java中英文翻译

Characteristics of LANs

The

main

Characteristics

of

a

LAN

include

its

throughput,delays,wiring

type

and

distances,security,and

discuss

these

characteristics

then

compare

the

characteristics

of major LANs.

Throughput

The throughput is the average total transmission rate when the LAN is

heavily loaded by many nodes.

In a shared LAN,the throughput is a fraction of the rate of the

fraction

is

called

the

efficiency

of

the

MAC

insyance,a

network

that

uses

a

MAC

protocol

with

an

efficiency

oh

65

percent

and

10-Mbps

transmitters

has

a

throughput

of

6.5

values

are

typical

for

a

shared

10-Mbps

throughput

of

a

token

ring network and that of FDDI are close to their thransmission rate.

Latency

The latency

is

the time

a packet takes

froms its

arrival at anetwork

interface until it reaches the destination explain in Section

4.8that this latency is almost aiways less than a fraction of a second

and is often much smaller.

Wiring Type and Distance

Some

LANs

use

twisted

wire

pairs,others

use

optical

fibers,Older

LANs

and

installations in special environments use coaxial maximum

length

of

the

connections

depends

on

the

LAN

and

on

the

l

values

are

100

m

for

twisted

pairs

and

a

few

kilometers for multimode fibers.

Security

Anoptical

fiber

is

more

difficult

to

tap

into

than

a

twisted

pair,which

improves the “physical”r,eavesdroppers rarely need to

tap

directly

into

a

link

to

gain

access

to

information.A

more

common

attack

is to use one of the computers attached on the LAN and configure it to

read

all

the

packets

that

travel

on

the

network(this

is

called

snooping).If sensitive pieces of information such as user passwords are

transmitted in the clear(nonencrypted),then the eavesdropper obtains

entry

points

into

a

rule,a

switched

LAN

is

more

secure

than

a shared LAN because a computer on such a network sees only the packets

intended for it.

Reliability

We

depend

increasingly

on

ingly,reliability

becomes

more

we

mentioned

in

the

opening

remarks

of

this

chapter,FDDA

is

designed

to

survive

a

link

or

node

Ethernet

keeps

on

working

when

some

of

its

nodes

or

links

ring

network

can

be

wired

with

bypass electronics to have a similar reliability.

Network Devices

Text

There

are

many

types

of

media

for

the

network,

and

each

one

has

advantages and disadvantages. One of the disadvantages of the type of

cable

that

we

primarily

use

(CAT5

UTP)

is

cable

length.

The

maximum

length

for UTP cable in a network is 100 meters (approximately 333 feet). If we

need

to

extend

our

network

beyond

that

limit,

we

must

add

a

device

to

our

network. This device is called a repeater.

The

term

repeater

comes

from

the

early

days

of

visual

communication,

when

a

man

situated

on

a

hill

would

repeat

the

signal

to

the

person

on

the

hill

to his right. It also comes from telegraph, telephone, microwave, and

optical communications, all of which use repeaters to strengthen their

signals

over

long

distances,

or

else

the

signals

will

eventually

fade

or

die out.

The

purpose

of

a

repeater

is

regenerate

and

retime

network

signals

at

the

bit

level

to

allow

them

to

travel

a

longer

distance

on

the

media.

Watch

out

for

the

Four

Repeater

Rule

for

10Mbps

Ethernet,

also

known

as

the

5-4-3

Rule,

when

extending LAN

segments.

This

rule

states

that

you

can

connect

five network segments end-to-end using four repeaters but only three

segments can have hosts (computers) on them.

The term repeater traditionally me

ant a single port “in” and a

single port “out” device. But in common terminology today the term

multiport repeater is often used as well. Repeaters are classified as

Layer 1 devices in the OSI model, because they act only on the bit level

and

look

at

no

other

information.

The

symbol

for

repeaters

is

not

standardized.

The purpose of a hub is to regenerate and retime network signals.

This

is

done

at

the

bit

level

to

a

large

number

of

hosts

(e.g.4,8,

or

even

24) using a process known as concentration. You will notice that this

definition

is

very

similar

to

the

repeater’s,

which

is

why

a

hub

is

also

known as a multi-port repeater. The difference is the number of cables

that connect to the device. Two reasons for using hubs are to create a

central

connection

point

for

the

wiring

media,

and

increase

the

reliability of the network. The reliability of the network is increased

by

allowing

any

single

cable

to

fail

without

disrupting

the

entire

network.

This

differs

from

the

bus

topology

where

having

one

cable

fail

will

disrupt

the

entire

network.

Hubs

are

considered

Layer

1

devices

because

they

only

regenerate the signal and broadcast it out all of their ports (network

connections).

E-commerce

(Electronic

Commerce,

is

abbreviated

as

E-commerce)

employs

the

way

on

the

basis

of

the

browser

/

server

under

the

environment

of Internet's open network, realize consumers' online shopping, online

trade

between

the

trade

companies

and

a

new

kind

of

commercial

operation

modes paid by mails online. E-commerce on Internet can be divided into

three respects: Information service, trade and paying. The main content

includes: Electronic market conditions advertisement; The electron is

chosen

and

exchange

of

trade,

electronic

trade

evidence;

Paying

by

mails

and settling account and online service after sale,etc.. The main trade

type is trade (C2C) of trade (B2B) and individual and man- to-man bet

between enterprises and personal trade (B2C) and enterprise,etc.. JSP

(Java Server Page) is that dynamic Web based on that Java has nothing to

do

but

with

the

platform

develops

technology,

there

is

very

high

operational

efficiency,

development

period

is

shorter,

it

is

stronger

to

expand

ability,

have

opening,

step

the

platform,

expandability

and

reusable characteristic. JAVABEAN is kind of a kind of

Java, become

through encapsulating and have a certain function or target of dealing

with a certain business, can visit Bean and method in JSP page Java code

inside

through

inlaying.

The

online

mobile

phone

store

is

a

WEB

application

program

based

on

that

JSP/JAVABEAN

technology

sets

up,

divide

into

2

parts

of

goods

show

of

the

front

desk

and

sale,

back- stage

management,

It

is

a

kind

of

typical

B2C

e-commerce

mode,

realize

the

main

function of e-commerce.

electronic

commerce

21

century

economy

grows

engine

not

only

in on microscopic affects the enterprise the management behavior and

consumer's

expense

behavior,

moreover

from

on

macroscopic

will

affect

the

international trade relations and the country future the competitive

ability. This article in view of the electronic commerce in our country

development

present

situation,

has

analyzed

the

question

which

exists

in

the

development,

proposed

the

corresponding

solution

and

the

suggestion,

according

to

the

physical

resource,

the

financial

resource

and

the

talented person develops our country electronic commerce, explores the

China electronic commerce development path.

Here nowadays develops the condition and the tendency two aspects

from the electronic commerce connotation and the characteristic as well

as

the

electronic

commerce

outlines

the

electronic

commerce,

by

will

have

the

direct- viewing

understanding

and

the

understanding

to

the

electronic

commerce. Makes the brief review afterwards to our country electronic

commerce

developing

process,

from

aspect

and

so

on

environment

condition,

profession and local condition makes the multianalysis to our country

electronic

commerce

development

present

situation

and

indicates

the

electronic

commerce

in

our

country

foreign

trade

status

and

the

function,

analyzes question which exists in the development, like lacks in the

strategic

plan

and

the

policy

support

is

insufficient,

the

corresponding

legal

laws

and

regulations

standard

standard

lag

and

so

on.

Finally

aims

at

the

question

to

propose

the

countermeasure

and

the

suggestion,

including

government

countermeasure

and

to

enterprise,

individual

request

and

so

on,

and

the

forecast

forecast

electronic

commerce

development

tendency

and

the

direction,

can

play

the

certain

impetus

role

by the time to our country electronic commerce health development .

abstract ] this article

with to know

the circumstances of

the matter the

power in the outline electronic

commerce right of

privacy and its in

the

protection

question

foundation,

discussed

in

the

electronic

commerce

the

right of privacy with to know the circumstances of the matter the power

conflict

question,

then

proposed

the

solution

two

conflict

principle

and

the means. [ Key word ] the electronic commerce right of privacy knows

the

circumstances

of the

matter

the

power

The

electronic

commerce

is

one

kind

of

brand-new

commercial

mechanism

which

under

the

whole

world

economic

integration

background

produces,

has

the

high

efficiency,

boundless

characteristic

and

so

on,

does

not

have

time

limit

and

low

cost,

receives

the

global

various

countries

government

and

the

enterprise

widely takes, has become at the beginning of for the 21st century one of

global economy biggest growth. The electronic commerce has had the huge

impact to the present legal system, if this article is going to discuss