In fact Rails itself was originally extracted from a standalone app written by

In fact rails itself was originally extracted from a

This preview shows page 98 - 100 out of 517 pages.

In fact, Rails itself was originally extracted from a standalone app written by the consulting group 37signals. Lastly, it is worth remembering that a key factor in the Web’s success has been the adoption of well- defined protocols and formats whose design allows separating the things that change from those that stay the same. TCP/IP, HTTP, and HTML have all gone through several major revisions, but all include ways to detect which version is in use, so a client can tell if it’s talking to an older server (or vice versa) and adjust its behavior accordingly. Although dealing with multiple protocol and language versions puts an additional burden on browsers, it has led to a remarkable result: A Web page created in 2011, using a markup language based on 1960s technology, can be retrieved using network protocols developed in 1969 and displayed by a browser created in 1992. Separating the things that change from those that stay the same is part of the path to creating long-lived software. Tim Berners-Lee, a computer scientist at CERN , led the development of HTTP and HTML in 1990. Both are now stewarded by the nonprofit vendor-neutral World Wide Web Consortium (W3C) . 2.11 To Learn More W3Schools is a free (advertising-supported) site with tutorials on almost all Web-related technologies. Nicole Sullivan , a self-described “CSS ninja,” has a great blog with indispensable CSS/HTML advice for more sophisticated sites. The World Wide Web Consortium (W3C) stewards the official documents describing the Web’s open standards, including HTTP, HTML, and CSS. The XML/XHTML Validator is one of many you can use to ensure the pages delivered by your SaaS app are standards-compliant. The Object-Oriented Design web site has numerous useful resources for developers using OO languages, including a nice catalog of the GoF design patterns with graphical descriptions of each pattern, some of which we will discuss in detail in Chapter 11 . M. Fowler. Patterns of Enterprise Application Architecture . Addison-Wesley Professional, 2002. ISBN 0321127420. URL eaaCatalog/ . E. Gamma, R. Helm, R. Johnson, and J. M. Vlissides. Design Patterns: Elements of Reusable Object-
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Oriented Software . Addison-Wesley Professional, 1994. ISBN 0201633612. 2.12 Suggested Projects Project 2.1. If the DNS service stopped working, would you still be able to surf the Web? Explain why or why not. Project 2.2. Suppose HTTP cookies didn’t exist. Could you devise another way to track a user across page views? (HINT: it involves modifying the URI and was a widely-used method before cookies were invented.) Project 2.3. Find a Web page for which the W3C’s online XHTML validator finds at least one error. Sadly, this should be easy. Read through the validation error messages and try to understand what each one means. Project 2.4. What port numbers are implied by each of the following URIs and why: 1.
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