Abstract
Over the past decades, the expansion of the converged Web-based facilities/infrastructures, together with new business perspectives, have created new needs for all (potential) categories of end-users. Although various effects were significant in most sectors (European Commission, 2005) the fast progress has, however, promoted more complex issues, especially for the delivery of multimedia-based applications. It is now a common view that there is a growing need for delivering high-quality services in the scope of liberalized and competitive markets, where multiple factors of different origin (i.e., technological, business, economic, regulatory, social, etc.) can drastically affect further deployment, establishment or upgrading of existing infrastructures and of any possible (innovative) services offered through them, especially if considering the continuous expansion of the broadband perspective (Chochliouros, & Spiliopoulou, 2005). Furthermore, multimedia applications are bandwidth consuming and new applications for absorbing the available assets appear. As the “converged” sector of information technologies, communication, and media industries is currently on the “edge” of a crucial phase of growth, several challenges appear in the global scene: Appropriate infrastructures for delivering mails, exchanging data files (of various forms of content) and simple Web browsing are now required to be adopted and used, to support the streaming of multimedia content and, simultaneously, to “compose” a reliable means of transmitting information between several entities (physical and legal persons) using digital facilities. Although technological advances have enhanced the deployment of faster (lesser latency) and greater (more bandwidth) “network lines” possessing significant advantages, the demands of the extravagant use of Internet from users worldwide (Dilley, Maggs, Parikh, Prokop, Sitaraman, & Weihl, 2002; Shoniregun, Chochliouros, Laperche, Logvynovskiy, & Spiliopoulou-Chochliourou, 2004), together with an extensive variance of services offered, were primary motives for researchers to develop a specific category of modern infrastructures, known as content distribution (or delivery) networks (CDNs) (Hull, 2002; Verma, 2002). The development of suitable content delivery networking comprises one of the most important challenges in the global networking area, together with the expansion of various IP trends. Content networks influence high-layer network intelligence to efficiently manage the delivery of various forms of data (which is becoming progressively more multimedia in nature). At an initial stage, they were built upon the structure of the public Internet (Saroiu, Gummadi, Dunn, Gribble, & Levy, 2002), to accelerate Web site performance (Johnson, Carr, Day, & Frans Kaashoek, 2000). This option has been fulfilled in numerous cases, and such intelligent network tools can be applied in other beneficial and profitable ways.
TopIntroduction
Over the past decades, the expansion of the converged Web-based facilities/infrastructures, together with new business perspectives, have created new needs for all (potential) categories of end-users. Although various effects were significant in most sectors (European Commission, 2005) the fast progress has, however, promoted more complex issues, especially for the delivery of multimedia-based applications.
It is now a common view that there is a growing need for delivering high-quality services in the scope of liberalized and competitive markets, where multiple factors of different origin (i.e., technological, business, economic, regulatory, social, etc.) can drastically affect further deployment, establishment or upgrading of existing infrastructures and of any possible (innovative) services offered through them, especially if considering the continuous expansion of the broadband perspective (Chochliouros, & Spiliopoulou, 2005). Furthermore, multimedia applications are bandwidth consuming and new applications for absorbing the available assets appear. As the “converged” sector of information technologies, communication, and media industries is currently on the “edge” of a crucial phase of growth, several challenges appear in the global scene: Appropriate infrastructures for delivering mails, exchanging data files (of various forms of content) and simple Web browsing are now required to be adopted and used, to support the streaming of multimedia content and, simultaneously, to “compose” a reliable means of transmitting information between several entities (physical and legal persons) using digital facilities.
Although technological advances have enhanced the deployment of faster (lesser latency) and greater (more bandwidth) “network lines” possessing significant advantages, the demands of the extravagant use of Internet from users worldwide (Dilley, Maggs, Parikh, Prokop, Sitaraman, & Weihl, 2002; Shoniregun, Chochliouros, Laperche, Logvynovskiy, & Spiliopoulou-Chochliourou, 2004), together with an extensive variance of services offered, were primary motives for researchers to develop a specific category of modern infrastructures, known as content distribution (or delivery) networks (CDNs) (Hull, 2002; Verma, 2002).
The development of suitable content delivery networking comprises one of the most important challenges in the global networking area, together with the expansion of various IP trends. Content networks influence high-layer network intelligence to efficiently manage the delivery of various forms of data (which is becoming progressively more multimedia in nature). At an initial stage, they were built upon the structure of the public Internet (Saroiu, Gummadi, Dunn, Gribble, & Levy, 2002), to accelerate Web site performance (Johnson, Carr, Day, & Frans Kaashoek, 2000). This option has been fulfilled in numerous cases, and such intelligent network tools can be applied in other beneficial and profitable ways.
According to the present market experience, several definitions may appear to depict both the specific nature and the usage of a CDN. Although some people think of it as the means for “delivery” of streaming video or television over the Internet (or over private networks), others consider it as Web switching or content-switching. An alternative approach suggests that it may be considered as a “way” to improve Web site performance. All possible approaches are real, to a certain extent, according to the specific application. In fact, a CDN is a network optimized to deliver specific content, such as static Web pages, transaction-based Web sites, streaming media, or even real-time video or audio, especially to enable the distribution and the delivery of rich media over wide area networks, such as the Internet or corporate WANs (Tiscali, 2005).
Key Terms in this Chapter
Streaming Media: Streaming media is sound (audio) and pictures (video) that are transmitted on the Internet in a streaming or continuous fashion, using data packets. The most effective reception of streaming media requires some form of broadband technology, such as cable modem or DSL.
Authentication, Authorisation, and Accounting (AAA): A term for a framework for intelligently controlling access to computer resources, enforcing policies, auditing usage, and providing the information necessary to bill for services. These combined processes are considered important for effective network management and security.
Authentication: An option providing a way of identifying a user, typically by having the user enter a valid user-name and valid password before access is granted. The process of authentication is based on each user having a unique set of criteria for gaining access.
MPEG2: It is a second set of flexible compression standards created by the MPEG (Moving Pictures Experts Group). This set of standards takes advantage of the fact that over 95% of digital video is redundant; however, some portions are much less redundant. MPEG2 handles this by using higher bit-rates (i.e., higher quality) for more complex pictures and lower bit-rates for simple pictures.
Universal Resource Locator (URL): It includes the protocol (e.g., HTTP, FTP), the domain name (or IP address), and additional path information (folder/file). On the Web, a URL may address a Web page file, image file, or any other file supported by the HTTP protocol.
Content Delivery: It is “a complete solution for distributing and delivering Web-based content closer to end-users.” Content delivery solutions improve Internet site performance, thus allowing objects to be positioned closer to the end-user while minimizing load and latency to the origin servers. Well-implemented related solutions can bypass Internet traffic jams, optimize bandwidth use, and reduce operating costs.
Content Routing Technologies: The technologies of content routing deal with delivering the content from the most appropriate place to the client requesting it. When deciding the most appropriate place, there are several different metrics that could affect this decision. These metrics are: network proximity, geographical proximity, response time, and user type.
Peering CDNs: Different CDNs are able to cooperate by exchanging content to provide their clients with an even larger variety of data and increasing the overall efficiency, but complicating at the same time the accounting, billing, and so forth, due to the fact that each company that provides a CDN usually has adopted its own metrics and services.
Content Delivery Network (CDN): It is a term coined in the late 1990s to describe a system of computers networked together across the Internet that cooperate transparently to deliver content (especially large media content) to end-users. CDNs are a vital component of the Internet’s content delivery value chain, servicing nearly a third of the Internet’s most popular content sites. A CDN is a network optimized to deliver specific content, such as static Web pages, transaction-based Web sites, streaming media, or even real-time video or audio. Its basic purpose is to quickly give users the most current content in a highly available graphics or streaming video, in a highly available fashion.
IP Multicast: IP Multicast is more efficient than normal Internet transmissions, because the server can broadcast a message to many recipients simultaneously. Unlike traditional Internet traffic that requires separate connections for each source-destination pair, IP Multicasting allows many recipients to share the same source. This means that just one set of packets is transmitted for all the destinations.
Secure Sockets Layer (SSL): A protocol developed by Netscape for transmitting private documents via the Internet. SSL works by using a private key to encrypt data that is transferred over the SSL connection. Both Netscape Navigator and Internet Explorer support SSL, and many Web sites use the protocol to obtain confidential user information, such as credit card numbers. (By convention, URLs that require an SSL connection start with https: instead of http:).
Streaming: A technique for transferring data, such that it can be processed as a steady and continuous stream. Streaming technologies are becoming increasingly important with the growth of the Internet because most users do not have fast enough access to download large multimedia files quickly. With streaming, the client browser (or plug-in) can start displaying the data before the entire file has been transmitted. For streaming to work, the client side receiving the data must be able to collect it and send it as a steady stream to the application that is processing the data and converting it to sound or pictures. This means that if the streaming client receives the data more quickly than required, it needs to save the excess data in a buffer. If the data doesn’t come quickly enough, the data’s presentation will not be smooth.