TMessage

 Create a TMessage object for storing objects. The "what" integer
 describes the type of message. Predifined ROOT system message types
 can be found in MessageTypes.h. Make sure your own message types are
 unique from the ROOT defined message types (i.e. 0 - 10000 are
 reserved by ROOT). In case you OR "what" with kMESS_ACK, the message
 will wait for an acknowledgement from the remote side. This makes
 the sending process synchronous. In case you OR "what" with kMESS_ZIP,
 the message will be compressed in TSocket using the zip algorithm
 (only if message is > 256 bytes).

 Create a TMessage object for reading objects. The objects will be
 read from buf. Use the What() method to get the message type.

 Clean up compression buffer.

 Change a buffer that was received into one that can be send, i.e.
 forward a just received message.

 Reset the message buffer so we can use (i.e. fill) it again.

 Set the message length at the beginning of the message buffer.
 This method is only called by TSocket::Send().

 Using this method one can change the message type a-posteriory.
 In case you OR "what" with kMESS_ACK, the message will wait for
 an acknowledgement from the remote side. This makes the sending
 process synchronous.

 Set the message compression level. Can be between 0 and 9 with 0
 being no compression and 9 maximum compression. In general the default
 level of 1 is the best compromise between achieved compression and
 cpu time. Compression will only happen when the message is > 256 bytes.

 Compress the message. The message will only be compressed if the
 compression level > 0 and the if the message is > 256 bytes.
 Returns -1 in case of error (when compression fails or
 when the message increases in size in some pathological cases),
 otherwise returns 0.

 Uncompress the message. The message will only be uncompressed when
 kMESS_ZIP is set. Returns -1 in case of error, 0 otherwise.

 TMessage objects cannot be copied or assigned