- Pearson Education
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- 7.44(w) x 9.20(h) x 2.11(d)
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Fundamentally, the objective in client/server computing is to distribute the computing workload so that you can accommodate more users and obtain more throughput. In the computing literature there has been a discussion about the relative merits of thin clients and fat clients. Essentially, a thin client performs very little processing and relies on the server for most computing tasks. Fat clients, on the other hand, offload computing tasks from the server, usually allowing more clients to be attached to a single server.
The Notes client provides end users with tremendous functionality. Some might call this a fat client, but I don't think that Notes is necessarily overweight. Essentially, Notes is a desktop database manager and communication package. It provides support for applications such as email, calendaring, and contact management. In addition, because of the replication features, you can store, manage, and execute complete applications in the Notes client on the desktop. All this power, however, comes at a price of disk storage and complexity. When a company installs Notes clients, it typically requires an administrator to administrate the users, passwords, and installation of software. Thus, in the past it has been unusual to find the Notes client being used by an individual at home unless it is to access a corporate network remotely.
The trend with Notes and Domino, however, is to make the Notes client usable as a Web browser and capable of being used with servers other than Domino. Domino also is moving toward a model where it can support Web browser clients as well as Notes clients. For example, Domino can execute agents on the server on behalf of any client, including Web browser clients.
Web servers and Web browsers have traditionally fallen into the thin client model because Web browsers have had limited functionality. It has been relatively difficult to develop complex applications for Web browsers because they haven't been capable. Web browsers, however, are becoming more and more powerful because of several factors.
Java applets are also being used to add intelligent functions on a Web browser client. Java can be used to develop complete user interfaces, simple controls, database access, and more. The Java language can also be used on the server. In this capacity, programs known as servlets, Java Server Pages QSPs), or Enterprise JavaBeans (EJB) can be developed to provide additional server-side functions. The main constraint to large, Java-based applications in a Web browser is communication bandwidth. On the Internet, most users still connect with modems, which are too slow to download large (say 1MB) Java applets. As bandwidth improves via cable modems, ISDN, DSL lines, and so forth, more and larger applications for the Internet will be possible. In corporate environments, bandwidth is usually sufficient to handle large Java applets. Thus, Java applets might be more useful today in corporate intranets than on the Web because of the bandwidth constraints.
Several layers of communications protocols are used in a networked environment. The lower layers of the protocol deal with hardware and the management of the movement of the data. Moving packets of data from a source computer through the network to the destination is the responsibility of these protocols.
Higher-layer protocols are used by applications to communicate between say, a client application and a server application. Often, to the user, both of these components are just pieces of a single application. The Notes client and Domino server, for example, can use special protocols to transfer database information from one to the other.
When the client and server parts of an application are relatively tightly coupled, the protocols used don't really matter too much as long as the client and server can communicate. However, as we move more and more toward the use of Internet protocols, even within corporations, standards become much more important. Using standard protocols allows the client and server programs to become less dependent on one another and allows users to select software pieces more independently. Web servers and browsers are the most successful example of this phenomenon. Many different kinds of Web servers are available, running on many different kinds of hardware platforms...
Meet the Author
Randall A. Tamura is Vice President of Engineering for PeopleLink, an Internet company that provides outsourcing of community services for Web sites. He is the author of four books on Notes and Domino, including the best-selling Special Edition Using Lotus Notes and Domino RS.
Tamura has more than 25 years of experience in the computer field, and has been working with Notes and Domino since release 3. Before joining PeopleLink, he was the president of Graphware Corporation, which provided Notes and Domino consulting services. Before founding Graphware, Tamura was the general manager of IBM's Engineering Systems Development organization in the Los Angeles area.
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Most Helpful Customer Reviews
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This was a highly anticipated book when it came out because it covered some very hot topics namely XML and Java. The book probably didn't quite live up to expectations but still provided a load of useful information about those topics. Today you're probably better off with purchasing Lotus Notes and Domino 6 Programming Bible. Brian Benz and Rocky Oliver have done a great job with that book.