The records added to injectors are called service providers, or simply providers. They specify two sets of information:
- Which requests are resolved by the service?
- How to create an instance of the service?
More specifically, providers have one of the following formats:
{provide: <token>, useClass: <class name>}{provide: <token>, useFactory: <function>, deps: [<dependency>,..]}{provide: <token>, useValue: <object or simple type instance>}
The token property specifies the kind of requests the provider is able to satisfy. Often, it is a class name, in which case the service is selected when this class name is identical to the type of the constructor parameter where the service must be injected:
{provide: ProductServerCommunicatior ...
