there is a faster way? Thanks.

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