Jini网络技术介绍(Technology Computer English)

 

Jini -- a technical specification developed by Sun

Microsystems that uses a small piece (48K) of Java code to

allow any network device with a Java virtual machine (JVM)

to announce its availability and provide its services to any

other device connected to the same network. Jini is based on

the concept of creating a "federation" of self-configuring

devices capable of transparently exchanging code when necessary

to simplify interactions between network devices.

Jini network technology provides simple mechanisms which

enable devices to plug together to form an impromptu community

-- a community put together without any planning,

installation, or human intervention. Each device provides

services that other devices in the community may use. These

devices provide their own interfaces, which ensures reliability

and compatibility.

Jini technology uses a lookup service with which devices

and services register. When a device plugs in, it goes

through an add-in protocol, called discovery and join-in.

The device first locates the lookup service (discovery) and

then uploads an object that implements all of its services'

interfaces (join).

To use a service, a person or a program locates it using the

lookup service. The service's object is copied from the lookup

service to the requesting device where it will be used. The

lookup service acts as an intermediary to connect a client

looking for a service with that service. Once the connection is

made, the lookup service is not involved in any of the resulting

interactions between that client and that service.

Jini是一种由Sun Microsystems公

司开发的技术规范它使用小块Java代码

(48KB)就能在任何具有Java虚拟机JVM

的网络设备上运行并为连接至相同网络

的其它设备提供服务Jini规范是基于创

建自配置设备联盟的概念这些自配

置设备在需要简化网络设备间的交互作用

时能透明地交换代码

Jini网络技术提供了简单的体系该

体系能够使设备插接在一起以形成临时工作

组即不经过任何规划安装或人工干涉

而连接在一起的工作组每台设备都能提供

服务工作组的其它设备也可以使用这些服

务这些设备有他们专用的接口这就保证

了体系的可靠性和兼容性

Jini技术使用查询服务设备和服务

利用查询来注册当接入一台设备时必

须通过一个名为发现和加入的附加协议

首先该设备寻找查询服务的地址发现

然后上载能够实现所有服务接口的对象

加入

要使用服务首先必须利用查询服

务程序来对程序确定地址将服务对象

从查询服务复制到将使用服务的应答设

备查询服务作为媒介来连接寻找服务

的客户和该服务一旦建立连接查询服

务就不再介入产生交互作用的任何客户

端和服务器

It doesn't matter where a service is implemented --

compatibility is ensured because each service provides everything

needed to interact with it. There is no central

repository of drivers, or anything else for that matter.

The Java programming language is the key to making

Jini technology work. Devices in a network employing

Jini technology are tied together using Java Remote

Method Invocation (RMI). By using the Java programming

language, a Jini network architecture is secure. The

discovery and join protocols, as well as the lookup

service, depend on the ability to move Java objects,

including their code, between Java virtual machines.

Jini technology not only defines a set of protocols

for discovery, join, and lookup, but also a leasing and

transaction mechanism to provide resilience in a dynamic

networked environment. The underlying technology and

services architecture is powerful enough to build a

fully distributed system on a network of workstations.

And the Jini network infrastructure is small enough

that a community of devices enabled by Jini network

software can be built out of the simplest devices. For

example, it is entirely feasible to build such a device

community out of home entertainment devices or a few

cellular telephones with no "computer" in sight.

在哪里实现服务其实并不重要因为

每个服务提供了用来交互的所有信息所以兼

容性得到了保证不存在驱动程序的中心储存

库或与此相关的其它因素

Java编程语言是完成Jini技术工作的

关键所在在一个网络中通过Java Remote

Method Invocation (RMI)将应用Jini技

术的设备紧密联结在一起使用Java编程语

言就保证了Jini网络体系结构的安全发

现和加入协议同查询服务一样都有能力在

Java虚拟机之间移动Java对象或者代码

Jini技术不仅定义了发现加入和查询的

一整套协议而且还确定了一套能够在动态网

络环境下具有弹性的事物处理机制底层技术

和服务机制足够强大可以用来在网络工作站

建造完全的分布式系统

同时Jini网络基础结构是如此之小以

致于用最简单的设备就可以建造出由Jini网络

软件激活的设备工作组例如在视野中没有

计算机的情况下仅仅通过数台家庭娱乐设

备或几个蜂窝电话就可以建造出一个设备工

作组这样的方案是完全可行的