Java Reference
In-Depth Information
networking protocols that are the Internet standard;
HTTP
is a protocol used
to transfer documents;
HTML
is a tag language specifically used for docu-
ments;
XML
is an emerging markup language for giving structure and mean-
ing to generic data. Table 2.1 lists the standards that will form the foundation
for the Java server-side standards.
Table 2.1 The standards that enable the Internet. They will insulate our server-side Java applica-
tions from the details of low-level message transfer, data presentation, and parsing.
Standard
Meaning
Purpose
TCP
Transmission Control Protocol
System layer for reliable message transmission pro-
tocol.
IP
Internet Protocol
System layer for distributed addressing and routing
protocol.
HTTP
Hypertext Transfer Protocol
Application layer for data transfer.
HTML
Hypertext Markup Language
Tag language used to add structure and meaning to
documents for presentation. It has evolved to
include increasing application content.
XML
Extensible Markup Language
Tag language used to add structure and meaning to
generic data.
2.2.4
TCP and IP provide low-level communications
TCP
/
IP
is a combination of two standards.
TCP
is used to provide message
transmission. That means it provides these services:
Data will get from the source to the destination, or an error will be
reported.
The data will reach the destination in the right order.
The data will reach the destination without duplication.
TCP
establishes a connection and disconnection protocol and a data-transfer
protocol. Attached to each message is a
TCP
header of 20 bytes or so that con-
tains the source address, destination address, sequence, acknowledgment
number, size, and a checksum for reliability.
IP
specifies a header, an address, and a routing protocol, among other things.
An
IP
header contains source, destination, size, and reliability information.
IP
addresses are like mailboxes, and they uniquely identify every logical site
on the Internet. Four numbers, separated by dots, represent an
IP
address. If
you are currently online, on most systems you can find your dotted address by