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Historically, programming across multiple machines has been error-prone, difficult, and complex.
The programmer had to know many details about the network and sometimes even the hardware. You usually needed to understand the various “layers” of the networking protocol, and there were a lot of different functions in each different networking library concerned with connecting, packing, and unpacking blocks of information; shipping those blocks back and forth; and handshaking. It was a daunting task.
However, the basic idea of distributed computing is not so difficult, and is abstracted very nicely in the Java libraries. You want to:
· Get some information from that machine over there and move it to this machine here, or vice versa. This is accomplished with basic network programming.
· Connect to a database, which may live across a network. This is accomplished with Java DataBase Connectivity (JDBC), which is an abstraction away from the messy, platform-specific details of SQL (the structured query language used for most database transactions).
· Provide services via a Web server. This is accomplished with Java’s servlets and JavaServer Pages (JSPs).
· Execute methods on Java objects that live on remote machines transparently, as if those objects were resident on local machines. This is accomplished with Java’s Remote Method Invocation (RMI).
· Use code written in other languages, running on other architectures. This is accomplished using the Extensible Markup Language (XML), which is directly supported by Java.
· Isolate business logic from connectivity issues, especially connections with databases including transaction management and security. This is accomplished using Enterprise JavaBeans (EJBs). EJBs are not actually a distributed architecture, but the resulting applications are usually used in a networked client-server system.
· Easily, dynamically, add and remove devices from a network representing a local system. This is accomplished with Java’s Jini.
Please note that each subject is voluminous and by itself the subject of entire books, so this book is only meant to familiarize you with the topics, not make you an expert (however, you can go a long way with the information presented here).
Historically, programming across multiple machines has been error-prone, difficult, and complex.
The programmer had to know many details about the network and sometimes even the hardware. You usually needed to understand the various “layers” of the networking protocol, and there were a lot of different functions in each different networking library concerned with connecting, packing, and unpacking blocks of information; shipping those blocks back and forth; and handshaking. It was a daunting task.
However, the basic idea of distributed computing is not so difficult, and is abstracted very nicely in the Java libraries. You want to:
· Get some information from that machine over there and move it to this machine here, or vice versa. This is accomplished with basic network programming.
· Connect to a database, which may live across a network. This is accomplished with Java DataBase Connectivity (JDBC), which is an abstraction away from the messy, platform-specific details of SQL (the structured query language used for most database transactions).
· Provide services via a Web server. This is accomplished with Java’s servlets and JavaServer Pages (JSPs).
· Execute methods on Java objects that live on remote machines transparently, as if those objects were resident on local machines. This is accomplished with Java’s Remote Method Invocation (RMI).
· Use code written in other languages, running on other architectures. This is accomplished using the Extensible Markup Language (XML), which is directly supported by Java.
· Isolate business logic from connectivity issues, especially connections with databases including transaction management and security. This is accomplished using Enterprise JavaBeans (EJBs). EJBs are not actually a distributed architecture, but the resulting applications are usually used in a networked client-server system.
· Easily, dynamically, add and remove devices from a network representing a local system. This is accomplished with Java’s Jini.
Please note that each subject is voluminous and by itself the subject of entire books, so this book is only meant to familiarize you with the topics, not make you an expert (however, you can go a long way with the information presented here).
