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SocketConnection.javaAPI DocJ2ME MIDP 2.07689Thu Nov 07 12:02:26 GMT 2002javax.microedition.io

SocketConnection

public interface SocketConnection implements StreamConnection
This interface defines the socket stream connection.

A socket is accessed using a generic connection string with an explicit host and port number. The host may be specified as a fully qualified host name or IPv4 number. e.g. socket://host.com:79 defines a target socket on the host.com system at port 79.

Note that RFC1900 recommends the use of names rather than IP numbers for best results in the event of IP number reassignment.

Closing Streams

Every StreamConnection provides a Connection object as well as an InputStream and OutputStream to handle the I/O associated with the connection. Each of these interfaces has its own close() method. For systems that support duplex communication over the socket connection, closing of the input or output stream SHOULD shutdown just that side of the connection. e.g. closing the InputStream will permit the OutputStream to continue sending data.

Once the input or output stream has been closed, it can only be reopened with a call to Connector.open(). The application will receive an IOException if an attempt is made to reopen the stream.

BNF Format for Connector.open() string

The URI must conform to the BNF syntax specified below. If the URI does not conform to this syntax, an IllegalArgumentException is thrown.

<socket_connection_string> ::= "socket://"<hostport>
<hostport> ::= host ":" port
<host> ::= host name or IP address (omitted for inbound connections, See ServerSocketConnection)
<port> ::= numeric port number

Examples

The following examples show how a SocketConnection would be used to access a sample loopback program.

SocketConnection sc = (SocketConnection)
Connector.open("socket://host.com:79");
sc.setSocketOption(SocketConnection.LINGER, 5);

InputStream is = sc.openInputStream();
OutputStream os = sc.openOutputStream();

os.write("\r\n".getBytes());
int ch = 0;
while(ch != -1) {
ch = is.read();
}

is.close();
os.close();
sc.close();
since
MIDP 2.0

Fields Summary
public final byte
DELAY
Socket option for the small buffer writing delay (0). Set to zero to disable Nagle algorithm for small buffer operations. Set to a non-zero value to enable.
public final byte
LINGER
Socket option for the linger time to wait in seconds before closing a connection with pending data output (1). Setting the linger time to zero disables the linger wait interval.
public final byte
KEEPALIVE
Socket option for the keep alive feature (2). Setting KEEPALIVE to zero will disable the feature. Setting KEEPALIVE to a non-zero value will enable the feature.
public final byte
RCVBUF
Socket option for the size of the receiving buffer (3).
public final byte
SNDBUF
Socket option for the size of the sending buffer (4).
Constructors Summary
Methods Summary
public java.lang.StringgetAddress()
Gets the remote address to which the socket is bound. The address can be either the remote host name or the IP address(if available).

return
the remote address to which the socket is bound.
exception
IOException if the connection was closed.

public java.lang.StringgetLocalAddress()
Gets the local address to which the socket is bound.

The host address(IP number) that can be used to connect to this end of the socket connection from an external system. Since IP addresses may be dynamically assigned, a remote application will need to be robust in the face of IP number reasssignment.

The local hostname (if available) can be accessed from System.getProperty("microedition.hostname")

return
the local address to which the socket is bound.
exception
IOException if the connection was closed.
see
ServerSocketConnection

public intgetLocalPort()
Returns the local port to which this socket is bound.

return
the local port number to which this socket is connected.
exception
IOException if the connection was closed.
see
ServerSocketConnection

public intgetPort()
Returns the remote port to which this socket is bound.

return
the remote port number to which this socket is connected.
exception
IOException if the connection was closed.

public intgetSocketOption(byte option)
Get a socket option for the connection.

param
option socket option identifier (KEEPALIVE, LINGER, SNDBUF, RCVBUF, or DELAY)
return
numeric value for specified option or -1 if the value is not available.
exception
IllegalArgumentException if the option identifier is not valid
exception
IOException if the connection was closed
see
#setSocketOption

public voidsetSocketOption(byte option, int value)
Set a socket option for the connection.

Options inform the low level networking code about intended usage patterns that the application will use in dealing with the socket connection.

Calling setSocketOption to assign buffer sizes is a hint to the platform of the sizes to set the underlying network I/O buffers. Calling getSocketOption can be used to see what sizes the system is using. The system MAY adjust the buffer sizes to account for better throughput available from Maximum Transmission Unit (MTU) and Maximum Segment Size (MSS) data available from current network information.

param
option socket option identifier (KEEPALIVE, LINGER, SNDBUF, RCVBUF, or DELAY)
param
value numeric value for specified option
exception
IllegalArgumentException if the value is not valid (e.g. negative value) or if the option identifier is not valid
exception
IOException if the connection was closed
see
#getSocketOption