javax.microedition.io
Interface SocketConnection

All Superinterfaces:

Connection, InputConnection, OutputConnection, StreamConnection

All Known Implementing Classes:

Protocol

public interface SocketConnection
extends 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.

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, CDC 1.1, Java Card 3.0

DELAY

static 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.

See Also:

Constant Field Values

LINGER

static 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.

See Also:

Constant Field Values

KEEPALIVE

static 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.

See Also:

Constant Field Values

RCVBUF

static final byte RCVBUF

Socket option for the size of the receiving buffer (3).

See Also:

Constant Field Values

SNDBUF

static final byte SNDBUF

Socket option for the size of the sending buffer (4).

See Also:

Constant Field Values

setSocketOption

void setSocketOption(byte option,
                     int value)
                     throws IOException

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.

Parameters:

option - socket option identifier (KEEPALIVE, LINGER, SNDBUF, RCVBUF, or DELAY)

value - numeric value for specified option

Throws:

IllegalArgumentException - if the value is not valid (e.g., negative value) or if the option identifier is not valid

IOException - if the connection was closed

See Also:

getSocketOption(byte)

getSocketOption

int getSocketOption(byte option)
                    throws IOException

Get a socket option for the connection.

Parameters:

option - socket option identifier (KEEPALIVE, LINGER, SNDBUF, RCVBUF, or DELAY)

Returns:

numeric value for specified option or -1 if the value is not available.

Throws:

IllegalArgumentException - if the option identifier is not valid

IOException - if the connection was closed

See Also:

setSocketOption(byte, int)

getLocalAddress

String getLocalAddress()
                       throws IOException

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")

Returns:

the local address to which the socket is bound.

Throws:

IOException - if the connection was closed.

See Also:

ServerSocketConnection

getLocalPort

int getLocalPort()
                 throws IOException

Returns the local port to which this socket is bound.

Returns:

the local port number to which this socket is connected.

Throws:

IOException - if the connection was closed.

See Also:

ServerSocketConnection

getAddress

String getAddress()
                  throws IOException

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).

Returns:

the remote address to which the socket is bound.

Throws:

IOException - if the connection was closed.

getPort

int getPort()
            throws IOException

Returns the remote port to which this socket is bound.

Returns:

the remote port number to which this socket is connected.

Throws:

IOException - if the connection was closed.