Database Reference
In-Depth Information
These data can then be transmitted between various systems that convert the neutral format to
system-specific formats, for example, to a relational form. Just as Java provides code portability,
XML provides data portability. XML is also used as the configuration language in J2EE.
11.2.3.4.3 Communication Services
11.2.3.4.3.1 HTTP/HTTPS —
Hypertext Transfer Protocol (HTTP) is a text-based protocol
used for communication across the Internet and supports Web browser interactions with the
HTTP servers listening on server machines. The protocol is stateless in that the server does not
maintain any client state—every request made by an HTTP client will have to provide all essential
information needed to process the request like
◾
The nature of the client (e.g., kind of browser)
◾
The kind of request
◾
The resource target on the server (e.g., a particular HTML page or servlet)
◾
he data to be sent to the server
Client requests are matched with server responses that provide information about the request like
◾
The Status of the request
◾
The MIME type of the response data
◾
he response data
HTTPS is the secure form of the HTTP in that the HTTP communication is transmitted over
the Secure Socket Layer (SSL).
11.2.3.4.3.2 Remote Method Invocation (RMI) —
RMI enables communication between
distributed objects transparent of their remote locations on the network by communicating with
a local proxy or a stub that is generated automatically to communicate with the corresponding
remote objects. The code for the proxy is generated automatically and communicates using sockets
with the remote object—there is helper code at the remote end that reads from the socket, pro-
cesses the bytes, and makes the method call on the remote object.
Initially, RMI allowed communication only between java objects. Subsequently, RMI began
to support communication with non-Java objects using RMI-IIOP (Internet Inter-ORB Protocol)
that is a CORBA transport protocol on top of TCP/IP. RMI enables developers to effectively con-
centrate on developing the business logic rather than worrying about the details of the distribution.
11.2.3.4.3.3 Java Message Service (JMS) —
JMS enables asynchronous communication
between producers and consumers in that a producer sends a message to a queue or topic, and,
rather than waiting for a response, it moves on to undertake other tasks. As and when they are
ready, consumers read messages from queues and topics.
JMS employs two models of communication:
1.
Point to point
: This involves the uses of FIFO queues and supports one-to-one and
many-to-one interactions between producers and consumers. Message objects are created by
the producers and sent to a named queue. Consumers who wish to read messages from the
