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[...]... corrupted frames; higher layers normally handle this behavior 1.3.3 Layer 3 Network Layer Moving up from the data link layer, which sends frames over a network, we reach the network layer The network layer deals with data packets, rather than frames, and introduces several important concepts, such as the network address and routing Packets are sent across the network, and in the case of the Internet, all... between networks, by creating network protocols that support internetwork communication or "internetting." The various protocols that make up the Internet must support a variety of networking gateways Hardware and software independence, by creating network protocols that would be interoperable with any CPU architecture, operating system, and networking card Reliability and robustness, by creating network. .. access a network (for example, allowing two desktop machines to access a local area network) Gateways connect one network to another—for example, a local area network to the Internet While routers and gateways are similar, a router does not have to bridge multiple networks In some cases, routers are also gateways While it is useful to understand such networking terminology as it is widely used in networking... of networking hardware is used, it will almost certainly support IP networking IP acts as a bridge between networks of different types, forming a worldwide network of computers and smaller subnetworks (see Figure 1-3) Indeed, many organizations use the IP and related protocols within their local area networks, as it can be applied equally well internally as externally Figure 1-3 Support for IP networking... operating system and device driver developers, who work with low-level assembly language and operating system calls Instead, programmers use standard Internet services, and let the operating system and device drivers handle such complexities This is one of the perks of being a network programmer Figure 1-6 Data encapsulation between OSI layers 15 1.8 Security Issues: Firewalls and Proxy Servers Network security... details of Layer n-1, Layer n-2, and so on Lower-level layers, for example, can be substituted and replaced without having to modify or redesign higher-level layers, or recompile application software For example, a network layer protocol can work with an Ethernet network and a token ring network, even though at the physical and data link layers, two different protocols and hardware devices are being... information There are a wide variety of network mediums, ranging from dial-up modems to local area networks At the physical and data link layers, various hardware types and network protocols can be used, making networks inter operable We as Java programmers do not need to concern ourselves with such issues, however, and in fact are unable to access such low-level network devices TCP/IP communication uses... model, dealing only with the network, transport, and application layers It is these layers, more than any others, that Java programmers must be familiar with As one moves higher and higher up the OSI levels, hardware issues are put aside and more and more levels of abstraction are introduced First there is the network layer, which deals with the dispatch of packets over a network and the issue of addresses... features such as class inheritance and visibility modifiers (the public, private, and protected keywords of Java) make object-oriented languages much easier and safer to work with than older procedural languages 21 Procedural languages can be used to develop networking software, and indeed C remains a popular choice today for Unix networking software However, network programming in any language is not... widely used in networking texts and protocol specifications, programmers do not generally need to be concerned with the implementation details of a network and its underlying architecture However, it is important for programmers to be aware of the various elements making up the network 1.2 How Do Networks Communicate? Networks consist of connections between computers and devices These connections are . Java Network Programming and Distributed Computing. The goal of this book is to introduce and explain the basic concepts of networking and discuss the practical aspects of Java network programming. . is uniquely suited for network programming and distributed computing. Whether you are a Java devotee who needs a solid working knowledge of network programming or a network programmer needing. Java™ Network Programming and Distributed Computing By David Reilly , Michael Reilly Publisher : Addison Wesley Pub Date : March 25, 2002 ISBN : 0-201-71037-4 Pages : 496 Java(TM) Network
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Xem thêm: Java™ Network Programming and Distributed Computing ppt, Java™ Network Programming and Distributed Computing ppt, Figure 1-2. Seven layers of the OSI Reference Model, Figure 1-4. Format of an IPv4 datagram packet, Figure 1-7. The firewall draws a line in the sand, insulating internal computers from the Internet., Figure 2-2. Exception class tree and categories, Figure 3-4. DNS server returns IP address, and caches query from another machine., Figure 4-5. Reading from a low-level stream is do, Figure 4-6. Output streams send data one byte at a time, sequentially., Figure 4-7. Entire graphs of objects may be serialized to an output stream., Figure 5-1. UDP packet transport over a network can be unreliable., Figure 5-2. DatagramPacket representation of a UDP packet, Figure 5-5. Packets are sent using a DatagramSocket., Table 6-1. Protocols and Their Associated Ports, Figure 7-2. Application processes can fork in two, having one or more subprocesses perform useful work., Figure 7-4. A thread-safe counter is achieved by synchronizing class methods., Figure 7-5. Piped communication is only one way, but two pipes may be used., Figure 7-7. Thread groups may contain threads and subgroups, which in turn may include more groups and threads., Table 9-3. Status Codes Used in HTTP, Figure 9-2. Format of the Universal Resource Locator, Table 10-1. Mapping of HTTP Request Types to Servlet Methods, Table 10-3. ServletRequest Parameter and Miscellaneous Methods, Table 10-6. Method of Functions in ServletContext, Figure 11-3. The RMI client stub calls the RMI server skeleton., Figure 11-4. RMI class loader decision process, Figure 11-8. Callback implemented by invoking a method on a listening object, Figure 11-10. Faulting reference, with the aid of activation system, passes information from activated object back to client., Table 12-1. Java Datatypes and Their Mapping to IDL Datatypes, Figure 13-1. Relationship between the JavaMail API and other services