ken@gvax.cs.cornell.edu (Ken Birman) (10/03/90)
A few postings back I indicated that our research effort is moving in a
new direction, towards a thorough system redesign for ISIS aimed at
simplifying the overall system architecture and taking better advantage
of features of "nucleus" operating systems like Mach and Chorus.
I've gotten a few inquiries about this from readers of this group who track
technologies, asking if we have anything written on this yet. We don't
(yet), but I have been sending out a short 3-page summary of our thinking.
I'm including the postscript of this below.
The summary does not include any discussion of products planned by ISIS V3.0
Isis Distributed Systems. We recognize that these plans are of more
immediate relevance for those of who are trying to figure out how (if)
to use ISIS in your organization, but we expect such issues to be addressed
by the IDS product announcement itself.
==== clip here, print to any post-script printer ====
%!PS-Adobe-2.0
%%Creator: dvips by Radical Eye Software
%%Title: isummary.dvi
%%Pages: 3 1
%%BoundingBox: 0 0 612 792
%%EndComments
%%BeginDocument: tex.pro
/TeXDict 200 dict def TeXDict begin /bdf{bind def}def /Inch{Resolution mul}
bdf /Dots{72 div Resolution mul}bdf /dopage{72 Resolution div dup neg scale
translate}bdf /@letter{Resolution dup -10 mul dopage}bdf /@note{@letter}bdf
/@a4{Resolution dup -10.6929133858 mul dopage}bdf /@translate{translate}bdf
/@scale{scale}bdf /@rotate{rotate}bdf /@landscape{[0 1 -1 0 0 0]concat
Resolution dup dopage}bdf /@legal{Resolution dup -13 mul dopage}bdf
/@manualfeed{statusdict /manualfeed true put}bdf /@copies{/#copies exch def}
bdf /@FontMatrix[1 0 0 -1 0 0]def /@FontBBox[0 0 1 1]def /dmystr(ZZf@@)def
/newname{dmystr cvn}bdf /df{/fontname exch def dmystr 2 fontname cvx(@@@)cvs
putinterval newname 7 dict def newname load begin /FontType 3 def /FontMatrix
@FontMatrix def /FontBBox @FontBBox def /BitMaps 256 array def /BuildChar{
CharBuilder}def /Encoding TeXEncoding def end fontname{/foo setfont}2 array
copy cvx def fontname load 0 dmystr 5 string copy cvn cvx put}bdf /dfe{
newname newname load definefont setfont}bdf /ch-image{ch-data 0 get}bdf
/ch-width{ch-data 1 get}bdf /ch-height{ch-data 2 get}bdf /ch-xoff{ch-data 3
get}bdf /ch-yoff{ch-data 4 get}bdf /ch-tfmw{ch-data 5 get}bdf /CharBuilder{
save 3 1 roll exch /BitMaps get exch get /ch-data exch def ch-data null ne{
ch-tfmw 0 ch-xoff neg ch-yoff neg ch-width ch-xoff sub ch-height ch-yoff sub
setcachedevice ch-width ch-height true[1 0 0 1 ch-xoff ch-yoff]{ch-image}
imagemask}if restore}bdf /dc{/ch-code exch def dup 0 get length 1 lt{pop[<00>
1 1 0 0 8.00]}if /ch-data exch def newname load /BitMaps get ch-code ch-data
put}bdf /bop{gsave /SaveImage save def pagesize 0 0 moveto}def /eop{clear
SaveImage restore showpage grestore}bdf /@start{/Resolution exch def
/TeXEncoding 256 array def 0 1 255{TeXEncoding exch 1 string dup 0 3 index put
cvn put}for}bdf /p{show}bdf /RuleMatrix[1 0 0 -1 0 -1]def /BlackDots 8 string
def /v{gsave currentpoint translate false RuleMatrix{BlackDots}imagemask
grestore}bdf /a{moveto}bdf /delta 0 def /tail{dup /delta exch def 0 rmoveto}
bdf /b{exch p tail}bdf /c{p delta 4 sub tail}bdf /d{p delta 3 sub tail}bdf /e{
p delta 2 sub tail}bdf /f{p delta 1 sub tail}bdf /g{p delta 0 rmoveto}bdf /h{
p delta 1 add tail}bdf /i{p delta 2 add tail}bdf /j{p delta 3 add tail}bdf /k{
p delta 4 add tail}bdf /l{p -4 0 rmoveto}bdf /m{p -3 0 rmoveto}bdf /n{p -2 0
rmoveto}bdf /o{p -1 0 rmoveto}bdf /q{p 1 0 rmoveto}bdf /r{p 2 0 rmoveto}bdf /s
{p 3 0 rmoveto}bdf /t{p 4 0 rmoveto}bdf /w{0 rmoveto}bdf /x{0 exch rmoveto}
bdf /y{3 -1 roll p moveto}bdf /bos{/section save def}bdf /eos{clear section
restore}bdf /SDict 200 dict def SDict begin /@SpecialDefaults{/hs 8.5 Inch def
/vs 11 Inch def /ho 0 def /vo 0 def /hsc 1 def /vsc 1 def /ang 0 def /CLIP
false def /BBcalc false def}bdf /@hsize{/hs exch def /CLIP true def}bdf
/@vsize{/vs exch def /CLIP true def}bdf /@hoffset{/ho exch def}bdf /@voffset{
/vo exch def}bdf /@hscale{@scaleunit div /hsc exch def}bdf /@vscale{
@scaleunit div /vsc exch def}bdf /@angle{/ang exch def}bdf /@scaleunit 100 def
/@rwi{10 div /rwi exch def}bdf /@llx{/llx exch def}bdf /@lly{/lly exch def}
bdf /@urx{/urx exch def}bdf /@ury{/ury exch def /BBcalc true def}bdf
/@setclipper{BBcalc{rwi urx llx sub div dup scale llx neg lly neg translate}{
hsc vsc scale}ifelse CLIP{newpath 0 0 moveto hs 0 rlineto 0 vs rlineto hs neg
0 rlineto closepath clip}{initclip}ifelse}bdf end /@MacSetUp{userdict /md
known{userdict /md get type /dicttype eq{md begin /letter{}def /note{}def
/legal{}def /od{txpose 1 0 mtx defaultmatrix dtransform exch atan/pa exch def
newpath clippath mark{transform{itransform moveto}}{transform{itransform
lineto}}{6 -2 roll transform 6 -2 roll transform 6 -2 roll transform{
itransform 6 2 roll itransform 6 2 roll itransform 6 2 roll curveto}}{{
closepath}}pathforall newpath counttomark array astore /gc xdf pop ct 39 0 put
10 fz 0 fs 2 F/|______Courier fnt invertflag{PaintBlack}if}def /txpose{pxs pys
scale ppr aload pop por{noflips{pop exch neg exch translate pop 1 -1 scale}if
xflip yflip and{pop exch neg exch translate 180 rotate 1 -1 scale ppr 3 get
ppr 1 get neg sub neg ppr 2 get ppr 0 get neg sub neg translate}if xflip yflip
not and{pop exch neg exch translate pop 180 rotate ppr 3 get ppr 1 get neg sub
neg 0 translate}if yflip xflip not and{ppr 1 get neg ppr 0 get neg translate}
if}{noflips{translate pop pop 270 rotate 1 -1 scale}if xflip yflip and{
translate pop pop 90 rotate 1 -1 scale ppr 3 get ppr 1 get neg sub neg ppr 2
get ppr 0 get neg sub neg translate}if xflip yflip not and{translate pop pop
90 rotate ppr 3 get ppr 1 get neg sub neg 0 translate}if yflip xflip not and{
translate pop pop 270 rotate ppr 2 get ppr 0 get neg sub neg 0 exch translate}
if}ifelse scaleby96{ppr aload pop 4 -1 roll add 2 div 3 1 roll add 2 div 2
copy translate .96 dup scale neg exch neg exch translate}if}def /cp{pop pop
showpage pm restore}def end}if}if}def /psf$TeXscale{65536 div}def /startTexFig
{/psf$SavedState save def userdict maxlength dict begin Resolution 72 div dup
neg scale currentpoint translate /psf$ury exch psf$TeXscale def /psf$urx exch
psf$TeXscale def /psf$lly exch psf$TeXscale def /psf$llx exch psf$TeXscale def
/psf$y exch psf$TeXscale def /psf$x exch psf$TeXscale def currentpoint /psf$cy
exch def /psf$cx exch def /psf$sx psf$x psf$urx psf$llx sub div def /psf$sy
psf$y psf$ury psf$lly sub div def psf$sx psf$sy scale psf$cx psf$sx div
psf$llx sub psf$cy psf$sy div psf$ury sub translate /showpage{}def /erasepage{
}def /copypage{}def @MacSetUp}def /doclip{psf$llx psf$lly psf$urx psf$ury
currentpoint 6 2 roll newpath 4 copy 4 2 roll moveto 6 -1 roll exch lineto
exch lineto exch lineto closepath clip newpath moveto}def /endTexFig{end
psf$SavedState restore}def /@beginspecial{SDict begin /SpecialSave save def
gsave Resolution 72 div dup neg scale currentpoint translate @SpecialDefaults}
bdf /@setspecial{ho vo translate @setclipper ang rotate /showpage{}def newpath
}bdf /@endspecial{grestore clear SpecialSave restore end}bdf /@defspecial{
SDict begin}bdf /@fedspecial{end}bdf /li{lineto}bdf /rl{rlineto}bdf /rc{
rcurveto}bdf /np{/SaveX currentpoint /SaveY exch def def newpath}bdf /st{
stroke SaveX SaveY moveto}bdf /fil{fill SaveX SaveY moveto}bdf /ellipse{
/endangle exch def /startangle exch def /yrad exch def /xrad exch def
/savematrix matrix currentmatrix def translate xrad yrad scale 0 0 1
startangle endangle arc savematrix setmatrix}bdf end
%%EndDocument
TeXDict begin 300 @start /fa df[<FFFFE0FFFFE003F80003F80003F80003F80003F80003
F80003F80003F80003F80003F80003F80003F80003F80003F80003F80003F80003F80003F80003
F80003F80003F80003F80003F80003F80003F80003F80003F80003F80003F80003F800FFFFE0FF
FFE0>19 34 -1 0 21]73 dc[<FFFF800FF0FFFF803FF807F000FF0C07F000FE0607F001FC0607
F001FC0007F001FC0007F001FC0007F001FC0007F001FC0007F001FC0007F001FC0007F001FC00
07F003F80007F007F00007F00FE00007FFFF800007FFFFC00007F007F00007F001F80007F000FC
0007F0007E0007F0007F0007F0007F0007F0007F0007F0007F0007F0007F0007F0007F0007F000
7E0007F000FC0007F001F80007F007F000FFFFFFC000FFFFFE0000>39 34 -2 0 42]82 dc[<03
FFFFF80003FFFFF8000003F800000003F800000003F800000003F800000003F800000003F80000
0003F800000003F800000003F800000003F800000003F800000003F800000003F800000003F800
000003F800000003F800000003F800000003F800000003F800000003F80000C003F800C0C003F8
00C0C003F800C0C003F800C0E003F801C0E003F801C06003F801807003F803807803F807807E03
F80F807FFFFFFF807FFFFFFF80>34 34 -2 0 39]84 dc[<01FC7FC007FF7FC00F83FE001E00FE
003E007E007C007E007C007E00FC007E00FC007E00FC007E00FC007E00FC007E00FC007E00FC00
7E00FC007E007C007E007E007E003E007E001F00FE000F81FE0007FF7E0001FC7E0000007E0000
007E0000007E0000007E0000007E0000007E0000007E0000007E0000007E0000007E0000007E00
0003FE000003FE00>26 35 -2 0 31]100 dc[<00FF0003FFC00FC0701F00303E00187E00007C
00007C0000FC0000FC0000FC0000FFFFF8FFFFF8FC00F8FC00F87C00F87C00F03E01F01E01E00F
87C007FF8000FE00>21 22 -2 0 26]101 dc[<01FFC0000FFFF8001F80FC007E003F007C001F
00F8000F80F8000F80F8000F8078001F807C003F801FFFFF0007FFFF000FFFFE001FFFF8001FFF
E0001C000000180000001800000009FE00000FFF80000F87C0001F03E0001E01E0003E01F0003E
01F0003E01F0003E01F0003E01F0001E01E0001F03E7800F87C78007FFBF8001FE0F00>25 33
-1 11 28]103 dc[<FFF1FFC0FFF1FFC01F807E001F807E001F807E001F807E001F807E001F80
7E001F807E001F807E001F807E001F807E001F807E001F807E001F807E001F807E001FC07E001F
C07E001FA07C001F98FC001F8FF8001F87E0001F8000001F8000001F8000001F8000001F800000
1F8000001F8000001F8000001F8000001F8000001F800000FF800000FF800000>26 35 -2 0 31
]104 dc[<FFF0FFF01F801F801F801F801F801F801F801F801F801F801F801F801F801F801F80
1F801F801F80FF80FF8000000000000000000000000000000E001F003F803F803F801F000E00>
12 36 -1 0 15]105 dc[<FFF1FFC0FFF1FFC01F807E001F80FC001F81F8001F83F0001F83F000
1F87E0001F8FC0001F8FC0001FDF80001FFF00001FBE00001F9E00001F8E00001F8700001F8380
001F80C0001F8070001F8038001F80FF801F80FF801F8000001F8000001F8000001F8000001F80
00001F8000001F8000001F8000001F8000001F8000001F800000FF800000FF800000>26 35 -2
0 30]107 dc[<FFF0FFF01F801F801F801F801F801F801F801F801F801F801F801F801F801F80
1F801F801F801F801F801F801F801F801F801F801F801F801F801F801F801F801F80FF80FF80>
12 35 -1 0 15]108 dc[<FFF1FFC0FFF1FFC01F807E001F807E001F807E001F807E001F807E00
1F807E001F807E001F807E001F807E001F807E001F807E001F807E001F807E001F807E001FC07E
001FC07E001FA07C001F98FC00FF8FF800FF87E000>26 22 -2 0 31]110 dc[<00FE0007FFC0
0F83E01F01F03E00F87C007C7C007CFC007EFC007EFC007EFC007EFC007EFC007EFC007E7C007C
7C007C7C007C3E00F81E00F00F83E007FFC000FE00>23 22 -2 0 28]111 dc[<C7F000EFFC00
FC1E00F00700E00780E00780C00780C00F80003F8007FF001FFF003FFE007FFC00FFF000FF0000
F80000F00300F00300700700780F001FFF0007F300>17 22 -2 0 22]115 dc[<00FC0003FE00
07E30007C1800FC1800FC1800FC1800FC1800FC1800FC0000FC0000FC0000FC0000FC0000FC000
0FC0000FC0000FC0000FC0000FC000FFFF00FFFF001FC0000FC00007C00003C00001C00001C000
00C00000C00000C00000C000>17 32 -1 0 22]116 dc dfe /fb df[<C000C000E00060006000
7000300030003800180018001C000C000C000E0006000600070003000300038001800180018001
C000C000C000E000600060007000300030003800180018001C000C000C000E0006000600070003
0003>16 45 -3 11 23]47 dc[<FFFC00FFFF80FFFFC0F007E0F001F0F000F8F0007CF0003CF0
001EF0001EF0001EF0000FF0000FF0000FF0000FF0000FF0000FF0000FF0000FF0000FF0000EF0
001EF0001EF0003CF0003CF00078F000F8F001F0F007E0FFFFC0FFFF80FFFC00>24 32 -5 0 33
]68 dc[<F0F0F0F0F0F0F0F0F0F0F0F0F0F0F0F0F0F0F0F0F0F0F0F0F0F0F0F0F0F0F0F0>4 32
-4 0 13]73 dc[<FFFF80FFFF80FFFF80F00000F00000F00000F00000F00000F00000F00000F0
0000F00000F00000F00000F00000F00000F00000F00000F00000F00000F00000F00000F00000F0
0000F00000F00000F00000F00000F00000F00000F00000F00000>17 32 -5 0 25]76 dc[<F00F
8078F00F8078F00F8078F019C078F019C078F019C078F039E078F039E078F030E078F070F078F0
70F078F070F078F0607078F0E07878F0E07878F0C03878F1C03C78F1C03C78F1801C78F1801C78
F3801E78F3000E78F3000E78F3000E78F6000778F6000778F6000778F4000378F4000378FC0003
F8F80001F8F80001F8>29 32 -5 0 40]77 dc[<F001F8F003F8F003F8F00378F00778F00778F0
0E78F00E78F00E78F01E78F01C78F03C78F03C78F03878F07878F07078F07078F0F078F0E078F1
E078F1E078F1C078F3C078F38078F38078F38078F70078F70078F60078FE0078FE0078FC0078>
21 32 -5 0 32]78 dc[<1F8F3FEF7FFFF83FF00FF00FF00FF80F7E0F1FFF07FF003F000F000F
000F401F701E7FFC3FF807E0>16 20 -2 0 22]97 dc[<03F00FFE1FFF3E0F3C0178007800F000
F000F000F000F000F000780078003C023E0E1FFE0FFC03F0>16 20 -2 0 20]99 dc[<01F80007
FE001FFF003E07003C0100780000700000F00000F00000F00000FFFF80FFFF80FFFF8070038078
07003C07003E1F001FFE000FFC0003F000>17 20 -1 0 20]101 dc[<03FC000FFF003FFFC07E
07E0F801F0F000F0F000F0F000F07803F03FFFE01FFFC03FFF803FFE0038000030000033E0003F
F8001FFC003E3E003C1E00780F00780F00780F00780F00780F003C1E003E3E001FFFF00FFFF003
E0F0>20 30 -1 10 23]103 dc[<F0F0F0F0F0F0F0F0F0F0F0F0F0F0F0F0F0F0F0F00000000000
000000F0F0F0F0>4 32 -3 0 11]105 dc[<F007803CF007803CF007803CF007803CF007803CF0
07803CF007803CF007803CF007803CF007803CF007803CF007803CF007803CF007803CF807C03C
F807C03CFE0FF07CF7FF3FF8F3FE1FF0F0FC07E0>30 20 -3 0 37]109 dc[<01F80007FE001F
FF803F0FC03C03C07801E07801E0F000F0F000F0F000F0F000F0F000F0F000F07801E07801E03C
03C03F0FC01FFF8007FE0001F800>20 20 -1 0 23]111 dc[<F000F000F000F000F000F000F0
00F000F000F000F000F000F800F800FC00FC00FF00F7E0F3E0F0E0>11 20 -3 0 16]114 dc[<
0FC07FF0FFF8F07CC03C003C003C007C03F80FF81FF03FC07C00780078007800780C3FFC1FFC07
F0>14 20 -1 0 17]115 dc[<07C00FF01FF01E201E001E001E001E001E001E001E001E001E00
1E001E001E001E00FFF0FFF0FFF01E001E001E001E001E001E00>12 26 -1 0 16]116 dc dfe
/fc df[<387CFEFEFE7C38>7 7 -4 0 15]46 dc[<FFFFC000FFFFC00007F0000007F0000007F0
000007F0000007F0000007F0000007F0000007F0000007F0600007F0600007F0600007F0600007
F1E00007FFE00007FFE00007F1E00007F0600007F0600007F0603007F0603007F0003007F00030
07F0007007F0006007F000E007F001E007F007E0FFFFFFE0FFFFFFE0>28 31 -2 0 33]70 dc[<
0FE07E3FF9FE7E0DE0FC05E0F803E0F803E0F803E07C03E03C03E01F03E007FBE0007FE00003E0
0C03E03F03E03F03E03F07C03F0F801FFF0007FC00>23 20 -1 0 25]97 dc[<00FF8007FFE00F
80703F00383E00187E00007C0000FC0000FC0000FC0000FFFFF8FFFFF8FC00F8FC00F87E00F87E
00F03F01F01F83E007FF8001FE00>21 20 -1 0 24]101 dc[<3FFC003FFC0007C00007C00007
C00007C00007C00007C00007C00007C00007C00007C00007C00007C00007C00007C00007C00007
C000FFFC00FFFC0007C00007C00007C00007C00007C00007C3C007C7E003C7E003E7E001F3E000
FFC0001F80>19 32 -1 0 16]102 dc[<FFE0FFE01F001F001F001F001F001F001F001F001F00
1F001F001F001F001F001F001F00FF00FF000000000000000000000000001C003F007F007F007F
003F001C00>11 33 -2 0 14]105 dc[<FFE3FF8FFEFFE3FF8FFE1F007C01F01F007C01F01F00
7C01F01F007C01F01F007C01F01F007C01F01F007C01F01F007C01F01F007C01F01F007C01F01F
007C01F01F007C01F01F807E01F01E807E01F01E407D01F01E70F9C3E0FE1FF07FC0FE0FE03F80
>39 20 -3 0 46]109 dc[<FFE3FFFFE3FF1F00F81F00F81F00F81F00F81F00F81F00F81F00F8
1F00F81F00F81F00F81F00F81F00F81F00F81E80F81EC0F81E61F0FE3FE0FE0FC0>24 20 -3 0
29]110 dc[<01FF0007FFC01F83F03E00F83E00F87C007C7C007CFC007EFC007EFC007EFC007E
FC007EFC007E7C007C7C007C3E00F83E00F81F83F007FFC001FF00>23 20 -1 0 26]111 dc[<
FFF000FFF0001F00001F00001F00001F00001F00001F00001F00001F00001F00001F00001F0000
1F03001F8FC01E8FC01E8FC01ECFC0FE7F80FE3E00>18 20 -2 0 22]114 dc[<01F003F807CC
0F860F860F860F860F860F800F800F800F800F800F800F800F800F800F80FFFCFFFC3F800F8007
80038003800380018001800180>15 29 -1 0 20]116 dc dfe /fd df[<804020201008080404
3C3C3C3C1C>6 14 -3 9 14]44 dc[<E0F0F8F870>5 5 -5 0 14]46 dc[<E0F0F8F870000000
000000000000000E1F1F0F07>8 20 -5 0 14]58 dc[<FFFFE000FFFFF80007803E0007800F00
07800780078003C003C003C003C001E003C001E003C001E001E000E001E001E001E001E001E001
E000F003C000F00F8000FFFE0000F00780007801E0007800F00078007800780078003C003C003C
003C003C003C003C003C001E003C001E0078001E00F801FFFFF001FFFFC0>30 31 -3 0 32]66
dc[<00FE000003FFC00007C0F0000F0018001C000C003C00060078000300780001807000018070
000180F0000000F0000000F000000070000000780000007800000078000000380000003C000000
3C0000001E0000300E0000300F000038078000380380003801E0003800F0007C007C00DC001F01
DC0007FF0C0000FC06>31 31 -6 0 33]67 dc[<FFFFC000FFFFF00007807C0007801E00078007
80078003C003C001C003C000E003C000F003C0007001E0007801E0003C01E0003C01E0003C00F0
001E00F0001E00F0001E00F0001E0078000E0078000E0078000E0078000E003C000E003C000E00
3C001E003C001C001E003C001E0078001E00F001FFFFE001FFFF80>31 31 -3 0 34]68 dc[<FF
F800FFF80007800007800007800007800003C00003C00003C00003C00001E00001E00001E00001
E00000F00000F00000F00000F000007800007800007800007800003C00003C00003C00003C0000
1E00001E00001E0001FFF001FFF0>20 31 -3 0 18]73 dc[<FFF03FF800FFF83FF800078007C0
000780078000078007800007800F000003C00F000003C00F000003C01E000003C01E000001E01E
000001E03C000001F03C000001F83C000000FC78000000F778000000F3F8000000F0F000000078
7000000078300000007818000000780C0000003C070000003C038000003C01C000003C00600000
1E003000001E001C00001E001F0001FFF07FE001FFF07FE0>35 31 -3 0 35]75 dc[<FFC00600
00FFE00600000E000F000006000F000006000F000006000F000003001F800003001F800003001F
800003003D800001803CC00001803CC000018078C000018078C00000C078600000C0F0600000C0
F0600000C0F060000061E030000061E030000061E030000063C030000033C018000033C0180000
33C018000037801800001F800C00001F800C00001F001E0001FF00FFE001FF00FFE0>35 31 -3
0 34]78 dc[<FFF00000FFF800000780000007800000078000000780000003C0000003C0000003
C0000003C0000001E0000001E0000001E0000001E0000000F0000000FFFE0000F0078000F001C0
007800E0007800F00078007800780078003C003C003C003C003C003C003C003C001E0038001E00
78001E00F001FFFFE001FFFF80>30 31 -3 0 31]80 dc[<81FC0000C7FF00007E0780007801C0
007000E00070007000300030003000380030003800000038000000380000003800000078000001
F800001FF800007FF00001FFE00003FF800003F8000003C0000007800000078000000380030003
8003000380030001C0030000C007800060078000381D80001FF9800007E0C0>26 31 -3 0 26]
83 dc[<07E000001FF800003C1C0000380700007003000070018000F000C000F0006000F00060
00F0006000780030007800300078003000780030003C0018003C0018003C0018003C0018001E00
0C001E000C001E000C001E000C000F0006000F0006000F0006000F000600078003000780030007
8007807FFC3FF87FFC3FF8>29 31 -9 0 34]85 dc[<3FFC00003FFE000001E0000001E0000001
E0000001E0000000E0000000F0000000F0000000F00000007000000078000000780000007C0000
00FE000000FE000000F3000001F1800001F1C00001E0C00003E0600003E0300003C0180003C01C
0007C00C0007800600078003000F8003800F0003E0FFF00FFCFFF00FFC>30 31 -9 0 34]89 dc
[<0F078030CCC0707CC0703C60F01C60F01C60F00E30F00E00F00E00F00E007807007807007807
003807003C03801C07800E0780070780038DC000F180>20 20 -4 0 23]97 dc[<07E000183800
300E00700700700200F00000F00000F00000F00000F000007800007800007800003C02001C0700
1E07800E078003018001C300007E00>17 20 -4 0 21]99 dc[<07E000183800380E0070070070
0200700000F00000F00000F00000F000007E00007BF800780E003803003C01801C01800E018007
018001C300007C00>17 20 -4 0 21]101 dc[<3C0000660000F300007B800033800001C00001
C00001C00001C00000E00000E00000E00000E00000F00000700000700000700000700000700000
3800003800003800003800003800001C00001C00001C0001FFE001FFE0000E00000E00000E0000
0E00000E0000070000070000071800073C0003BC00019C0000F8>22 41 2 9 14]102 dc[<6007
80E00CC0700C60701C20700C30700E30380E183807003807003807001C03801C03801C03801E03
800E01C00F01C00F01C00E8180076300073E0007000007000003800003800003800003800001C0
0001C00001C0000FC0000FE00001E000>21 32 -3 0 23]104 dc[<0F00198018C0384018601C
601C300E000E000E00070007000700C3806380618021C0318019800F0000000000000000000000
0000000000E000F000F00060>12 31 -3 0 14]105 dc[<601E00E031007031807070C07070C0
7070C038386038700038700038E0001FC0001E00001D00001C80000E40C00E21E00E11E00E08E0
0704600703C007000007000003800003800003800003800001C00001C00001C0000FC0000FE000
01E000>19 32 -3 0 21]107 dc[<3C006600E600E300E300E300718070007000700038003800
380038001C001C001C001C000E000E000E000E0007000700070007000380038003801F801FC003
C0>10 32 -4 0 12]108 dc[<1801801E0038038033001C01C031801C01C070801C01C030C01C
01C038C00E00E038600E00E01C000E00E01C000E00E01C000700700E000700700E000700700E00
C780780E00638038070063C03C070063E034070033A03206003318618C001E07C0F800>35 20
-3 0 37]109 dc[<1800F03801981C018C1C03841C01861C01C60E01C30E00E00E00E00E00E007
0070070070070070C7807063803863C03863E03033A0303318601E07C0>24 20 -3 0 26]110
dc[<07C000187000301800700E00700F00F00700F00780F003C0F003C0F003C07801E07801E078
01E03C01E01C01E01E01C00E01C003018001C300007C00>19 20 -4 0 23]111 dc[<FFC000FF
C0001C00000E00000E00000E00000E0000070000070000071E0007638003C1C003C0E003C07003
807801C03801C03C01C03C01C03C00E01E00E01E00E01E18E01E0C701E0C701E0C781C067C1C06
661803C1E0>23 29 0 9 23]112 dc[<1800003800001C00001C00001C00001C00000E00000E00
000E00000E0000070000070000070000C700006381806383C063C3C033E1C03331801E0F00>18
20 -3 0 19]114 dc[<1F8030606010E008F00CF00C700E000E003E03FC07F80FF00F800C000C
0E0C0F0C0F0603030600FC>16 20 -3 0 19]115 dc[<1E003100708070C07060706038303800
380038001C001C001C001C000E000E000E000E00FFF0FFF007000700038003800380038001C001
80>12 28 -4 0 15]116 dc[<03E1E00613300E0F300C07180C07180E07180E038C0E03800E03
800E03800701C00701C00701C0C381C06380E06180E021C0E03180E01980700F0060>22 20 -3
0 24]117 dc[<01E0000718000E04000E06000E02000E03000E03000E01800E01800E01800700
C00700C00700C0C380C06380E06180E021C1E03183E01983C00F01C0>19 20 -3 0 21]118 dc[
<01F0F80007198400060F82000E0783000E0701000E0381800E0381800E0380C00E0380C00E03
80C00701C0600701C0600701C060C381C0606380E0706180E07021C0E0F03180E1F0198071E00F
0060E0>28 20 -3 0 30]119 dc[<1F000031C000606000703000783800781C00001C00000E00
000E0003EE00061E000E0F000C07000C07000E07000E03800E03800E03800E03800701C00701C0
0701C0C381C06380E06180E021C0E03180E01980700F0060>20 29 -3 9 22]121 dc dfe /fe
df[<7FE3FF007FE3FF000700700007007000070070000700700007007000070070000700700007
0070000700700007007000070070000700700007007000070070000700700007007000FFFFFF80
FFFFFF80070070000700700007007000070070000700700007007000070070000300F0300380F8
7801C0787800F06E30001F83E0>29 32 0 0 27]11 dc[<7FC3FE7FC3FE0700E00700E00700E0
0700E00700E00700E00700E00700E00700E00700E00700E00700E00700E00700E00700E00700E0
FFFFE0FFFFE00700000700000700000700000700000700000701E00701E00381E001C0C000E0C0
003F00>23 32 0 0 25]12 dc[<7FE7FE7FE7FE0700E00700E00700E00700E00700E00700E007
00E00700E00700E00700E00700E00700E00700E00700E00700E00700E0FFFFE0FFFFE00700E007
00E00700E00700E00700E00700E00700E00700E00381E001C1E000E0E0003FE0>23 32 0 0 25]
13 dc[<402020101008100808040804040204020402743AFC7EFC7EF87C7038>15 14 -2 -18
23]34 dc[<40201010080804040474FCFCF870>6 14 -4 -18 13]39 dc[<0020004000800100
020006000C000C00180018003000300030007000600060006000E000E000E000E000E000E000E0
00E000E000E000E000E0006000600060007000300030003000180018000C000C00060002000100
008000400020>11 46 -3 12 18]40 dc[<800040002000100008000C00060006000300030001
800180018001C000C000C000C000E000E000E000E000E000E000E000E000E000E000E000E000C0
00C000C001C001800180018003000300060006000C0008001000200040008000>11 46 -3 12
18]41 dc[<40201010080804040474FCFCF870>6 14 -4 9 13]44 dc[<FFC0FFC0>10 2 -1 -9
15]45 dc[<70F8F8F870>5 5 -4 0 13]46 dc[<C000C000E00060006000700030003000380018
0018001C000C000C000E0006000600070003000300038001800180018001C000C000C000E00060
0060007000300030003800180018001C000C000C000E00060006000700030003>16 45 -3 11
23]47 dc[<03F0000E1C001C0E00380700380700700380700380700380F003C0F003C0F003C0F0
03C0F003C0F003C0F003C0F003C0F003C0F003C0F003C0F003C0F003C070038070038070038038
07003807001C0E000E1C0003F000>18 29 -2 0 23]48 dc[<FFFEFFFE03800380038003800380
03800380038003800380038003800380038003800380038003800380038003800380F380FF800F
8003800180>15 29 -4 0 23]49 dc[<FFFF80FFFF807FFF802000801000400800400400400200
0003000001800000E000007000003800001C00001E00000F00000F800007800007C02007C0F803
C0F803C0F807C0F007C0400780600F00303F001FFC0007F000>18 29 -2 0 23]50 dc[<07F000
1FFC00381E00400F00F00F80F80780F807C0F807C02007C00007C00007C0000780000F00000E00
001C0003F000003800001C00000E00000F00000F80000F80380780780F80780F80780F00301E00
1FFC0007F000>18 29 -2 0 23]51 dc[<07E0001FF800381E00600F00400780E00380F003C0F0
03C07003C00003C00003C00003C0000380000380100700180600160C0011F00010000010000010
00001000001000001000001FE0001FF8001FFC001FFE00180300>18 29 -2 0 23]53 dc[<70F8
F8F8700000000000000000000070F8F8F870>5 20 -4 0 13]58 dc[<001FF00000E01F000100
01C0060000700800000008000000100F07802030CC4020605C2040C03C2041C01C1041C01C1081
801C1083801C1083801C1083801C1083801C1083801C1083801C1081801C1041C01C2041C01C20
40C02020206040402030C040100F00800800010008000100060006000100080000E07000001F80
00>28 32 -3 0 35]64 dc[<FFC03FFEFFC03FFE0F0003C0060003C00200078002000780020007
8001000F0001000F0001FFFF0000FFFE0000801E0000803E0000403C0000403C0000607C000020
7800002078000010F0000010F0000010F0000009E0000009E0000009E0000007C0000007C00000
07C00000038000000380000003800000010000>31 31 -1 0 34]65 dc[<FFFFF000FFFFFC0007
803E0007801F0007800F8007800780078007C0078007C0078007C0078007C0078007C007800780
07800F8007800F0007801E0007803C0007FFF80007803C0007801E0007801F0007800F0007800F
8007800F8007800F8007800F8007800F8007801F0007801E0007803E00FFFFF800FFFFE000>26
31 -2 0 32]66 dc[<001FE000007FF80001F80C0003C00200078001000F0000801E0000803E00
00403C0000407C0000407C00000078000000F8000000F8000000F8000000F8000000F8000000F8
000000F8000000780000007C0000407C0000403C0000403E0000C01E0000C00F0001C0078003C0
03C007C001F81DC0007FF0C0001FC040>26 31 -3 0 33]67 dc[<FFFFE000FFFFFC0007803E00
07800F0007800780078003C0078001E0078001E0078001F0078000F0078000F0078000F8078000
F8078000F8078000F8078000F8078000F8078000F8078000F8078000F8078000F0078000F00780
01F0078001E0078003E0078003C00780078007800F0007803E00FFFFFC00FFFFE000>29 31 -2
0 35]68 dc[<FFFFFF80FFFFFF8007800780078001C0078000C0078000C0078000400780004007
80004007800020078080200780802007808000078080000781800007FF800007FF800007818000
078080000780800007808080078080800780008007800080078001800780010007800100078003
0007800F00FFFFFF00FFFFFF00>27 31 -2 0 31]69 dc[<FFFE0000FFFE000007800000078000
000780000007800000078000000780000007800000078000000780800007808000078080000780
80000781800007FF800007FF800007818000078080000780800007808080078080800780008007
8000800780018007800100078001000780030007800F00FFFFFF00FFFFFF00>25 31 -2 0 30]
70 dc[<000FE020007FFC6001F80EE003E003E0078001E00F0001E01E0001E03E0001E03C0001
E07C0001E07C0001E078007FFCF8007FFCF8000000F8000000F8000000F8000000F8000000F800
0000780000007C0000207C0000203C0000203E0000601E0000600F0000E0078001E003E003E001
F80EE0007FF860000FE020>30 31 -3 0 36]71 dc[<FFF8FFF8FFF8FFF807800F0007800F0007
800F0007800F0007800F0007800F0007800F0007800F0007800F0007800F0007800F0007800F00
07800F0007FFFF0007FFFF0007800F0007800F0007800F0007800F0007800F0007800F0007800F
0007800F0007800F0007800F0007800F0007800F00FFF8FFF8FFF8FFF8>29 31 -2 0 34]72 dc
[<FFFCFFFC07800780078007800780078007800780078007800780078007800780078007800780
0780078007800780078007800780078007800780FFFCFFFC>14 31 -1 0 16]73 dc[<FFFC3FFC
FFFC3FFC078007C0078007800780078007800F0007801E0007801E0007803C0007803C00078078
000780F00007C0F00007A1E0000791E0000793C000078F80000787800007830000078100000780
800007804000078020000780100007800800078004000780020007800100078003C0FFFC0FFCFF
FC0FFC>30 31 -2 0 35]75 dc[<FFE0C1FFF8FFE0C1FFF80E00C00F000401E00F000401E00F00
0401E00F000403900F000403900F000407080F000407080F000407080F00040E040F00040E040F
00040E040F00041C020F00041C020F00041C020F000438010F000438010F000438010F00047000
8F000470008F000470008F0004E0004F0004E0004F0005C0002F0005C0002F0005C0002F000780
001F00FF80001FF8FF80001FF8>37 31 -2 0 42]77 dc[<FFE00100FFE003000E000300040007
000400070004000F0004001F0004001F0004003D0004003D00040079000400F1000400F1000401
E1000401E1000403C1000407810004078100040F0100040F0100041E0100043C0100043C010004
7801000478010004F0010005E0010005E0010007C00380FFC03FF8FF803FF8>29 31 -2 0 34]
78 dc[<003FC00000F0F00003C03C0007801E000F000F001E0007801E0007803C0003C07C0003
E07C0003E0780001E0F80001F0F80001F0F80001F0F80001F0F80001F0F80001F0F80001F0F800
01F0F80001F0780001E07C0003E03C0003C03C0003C01E0007801E0007800F000F0007801E0003
C03C0000E07000003FC000>28 31 -3 0 35]79 dc[<FFFC0000FFFC0000078000000780000007
800000078000000780000007800000078000000780000007800000078000000780000007800000
0780000007FFF00007807C0007801E0007801F0007800F0007800F8007800F8007800F8007800F
8007800F8007800F0007801F0007801E0007807C00FFFFF800FFFFE000>25 31 -2 0 31]80 dc
[<FFFC07E0FFFC1F1807803E0407807E0407807C0407807C0007807C0007807C00078078000780
780007807800078070000780F0000780E0000781C00007FF80000780F0000780780007803C0007
801E0007801F0007801F0007801F0007801F0007801F0007801E0007803E0007803C000780F800
FFFFE000FFFF8000>30 31 -2 0 33]82 dc[<83F800CFFC00FC0E00F00300C00380C001808001
C08001C08001C00001C00003C00003C0000780001F8003FF000FFE001FFC003FF0007F00007800
00F00000F00000E00080E00080E00080E001807003803007803C1F801FF98007E080>18 31 -3
0 25]83 dc[<07FFFE0007FFFE00000F0000000F0000000F0000000F0000000F0000000F000000
0F0000000F0000000F0000000F0000000F0000000F0000000F0000000F0000000F0000000F0000
000F0000000F0000800F0010800F0010800F0010800F0010C00F0030400F0020400F0020600F00
60780F01E07FFFFFE07FFFFFE0>28 31 -2 0 33]84 dc[<000FC000003FF0000078380000E00C
0001C0040003C00200038002000780010007800100078001000780010007800100078001000780
010007800100078001000780010007800100078001000780010007800100078001000780010007
8001000780010007800100078001000780010007800380FFFC3FF8FFFC3FF8>29 31 -2 0 34]
85 dc[<000100000003800000038000000380000007C0000007C000000FE000000F2000000F20
00001E1000001E1000001E1000003C0800003C0800007C0C00007804000078040000F0020000F0
020000F0020001E0010001E0010003E0008003C0008003C0008007800040078000400F8000600F
8000F0FFF003FEFFF003FE>31 31 -1 0 34]86 dc[<000400020000000C00030000000E000700
00000E00070000001E00078000001F000F8000001F000F8000003F000FC000003C801E4000003C
801E4000003C801E40000078403C20000078403C20000078403C200000F02078100000F0207810
0000F02078100001E010F0080001E010F0080001E010F0080003C009F0040003C009E0040003C0
09E0040007800FE00200078007C00200078007C002000F0007C001000F00078001000F00078007
80FFF07FF81FF0FFF07FF81FF0>44 31 -1 0 47]87 dc[<FFE01FFEFFE01FFE0F8007C0030007
C00100078001800F0000801F0000401E0000603C0000207C00001078000018F8000009F0000005
E0000007E0000003C00000078000000F8000000F8000001E4000003E4000003C2000007C100000
78100000F0080001F00C0001E0040003C0060007C007807FF83FF87FF83FF8>31 31 -1 0 34]
88 dc[<007FFE00007FFE000003C0000003C0000003C0000003C0000003C0000003C0000003C0
000003C0000003C0000003C0000003C0000007C0000007A000000FB000001F1000001E0800003E
0800003C0400007C040000F8020000F0030001F0010001E0008003E0008007C00040078000400F
8000F0FFF003FFFFF003FF>32 31 -1 0 34]89 dc[<381C7C3EFC7EFC7EB85C80408040804040
2040202010201010080804>15 14 -5 -18 23]92 dc[<0F83C0386720781E10F01E10F00E10F0
0E10F00E10780E00380E001E0E00078E0000FE00000E00000E00000E00300E00781C0078180030
30001FE000>20 20 -2 0 23]97 dc[<083E000CC3000D01C00F00E00E00E00E00700E00700E00
780E00780E00780E00780E00780E00780E00700E00700E00E00F00E00F01C00EC3800E3E000E00
000E00000E00000E00000E00000E00000E00000E00000E0000FE0000FE00000E0000>21 32 -1
0 25]98 dc[<03F00E0C1C023801380170007000F000F000F000F000F000F00070007000380C38
1E1C1E0E0C03F8>16 20 -2 0 20]99 dc[<03E3F80E1BF81C0780380780380380700380700380
F00380F00380F00380F00380F00380F003807003807003803803803803801C0780061B8003E380
000380000380000380000380000380000380000380000380000380003F80003F80000380>21 32
-2 0 25]100 dc[<01F8000706000C0100180080380080700000700000F00000F00000F00000FF
FF80F00380F003807003807007003807003807001C0E000E1C0003F000>17 20 -1 0 20]101
dc[<7FF07FF00700070007000700070007000700070007000700070007000700070007000700FF
F0FFF007000700070007000700070007000706038F018F00C6007C>16 32 0 0 14]102 dc[<03
FC001C03803000C0600060C00030C00030C00030C000306000703001E00FFFC01FFF803FFE0030
000030000020000020000033E0001E38001C1C00380E00780F00780F00780F00780F00780F0038
0E001C1C300E3A3003E1E0>20 30 -1 10 23]103 dc[<FFE7FCFFE7FC0E01C00E01C00E01C00E
01C00E01C00E01C00E01C00E01C00E01C00E01C00E01C00E01C00E01C00F01C00F01C00E81800E
43000E3E000E00000E00000E00000E00000E00000E00000E00000E00000E0000FE0000FE00000E
0000>22 32 -1 0 25]104 dc[<FFC0FFC00E000E000E000E000E000E000E000E000E000E000E
000E000E000E000E007E007E000E000000000000000000000000001C001E003E001E001C00>10
31 0 0 12]105 dc[<3F006180F0C0F06060700070007000700070007000700070007000700070
007000700070007000700070007000700070007000F007F007F000700000000000000000000000
0000E001F001F001F000E0>12 40 2 9 14]106 dc[<FFCFF8FFCFF80E03C00E03800E07800E07
000E0E000E1E000E1C000F38000EF8000E70000E30000E10000E08000E04000E02000E07800E0F
F00E0FF00E00000E00000E00000E00000E00000E00000E00000E00000E0000FE0000FE00000E00
00>21 32 -1 0 24]107 dc[<FFE0FFE00E000E000E000E000E000E000E000E000E000E000E00
0E000E000E000E000E000E000E000E000E000E000E000E000E000E000E000E00FE00FE000E00>
11 32 0 0 12]108 dc[<FFE7FE7FE0FFE7FE7FE00E00E00E000E00E00E000E00E00E000E00E0
0E000E00E00E000E00E00E000E00E00E000E00E00E000E00E00E000E00E00E000E00E00E000E00
E00E000E00E00E000F00F00E000F00F00E00FE81C81C00FE618618000E1F01F000>35 20 -1 0
38]109 dc[<FFE7FCFFE7FC0E01C00E01C00E01C00E01C00E01C00E01C00E01C00E01C00E01C0
0E01C00E01C00E01C00E01C00F01C00F01C0FE8180FE43000E3E00>22 20 -1 0 25]110 dc[<
01F800070E001C03803801C03801C07000E07000E0F000F0F000F0F000F0F000F0F000F0F000F0
7000E07000E03801C03801C01C0380070E0001F800>20 20 -1 0 23]111 dc[<FFE000FFE000
0E00000E00000E00000E00000E00000E00000E00000E3E000EC3000F01C00F01E00E00E00E00F0
0E00700E00780E00780E00780E00780E00780E00780E00700E00F00E00E00F00E0FF01C0FEC380
0E3E00>21 29 -1 9 25]112 dc[<003FF8003FF8000380000380000380000380000380000380
00038003E3800E13801C0B80380780380380780380700380F00380F00380F00380F00380F00380
F003807003807803803803803C07801C058006198003E080>21 29 -2 9 24]113 dc[<FFE0FF
E00E000E000E000E000E000E000E000E000E000E000E000E000E000F0C0F1EFF1EFE8C0E78>15
20 -1 0 18]114 dc[<8F80D060E030C018C01880188018803800700FF03FE07F807800E000C0
10C010C010403030701F90>13 20 -2 0 18]115 dc[<01E0031006100E080E080E080E080E08
0E000E000E000E000E000E000E000E000E000E00FFF83FF80E000E000600060002000200020002
00>13 28 -1 0 18]116 dc[<01F1FC030DFC0603C00E03C00E01C00E01C00E01C00E01C00E01
C00E01C00E01C00E01C00E01C00E01C00E01C00E01C00E01C0FE1FC0FE1FC00E01C0>22 20 -1
0 25]117 dc[<00200000700000700000700000E80000E80001EC0001C40001C4000382000382
000382000701000701000E00800E00800E00801E00E0FF83F8FF83F8>21 20 -1 0 24]118 dc[
<004008000060180000E01C0000E01C0000F03C0001D03A0001D0320003C87300038871000388
61000704E0800704C0800707C0800E03C0400E0380400E0380401C0380601C038070FF9FE1FCFF
9FE1FC>30 20 -1 0 33]119 dc[<FF07FEFF07FE0E01E00201C0030380010700008700004E00
007C00003C0000380000780000EC0000E40001C2000381000701800701C07FC3FC7FC3FC>23 20
0 0 24]120 dc[<3C0000620000F10000F08000F0800000400000400000400000200000200000
700000700000700000E80000E80001EC0001C40001C4000382000382000382000701000701000E
00800E00800E00801E00E0FF83F8FF83F8>21 29 -1 9 24]121 dc[<FFFE700E700638021C03
1E010E0107010780038001C001E000E0407040784038201C200E380E3FFF>16 20 -1 0 20]
122 dc[<FFFFFC>22 1 0 -12 23]123 dc dfe end
%%EndProlog
%%BeginSetup
%%Feature: *Resolution 300
TeXDict begin /pagesize { @letter } bdf
%%EndSetup
%%Page: 1 1
bop 632 307 a fa(Redesigning)20 b(the)e(Isis)h(T)-5 b(o)r(olkit)718 413 y fd
(Pr)n(of.)21 b(Kenneth)15 b(P.)h(Birman)645 470 y(Dep)n(artment)g(of)h(Comput\
er)g(Scienc)n(e)603 526 y(Cornel)r(l)f(University,)f(Ithac)n(a,)h(New)g(Y)m
(ork)146 633 y fe(The)j fb(Isis)g fe(system)g(is)h(a)e(to)q(olkit)i(for)e(bui\
lding)k(distributed)f(applications.)33 b(Built)20 b(in)g(la)o(y)o(ers,)g(the)
75 689 y(system)15 b(supp)q(orts)h(a)f(core)h(set)g(of)f(mec)o(hanisms)h(for)
f(fault-toleran)o(t)h(pro)q(cess-group)g(comm)o(unication,)75 746 y(on)d(top)
g(of)g(whic)o(h)h(to)q(ols)f(are)g(pro)o(vided)i(for)d(managing)h(replicated)
i(data,)e(sync)o(hronization,)h(detecting)75 802 y(and)19 b(reacting)f(to)g
(system)g(recon\014gurations)g(and)h(failures,)g(distributed)h(computation,)f
(and)f(man)o(y)75 858 y(other)h(op)q(erations.)34 b fb(Isis)20 b fe(pro)q(ces\
s)g(groups)g(are)f fd(virtual)r(ly)i(synchr)n(onous:)29 b fe(they)19 b(pro)o
(vide)i(users)f(with)75 915 y(the)g(illusion)k(of)19 b(a)i(greatly)f(simpli\
\014ed)j(programming)c(en)o(vironmen)o(t)i(\(a)f(sync)o(hronous)g(one\))g(whi\
le)75 971 y(actually)d(executing)g(extremely)f(async)o(hronously)l(.)22 b(Usi\
ng)17 b(this)f(approac)o(h,)f(it)h(is)h(easy)e(to)g(build)j(high)75 1028 y
(p)q(erformance,)d(highly)h(reliable)h(soft)o(w)o(are)c(that)h(main)o(tains)h
(consistency)g(and)g(a)o(v)m(ailabilit)o(y)i(ev)o(en)e(as)g(it)75 1084 y(reac\
ts)g(dynamically)i(to)d(failures,)i(o)o(v)o(erloads)f(and)g(other)g(condition\
s.)146 1141 y fb(Isis)e fe(has)g(b)q(een)i(applied)g(in)f(a)f(n)o(um)o(b)q
(er)h(of)f(settings.)19 b(Commercially)l(,)c(these)e(include)j(sev)o(eral)d
(ma)s(jor)75 1197 y(\014nancial)21 b(trading)f(and)g(banking)g(systems,)g(fac\
tory)f(\015o)q(or)g(automation)g(pro)s(jects,)h(scien)o(ti\014c)h(com-)75 1254
y(puting)f(applications,)i(telecomm)o(unications)f(pro)s(jects,)e(medical)i
(database)e(and)g(wide-area)h(signal)75 1310 y(pro)q(cessing)f(applications.)
29 b(A)o(t)17 b(Cornell,)i fb(Isis)f fe(is)g(used)h(within)g fb(Meta/Lomita)p
fe(,)d(a)i(system)f(for)g(instru-)75 1367 y(men)o(ting)i(a)f(distributed)h
(program)f(or)f(system)h(and)h(programming)e(realtime)i(reactiv)o(e)g(con)o
(trol)f(ap-)75 1423 y(plications,)f fb(Deceit)p fe(,)e(a)g(transparen)o(tly)g
(fault-toleran)o(t)g(\014le)i(system)e(compatible)h(with)g(the)f(SUN)h(NFS)75
1479 y(standard,)g(and)h fb(Nmgr)p fe(,)e(a)i(net)o(w)o(ork)e(resource)i(mana\
gemen)o(t)f(and)h(load)g(sharing)g(utilit)o(y)l(,)h(Our)f(activ)o(e)75 1536 y
(user)i(comm)o(unit)o(y)f(no)o(w)h(includes)i(at)d(least)h(a)f(h)o(undred)i
(sites,)f(and)g(h)o(undreds)h(of)e(other)g(companies)75 1592 y(and)d(researc)
o(h)g(groups)g(ha)o(v)o(e)g(exp)q(erimen)o(ted)i(with)e(the)h(system)e(or)h
(used)h(it)f(in)h(protot)o(yping.)146 1649 y(Although)h fb(Isis)h fe(has)f
(b)q(een)h(successful)g(for)f(an)g(academic)h(e\013ort,)e(the)h(exp)q(erience)
j(of)c(ha)o(ving)i(real)75 1705 y(users)h(forced)g(a)f(rapid)i(and)f(unstruct\
ured)g(system)g(ev)o(olution.)31 b(On)20 b(the)f(p)q(ositiv)o(e)g(side,)i fb
(Isis)e fe(w)o(orks)75 1762 y(quite)d(w)o(ell.)22 b(Y)l(et,)15 b(users)h(ha)o
(v)o(e)f(b)q(een)h(critical)h(of)e(the)h(o)o(v)o(erall)f(complexit)o(y)i(of)e
(the)g(system,)g(and)g(man)o(y)75 1818 y(complain)i(that)d(it)i(pro)o(vides)g
(to)q(o)f(man)o(y)f(options.)21 b(A)o(t)15 b(the)g(same)g(time,)h(they)f(ha)o
(v)o(e)g(ask)o(ed)g(for)g(higher)75 1875 y(p)q(erformance,)e(impro)o(v)o(ed)g
(scalabilit)o(y)l(,)i(mec)o(hanisms)f(for)e(exploiting)j(sp)q(ecial)f(hardw)o
(are,)f(and)g(options)75 1931 y(to)j(impro)o(v)o(e)g(co)q(existence)h(with)g
(other)f(to)q(olkits,)g(suc)o(h)h(as)f(X11,)f(Sybase,)i(and)f(so)g(forth.)23 b
(They)16 b(w)o(an)o(t)75 1988 y(a)j(system)g(that)f(will)j(run)f(under)g(ev)o
(ery)f(conceiv)m(able)j(v)o(ersion)e(of)e(UNIX,)i(as)f(w)o(ell)h(as)f(sev)o
(eral)h(non-)75 2044 y(UNIX)13 b(systems)f(lik)o(e)i(DEC's)d(VMS)h(and)h(IBM'\
s)f(VM/CMS.)g(They)g(w)o(an)o(t)g(b)q(etter)g(supp)q(ort)h(for)e(ob)s(ject-)
75 2100 y(orien)o(ted)16 b(programming.)j(And,)c(they)h(w)o(an)o(t)e(commerci\
al)i(supp)q(ort.)146 2157 y(In)j(ligh)o(t)h(of)f(this,)h(it)g(ma)o(y)e(seem)i
(implausible)i(that)c fb(Isis)i fe(could)g(ha)o(v)o(e)f(attracted)f(a)h(subst\
an)o(tial,)75 2213 y(div)o(erse)11 b(user)f(comm)o(unit)o(y)h(that)e(includes)
k(man)o(y)d(extremely)h(capable)g(dev)o(elop)q(ers.)19 b(Y)l(et,)11 b(this)g
(is)g(clearly)75 2270 y(the)17 b(case.)27 b(Moreo)o(v)o(er,)16 b(w)o(e)h(had)
g(exp)q(ected)i(most)d fb(Isis)i fe(users)f(to)g(program)f(using)i(a)f(small)
h(n)o(um)o(b)q(er)f(of)75 2326 y(pro)q(cess)c(groups,)g(using)h(a)e(clien)o
(t-serv)o(er)i(mo)q(del,)g(fo)q(cusing)g(on)f(complex)h(distributed)g(algorit\
hms.)19 b(T)l(o)75 2383 y(our)f(surprise,)i(man)o(y)e fb(Isis)h fe(users)g
(ha)o(v)o(e)f(seized)i(up)q(on)g(groups)e(as)g(a)h(completely)h(new)f(program\
ming)75 2439 y(paradigm.)29 b(Applications)20 b(use)e(large)g(n)o(um)o(b)q
(ers)g(of)g(groups)g(and)g(use)h(groups)e(in)i(w)o(a)o(ys)e(w)o(e)h(had)g(not)
964 2577 y(1)g eop
%%Page: 2 2
bop 75 307 a fe(an)o(ticipated.)23 b(A)o(t)15 b(the)h(same)f(time,)h(most)f
(users)h(lea)o(v)o(e)g(the)f(complex)i(distributed)g(algorithms)f(to)f(us:)75
364 y(if)h(the)f(to)q(olkit)g(do)q(esn't)g(solv)o(e)h(a)f(problem,)g(t)o(ypic\
al)h(users)g(are)e(not)h(prepared)h(to)e(\014ll)j(the)e(gaps.)146 420 y(W)l
(e'v)o(e)e(b)q(een)j(forced)e(to)g(t)o(w)o(o)e(conclusions.)22 b(On)14 b(the)
h(one)f(hand,)g(it)h(seems)f(that)g(something)g(ab)q(out)75 477 y fb(Isis)20 b
fe(is)h(fundamen)o(tally)g(righ)o(t.)33 b(Distributed)21 b(systems)e(users)h
(really)h(do)f(w)o(an)o(t)f(and)h(need)h(p)q(o)o(w)o(erful)75 533 y(distribut\
ed)d(programming)e(to)q(ols)g(that)g(go)g(b)q(ey)o(ond)h(what)e(Unix)j(and)e
(Mac)o(h)g(pro)o(vide.)24 b(There)17 b(is)g(an)75 589 y(enormous)i(demand)g
(for)f(customized,)i(fault-toleran)o(t,)f(self-managing)h(distributed)g(soft)
o(w)o(are,)e(and)75 646 y fb(Isis)c fe(resp)q(onds)g(to)f(this.)19 b(A)o(t)13
b(the)h(same)f(time,)h(ho)o(w)o(ev)o(er,)f fb(Isis)g fe(needs)i(to)e(b)q(e)h
(rethough)o(t)e(with)i(the)g(b)q(ene\014t)75 702 y(of)j(exp)q(erience.)29 b
(W)l(e)17 b(need)h(to)f(rebuild)i(the)f(system)f(around)g(those)g(asp)q(ects)
h(that)e(w)o(ork)h(w)o(ell,)h(while)75 759 y(eliminating)f(or)e(consolidating)
i(as)d(man)o(y)h(of)g(the)g(less)h(imp)q(ortan)o(t)f(asp)q(ects)g(as)g(p)q
(ossible.)146 815 y(With)j(this)g(goal,)g(the)g fb(Isis)g fe(Pro)s(ject)f(has)
h(no)o(w)f(launc)o(hed)i(a)f(system)f(redesign)i(e\013ort.)27 b(Our)18 b(hop)
q(e)75 872 y(is)e(to)e(address)h(these)h(issues)g(while)g(also)f(in)o(tegrati\
ng)h fb(Isis)f fe(b)q(etter)g(in)o(to)g(the)h(new)f(w)o(a)o(v)o(e)f(of)h(ligh)
o(t)o(w)o(eigh)o(t)75 928 y(op)q(erating)g(systems,)g(suc)o(h)g(as)g(Amo)q
(eba,)g(Chorus,)g(Mac)o(h,)f(the)h(X-k)o(ernel)h(and)g(V.)146 985 y(The)i(arc)
o(hitecture)g(w)o(e)g(en)o(vision)i(rev)o(olv)o(es)e(around)g(a)f(small)i(mo)
q(dule)h(implemen)o(ting)g(groups)d(of)75 1041 y(comm)o(unication)12 b(endp)q
(oin)o(ts)h(\(Mac)o(h)e(send{righ)o(ts,)h(Chorus)g(p)q(orts,)f(etc.\),)g(and)
h(based)g(on)g(our)f(recen)o(tly)75 1098 y(dev)o(elop)q(ed)19 b(\\fast)e(caus\
al)h(m)o(ulticast")g(proto)q(col.)27 b(Most)16 b(of)i(the)f(curren)o(t)h(core)
f(of)h fb(Isis)g fe(will)h(either)f(b)q(e)75 1154 y(eliminated)k(or)e(mo)o
(v)o(ed)f(to)h(outb)q(oard)f(serv)o(ers)h(running)h(on)f(a)g(small)g(subsets)
h(of)e(the)h(mac)o(hines)h(in)75 1210 y(a)f(net)o(w)o(ork.)36 b(The)20 b(core)
h(mo)q(dule)h(itself)f(could)h(b)q(e)f(dropp)q(ed)h(in)o(to)f(the)f(k)o(ernel)
i(on)e(Chorus)h(or)f(in)o(to)75 1267 y(the)f(Mac)o(h)g(net)o(w)o(ork)e(messag\
e)i(serv)o(er,)g(giving)h(users)f(who)g(w)o(an)o(t)e(pro)q(cess)j(group)e(fac\
ilities)j(greatly)75 1323 y(impro)o(v)o(ed)14 b(p)q(erformance.)19 b(Y)l(et,)
14 b(the)g(same)g(mo)q(dule)h(could)f(also)g(run)g(completely)h(outside)g(the)
f(k)o(ernel,)75 1380 y(or)h(ev)o(en)g(on)g(top)g(of)g(UNIX,)g(th)o(us)g(retai\
ning)h(the)g(p)q(ortabilit)o(y)g(of)f(our)g(curren)o(t)g(design.)146 1436 y
(W)l(e)d(are)g(rethinking)i(the)f(to)q(olkit)g(in)o(terface)g(to)e(eliminate)
k(o)o(v)o(erlap)d(with)h(the)g(emerging)f(standards)75 1493 y(for)i(m)o(ultit\
hreading,)h(IPC,)f(stub)g(generation,)h(naming,)f(and)h(so)f(forth.)19 b(A)o
(t)13 b(the)i(same)f(time,)g(w)o(e)g(plan)75 1549 y(to)k(presen)o(t)h(new)g
(sev)o(eral)f(in)o(terfaces)h(to)f(the)h(core)f(proto)q(cols.)31 b(These)19 b
(migh)o(t)f(include)j(a)d(simpli\014ed)75 1606 y(set)j(of)f(facilities)j(for)
d(transparen)o(t)g(fault-tolerance,)j(a)d(database)h(in)o(tegration)g(to)q
(olkit,)h(or)e(ev)o(en)h(a)75 1662 y(collection)g(of)e(to)q(ols)g(for)g(ob)s
(ject-orien)o(ted)h(programming.)31 b(Our)20 b(new)g(system)f(will)i(also)e
(b)q(e)h(b)q(etter)75 1719 y(able)c(to)f(exploit)h(sp)q(ecial)h(comm)o(unicat\
ions)f(hardw)o(are)e(or)h(m)o(ultipro)q(cessor)h(CPU)f(arc)o(hitectures.)146
1775 y(Implemen)o(tation)g(of)g(our)f(new)h(arc)o(hitecture)g(will)i(so)q(on)
d(start)g(under)h(Mac)o(h)f(and)h(Chorus,)g(and)f(is)75 1831 y(exp)q(ected)i
(to)d(tak)o(e)h(at)f(least)i(a)f(y)o(ear)g(to)f(eigh)o(teen)i(mon)o(ths.)k
(W)l(e'v)o(e)14 b(b)q(een)i(fortunate)d(to)h(ha)o(v)o(e)g(receiv)o(ed)75 1888
y(a)h(great)f(deal)i(of)f(help)h(and)g(advice)g(from)e(b)q(oth)i(the)f(Chorus)
g(and)g(Mac)o(h)g(systems)g(groups,)f(and)i(from)75 1944 y(F)l(ranklin)g(Reyn\
olds)h(of)e(the)g(OSF)g(Researc)o(h)h(Institute.)146 2001 y(As)h(w)o(e)h(lo)q
(ok)g(to)o(w)o(ards)e(the)h(next)h(generation)g(of)f(computing)h(systems,)g
(the)g fb(Isis)g fe(group)f(b)q(eliev)o(es)75 2057 y(that)f(the)h(distinction\
s)i(b)q(et)o(w)o(een)e(lo)q(ose)h(and)f(closely)h(coupled)g(pro)q(cessors)f
(will)i(fade.)25 b(Comm)o(unica-)75 2114 y(tions)14 b(bandwidth)h(and)g(pro)q
(cessor)f(cycles)h(are)f(no)g(longer)g(the)g(issues.)20 b fd(Softwar)n(e)15 b
fe(lo)q(oms)f(as)f(the)i(single)75 2170 y(ma)s(jor)i(barrier)i(to)g(e\013ecti\
v)o(ely)g(utilizing)j(the)d(computing)g(en)o(vironmen)o(ts)g(of)f(the)h(futur\
e.)31 b(Systems)75 2227 y(lik)o(e)13 b(V,)f(Amo)q(eba,)h(Mac)o(h,)f(Chorus)g
(and)h(the)f(X-k)o(ernel)h(ha)o(v)o(e)f(demonstrated)g(imp)q(ortan)o(t)g(p)q
(erformance)75 2283 y(b)q(ene\014ts)k(for)e(ligh)o(t)o(w)o(eigh)o(t)g(k)o(ern\
els)i(in)f(message)f(passing)h(applications.)21 b(And,)15 b(there)g(are)f(equ\
ally)i(im-)75 2340 y(p)q(ortan)o(t)i(adv)m(an)o(tages)g(to)g(standardization.)
31 b(But,)19 b(w)o(e)f(need)i(more)e(than)h(p)q(oin)o(t{to{p)q(oin)o(t)f(mess\
age)75 2396 y(passing)k(to)g(dev)o(elop)h(high)g(reliabilit)o(y)h(soft)o(w)o
(are)c(for)i(massiv)o(e,)h(concurren)o(t)f(en)o(vironmen)o(ts.)41 b(Dis-)75
2452 y(tributed)14 b(systems)f(users)g(are)g(demanding)h(supp)q(ort)f(for)g
(new)g(st)o(yles)h(of)e(distributed)j(computing,)f(new)964 2577 y(2)g eop
%%Page: 3 3
bop 75 307 a fe(and)16 b(more)f(in)o(tegrated)h(distributed)h(en)o(vironmen)
o(ts,)e(automated)g(self-con)o(trolling)i(distributed)h(soft-)75 364 y(w)o
(are,)g(and)g(fault-tolerance.)29 b(Pro)q(cess)18 b(group)g(mec)o(hanisms)h
(o\013er)e(the)h(b)q(est)g(a)o(v)m(ailable)i(resp)q(onse)f(to)75 420 y(this)d
(o)o(v)o(erwhelming,)f(nearly)h(univ)o(ersal)g(need.)75 540 y fc(F)l(or)23 b
(more)e(information.)44 b fe(The)21 b(author)f(of)h(this)g(article,)i(Ken)e
(Birman,)i(has)d(headed)i(the)f fb(Isis)75 597 y fe(pro)s(ject)16 b(since)h
(its)g(inception)h(and)e(is)h(leading)h(the)f(group)f(in)o(v)o(olv)o(ed)h(in)
g(the)g(system)e(redesign.)25 b(He)16 b(is)75 653 y(also)f(Presiden)o(t)g(and)
g(CEO)f(of)h(Isis)g(Distributed)h(Systems,)e(Inc.)21 b(Dr.)e(Rob)q(ert)c(Co)q
(op)q(er)f(is)i(the)e(second)75 710 y(principal)k(arc)o(hitect)e(in)g(the)g
(redesign)g(e\013ort.)k(Birman)c(and)g(Co)q(op)q(er)f(are)g(joined)i(in)f(thi\
s)g(e\013ort)f(b)o(y)g(a)75 766 y(substan)o(tial)h(group)e(of)h(studen)o(ts)g
(and)h(researc)o(hers.)146 822 y(Prof.)33 b(Keith)21 b(Marzullo)f(heads)g(the)
g fb(Meta)g fe(pro)s(ject)f(and)i(dev)o(elop)q(ed)g(RNFS,)f(a)g(replicated)h
(\014le)75 879 y(system)g(that)g(w)o(as)g(a)g(predecessor)h(of)g fb(Deceit)p
fe(.)40 b(Graduate)21 b(studen)o(t)g(Alex)i(Siegel)g(is)f(the)g(primary)75 935
y(dev)o(elop)q(er)16 b(of)f fb(Deceit)p fe(.)146 992 y(There)h(are)f(man)o
(y)g(pap)q(ers)i(on)e(the)h(curren)o(t)g(v)o(ersions)g(of)f fb(Isis)p fe(,)h
fb(Meta)g fe(and)g fb(Deceit)p fe(.)22 b(Moreo)o(v)o(er,)14 b(our)75 1048 y
(group)i(is)h(curren)o(tly)g(writing)g(sev)o(eral)f(new)h(tec)o(hnical)g(rep)
q(orts)f(concerned)i(with)e(the)h(design)g(c)o(hoices)75 1105 y(underlying)12
b(our)e(new)h(arc)o(hitecture,)g(issues)g(of)f(scaling)i(and)e(lo)q(calit)o
(y)h(and)g(p)q(erformance.)18 b(The)11 b(existing)75 1161 y(v)o(ersions)17 b
(of)e fb(Isis)i fe(and)g fb(Meta)f fe(ha)o(v)o(e)g(b)q(een)i(distributed)g
(to)d(more)h(than)g(500)g(sites)h(w)o(orldwide,)g(and)f(are)75 1218 y(a)o(v)m
(ailable)g(from)e(Cornell)i(Univ)o(ersit)o(y)l(.)21 b(Commercially)15 b(enhan\
ced)h(v)o(ersions)f(are)g(b)q(eing)h(dev)o(elop)q(ed)g(b)o(y)75 1274 y fb(Isi\
s)g fe(Distributed)g(Systems)g(Inc.)22 b(F)l(or)15 b(more)g(information)h(ab)
q(out)f fb(Isis)h fe(and)g fb(Meta)p fe(,)f(or)g(to)g(b)q(e)h(added)h(to)75
1331 y(our)c(mailing)i(list,)g(email)f(to)f(isis@cs.cornell.edu.)22 b(\(Reque\
sts)14 b(concerning)h(the)e(commercial)i(v)o(ersions)75 1387 y(of)g fb(Isis)g
fe(and)h fb(Meta)f fe(will)i(b)q(e)f(forw)o(arded)e(to)h(the)g(ISIS)h(Distrib\
uted)h(Systems\).)964 2577 y(3)g eop
%%Trailer
end
%%EOF