Difference between repository and service?

133
votes

What's the difference between a repository and a service? I don't seem to grasp it.

I'm talking about data access through a data access layer, typically with linq to sql.

Very often i see repositories with simple CRUD methods, and services with more business-specific methods.

We can take this blog post as an example. If you look at the interfaces at the bottom (images), he has two repositories and two services. How does one know what to put where?

As I said, repositories seems to be more for CRUD-like operations and Services more business oriented.

Thanks

4
design-patterns
Can you calarify? In what context? Like most words, the context these words are being used in helps to define the meaning. – David
Note: I'n not talking about web services or something here. I'm talking about data access through a data layer. – alexn

4 Answers

106
votes

A Repository is essentially a facade for persistence that uses Collection style semantics (Add, Update, Remove) to supply access to data/objects. It is a way of decoupling the way you store data/objects from the rest of the application.

A service supplies coordination or other "services" that are required to operate your application. They are very different in that Services don't typically know how to access data from persistence, and repositories typically only access data/objects for any services you may have.

194
votes

The repository is where the data is stored. The service is what manipulates the data.

In a real-world situation comparison, if your money is stored in a vault in a bank, the vault is the repository. The teller that deposits, withdraws, etc is the service.

16
votes

I would say as a first try, in the general sense (until you give more context if you have one):

  • a repository is where you place some global objects, to be used later.
  • a service is a business logic code, made explicit (and ideally separated from the Presentation layer, and database layer ?)
2
votes

Take for instance in a MVC application.The Controller gives instruction to the Service and the service talks to the Repository to do some CRUD to the data in database.

This is done using DI(Dependency Injection:this is like a child telling the father to give him money but is not bothered about how the money is gotten,so the methods of getting the money was abstracted from the child's knowledge)

Repository prepares the dishes in the kitchen

Service calls the one or multiple chef(methods in a repository) to get a specific tailored meal