IDL(接口描述语言)

IDL通过一种中立的方式来描述接口，使得在不同平台上运行的对象和用不同语言编写的程序可以相互通信交流；比如，一个组件用C++写成，另一个组件用Java写成。

IDL建立起了两个不同操作系统间通信的桥梁。

Android Interface Definition Language（AIDL）

It allows you to define the programming interface that both the client and service agree upon in order to communicate with each other using interprocess communication (IPC). On Android, one process cannot normally access the memory of another process. So to talk, they need to decompose their objects into primitives that the operating system can understand, and marshall the objects across that boundary for you

它允许你定义一个客户端和服务端同意为了相互联系，运用IPC的程序接口。在android上，一个进程通常不能进入另一个进程的存储器中，为了交互，需要将他们的对象分解成操作系统可以理解的原语，然后为你跨越边界的对象