KMStreamMessage Class Reference
Overview
A StreamMessage object is used to send a stream of primitive types. It is filled and read sequentially. It inherits from the Message interface and adds a stream message body. Its methods are based largely on those found in the Java platform: java.io.DataInputStream and java.io.DataOutputStream.
The primitive types can be read or written explicitly using methods for each type. They may also be read or written generically as objects. For instance, a call to StreamMessage.writeInt(6) is equivalent to StreamMessage.writeObject(new Integer(6)). Both forms are provided, because the explicit form is convenient for static programming, and the object form is needed when types are not known at compile time.
When the message is first created, and when clearBody is called, the body of the message is in write-only mode. After the first call to reset has been made, the message body is in read-only mode. After a message has been sent, the client that sent it can retain and modify it without affecting the message that has been sent. The same message object can be sent multiple times. When a message has been received, the provider has called reset so that the message body is in read-only mode for the client.
If clearBody is called on a message in read-only mode, the message body is cleared and the message body is in write-only mode.
If a client attempts to read a message in write-only mode, a KMMessageNotReadableException is thrown.
If a client attempts to write a message in read-only mode, a KMMessageNotWriteableException is thrown.
StreamMessage objects support the following conversion table. The marked cases must be supported. The unmarked cases must throw a KMJMSException. The String-to-primitive conversions may throw a runtime exception if the primitive’s valueOf() method does not accept it as a valid String representation of the primitive.
A value written as the row type can be read as the column type.
| | boolean byte short char int long float double String byte[]
|----------------------------------------------------------------------
|boolean | X X
|byte | X X X X X
|short | X X X X
|char | X X
|int | X X X
|long | X X
|float | X X X
|double | X X
|String | X X X X X X X X
|byte[] | X
|----------------------------------------------------------------------
Attempting to read a null value as a primitive type must be treated as calling the primitive’s corresponding valueOf(String) conversion method with a null value. Since char does not support a String conversion, attempting to read a null value as a char must throw an exception.
Tasks
-
– readBoolean
Reads a boolean from the stream message.
-
– readByte
Reads a byte value from the stream message.
-
– readShort
Reads a 16-bit integer from the stream message.
-
– readChar
Reads a Unicode character value from the stream message.
-
– readInt
Reads a 32-bit integer from the stream message.
-
– readLong
Reads a 64-bit integer from the stream message.
-
– readFloat
Reads a float from the stream message.
-
– readDouble
Reads a double from the stream message.
-
– readString
Reads a String from the stream message.
-
– readBytes:
Reads a byte array field from the stream message into the specified byte[] object (the read buffer).
-
– readObject
Reads an object from the stream message.
-
– writeBoolean:
Writes a boolean to the stream message. The value true is written as the value (byte)1; the value false is written as the value (byte)0.
-
– writeByte:
Writes a byte to the stream message.
-
– writeShort:
Writes a short to the stream message.
-
– writeChar:
Writes a char to the stream message.
-
– writeInt:
Writes an int to the stream message.
-
– writeLong:
Writes a long to the stream message.
-
– writeFloat:
Writes a float to the stream message.
-
– writeDouble:
Writes a double to the stream message.
-
– writeString:
Writes a String to the stream message.
-
– writeBytes:
Writes a byte array field to the stream message.
-
– writeBytes:offset:length:
Writes a portion of a byte array as a byte array field to the stream message.
-
– writeObject:
Writes an object to the stream message.
-
– reset
Puts the message body in read-only mode and repositions the stream to the beginning.
Instance Methods
readBoolean
Reads a boolean from the stream message.
- (BOOL)readBoolean
Return Value
the boolean value read
Exceptions
- KMJMSException
if the JMS provider fails to read the message due to some internal error.
- KMMessageEOFException
if unexpected end of message stream has been reached.
- KMMessageFormatException
if this type conversion is invalid.
- KMMessageNotReadableException
if the message is in write-only mode.
Declared In
KMStreamMessage.h
readByte
Reads a byte value from the stream message.
- (char)readByte
Return Value
the next byte from the stream message as a 8-bit byte
Exceptions
- KMJMSException
if the JMS provider fails to read the message due to some internal error.
- KMMessageEOFException
if unexpected end of message stream has been reached.
- KMMessageFormatException
if this type conversion is invalid.
- KMMessageNotReadableException
if the message is in write-only mode.
Declared In
KMStreamMessage.h
readBytes:
Reads a byte array field from the stream message into the specified byte[] object (the read buffer).
- (int)readBytes:(NSData *)value
Parameters
- value
the buffer into which the data is read
Return Value
the total number of bytes read into the buffer, or -1 if there is no more data because the end of the byte field has been reached
Discussion
To read the field value, readBytes should be successively called until it returns a value less than the length of the read buffer. The value of the bytes in the buffer following the last byte read is undefined.
If readBytes returns a value equal to the length of the buffer, a subsequent readBytes call must be made. If there are no more bytes to be read, this call returns -1.
If the byte array field value is null, readBytes returns -1.
If the byte array field value is empty, readBytes returns 0.
Once the first readBytes call on a byte[] field value has been made, the full value of the field must be read before it is valid to read the next field. An attempt to read the next field before that has been done will throw a KMMessageFormatException.
To read the byte field value into a new byte[] object, use the readObject method.
Exceptions
- KMJMSException
if the JMS provider fails to read the message due to some internal error.
- KMMessageEOFException
if unexpected end of message stream has been reached.
- KMMessageFormatException
if this type conversion is invalid.
- KMMessageNotReadableException
if the message is in write-only mode.
See Also
Declared In
KMStreamMessage.h
readChar
Reads a Unicode character value from the stream message.
- (char)readChar
Return Value
a Unicode character from the stream message
Exceptions
- KMJMSException
if the JMS provider fails to read the message due to some internal error.
- KMMessageEOFException
if unexpected end of message stream has been reached.
- KMMessageFormatException
if this type conversion is invalid
- KMMessageNotReadableException
if the message is in write-only mode.
Declared In
KMStreamMessage.h
readDouble
Reads a double from the stream message.
- (double)readDouble
Return Value
a double value from the stream message
Exceptions
- KMJMSException
if the JMS provider fails to read the message due to some internal error.
- KMMessageEOFException
if unexpected end of message stream has been reached.
- KMMessageFormatException
if this type conversion is invalid.
- KMMessageNotReadableException
if the message is in write-only mode.
Declared In
KMStreamMessage.h
readFloat
Reads a float from the stream message.
- (float)readFloat
Return Value
a float value from the stream message
Exceptions
- KMJMSException
if the JMS provider fails to read the message due to some internal error.
- KMMessageEOFException
if unexpected end of message stream has been reached.
- KMMessageFormatException
if this type conversion is invalid.
- KMMessageNotReadableException
if the message is in write-only mode.
Declared In
KMStreamMessage.h
readInt
Reads a 32-bit integer from the stream message.
- (int)readInt
Return Value
a 32-bit integer value from the stream message, interpreted as an int
Exceptions
- KMJMSException
if the JMS provider fails to read the message due to some internal error.
- KMMessageEOFException
if unexpected end of message stream has been reached.
- KMMessageFormatException
if this type conversion is invalid.
- KMMessageNotReadableException
if the message is in write-only mode.
Declared In
KMStreamMessage.h
readLong
Reads a 64-bit integer from the stream message.
- (long long)readLong
Return Value
a 64-bit integer value from the stream message, interpreted as a long
Exceptions
- KMJMSException
if the JMS provider fails to read the message due to some internal error.
- KMMessageEOFException
if unexpected end of message stream has been reached.
- KMMessageFormatException
if this type conversion is invalid.
- KMMessageNotReadableException
if the message is in write-only mode.
Declared In
KMStreamMessage.h
readObject
Reads an object from the stream message.
- (KCObject *)readObject
Return Value
a object from the stream message, in objectified format (for example, if the object was written as an int, an NSNumber is returned)
Discussion
This method can be used to return, in objectified format, an object that has been written to the stream with the equivalent writeObject method call, or its equivalent primitive writeType method.
Note that byte values are returned as NSData, not byte[].
An attempt to call readObject to read a byte field value into a new byte[] object before the full value of the byte field has been read will throw a KMMessageFormatException.
Exceptions
- KMJMSException
if the JMS provider fails to read the message due to some internal error.
- KMMessageEOFException
if unexpected end of message stream has been reached.
- KMMessageFormatException
if this type conversion is invalid.
- KMMessageNotReadableException
if the message is in write-only mode.
Declared In
KMStreamMessage.h
readShort
Reads a 16-bit integer from the stream message.
- (short)readShort
Return Value
a 16-bit integer from the stream message
Exceptions
- KMJMSException
if the JMS provider fails to read the message due to some internal error.
- KMMessageEOFException
if unexpected end of message stream has been reached.
- KMMessageFormatException
if this type conversion is invalid.
- KMMessageNotReadableException
if the message is in write-only mode.
Declared In
KMStreamMessage.h
readString
Reads a String from the stream message.
- (NSString *)readString
Return Value
a Unicode string from the stream message
Exceptions
- KMJMSException
if the JMS provider fails to read the message due to some internal error.
- KMMessageEOFException
if unexpected end of message stream has been reached.
- KMMessageFormatException
if this type conversion is invalid.
- KMMessageNotReadableException
if the message is in write-only mode.
Declared In
KMStreamMessage.h
reset
Puts the message body in read-only mode and repositions the stream to the beginning.
- (void)reset
Exceptions
- KMJMSException
if the JMS provider fails to reset the message due to some internal error.
- KMMessageFormatException
if the message has an invalid format.
Declared In
KMStreamMessage.h
writeBoolean:
Writes a boolean to the stream message. The value true is written as the value (byte)1; the value false is written as the value (byte)0.
- (void)writeBoolean:(BOOL)value
Parameters
- value
the boolean value to be written
Exceptions
- KMJMSException
if the JMS provider fails to write the message due to some internal error.
- KMMessageNotWriteableException
if the message is in read-only mode.
Declared In
KMStreamMessage.h
writeByte:
Writes a byte to the stream message.
- (void)writeByte:(char)value
Parameters
- value
the byte value to be written
Exceptions
- KMJMSException
if the JMS provider fails to write the message due to some internal error.
- KMMessageNotWriteableException
if the message is in read-only mode.
Declared In
KMStreamMessage.h
writeBytes:
Writes a byte array field to the stream message.
- (void)writeBytes:(NSData *)value
Parameters
- value
the byte array value to be written
Discussion
The byte array value is written to the message as a byte array field. Consecutively written byte array fields are treated as two distinct fields when the fields are read.
Exceptions
- KMJMSException
if the JMS provider fails to write the message due to some internal error.
- KMMessageNotWriteableException
if the message is in read-only mode.
Declared In
KMStreamMessage.h
writeBytes:offset:length:
Writes a portion of a byte array as a byte array field to the stream message.
- (void)writeBytes:(NSData *)value offset:(int)offset length:(int)length
Parameters
- value
the byte array value to be written
- offset
the initial offset within the byte array
- length
the number of bytes to use
Discussion
The a portion of the byte array value is written to the message as a byte array field. Consecutively written byte array fields are treated as two distinct fields when the fields are read.
Exceptions
- KMJMSException
if the JMS provider fails to write the message due to some internal error.
- KMMessageNotWriteableException
if the message is in read-only mode.
Declared In
KMStreamMessage.h
writeChar:
Writes a char to the stream message.
- (void)writeChar:(unichar)value
Parameters
- value
the char value to be written
Exceptions
- KMJMSException
if the JMS provider fails to write the message due to some internal error.
- KMMessageNotWriteableException
if the message is in read-only mode.
Declared In
KMStreamMessage.h
writeDouble:
Writes a double to the stream message.
- (void)writeDouble:(double)value
Parameters
- value
the double value to be written
Exceptions
- KMJMSException
if the JMS provider fails to write the message due to some internal error.
- KMMessageNotWriteableException
if the message is in read-only mode.
Declared In
KMStreamMessage.h
writeFloat:
Writes a float to the stream message.
- (void)writeFloat:(float)value
Parameters
- value
the float value to be written
Exceptions
- KMJMSException
if the JMS provider fails to write the message due to some internal error.
- KMMessageNotWriteableException
if the message is in read-only mode.
Declared In
KMStreamMessage.h
writeInt:
Writes an int to the stream message.
- (void)writeInt:(int)value
Parameters
- value
the int value to be written
Exceptions
- KMJMSException
if the JMS provider fails to write the message due to some internal error.
- KMMessageNotWriteableException
if the message is in read-only mode.
Declared In
KMStreamMessage.h
writeLong:
Writes a long to the stream message.
- (void)writeLong:(long long)value
Parameters
- value
the long value to be written
Exceptions
- KMJMSException
if the JMS provider fails to write the message due to some internal error.
- KMMessageNotWriteableException
if the message is in read-only mode.
Declared In
KMStreamMessage.h
writeObject:
Writes an object to the stream message.
- (void)writeObject:(NSObject *)value
Parameters
- value
the object to be written
Discussion
This method works only for the objectified primitive object types (Integer, Double, Long…), String objects, and byte arrays.
Exceptions
- KMJMSException
if the JMS provider fails to write the message due to some internal error.
- KMMessageFormatException
if the object is invalid.
- KMMessageNotWriteableException
if the message is in read-only mode.
Declared In
KMStreamMessage.h
writeShort:
Writes a short to the stream message.
- (void)writeShort:(short)value
Parameters
- value
the short value to be written
Exceptions
- KMJMSException
if the JMS provider fails to write the message due to some internal error.
- KMMessageNotWriteableException
if the message is in read-only mode.
Declared In
KMStreamMessage.h
writeString:
Writes a String to the stream message.
- (void)writeString:(NSString *)value
Parameters
- value
the String value to be written
Exceptions
- KMJMSException
if the JMS provider fails to write the message due to some internal error.
- KMMessageNotWriteableException
if the message is in read-only mode.
Declared In
KMStreamMessage.h