%include sasinit ;
goptions ftitle=simplex hpos=100 vpos=40 ;

title ls=5 ' ' ;
footnote h=1 c=blue f=simplex j=r '1';
proc gslide ;
note j=c c=black f=simplex h=2 'Techniques for writing a DECnet/VMS server' ;
note j=c c=black f=simplex h=2 'Bob Graham, Dow Chemical, La. Division' ;
note j=c c=black f=simplex h=2 'April, 1987' ;
run;

title h=2.5 c=black j=l ls=3 '  ' 'What you need to know' ;
footnote h=1 c=blue f=simplex j=r '2';
proc gslide ;
note h=1.8 c=green f=special '    J' c=blue f=simplex ' How to declare a network object' ;
note h=1.8 c=green f=special '    J' c=blue f=simplex ' How to use non-transparent network access ' ;
note h=1.8 c=green f=special '    J' c=blue f=simplex ' How to write AST driven program ';
note h=1.8 c=green f=special '    J' c=blue f=simplex ' How to debug a network process ';
run;

title h=2.5 c=black j=l ls=3 '  ' 'Why you would want to write a server';
footnote h=1 c=blue f=simplex j=r '3';
proc gslide ;
note h=2 c=green f=special '    J' c=blue f=simplex ' performance';
note h=2 c=green f=special '        J' c=blue f=simplex ' fast connect time';
note h=2 c=green f=special '        J' c=blue f=simplex ' no process creation';
note h=2 c=green f=special '        J' c=blue f=simplex ' no image activation';
note h=2 c=green f=special '        J' c=blue f=simplex ' no file opens, database init, etc.';
run;

footnote h=1 c=blue f=simplex j=r '4';
proc gslide ;
note h=2 c=green f=special '    J' c=blue f=simplex ' lower load on system';
note h=2 c=green f=special '        J' c=blue f=simplex ' one process instead of many';
note h=2 c=green f=special '        J' c=blue f=simplex ' reduces/eliminates locking';
note h=2 c=green f=special '        J' c=blue f=simplex ' easier to do caching';
run;

footnote h=1 c=blue f=simplex j=r '5';
proc gslide ;
note h=2 c=green f=special     '    J' c=blue f=simplex ' gain control over service';
note h=2 c=green f=special '        J' c=blue f=simplex ' eliminates access control for links';
note h=2 c=green f=special '        J' c=blue f=simplex ' can implement own security design';
note h=2 c=green f=special '        J' c=blue f=simplex ' can keep counters for usage logging';
run;

footnote h=1 c=blue f=simplex j=r '6';
proc gslide ;
note h=2   c=green f=special '    J'     c=blue f=simplex ' DOWDIR as an example';
note h=1.8 c=green f=special '        J' c=blue f=simplex ' needed fast method to look up MAIL users';
note h=1.8 c=green f=special '        J' c=blue f=simplex ' opening and reading keyed file across';
note h=1.8       f=special '         ' c=blue f=simplex '   the network was too slow';
note h=1.8 c=green f=special '        J' c=blue f=simplex ' having a copy on every node was unworkable';
note h=1.8 c=green f=special '        J' c=blue f=simplex ' DOWDIR has 6 servers for 600+ nodes';
note h=1.8 c=green f=special '        J' c=blue f=simplex ' response time depends mainly on number';
note h=1.8       f=special '         ' c=blue f=simplex '   of hops to server';
note h=1.8 c=green f=special '        J' c=blue f=simplex ' typically < 1 second for nearby server';
run;

title h=2.5 c=black j=l ls=3 '  ' 'Basic run-time scheme of server';
footnote h=1 c=blue f=simplex j=r '7';
proc gslide ;
note h=2 c=green f=special '    J' c=blue f=simplex ' process is created';
note h=2 c=green f=special '    J' c=blue f=simplex ' do application initialization';
note h=2 c=green f=special '        J' c=blue f=simplex ' open files';
note h=2 c=green f=special '        J' c=blue f=simplex ' load caches';
note h=2 c=green f=special '        J' c=blue f=simplex ' consistancy checks';
note h=2 c=green f=special '    J' c=blue f=simplex ' create network mailbox';
note h=2 c=green f=special '    J' c=blue f=simplex ' open channel to network';
note h=2 c=green f=special '    J' c=blue f=simplex ' declare network object';
run;

footnote h=1 c=blue f=simplex j=r '8';
proc gslide ;
note h=2 c=green f=special '    J' c=blue f=simplex ' wait for something to happen';
note h=2 c=green f=special '        J' c=blue f=simplex ' connect request arrives in mailbox';
note h=2 c=green f=special '        J' c=blue f=simplex ' connect is accepted or rejected'; 
note h=2 c=green f=special '        J' c=blue f=simplex ' processes transactions';
note h=2 c=green f=special '        J' c=blue f=simplex ' breaks link when done';
note h=2 c=green f=special '    J' c=blue f=simplex ' shutsdown when MSG$_  NETSHUT received';
run;

title h=2.5 c=black j=l ls=3 '  ' 'How to get the server started';
footnote h=1 c=blue f=simplex j=r '9';
proc gslide ;
note h=2 c=green f=special '    J' c=blue f=simplex ' at least two different methods';
note h=2 c=green f=special '    J' c=blue f=simplex " actual code doesn't HAVE to be different";
note h=2       f=special '     ' c=blue f=simplex '   for the two methods';
run;

title2 h=2.0 c=black j=l ls=1 '  ' 'with RUN command' ;
footnote h=1 c=blue f=simplex j=r '10';
proc gslide ;
note h=1.8 c=green f=special '        J' c=blue f=simplex ' RUN/DETACH command in SYSTARTUP.COM';
note h=1.8 c=green f=special '        J' c=blue f=simplex ' must run AFTER network is up';
note h=1.8 c=green f=special '            J' c=blue f=simplex ' after STARTNET.COM';
note h=1.8 c=rec f=special '            J' c=blue f=simplex ' synchronize on STARTNET job';
run;

footnote h=1 c=blue f=simplex j=r '11a';
proc gslide ;
note h=2 c=green f=special '        J' c=blue f=simplex ' Pros';
note h=2 c=green f=special '            J' c=blue f=simplex ' easy to do';
note h=2 c=green f=special '            J' c=blue f=simplex ' avoid expensive initialization code' ; 
note h=2 c=green f=special '            J' c=blue f=simplex ' retain context ' ;
note h=2 c=green f=special '             ' c=blue f=simplex '   updates forward to other servers';
note h=2 c=green f=special '            J' c=blue f=simplex " first connection doesn't wait";
note h=2       f=special '             ' c=blue f=simplex "   for process creation";
run;

footnote h=1 c=blue f=simplex j=r '11b';
proc gslide ;
note h=2 c=green f=special '        J' c=blue f=simplex ' Cons';
note h=2 c=green f=special '            J' c=blue f=simplex ' server always running, uses memory,';
note h=2       f=special '             ' c=blue f=simplex '   and balance set slot';
note h=2 c=green f=special '            J' c=blue f=simplex ' have to manually start if network is'; 
note h=2       f=special '             ' c=blue f=simplex '   shutdown and restarted';
run;

title2 h=2.0 c=black j=l ls=1 '  ' '"Pop-Up" Server' ; 
footnote h=1 c=blue f=simplex j=r '12';
proc gslide ;
note h=2 c=green f=special '        J' c=blue f=simplex ' Let DECnet create server process';
note h=2 c=green f=special '        J' c=blue f=simplex ' create UAF record, include';
note h=2 c=green f=special '         ' c=blue f=simplex '   LGICMD and network only access';
note h=2 c=green f=special '            J' c=blue f=simplex ' needs SYSNAM privilege';
note h=2 c=green f=special '        J' c=blue f=simplex ' define object including ';
note h=2 c=green f=special '         ' c=blue f=simplex '   username/password and image file';
note h=2 c=green f=special '        J' c=blue f=simplex ' LGICMD checks NCB for valid request ' ;
run;

footnote h=1 c=blue f=simplex j=r '13';
proc gslide ;
note h=2 c=green f=special '        J' c=blue f=simplex ' Pros';
note h=2 c=green f=special '            J' c=blue f=simplex ' server "pops up" when needed,';
note h=2 c=green f=special '             ' c=blue f=simplex '   goes away when not needed';
note h=2 c=green f=special '            J' c=blue f=simplex ' can create new server when is full';
note h=2 c=green f=special '        J' c=blue f=simplex ' Cons';
note h=2 c=green f=special '            J' c=blue f=simplex ' slightly more complicated to do';
note h=2 c=green f=special '            J' c=blue f=simplex ' first connection may take awhile';
note h=2 c=green f=special '            J' c=blue f=simplex ' initialization code done repeatedly';
run;

title h=2.5 c=black j=l ls=3 '  ' 'Non-transparent task-to-task concepts';
title2;
footnote h=1 c=blue f=simplex j=r '14';
proc gslide ;                                                               
note h=2 c=green f=special '    J' c=blue f=simplex ' $ASSIGN to create a channel to _  NET:';
note h=2 c=green f=special '        J' c=blue f=simplex ' creates a new NETnn device';
note h=2 c=green f=special '        J' c=blue f=simplex ' channel is communication path to DECnet';
note h=2 c=green f=special '        J' c=blue f=simplex " doesn't create a link";
note h=2 c=green f=special '        J' c=blue f=simplex ' can associate a mailbox to channel';
note h=2 c=green f=special '         ' c=blue f=simplex '   for special DECnet messages';
run;

footnote h=1 c=blue f=simplex j=r '15';
proc gslide ;
note h=2 c=green f=special '    J' c=blue f=simplex ' $QIO (IO$_  ACCESS) to create a link';
note h=2 c=green f=special '    J' c=blue f=simplex ' $QIO (IO$_  DEACCESS) to break link';
note h=2 c=green f=special '    J' c=blue f=simplex ' send/receive data is the same as transparent';
note h=2 c=green f=special '    J' c=blue f=simplex ' a non-tranparent task CAN communicate,';
note h=2 c=green f=special '     ' c=blue f=simplex '   with a transparent one';
run;

title h=2.5 c=black j=l ls=3 '  ' 'Create and open channel to network';
footnote h=1 c=blue f=simplex j=r '16';
proc gslide ;
note h=2 c=green f=special '    J' c=blue f=simplex ' $ASSIGN to "_  NET:" with associated mailbox';
note h=2 c=green f=special '    J' c=blue f=simplex ' network channel is used for control purposes, ';
note h=2 c=green f=special '     ' c=blue f=simplex '   not logical links';
note h=2 c=green f=special '        J' c=blue f=simplex ' declare self to be network object';
note h=2 c=green f=special '        J' c=blue f=simplex ' reject connection requests';
run;

footnote h=1 c=blue f=simplex j=r '17';
proc gslide ;
note h=2 c=green f=special '    J' c=blue f=simplex ' mailbox receives control messages';
note h=2 c=green f=special '        J' c=blue f=simplex ' connection requests';
note h=2 c=green f=special '        J' c=blue f=simplex ' network shutdown messages';
note h=2 c=green f=special '        J' c=blue f=simplex ' interrupt data';
note h=2 c=green f=special '    J' c=blue f=simplex ' easiest to do with LIB$ASN_  WTH_  MBX';
run;

footnote h=1 c=blue f=simplex j=r '18';
proc gslide ;
note h=2 c=green f=special '    J' c=blue f=simplex ' hints:';
note h=2 c=green f=special '        J' c=blue f=simplex " don't forget leading underscore,";
note h=2 c=blue c=blue f=simplex '            some joker may have logical "NET" defined' ; 
note h=2 c=green f=special '        J' c=blue f=simplex ' may define a logical name for mailbox';
note h=2 c=green f=special '            J' c=blue f=simplex ' other program can send control message' ; 
note h=2 c=green f=special '                J' c=blue f=simplex ' shutdown without shutting DECnet'; 
note h=2 c=green f=special '            J' c=blue f=simplex ' do $GETDVI on channel to get name';
note h=2 c=green f=special '            J' c=blue f=simplex ' use $CRELNM to create logical name';
run;

title h=2.5 c=black j=l ls=3 '  ' 'Declare network object';
footnote h=1 c=blue f=simplex j=r '19';
proc gslide ;
note h=2 c=green f=special '    J' c=blue f=simplex ' need SYSNAM to declare object number';
note h=2 c=green f=special '    J' c=blue f=simplex ' $QIO (IO$_  ACPCONTROL) on network channel';
note h=2 c=green f=special '    J' c=blue f=simplex ' other operations possible with this function,';
note h=2 c=green f=special '     ' c=blue f=simplex '   this is only one documented';
note h=2 c=blue f=simplex '        (8.6.2.10, VAX/VMS Networking Manual)';
note h=2 c=green f=special '    J' c=blue f=simplex ' P1 is 5 byte buffer, by descriptor';
note h=2 c=green f=special '    J' c=blue f=simplex ' buffer and descriptor must be READ/WRITE';
note h=2 c=green f=special '    J' c=blue f=simplex ' see $NFBDEF macro in SYS$LIBRARY:LIB.MLB';
run;

footnote h=1 c=blue f=simplex j=r '20';
proc gslide ;
note h=2 c=green f=special '    J' c=blue f=simplex ' if started via RUN, then translate logical name';
note h=2 c=blue c=blue f=simplex'        or hardcode the object number';
note h=2 c=green f=special '    J' c=blue f=simplex ' "pop-up" server can get object number from NCB'; 
note h=2 c=green f=special '        J' c=blue f=simplex ' translate SYS$NET to get NCB';
note h=2 c=green f=special '        J' c=blue f=simplex ' destination descriptor is last part of NCB';
note h=2 c=green f=special '    J' c=blue f=simplex ' $CANCEL on channel removes object definition';
run;

title h=2.5 c=black j=l ls=3 '  ' 'Mailbox operations';
footnote h=1 c=blue f=simplex j=r '21';
proc gslide ;
note h=2 c=green f=special '    J' c=blue f=simplex ' always have a read posted, or';
note h=2 c=green f=special '     ' c=blue f=simplex '   have write-attention AST posted';
note h=2 c=green f=special '    J' c=blue f=simplex ' messages have fixed format ';
note h=2 c=green f=special '     ' c=blue f=simplex '   (8.6.1.2 in VAX/VMS Network Manual)';
note h=2 c=green f=special '    J' c=blue f=simplex ' first word in message indicates the type';
note h=2 c=green f=special '        J' c=blue f=simplex ' types are defined in $MSGDEF';
note h=2 c=green f=special '            J' c=blue f=simplex ' MSG$_  CONNECT - connection request';
note h=2 c=green f=special '            J' c=blue f=simplex ' MSG$_  NETSHUT - network shutting down';
note h=2 c=green f=special '            J' c=blue f=simplex ' MSG$_  INTMSG  - interrupt data';
note h=2 c=green f=special '            J' c=blue f=simplex ' link failures';
run;

footnote h=1 c=blue f=simplex j=r '22';
proc gslide ;
note h=2 c=green f=special '    J' c=blue f=simplex ' second word is unit number of NET device';
note h=2 c=green f=special '    J' c=blue f=simplex ' device name, as counted string';
note h=2 c=green f=special '        J' c=blue f=simplex ' always "NET" for DECnet mailboxes';
note h=2 c=green f=special '    J' c=blue f=simplex ' identifies link device (NETnn)';
note h=2 c=green f=special '        J' c=blue f=simplex ' for interrupt data and link failure messages';
note h=2 c=green f=special '        J' c=blue f=simplex ' why connect routine should get unit number';
run;

footnote h=1 c=blue f=simplex j=r '23';
proc gslide ;
note h=2 c=green f=special '    J' c=blue f=simplex ' rest of message is data as counted string';
note h=2 c=green f=special '        J' c=blue f=simplex ' NCB for MSG$_  CONNECT';
note h=2 c=green f=special '    J' c=blue f=simplex ' easiest to have single mailbox associated ';
note h=2 c=green f=special '        J' c=blue f=simplex ' with network control channel';
note h=2 c=green f=special '        J' c=blue f=simplex ' and all active links';
run;

title h=2.5 c=black j=l ls=3 '  ' 'Connect request';
footnote h=1 c=blue f=simplex j=r '24';
proc gslide ;                         
note h=2 c=green f=special '    J' c=blue f=simplex ' extract NCB from mailbox message';
note h=2 c=green f=special '    J' c=blue f=simplex ' can extract optional data from NCB';
note h=2 c=green f=special '        J' c=blue f=simplex ' protocol version levels';
note h=2 c=green f=special '        J' c=blue f=simplex ' buffer sizes supported';
note h=2 c=green f=special '        J' c=blue f=simplex ' special privileges, access modes, etc.';
run;

footnote h=1 c=blue f=simplex j=r '25';
proc gslide ;
note h=2 c=green f=special '    J' c=blue f=simplex ' reject if insufficient resources';
note h=2 c=green f=special '        J' c=blue f=simplex ' QIO (IO$_  ACCESS .or. IO$M_  ABORT)';
note h=2 c=green f=special '        J' c=blue f=simplex ' on network control channel';
note h=2 c=green f=special '        J' c=blue f=simplex ' NCB is P1 parameter';
run;

footnote h=1 c=blue f=simplex j=r '26';
proc gslide ;
note h=2 c=green f=special '    J' c=blue f=simplex ' accept if sufficient resources';
note h=2 c=green f=special '        J' c=blue f=simplex ' assign another channel to "_  NET:"';
note h=2 c=green f=special '        J' c=blue f=simplex ' use network control channel mailbox';
note h=2 c=green f=special '        J' c=blue f=simplex ' initialize link context';
note h=2 c=green f=special '            J' c=blue f=simplex ' zero counters';
note h=2 c=green f=special '            J' c=blue f=simplex ' store protocol version, etc.';
note h=2 c=green f=special '            J' c=blue f=simplex ' flag link as INITIALIZING';
run;

footnote h=1 c=blue f=simplex j=r '27';
proc gslide ;
note h=2 c=green f=special '        J' c=blue f=simplex ' get the unit number of the NETnn device';
note h=2 c=green f=special '            J' c=blue f=simplex ' see note about link failure messages';
note h=2 c=green f=special '        J' c=blue f=simplex ' accept link $QIO (IO$_  ACCESS)';
note h=2 c=green f=special '            J' c=blue f=simplex ' P1 is NCB';
note h=2 c=green f=special '            J' c=blue f=simplex ' modify NCB to send optional data back';
note h=2 c=green f=special '        J' c=blue f=simplex ' completion AST posts read on link';
run;

title h=2.5 c=black j=l ls=3 '  ' 'Process transactions';
footnote h=1 c=blue f=simplex j=r '28';
proc gslide ;
note h=2 c=green f=special '    J' c=blue f=simplex ' driven by READ completion AST '; 
note h=2 c=green f=special '    J' c=blue f=simplex ' simplest - $WAKE the process';
note h=2 c=green f=special '        J' c=blue f=simplex ' mainline scans links for completed reads';
note h=2 c=green f=special '        J' c=blue f=simplex ' processes each one request';
note h=2 c=green f=special '        J' c=blue f=simplex ' goes back to $HIBER';
note h=2 c=green f=special '    J' c=blue f=simplex ' variation would be to queue requests';
note h=2 c=green f=special '        J' c=blue f=simplex ' mainline code could do them FIFO';
run;

footnote h=1 c=blue f=simplex j=r '29';
proc gslide ;
note h=2 c=green f=special '    J' c=blue f=simplex ' Most sophisticated - be completely AST driven';
note h=2 c=green f=special '        J' c=blue f=simplex ' read completion AST processes request';
note h=2 c=green f=special '        J' c=blue f=simplex ' request would have to be done in AST mode';
note h=2 c=green f=special '        J' c=blue f=simplex ' for example:';
note h=2 c=green f=special '            J' c=blue f=simplex ' access an RMS file with multiple streams';
note h=2 c=green f=special '             ' c=blue f=simplex '   and RAB$M_  ASY (asynchronous I/O) set';
run;

footnote h=1 c=blue f=simplex j=r '30';
proc gslide ;
note h=2 c=green f=special '    J' c=blue f=simplex ' response via $QIO to link (IO$_  WRITEVBLK)';
note h=2 c=green f=special '    J' c=blue f=simplex ' WRITE completion AST posts the next read';
note h=2 c=green f=special '    J' c=blue f=simplex ' WRITE and READ ASTs check IOSB status';
note h=2 c=green f=special '        J' c=blue f=simplex ' disconnect link if I/O failed' ;
run;

title h=2.5 c=black j=l ls=3 '  ' 'Disconnecting links';
footnote h=1 c=blue f=simplex j=r '31';
proc gslide ;
note h=2 c=green f=special '    J' c=blue f=simplex ' by doing $DASSGN on link channel'; 
note h=2 c=green f=special '    J' c=blue f=simplex ' or $QIO (IO$_  DEACCESS), keeps channel';
note h=2 c=green f=special '    J' c=blue f=simplex ' done for several reasons';
note h=2 c=green f=special '        J' c=blue f=simplex ' receive failure/disconnect mbx message';
note h=2 c=green f=special '        J' c=blue f=simplex ' IOSB status on link I/O indicates failure';
note h=2 c=green f=special '        J' c=blue f=simplex ' can have inactivity timeout on links';
note h=2 c=green f=special '            J' c=blue f=simplex ' links are cheap to create';
note h=2 c=green f=special '            J' c=blue f=simplex ' limited number of links possible';
note h=2 c=green f=special '            J' c=blue f=simplex ' remote process just creates new link';
run;

title h=2.5 c=black j=l ls=3 '  ' 'Link context';
footnote h=1 c=blue f=simplex j=r '32';
proc gslide ;
note h=2 c=green f=special '    J' c=blue f=simplex " pass pointer to context data as ";
note h=2 c=green f=special '     ' c=blue f=simplex " AST parameter to completion AST's";
note h=2 c=green f=special '    J' c=blue f=simplex ' possible context variables';
note h=2 c=green f=special '        J' c=blue f=simplex ' channel number for link';
note h=2 c=green f=special '        J' c=blue f=simplex ' unit number of link NETnn device';
note h=2 c=green f=special '        J' c=blue f=simplex ' I/O status block and buffer';
note h=2 c=green f=special '        J' c=blue f=simplex ' link state ( ACTIVE, PENDING, ... )';
note h=2 c=green f=special '        J' c=blue f=simplex ' protocol version being used';
note h=2 c=green f=special '        J' c=blue f=simplex ' link counters';
note h=2 c=green f=special '        J' c=blue f=simplex ' RAB to database file';
run;

title h=2.5 c=black j=l ls=3 '  ' 'Debugging your server';
footnote h=1 c=blue f=simplex j=r '33';
proc gslide ;
note h=2 c=green f=special '    J' c=blue f=simplex ' have the proper privileges (at least SYSNAM)';
note h=2 c=green f=special '    J' c=blue f=simplex ' two terminal method';
note h=2 c=green f=special '        J' c=blue f=simplex ' RUN the server from one terminal';
note h=2 c=green f=special '        J' c=blue f=simplex ' RUN remote program from another terminal';
note h=2 c=green f=special '    J' c=blue f=simplex ' single terminal method';
note h=2 c=green f=special '        J' c=blue f=simplex ' RUN the server from the terminal';
note h=2 c=green f=special '        J' c=blue f=simplex ' do SPAWN from the debugger';
note h=2 c=green f=special '        J' c=blue f=simplex ' RUN remote program from the subprocess';
note h=2 c=green f=special '        J' c=blue f=simplex ' ATTACH between the two';
run;