Figure 5‑1 The .NET Framework in Context
Looking at Figure 5‑1 we see the lifespan of managed code from source code to execution. You write the source code. Your sources take advantage of features of the CLR as well as the reusable types in the FCL. You compile your sources with a compiler that supports the .NET Framework. The compiler turns your sources into an executable file consisting of IL and metadata.
When a user runs your executable the system loads the CLR into your process’ address space and the CLR JIT-compiles your IL (and metadata) into machine code and executes it. Meanwhile, your code references pre-jitted types in the FCL (as well as other reusable component libraries) and does its job, all the time being fully managed by the Common Language Runtime.
Note: This is the basic execution scenario of managed code. It is also possible for unmanaged software to host the CLR. In this case, the unmanaged application sits between the CLR and the operating system itself. Internet Explorer and Internet Information Services are two examples of existing Runtime Hosts; however any application can be designed to host the runtime.
In Figure 5‑1 the FCL and the CLR are really the pieces that make up the .NET Framework. Everything else is underlying OS, your code, and tools.
Once you are comfortable with the breadth of what the .NET Framework does, then you can begin to see how this technology is applied.
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