Một ebook miễn phí từ Oreilly xuất bản, Web Client Lập trình với Perl, một phiên bản trực tuyến. Cuốn sách này là cho các quản trị web những người duy trì một lượng lớn dữ liệu. Quản trị viên có thể thay thế nhiệm vụ bảo trì hướng dẫn sử dụng với các robot web để phát hiện và sửa các vấn đề với các trang web. Robot thực hiện nhiệm vụ chính xác hơn và nhanh chóng hơn so với bàn tay con người | Chapter 1 Introduction- Web Client Programming with Perl So what does Web client programming mean and what do you need to learn to do it A web client is an application that communicates with a web server using Hypertext Transfer Protocol HTTP . Hypertext Transfer Protocol is the protocol behind the World Wide Web. With every web transaction HTTP is invoked. HTTP is behind every request for a web document or graphic every click of a hypertext link and every submission of a form. The Web is about distributing information over the Internet and HTTP is the protocol used to do so. Most web users never think about HTTP just as most TV viewers don t think about how video images get from the studio to their home. But this book is not for the average web user. This book is for people who want to do something that available web software won t let them do. Why Write Your Own Clients With the proliferation of available web browsers you might wonder why you would want to write your own client program. The answer is that by writing your own client programs you can leap beyond the preprogrammed functionality of a browser. For example the following scenarios are all possible An urgent document is sent out via Federal Express and the sender wants to know the status of the document the moment it becomes available. He enters the FedEx airbill tracking number into a program that notifies him of events as the FedEx server reports them. Since the document is urgent he configures the program to contact him if the document is not delivered by the next morning. A system administrator would like to verify that all hyperlinks and image references are valid at her site. She runs a program to verify all documents at the site and report the results. She then finds some common mistakes in numerous documents and runs another program to automatically fix them. An investor keeps a stock portfolio online and runs a program to check stock prices. The online portfolio is updated automatically as .