File Doc Category Size Date Package
DatagramConnection.java API Doc phoneME MR2 API (J2ME) 7152 Wed May 02 17:59:54 BST 2007 javax.microedition.io

DatagramConnection

public interface DatagramConnection implements Connection

This interface defines the capabilities that a datagram connection must have.

Reminder: In common with all the other addressing schemes used for I/O in CLDC, the syntax for datagram addressing is not defined in the CLDC Specification. Syntax definition can only be take place at the profile level. The reason for this is that the datagram interface classes of CLDC can be used for implementing various kinds of datagram protocols. Examples include IP and WDP networks as well as infrared beaming protocols used by various PDAs and other devices. All these protocols use very different addressing mechanisms.

In the sample implementation provided as part of the CLDC implementation, the following addressing scheme is used for UDP datagrams.

The parameter string describing the target of a connection in the CLDC implementation takes the following form:

{protocol}://[{host}]:[{port}]

A datagram connection can be opened in a "client" mode or "server" mode. If the "//{host}" part is missing then the connection is opened as a "server" (by "server", we mean that a client application initiates communication). When the "//{host}" part is specified, the connection is opened as a "client".

Examples:

A datagram connection for accepting datagrams
datagram://:1234

A datagram connection for sending to a server:
datagram://123.456.789.12:1234

Note that the port number in "server mode" (unspecified host name) is that of the receiving port. The port number in "client mode" (host name specified) is that of the target port. The reply-to port in both cases is never unspecified. In "server mode", the same port number is used for both receiving and sending. In "client mode", the reply-to port is always dynamically allocated.

The allocation of datagram objects is done in a more abstract way than in J2SE. This is to allow a single platform to support several different datagram interfaces simultaneously. Datagram objects must be allocated by calling the "newDatagram" method of the DatagramConnection object. The resulting object is defined using another interface type called "javax.microedition.io.Datagram".

version: 1.1 1/7/2000

Fields Summary
Constructors Summary
Methods Summary
public int getMaximumLength()
Get the maximum length a datagram can be.
return
The maximum length a datagram can be.
exception
IOException If an I/O error occurs.
public int getNominalLength()
Get the nominal length of a datagram.
return
The nominal length a datagram can be.
exception
IOException If an I/O error occurs.
public Datagram newDatagram(int size)
Make a new datagram object automatically allocating a buffer.
param
size The length of the buffer to be allocated for the datagram
return
A new datagram
exception
IOException If an I/O error occurs.
exception
IllegalArgumentException if the length is negative or larger than the buffer
public Datagram newDatagram(int size, java.lang.String addr)
Make a new datagram object.
param
size The length of the buffer to be used
param
addr The I/O address to which the datagram will be sent
return
A new datagram
exception
IOException If an I/O error occurs.
exception
IllegalArgumentException if the length is negative or larger than the buffer, or if the address parameter is invalid
public Datagram newDatagram(byte[] buf, int size)
Make a new datagram object.
param
buf The buffer to be used in the datagram
param
size The length of the buffer to be allocated for the datagram
return
A new datagram
exception
IOException If an I/O error occurs.
exception
IllegalArgumentException if the length is negative or larger than the buffer, or if the buffer parameter is invalid
public Datagram newDatagram(byte[] buf, int size, java.lang.String addr)
Make a new datagram object.
param
buf The buffer to be used in the datagram
param
size The length of the buffer to be used
param
addr The I/O address to which the datagram will be sent
return
A new datagram
exception
IOException If an I/O error occurs.
exception
IllegalArgumentException if the length is negative or larger than the buffer, or if the address or buffer parameters is invalid
public void receive(Datagram dgram)
Receive a datagram.
param
dgram A datagram.
exception
IOException If an I/O error occurs.
exception
InterruptedIOException Timeout or upon closing the connection with outstanding I/O.
public void send(Datagram dgram)
Send a datagram.
param
dgram A datagram.
exception
IOException If an I/O error occurs.
exception
InterruptedIOException Timeout or upon closing the connection with outstanding I/O.