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\subsection*{NAME}

\noindent BLAST (RPC Blast Micro-Protocol)

\subsection*{SPECIFICATION}

\noindent 
S. O'Malley and L. Peterson.  A Dynamic Network Architecture.  {\it
ACM Transactions on Computer Systems 10}, 2 (May 1992), 110--143.


\medskip
\noindent  S. O'Malley and L. Peterson. {\it A New Methodology for
Implementing Network Software}, University of Arizona Tech Report
TR90-29, August 1990.

\medskip
\noindent  B. Welch. {\it The Sprite remote procedure call}. 
University of California at Berkeley, Tech Report UCB/CSD 86/302,
June 1986.

\subsection*{SYNOPSIS}

\noindent 
BLAST is a micro-protocol version of Sprite RPC's
fragmentation algorithm. The algorithm was extracted from Sprite and
made into a stand-alone protocol. BLAST takes a large message,
fragments it into smaller packets, and sends them. 
The maximum packet size accepted by BLAST (as returned by the GETMAXPACKET
control op) is the product of the maximum number of fragments handled
by BLAST (16 by default) and the optimal packet size of BLAST's lower
protocol. 

The receiver gathers all of the packets and sends a NACK if it has
reason to believe (through timeouts or other considerations) that
a packet has been dropped.
BLAST can handle any
number on outstanding messages between two hosts (buffer space
permitting, of course). The protocol is bi-directional; i.e., it
supports blasts in both directions over the same session. Small
messages take a short cut through the protocol and do not require the
allocation of any resources.  

The sender keeps a copy of the message
around until a timeout occurs or the higher level protocol that sent
the message notifies BLAST that it can free the message (through a
FREERESOURCES control op.)
Because the sending BLAST may timeout and release a message before all
fragments have been received, BLAST is not reliable. 
It is, however, very persistent.

\subsection*{REALM}

BLAST is in the ASYNC realm.

\subsection*{PARTICIPANTS}

BLAST neither removes nor adds anything to the participant stacks.

\subsection*{CONTROL OPERATIONS}

\begin{description}

\item[{\tt BLAST\_SETOUTSTANDINGMSGS:}]
Set the number of outstanding messages allowed (protocol only).
\begin{description}
\item[{\rm Input:}] {\tt int} 
\item[{\rm Output:}] none
\end{description}

\item[{\tt BLAST\_GETOUTSTANDINGMSGS:}]
Get the number of outstanding messages allowed (protocol only).
\begin{description}
\item[{\rm Input:}]  none
\item[{\rm Output:}] {\tt int} 
\end{description}

\end{description}

\subsection*{CONFIGURATION}

BLAST requires only its lower transport protocol.  Since BLAST doesn't
use host addresses, it can sit on top of protocols using different
address types without modification.

\subsection*{AUTHOR}

\noindent Sean O'Malley and Ed Menze