org.deepsymmetry.beatlink.dbserver

Class Field

java.lang.Object

org.deepsymmetry.beatlink.dbserver.Field

Direct Known Subclasses:

BinaryField, NumberField, StringField

public abstract class Field
extends Object

All dbserver messages are made up of lists of fields, which are type-tagged values.

Author:

James Elliott

Constructor Summary

Constructors

Constructor and Description
Field()

Method Summary

Modifier and Type	Method and Description
abstract byte	getArgumentTag() Get the value which identifies this type of field in a message argument list.
abstract ByteBuffer	getBytes() Get the bytes which represent this field when sent over the network, including the leading type tag.
abstract long	getSize() Get the size, in bytes, of the network representation of this field, excluding the leading type tag and length bytes (if any).
abstract byte	getTypeTag() Get the value which identifies the start of this field in the network stream.
static Field	read(DataInputStream is) Read a field from the supplied stream, starting with the tag that identifies the type, and reading enough to collect the corresponding value.
void	write(WritableByteChannel channel) Write the field to the specified channel.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Field

public Field()

Method Detail

getBytes

public abstract ByteBuffer getBytes()

Get the bytes which represent this field when sent over the network, including the leading type tag.

Returns:

a freshly rewound buffer containing the full set of bytes which should be transmitted for this field.

getSize

public abstract long getSize()

Get the size, in bytes, of the network representation of this field, excluding the leading type tag and length bytes (if any).

Returns:

the number of bytes which will be written after the type tag (and length indicator, if present) when sending this field.

getTypeTag

public abstract byte getTypeTag()

Get the value which identifies the start of this field in the network stream.

Returns:

the tag which tells the recipient that this particular type of field is coming.

getArgumentTag

public abstract byte getArgumentTag()

Get the value which identifies this type of field in a message argument list.

Returns:

the tag which is used instead of the type tag for some reason when putting together the argument type list for a dbserver message.

read

public static Field read(DataInputStream is)
                  throws IOException

Read a field from the supplied stream, starting with the tag that identifies the type, and reading enough to collect the corresponding value.

Parameters:

is - the stream on which a type tag is expected to be the next byte, followed by the field value.

Returns:

the field that was found on the stream.

Throws:

IOException - if there is a problem reading the field.

write

public void write(WritableByteChannel channel)
           throws IOException

Write the field to the specified channel.

Parameters:

channel - the channel to which it should be written

Throws:

IOException - if there is a problem writing to the channel