将ObjectCache与PerCall服务一起使用

Question

I currently have a WCF RESTful service with InstanceContextMode = InstanceContextMode .PerCall . I did this because the service methods interact with an Entity Framework model and I read that I should use PerCall rather than Single . Now, I wanted to add a new service method that returns a large dataset. My original thought was to spin a thread off on the service startup, and cache the dataset so when the service method is called, I wouldn't have to hit to database... I'd just return the cache. The problem with that though is that I cannot do this because I'm using PerCall , so after the instance is destroyed, so is my cache.

My question is, what caching options do I have? Do I really need PerCall or can I make it a singleton, but just make sure that the EF context is new for every call?

Answer 1

You are right about EF context and lifetime; it should be as short-lived as possible. In a web(-service) scenario it usually means 'per request/call' (at the longest).

Off course, you could handle the lifetimes yourself, but this is a scenario in which an IoC container with DI really shines. You just register your services and the EF context as 'per request' and the cache as a singleton, and the container will do the heavy lifting and injecting the correct dependencies for you. You can also do more fine grained lifetime scoping if that's desirable.

Some of the most common:

• Ninject
• autofac
• Unity
• Castle Windsor

There are lots of good tutorials and guides for setting up the most popular IoC containers with WCF, like " How to Use Dependency Injection (Ninject) with WCF Services ".