CSLA 4 for Beginners: A Simple and Easy Way to Learn Business Objects

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If you are a .NET developer who wants to create powerful and scalable business applications, you might have heard of Csla 4. But what is Csla 4 and how can you use it effectively? In this article, we will answer these questions and more. We will explain what Csla 4 is, why you should use it, and what benefits it offers. We will also show you how to get started with Csla 4, how to use its features and tools, and where to find more resources. By the end of this article, you will have a clear understanding of Csla 4 and how it can help you develop better business applications.

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Introduction

Csla 4 is a framework for creating business applications using .NET technologies. It was created by Rockford Lhotka, a renowned software architect and author of several books on .NET development. Csla stands for Component-based Scalable Logical Architecture, and it is designed to help developers create business objects that encapsulate business logic, data access, validation, authorization, and serialization. Csla also provides support for n-tier architectures, where business objects can be distributed across multiple physical tiers or layers.

What is Csla 4?

Csla 4 is the latest version of the Csla framework, which was first released in 1998. It supports .NET Framework 4.x, .NET Core, .NET Standard, Xamarin, Blazor, and other .NET platforms. It also supports various data access technologies, such as Entity Framework, NHibernate, LINQ to SQL, ADO.NET, and more. Csla 4 is an open-source project that is available on GitHub and NuGet.

Why use Csla 4?

Csla 4 is a framework that helps developers create business applications that are maintainable, testable, reusable, and scalable. It does so by providing a set of features and tools that simplify the development process and enforce best practices. Some of the reasons to use Csla 4 are:

• It allows you to focus on the business logic rather than the plumbing code.

• It enables you to create consistent and coherent business objects that follow the same rules and behaviors.

• It reduces the complexity and duplication of code by providing common functionality for data access, validation, authorization, serialization, etc.

• It supports multiple data sources and platforms without requiring changes to the business objects.

• It facilitates the implementation of n-tier architectures that improve performance, scalability, security, and flexibility.

What are the benefits of Csla 4?

Csla 4 offers many benefits for developers who want to create high-quality business applications using .NET technologies. Some of these benefits are:

• It increases productivity and efficiency by reducing the amount of code you have to write and debug.

• It improves code quality and reliability by enforcing standards and conventions.

• It enhances code readability and maintainability by separating the business logic from the presentation and data layers.

• It boosts code reusability and extensibility by allowing you to inherit, override, and compose business objects.

• It supports agile development and testing by enabling you to create unit tests and mock objects easily.

How to use Csla 4

Now that you know what Csla 4 is and why you should use it, let's see how you can use it in your .NET projects. In this section, we will cover the following topics:

• Getting started with Csla 4

• Using Csla 4 features

• Using Csla 4 tools

Getting started with Csla 4

To start using Csla 4 in your .NET projects, you need to do three things:

• Installing Csla 4

• Creating a Csla 4 project

• Configuring Csla 4

Installing Csla 4

The easiest way to install Csla 4 is to use NuGet, the package manager for .NET. You can use NuGet to install Csla 4 for different platforms and data access technologies. For example, to install Csla 4 for .NET Framework 4.x and Entity Framework 6, you can use the following command in the Package Manager Console:

Install-Package Csla -Version 4.11.2 Install-Package Csla.Data.EF6 -Version 4.11.2

You can also use the NuGet Package Manager in Visual Studio to search and install Csla 4 packages. For more information on how to install Csla 4 using NuGet, please refer to the official documentation.

Creating a Csla 4 project

To create a Csla 4 project, you can use Visual Studio templates that are provided by Csla. These templates help you create projects that are preconfigured for using Csla 4 features and tools. You can find these templates in the New Project dialog under the Visual C# category. For example, to create a Csla 4 project for .NET Framework 4.x and Entity Framework 6, you can select the template called "Csla Windows Forms Application (.NET Framework) with Entity Framework". This will create a solution that contains three projects:

• A Windows Forms project that contains the user interface.

• A class library project that contains the business objects.

• A class library project that contains the data access layer.

You can also create your own projects without using the templates, but you will have to add references to the Csla assemblies and configure them manually.

Configuring Csla 4

To configure Csla 4, you need to set some properties and settings that control how Csla works. You can do this in different ways, such as using app.config files, code, or attributes. Some of the common properties and settings that you need to configure are:

• Csla.ApplicationContext.DataPortalProxy: This property specifies the type of proxy that is used to communicate between the client and the server in an n-tier architecture. The default value is Csla.DataPortalClient.LocalProxy, which means that there is no proxy and the data portal runs in the same process as the client. You can change this value to use different types of proxies, such as Csla.DataPortalClient.WcfProxy, Csla.DataPortalClient.HttpProxy, or Csla.DataPortalClient.WebApiProxy.

• Csla.ApplicationContext.DataPortalUrlString: This property specifies the URL of the data portal service that is used by the proxy in an n-tier architecture. The default value is empty, which means that there is no data portal service. You can set this value to point to a WCF service, an HTTP service, or a Web API service that hosts the data portal.

Using Csla 4 features

Csla 4 provides a rich set of features that help you create business objects that encapsulate business logic, data access, validation, authorization, and serialization. In this section, we will briefly introduce some of these features and how to use them.

Business objects

Business objects are the core of Csla 4. They represent the entities and concepts of your business domain, such as customers, orders, products, etc. They also contain the rules and behaviors that define how these entities and concepts interact with each other and with the data sources. Csla 4 provides several types of business objects that you can use depending on your needs. Some of these types are:

• Csla.BusinessBase<T>: This is the base class for editable business objects that support CRUD (create, read, update, delete) operations. It provides functionality such as tracking changes, managing identity, implementing data access methods, etc.

• Csla.ReadOnlyBase<T>: This is the base class for read-only business objects that only support read operations. It provides functionality such as caching data, implementing data access methods, etc.

• Csla.BusinessListBase<T,C>: This is the base class for editable collections of business objects that support CRUD operations. It provides functionality such as managing child objects, implementing data access methods, etc.

• Csla.ReadOnlyListBase<T,C>: This is the base class for read-only collections of business objects that only support read operations. It provides functionality such as caching data, implementing data access methods, etc.

• Csla.CommandBase<T>: This is the base class for command objects that perform actions or calculations without returning any data. It provides functionality such as executing commands on the server, serializing parameters and results, etc.

To create a business object using Csla 4, you need to inherit from one of these base classes and override some methods and properties. For example, to create a simple editable business object that represents a customer, you can write something like this:

[Serializable] public class Customer : BusinessBase<Customer> // Define properties public static readonly PropertyInfo<int> IdProperty = RegisterProperty<int>(c => c.Id); public int Id get return GetProperty(IdProperty); private set LoadProperty(IdProperty, value); public static readonly PropertyInfo<string> NameProperty = RegisterProperty<string>(c => c.Name); public string Name get return GetProperty(NameProperty); set SetProperty(NameProperty, value); public static readonly PropertyInfo<string> EmailProperty = RegisterProperty<string>(c => c.Email); public string Email get return GetProperty(EmailProperty); set SetProperty(EmailProperty, value); // Define factory methods public static Customer NewCustomer() return DataPortal.Create<Customer>(); public static Customer GetCustomer(int id) return DataPortal.Fetch<Customer>(id); // Define data access methods protected override void DataPortal_Create() // Initialize properties with default values Id = -1; Name = string.Empty; Email = string.Empty; BusinessRules.CheckRules(); protected override void DataPortal_Fetch(int id) // Fetch data from database using (var ctx = DbContextManager<MyDbContext>.GetManager()) var data = ctx.DbContext.Customers.Find(id); if (data != null) Id = data.Id; Name = data.Name; Email = data.Email; protected override void DataPortal_Insert() // Insert data into database using (var ctx = DbContextManager<MyDbContext>.GetManager()) var data = new CustomerEntity(); data.Name = Name; data.Email = Email; ctx.DbContext.Customers.Add(data); ctx.DbContext.SaveChanges(); Id = data.Id; protected override void DataPortal_Update() // Update data in database using (var ctx = DbContextManager<MyDbContext>.GetManager()) var data = ctx.DbContext.Customers.Find(Id); if (data != null) data.Name = Name; data.Email = Email; ctx.DbContext.SaveChanges(); protected override void DataPortal_DeleteSelf() // Delete data from database DataPortal_Delete(Id); protected void DataPortal_Delete(int id) // Delete data from database using (var ctx = DbContextManager<MyDbContext>.GetManager()) var data = ctx.DbContext.Customers.Find(id); if (data != null) ctx.DbContext.Customers.Remove(data); ctx.DbContext.SaveChanges();

As you can see, the business object defines three properties: Id, Name, and Email. It also defines five factory methods: NewCustomer, GetCustomer, Save, Delete, and Clone. These methods are used to create, fetch, save, delete, and copy instances of the business object. Finally, it defines six data access methods: DataPortal_Create, DataPortal_Fetch, DataPortal_Insert, DataPortal_Update, DataPortal_DeleteSelf, and DataPortal_Delete. These methods are used to perform CRUD operations on the database using Entity Framework.

To use this business object in your application, you can write something like this:

// Create a new customer var customer = Customer.NewCustomer(); customer.Name = "John Doe"; customer.Email = "john.doe@example.com"; customer.Save(); // Fetch an existing customer var customer = Customer.GetCustomer(1); Console.WriteLine(customer.Name); // Update an existing customer customer.Name = "Jane Doe"; customer.Save(); // Delete an existing customer customer.Delete();

As you can see, using Csla 4 business objects is very simple and intuitive. You don't have to worry about the details of data access, validation, authorization, serialization, etc. Csla 4 handles all of that for you behind the scenes.

Data access

Data access is the process of reading and writing data from and to various data sources, such as databases, web services, files, etc. Csla 4 provides a flexible and powerful way of performing data access using different technologies and patterns. Some of the features that Csla 4 offers for data access are:

• Csla.DataPortal: This is the core component of Csla 4 that handles the communication between the client and the server in an n-tier architecture. It also invokes the data access methods of the business objects and handles exceptions and transactions.

• Csla.Data: This is a namespace that contains various classes and methods that help you work with data sources and data objects. For example, it provides classes such as Csla.Data.SafeDataReader, Csla.Data.ObjectAdapter, Csla.Data.DynamicListBase, etc.

• Csla.Data.EF6: This is a namespace that contains classes and methods that help you work with Entity Framework 6 as a data access technology. For example, it provides classes such as Csla.Data.EF6.DbContextManager, Csla.Data.EF6.EFRepository, Csla.Data.EF6.EFUnitOfWork, etc.

• Csla.Data.Linq: This is a namespace that contains classes and methods that help you work with LINQ as a data access technology. For example, it provides classes such as Csla.Data.Linq.LinqRepository, Csla.Data.Linq.LinqUnitOfWork, etc.

• Csla.Server.Hosts: This is a namespace that contains classes and methods that help you host the data portal service on different platforms and technologies. For example, it provides classes such as Csla.Server.Hosts.WcfPortal, Csla.Server.Hosts.HttpPortal, Csla.Server.Hosts.WebApiPortal, etc.

To perform data access using Csla 4, you need to implement the data access methods of your business objects using your preferred technology and pattern. For example, to perform data access using Entity Framework 6 and the repository pattern, you can write something like this:

// Define a repository interface public interface ICustomerRepository CustomerEntity GetById(int id); void Insert(CustomerEntity entity); void Update(CustomerEntity entity); void Delete(int id); // Implement a repository class public class CustomerRepository : ICustomerRepository GetById(int id) // Get an entity by id from the database using (var ctx = DbContextManager<MyDbContext>.GetManager()) return ctx.DbContext.Customers.Find(id); public void Insert(CustomerEntity entity) // Insert an entity into the database using (var ctx = DbContextManager<MyDbContext>.GetManager()) ctx.DbContext.Customers.Add(entity); ctx.DbContext.SaveChanges(); public void Update(CustomerEntity entity) // Update an entity in the database using (var ctx = DbContextManager<MyDbContext>.GetManager()) var data = ctx.DbContext.Customers.Find(entity.Id); if (data != null) data.Name = entity.Name; data.Email = entity.Email; ctx.DbContext.SaveChanges(); public void Delete(int id) // Delete an entity from the database using (var ctx = DbContextManager<MyDbContext>.GetManager()) var data = ctx.DbContext.Customers.Find(id); if (data != null) ctx.DbContext.Customers.Remove(data); ctx.DbContext.SaveChanges(); // Use the repository in the data access methods of the business object protected override void DataPortal_Fetch(int id) // Fetch data from the repository var repository = new CustomerRepository(); var data = repository.GetById(id); if (data != null) Id = data.Id; Name = data.Name; Email = data.Email; protected override void DataPortal_Insert() // Insert data into the repository var repository = new CustomerRepository(); var data = new CustomerEntity(); data.Name = Name; data.Email = Email; repository.Insert(data); Id = data.Id; protected override void DataPortal_Update() // Update data in the repository var repository = new CustomerRepository(); var data = new CustomerEntity(); data.Id = Id; data.Name = Name; data.Email = Email; repository.Update(data); protected override void DataPortal_DeleteSelf() // Delete data from the repository DataPortal_Delete(Id); protected void DataPortal_Delete(int id) // Delete data from the repository var repository = new CustomerRepository(); repository.Delete(id);

As you can see, using Csla 4 data access features is very flexible and powerful. You can use any technology and pattern that suits your needs and preferences. You can also switch between different technologies and patterns without affecting your business objects.

Validation and authorization

Validation and authorization are two important aspects of creating business applications. Validation is the process of checking whether the data entered by the user or received from the data source is valid and conforms to the business rules. Authorization is the process of checking whether the user or role has permission to access or modify a business object or a property or method of a business object. Csla 4 provides a comprehensive and easy way of performing validation and authorization using different features and tools. Some of these features and tools are:

• Csla.Rules: This is a namespace that contains classes and methods that help you create and execute validation and authorization rules for your business objects. For example, it provides classes such as Csla.Rules.BusinessRule, Csla.Rules.AuthorizationRule, Csla.Rules.CommonRules, etc.

• Csla.Rules.RuleManager: This is a class that manages the validation and authorization rules for a business object. It allows you to add, remove, get, and execute rules for a business object or a property or method of a business object.

• Csla.Rules.IBusinessObject: This is an interface that defines the methods and properties that a business object must implement to support validation and authorization rules. For example, it defines methods such as CheckRules, AddBusinessRules, AddAuthorizationRules, etc.

• Csla.Security.CslaIdentity: This is a class that represents the identity of a user who interacts with a business application. It inherits from System.Security.Principal.IIdentity and provides additional properties and methods that are useful for authorization.

Csla.Security.CslaPrincipal: This is a class that represents the pri