Module 11: Networked Applications
Study Guide( A lot from Chapter 11)

Summary: We wrap up the textbook by returning to a deeper investigation of networked applications, a topic we introduced during the first week. There’s an old presidential campaign slogan coined years ago to encourage candidates to focus on what’s important to voters: “It’s the economy, stupid.” The equivalent for network and IT professionals is: “It’s the applications, stupid.” In the early days, computer applications were cryptic and the infrastructure needed to run them was incredibly expensive. Things have changed, thanks to the emergence of web technologies and smartphone/tablet apps that provide highly functional application interfaces and the “cloud,” which is transforming how applications are delivered to users. Cloud Computing is one of the most important trends in IT. The cloud used to refer to the network itself, and we still use that metaphor when we talk about networks. But today, the cloud is more about applications and services. These cloud services may be simple from the user’s perspective, but inside the cloud, there’s a lot of complexity for us to explore. We’ll address a number of different applications and application architectures, as well as the application protocols that are used to deliver e-mail, VoIP, file sharing, and advanced web services. It is likely that many of you will have a job in coming years where you are using, deploying, or supporting cloud-based services. Your understanding of what is happening inside the cloud will enable you to be much more informed about those applications.

Expected Learning Outcomes
After completing this module, you should be able to define key terms: request/response cycle; SMTP; RFC 822/2822; POP; IMAP; MIME; SIP; CODEC; Java applet; Skype

explain how cloud-based services might enable a business like a pizza shop to expand and become more profitable. explain how changes in computing technology and networking has spurred the development of alternative networked application architectures, including terminal to host, client/server, and peer to peer. explain why networked applications are emerging as an increasingly desirable target for hackers who have historically targeted their hacking efforts towards operating system flaws. explain the architecture of Internet e-mail systems and the key e-mail standards that enable interoperability of e-mail across multiple systems and applications. explain how voice over IP provides telephony services and how it integrates with the PSTN. explain why VoIP uses UDP rather than TCP as a transport protocol and explain how RTP is used to overcome limitations of UDP. describe the application architecture of the World Wide Web and explain how the HTML and HTTP standards fit into this architecture. explain the concept and potential benefits and issues associated with cloud computing and differentiate between variations of cloud computing: software as a service and cloud utility computing. explain the role that virtualization technology plays in the delivery of cloud services. explain how a service-oriented architecture enables business partners to more effectively integrate their information systems. explain the benefits and limitations of peer-to-peer application architecture and explain how they are used for file sharing on the Internet, including BitTorrent. summarize the major elements of the Skype VoIP system.

Review Questions

1. What is meant by the concept of a networked application architecture? Why are there so many different varieties of networked application architectures? What is a hybrid networked application architecture?

2. Explain the costs and benefits of terminal-host application environments that utilize dumb terminals. Do organizations still use these systems? If so, why?

3. How does a client-server architecture differ from a terminal-host architecture? Describe the difference