I am studying and developing a new project and a little studying about Windows Phone 7.1, I saw that they suggest / indicate the use of POCO classes, for database mapping (It seems to me that Windows Phone 7.1 uses some compact version of EF (Entity Framework), I did not study the Windows Phone case very much, because this is not the time to study this in depth, I just studied the basics to understand their concepts .
But what I would like to understand better is:
Why using POCO classes?
A POCO object has no dependency on an external framework .
Exemplo: In my business layer, I create POCO objects so that this layer does not have
dependence on technologies and external frameworks. Thus, I can change technologies and / or
frameworks without messing with my business layer (which is the "heart" of the software).
What is the advantage that this can bring?
Why is it used in a Project?
I believe that given the benefits mentioned in the other answers, it is interesting to use them.
And what is actually POCO classes? (Conceptually speaking)
"Plain Old CLR Object"
A class with no attributes that describe the infrastructure concerns, external frameworks, or other responsibilities that your domain objects should not have.
Examples:
[EdmEntityTypeAttribute(NamespaceName="SistemaOS.Model", Name="Pessoas")]
[Serializable()]
[DataContractAttribute(IsReference=true)]
public partial class Pessoas : EntityObject
{
[EdmScalarPropertyAttribute(EntityKeyProperty=true, IsNullable=false)]
[DataMemberAttribute()]
public global::System.Int32 id_pessoa
{
get
{
return _id_pessoa;
}
set
{
if (_id_pessoa != value)
{
Onid_pessoaChanging(value);
ReportPropertyChanging("id_pessoa");
_id_pessoa = StructuralObject.SetValidValue(value,"id_pessoa");
ReportPropertyChanged("id_pessoa");
Onid_pessoaChanged();
}
}
}
}
//Ao trocar meu framework de persistência eu não precisarei mexer nessa classe de negócio
public class Pessoa
{
public string Nome { get; set; }
public string Sobrenome { get; set; }
public int Cpf { get; set; }
public string NomeCompleto()
{
return Nome + " " + Sobrenome;
}
}
The term is used to identify an object as a simple object, over and above the complex and specialized objects that frameworks like ORMs generally use.
Enables a simple data storage mechanism, and simplifies serialization / passing of data between layers.
Very helpful with Dependency Injection and project pattern Repository
Decrease Complexity and Dependency between Other Layers (Layers that use refer to the POCO and the POCO does not reference anything) which helps to decrease the coupling
Improves "testability" through simplification
Reference: Wikipedia