A good book to learn the HTTP protocol

I've always thought that to write Web programs, you have to understand the HTTP protocol, and from my own experience, after you know the HTTP protocol, the APIs that involve Web programming in J2ee,.net are clear, why, because network protocols are the cornerstone of all web-based systems, As long as there are features in the network protocol that will be reflected in the API, here are 3 good books for learning the HTTP protocol:

1.O ' Reilly-http Pocket Reference: This is a relatively short book that introduces the HTTP protocol and can be used as an introductory reading

2.O ' Reilly-http The definitive Guide: This is a book of books, because it contains a lot of content, can be used as a comprehensive learning of the HTTP Protocol's preferred reading

3.sams-http Developers Handbook: This is slightly simpler than the HTTP the definitive guide definitive than the HTTP the guide. But from my point of view, this book is better than http the definitive guide, because it is less than the HTTP essence, I think this book is the Web Programmer's preferred reading