.TH DISGEN 1 "1 November 1995"
.SH NAME
disgen \- DIS protocol compiler
.SH SYNOPSIS
.BI disgen " infile"
.br
.B disgen
[
.BI \-D name [= value ]
] [
.B \-I
[
.BI \-K " seconds"
] ] [
.B \-L
] [
.B \-T
]
.I infile
.br
.B disgen
.B "\-c \|| \|\-h \|| \|\-l \|| \|\-m \|| \|\-t"
[
.BI \-o " outfile"
]
[
.I infile
]
.br
.B disgen
.B \-s
.I transport
[
.BI \-o " outfile"
]
[
.I infile
]
.SH DESCRIPTION
.IX "compilers" disgen "" "\fLdisgen\fR \(em generate RPC protocols, C header files"
.IX disgen "" "\fLdisgen\fR \(em generate RPC protocol, C header files, and server skeleton"
.IX RPC "generate protocols \(em \fLdisgen\fR"
.LP
.B disgen
generates C code to implement the
.SM Distributed Interactive Simulation
protocol.
The input to
.B disgen
is a language similar to C
known as the
.SM RPC
Language (Remote Procedure Call Language).
Information about the syntax of
.SM RPC
Language is available in the
.RI ` rpcgen ' " Programming Guide"
in the
.TX NETP
manual.
.LP
.B disgen
is normally used as in the first synopsis where it takes an input file
and generates four output files.
If the
.I infile
is named
.BR proto.x ,
then
.B disgen
generates a header file in
.BR proto.h ,
.SM XDR
routines in
.BR proto_xdr.c ,
server side stubs in
.BR proto_svc.c ,
and client side stubs in
.BR proto_clnt.c .
With the
.B \-T
option, it also generates the
.SM RPC
dispatch table in
.BR proto_tbl.i .
.LP 
The second synposis provides special features which
allow for the creation of more sophisticated
.SM RPC
servers.
These features include support for
.SM RPC
dispatch tables,
and user provided
.BR #defines .
The entries in the
.SM RPC
dispatch table contain:
.LP
.RS
.PD 0
.TP 3
\(bu
pointers to the service routine corresponding
to that procedure
.TP
\(bu
a pointer to the input and output arguments
.TP
\(bu
the size of these routines
.PD
.RE
.LP
A server can use the dispatch table to check authorization
and then to execute the service routine;
a client library may use it to deal with the details
of storage management and
.SM XDR
data conversion.
.LP
The other two synopses shown above are used when one does not want to
generate all the output files, but only a particular one. Their
usage is described in the
.SM EXAMPLES
section below.
.LP
The C-preprocessor,
.BR cpp (1),
is run on the input file before it is actually
interpreted by
.BR disgen ,
so all the
.B cpp
directives are legal within an
.B disgen
input file. For each type of output file,
.B disgen
defines a special
.B cpp
symbol for use by the
.B disgen
programmer:
.LP
.RS
.PD 0
.TP 12
.SB RPC_HDR
defined when compiling into header files
.TP
.SB RPC_XDR
defined when compiling into
.SM XDR
routines
.TP
.SB RPC_SVC
defined when compiling into server side stubs
.TP
.SB RPC_CLNT
defined when compiling into client side stubs
.TP
.SB RPC_TBL
defined when compiling into
.SM RPC
dispatch tables
.PD
.RE
.LP
In addition,
.B disgen
does a little preprocessing of its own.
Any line beginning with
.RB ` % '
is passed directly into the output file, uninterpreted by
.BR disgen .
For every data type referred to in
.IR infile ,
.B disgen
assumes that there exists a routine with the string
.RB ` xdr_ '
prepended to the data type.
If this routine does not exist in the
.SM RPC/XDR
library, it must be provided.
Providing an undefined data type
allows customization of
.SM XDR
routines.
.SH OPTIONS
.TP 12
.B \-c
Compile into
.SM XDR
routines.
.TP
.BI \-D name [= value ]
Define a symbol
.IR name .
Equivalent to the
.B #define
directive in the source.
If no
.I value
is given,
.I name
is defined as 1.
This option may be called more than once.
.TP
.B \-h
Compile into C data-definitions (a header file).
The
.B \-T
option can be used in conjunction to produce a header file which supports
.SM RPC
dispatch tables.
.TP
.B \-I
Compile support for
.BR inetd (8C)
in the server side stubs.
Such servers can be self started or can be started by
.BR inetd .
When the server is self-started, it backgrounds itself by default.
A special define symbol
.SB RPC_SVC_FG
can be used to run the server process in foreground, or alternately the
user may just compile it without the
.B \-I
option.
If there are no pending client requests, the
.B inetd
servers exit after 120 seconds (default).
The default can be changed with the
.B \-K
option.
All the error messages for
.B inetd
servers are always logged in with
.BR syslog (3).
.TP
.BI \-K " seconds"
If the server was started by
.BR inetd ,
specify the time in seconds after which the server should exit if there is
no further activity.
This option is useful for customization.
If
.I seconds
is 0, the server exits after serving that given request.
If
.I seconds
is
\-1, the server hangs around for ever after being started by
.BR inetd .
This option is valid only with the
.B \-I
option.
.TP
.B \-l
Compile into client side stubs.
.TP
.B \-L
When the servers are started in foreground, use
.B syslog(\|)
to log the server errors instead of printing them on the standard error.
.TP
.B \-m
Compile into server side stubs, but do not generate a \*(lqmain\*(rq routine.
This option is useful for doing callback-routines and for people who
need to write their own \*(lqmain\*(rq routine to do initialization.
For
.B inetd
support, they should be compiled with the
.B \-I
option. In such cases, it defines 2 global variables:
.B _rpcpmstart
and
.BR _rpcfdtype .
The value of
.B _rpcpmstart
should be 1 or 0 depending upon whether it was started by
.B inetd
or not. The value of
.B _rpcfdtype
should be
.SB SOCK_STREAM
or
.SB SOCK_DGRAM
depending upon the type of the connection.
.TP
.BI \-o " outfile"
Specify the name of the output file.
If none is specified, the standard output is used
.RB ( \-c ,
.BR \-h ,
.BR \-l ,
.BR \-m ,
.B \-s
and
.B \-t
modes only).
.TP
.BI \-s " transport"
Compile into server side stubs for the given transport.
The supported transports are
.B udp
and
.BR tcp .
This option may be called more than once
so as to compile a server that serves multiple transports.
For
.B inetd
support, they should be compiled with the
.B \-I
option.
.TP
.B \-t
Compile into
.SM RPC
dispatch table.
.TP
.B \-T
Generate the code to support
.SM RPC
dispatch tables.
.LP
The options 
.BR \-c ,
.BR \-h ,
.BR \-l ,
.BR \-m ,
.B \-s
and
.B \-t
are used exclusively to generate a particular type of file, while the options
.BR \-D ,
.BR \-I ,
.B \-L
and
.B \-T
are global and can be used with the other options.
.br
.ne 5
.SH EXAMPLES
.LP
The following example generates all the five files:
.BR prot.h,
.BR prot_clnt.c ,
.BR prot_svc.c ,
.B prot_xdr.c
and
.BR prot_tbl.i .
The server error messages are logged, instead of being sent
to the standard error.
.IP
.ft B
example% disgen \-LT prot.x
.ft R
.LP
The following example generates
.BR prot.h ,
.BR prot_clnt.c ,
.B prot_xdr.c
and
.BR prot_svc.c .
.B prot_svc.c
supports server invocation by
.BR inetd .
If the server is started by
.BR inetd ,
the server exits after 20 seconds of inactivity.
.IP
.ft B
example% disgen \-I \-K 20 prot.x
.ft R
.LP
The following example sends the header file
(with support for dispatch tables)
on the standard output.
.IP
.ft B
example% disgen \-hT prot.x
.ft R
.LP
The following example sends the server side stubs
file for the transport
.B tcp
on the standard output.
.IP
.ft B
example% disgen \-s tcp prot.x
.ft R
.SH "SEE ALSO"
.BR cpp (1),
.BR rpc (3N),
.BR inetd (8C)
.LP
.RI ` disgen ' " Programming Guide"
in
.TX NETP
.br
.ne 7
.SH BUGS
.LP
The
.SM RPC
Language does not support nesting of structures.
As a work-around,
structures can be declared at the top-level,
and their name used inside other structures in
order to achieve the same effect.
.LP
Name clashes can occur when using program definitions, since the apparent
scoping does not really apply.
Most of these can be avoided by giving
unique names for programs, versions, procedures and types.