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DEV
345Com
paring .NET and Java
David C
happellPrincipalC
happell & A
ssociatesw
ww
.davidchappell.com
Stan
dard
Lib
rary
Application Platform
s Today
Op
erating
System
Ru
ntim
e En
viron
men
t
Brow
serA
ppsW
eb Services
Apps
Other
Apps
LocalA
pps
GU
IS
ervicesT
ransactionS
ervicesW
ebS
criptingD
ataA
ccessM
oreR
emote
Access
DEV
349The M
icrosoft .NET
component m
odelBertrand M
eyerProfessor of Softw
are Engineering, ETH Zürich
Scientific advisor, Eiffel Software, Santa Barbara
Component developm
ent with
COM
and CORBA
Component “Bus”
Servercom
ponentClient
component
IDL Stub
IDL spec
module R
eservation{interface Flight_booking {Price ticket_price
(in Date day, in Flight num
ber)raises (invalid_date, invalid_num
ber);exception invalid_date {D
ate when; };
readonly attribute string name;
...}};
The role of IDL
•Provide language-neutral interfacedescription of a m
odule’s operations•
As a result, enable clients and suppliers
written in different im
plementation
languages
The trouble with ID
L•
Programm
ers must w
rite IDL interface in
addition to actual software
•If from
an O-O
language, IDL duplicates
information present in the code, e.g. C
++header file, Eiffel contract form
•Perils of duplication
•ID
L compiler goes the w
rong way!
•H
owever: som
e tools ease the process.
Pre-.NET approaches: sum
mary
•O
bject technology is best known basis
•Inform
ation hiding is key•
O-O
sufficient by itself: need forautonom
ous components
•Current approaches too heavy: extra w
ork toturn m
odule (e.g. class) into component
•ID
L is a killer
DEV
200.N
ET Framew
ork Overview
Chris Anderson
Software A
rchitect, .NET Client
Microsoft Corporation
.NET Fram
ework
Design G
oals
•D
ramatically sim
plifies development and
deployment
•U
nifies programm
ing models
•Provides robust and secure executionenvironm
ent•
Supports multiple program
ming languages
Framew
ork, Languages,A
nd Tools
Op
erating
System
Op
erating
System
Co
mm
on
Lan
gu
age R
un
time
Co
mm
on
Lan
gu
age R
un
time
Base C
lass Lib
raryB
ase Class L
ibrary
AD
O.N
ET
and
XM
LA
DO
.NE
T an
d X
ML
AS
P.N
ET
AS
P.N
ET
Web
Fo
rms W
eb S
ervicesW
eb F
orm
s Web
Services
Mo
bile In
ternet T
oo
lkitM
ob
ile Intern
et To
olkit
Win
do
ws
Win
do
ws
Fo
rms
Fo
rms
Co
mm
on
Lan
gu
age S
pecificatio
nC
om
mo
n L
ang
uag
e Sp
ecification
VB
VB
C+
+C
++
C#
C#
JScrip
tJS
cript
J#J#
Visual Studio.NET Visual Studio.NET
Framew
ork, Languages, And Tools
Op
erating
System
Op
erating
System
Co
mm
on
Lan
gu
age R
un
time
Co
mm
on
Lan
gu
age R
un
time
Base C
lass Lib
raryB
ase Class L
ibrary
AD
O.N
ET
and
XM
LA
DO
.NE
T an
d X
ML
AS
P.N
ET
AS
P.N
ET
Web
Fo
rms W
eb S
ervicesW
eb F
orm
s Web
Services
Mo
bile In
ternet T
oo
lkitM
ob
ile Intern
et To
olkit
Win
do
ws
Win
do
ws
Fo
rms
Fo
rms
Co
mm
on
Lan
gu
age S
pecificatio
nC
om
mo
n L
ang
uag
e Sp
ecification
VB
VB
C+
+C
++
C#
C#
JScrip
tJS
cript
J#J#
Visual Studio.NET Visual Studio.NET
The .NET Evolution
Befo
re CO
M, ap
plicatio
ns w
ereB
efore C
OM
, app
lication
s were
com
pletely sep
arate entities
com
pletely sep
arate entities
with
little or n
o in
tegratio
nw
ith little o
r no
integ
ration
Ap
plicatio
nA
pp
lication
Co
de an
d d
ataC
od
e and
data
structu
resstru
ctures
The .NET Evolution
CO
M p
rovid
es a way fo
rC
OM
pro
vides a w
ay for
com
po
nen
ts to in
tegrate;
com
po
nen
ts to in
tegrate;
Ho
wever, each
Ho
wever, each
com
po
nen
t mu
st pro
vide
com
po
nen
t mu
st pro
vide
the
the “ “p
lum
bin
gp
lum
bin
g” ” an
d an
do
bjects can
no
to
bjects can
no
td
irectly interact
directly in
teract
The .NET Evolution
With
the .N
ET
Fram
ewo
rkW
ith th
e .NE
T F
ramew
ork
com
mo
n lan
gu
age ru
ntim
e,co
mm
on
lang
uag
e run
time,
com
po
nen
ts are bu
ilt on
aco
mp
on
ents are b
uilt o
n a
com
mo
n su
bstrate; N
oco
mm
on
sub
strate; No
“ “plu
mb
ing
plu
mb
ing
” ” is need
ed an
d is n
eeded
and
ob
jects can d
irectly interact
ob
jects can d
irectly interact
Assem
bly
Assem
bly
Compilation A
nd Execution
So
urce
So
urce
Co
de
Co
de
Lan
gu
age
Lan
gu
age
Co
mp
ilerC
om
piler
Co
mp
ilation
Co
mp
ilation
At in
stallation
or th
eA
t installatio
n o
r the
first time each
first time each
meth
od
is calledm
etho
d is called
Execu
tion
Execu
tion
JITJIT
Co
mp
ilerC
om
piler
Native
Native
Co
de
Co
de
Code (IL)Code (IL)
Metadata
Metadata
Simplify D
evelopment
•Com
pletely eliminates CO
M plum
bing•
No m
ore…–
Registration–
GU
IDs
–.ID
L files–
HRESU
LTs–
IUnknow
n–
AddRef/Release
–CoCreateInstance
=>self described apps=>self described apps
=>hierarchical namespaces
=>hierarchical namespaces
=>unified object model
=>unified object model
=>structured exceptions=>structured exceptions
=>comm
on root object=>com
mon root object
=>garbage collector=>garbage collector
=> =>” ”newnew
” ” operator operator
Simplify D
evelopment
•Com
mon Type System
–Com
mon instance and type definition
•Enables clean O
O program
ming
–Classes and interfaces
–Constructors, properties, m
ethods, events–
Cross language inheritance•
Built-in interoperability–
With CO
M–
With native (W
in32® style) D
LLs
Robust Environment
•A
utomatic lifetim
e managem
ent–
All objects are garbage collected
•Exception handling–
Error handling first class and mandatory
•Type-safety–
No buffer overruns, N
o unsafe casts, Uninitialized
variables
Secure Environment
•Security designed-in
•Code access security enforcem
ent–
Security based on the identity of code–
Adm
inistratively configurable via policy•
ASP.N
ET integrated authenticationof user–
Window
s identity, Passport®, form
s-based, …•
Cryptography library with X
ML
DSIG
support–
Digital signature for X
ML (w
ww
.w3.org/signature)
Simplify D
eployment A
ndM
anagement
•Zero-im
pact install–
Applications and com
ponents can be shared orprivate
•Side-by-side execution–
Multiple versions of the sam
e component can co-
exist on a system•
Assem
blies–
Contain dependency information
Op
erating
System
Op
erating
System
Co
mm
on
Lan
gu
age R
un
time
Co
mm
on
Lan
gu
age R
un
time
Base C
lass Lib
raryB
ase Class L
ibrary
AD
O.N
ET
and
XM
LA
DO
.NE
T an
d X
ML
AS
P.N
ET
AS
P.N
ET
Web
Fo
rms W
eb S
ervicesW
eb F
orm
s Web
Services
Mo
bile In
ternet T
oo
lkitM
ob
ile Intern
et To
olkit
Win
do
ws
Win
do
ws
Fo
rms
Fo
rms
Co
mm
on
Lan
gu
age S
pecificatio
nC
om
mo
n L
ang
uag
e Sp
ecification
VB
VB
C+
+C
++
C#
C#
JScrip
tJS
cript
J#J#
Visual Studio.NET Visual Studio.NET
Framew
ork, Languages, And Tools
Unify Program
ming M
odels
Win
do
ws A
PI
Win
do
ws A
PI
.NE
T F
ramew
ork
.NE
T F
ramew
ork
Co
nsisten
t AP
I availability reg
ardless o
fC
on
sistent A
PI availab
ility regard
less of
lang
uag
e and
pro
gram
min
g m
od
ellan
gu
age an
d p
rog
ramm
ing
mo
del
AS
PA
SP
Stateless,
Stateless,
Co
de em
bed
ded
Co
de em
bed
ded
in H
TM
L p
ages
in H
TM
L p
ages
MF
C/A
TL
MF
C/A
TL
Su
bclassin
gS
ub
classing
, ,P
ow
er,P
ow
er,E
xpressiven
essE
xpressiven
ess
VB
Fo
rms
VB
Fo
rms
RA
D,
RA
D,
Co
mp
ositio
n,
Co
mp
ositio
n,
Deleg
ation
Deleg
ation
How
Much Sim
pler?W
ind
ow
s AP
IW
ind
ow
s AP
IHWND HWND
hwndMain hwndMain
= =
CreateWindowExCreateWindowEx
( ( 0, " 0, "
MainWClassMainWClass
", "Main Window",", "Main Window",
WS_OVERLAPPEDWINDOW | WS_HSCROLL | WS_VSCROLL,
WS_OVERLAPPEDWINDOW | WS_HSCROLL | WS_VSCROLL,
CW_USEDEFAULT, CW_USEDEFAULT,
CW_USEDEFAULT, CW_USEDEFAULT,
CW_USEDEFAULT, CW_USEDEFAULT,
CW_USEDEFAULT, CW_USEDEFAULT,
(HWND)NULL, (HMENU)NULL,
(HWND)NULL, (HMENU)NULL,
hInstancehInstance
, NULL);, NULL);
ShowWindowShowWindow
( (hwndMainhwndMain
, SW_SHOWDEFAULT);, SW_SHOWDEFAULT);
UpdateWindowUpdateWindow
( (hwndMainhwndMain
););
.NE
T F
ramew
ork
.NE
T F
ramew
ork
Dim Dim
form form
As NewAs New
Form() Form()
form.Text = "Main Window"form.Text = "Main Window"form.Show()form.Show()
Factored And Extensible
•The Fram
ework is not a “black box”
•A
ny .NET class is available for you to extend
through inheritance–
Gives developers m
uch more head room
•Plug and Play com
ponents and!subsystems
The .NET Fram
ework Library
Base C
lass Lib
raryB
ase Class L
ibrary
AD
O.N
ET
and
XM
LA
DO
.NE
T an
d X
ML
Web
Fo
rms W
eb S
ervicesW
eb F
orm
s Web
Services
Mo
bile In
ternet T
oo
lkitM
ob
ile Intern
et To
olkit
Win
do
ws
Win
do
ws
Fo
rms
Fo
rms
AS
P.N
ET
AS
P.N
ET
System
S
ystem
System
.Data
System
.Data
System
.Xm
lS
ystem.X
ml
System
.Web
System
.Web
Glo
balizatio
nG
lob
alization
Diag
no
sticsD
iagn
ostics
Co
nfig
uratio
nC
on
figu
ration
Co
llection
sC
ollectio
ns
Reso
urces
Reso
urces
Reflectio
nR
eflection
Net
Net
IO IO
Th
readin
gT
hread
ing
Text
Text
ServiceP
rocess
ServiceP
rocess
Secu
rityS
ecurity
Co
mm
on
Co
mm
on
OleD
bO
leDb
SQ
LT
ypes
SQ
LT
ypes
Sq
lClien
tS
qlC
lient
XP
athX
Path
XS
LT
XS
LT
Ru
ntim
eR
un
time
Intero
pS
ervicesIn
terop
Services
Rem
otin
gR
emo
ting
Serializatio
nS
erialization
Serializatio
nS
erialization
Co
nfig
uratio
nC
on
figu
ration
Sessio
nS
tateS
ession
State
Cach
ing
Cach
ing
Secu
rityS
ecurity
Services
ServicesD
escriptio
nD
escriptio
n
Disco
veryD
iscovery
Pro
toco
lsP
roto
cols
UI
UIHtm
lCo
ntro
lsH
tmlC
on
trols
Web
Co
ntro
lsW
ebC
on
trols
System
.Draw
ing
System
.Draw
ing
Imag
ing
Imag
ing
Draw
ing
2DD
rawin
g2D
Text
Text
Prin
ting
Prin
ting
System
.Win
do
ws.F
orm
sS
ystem.W
ind
ow
s.Fo
rms
Desig
nD
esign
Co
mp
on
entM
od
elC
om
po
nen
tMo
del
The .NET Fram
ework Library
Base Framew
orkS
ystemS
ystem
Th
readin
gT
hread
ing
Text
Text
ServiceP
rocess
ServiceP
rocess
Secu
rityS
ecurity
Reso
urces
Reso
urces
Reflectio
nR
eflection
Net
Net
IO IO Glo
balizatio
nG
lob
alization
Diag
no
sticsD
iagn
ostics
Co
nfig
uratio
nC
on
figu
ration
Co
llection
sC
ollectio
ns
Ru
ntim
eR
un
time
Serializatio
nS
erialization
Rem
otin
gR
emo
ting
Intero
pS
ervicesIn
terop
Services
Data A
nd XM
LS
ystem.D
ataS
ystem.D
ata
System
.Xm
lS
ystem.X
ml
SQ
LT
ypes
SQ
LT
ypes
SQ
LC
lient
SQ
LC
lient
Co
mm
on
Co
mm
on
OleD
bO
leDb
Serializatio
nS
erialization
XP
athX
Path
XS
LT
XS
LT
ASP.N
ETS
ystem.W
ebS
ystem.W
eb
Cach
ing
Cach
ing
Co
nfig
uratio
nC
on
figu
ration
Services
Services
UI
UI
Sessio
nS
tateS
ession
State
Htm
lCo
ntro
lsH
tmlC
on
trols
Web
Co
ntro
lsW
ebC
on
trols
Descrip
tion
Descrip
tion
Disco
veryD
iscovery
Secu
rityS
ecurity
Pro
toco
lsP
roto
cols
Window
s® Form
s
System
.Draw
ing
System
.Draw
ing
Draw
ing
2DD
rawin
g2D
Imag
ing
Imag
ing
Prin
ting
Prin
ting
Text
Text
System
.Win
do
ws.F
orm
sS
ystem.W
ind
ow
s.Fo
rms
Desig
nD
esign
Co
mp
on
entM
od
elC
om
po
nen
tMo
del
Op
erating
System
Op
erating
System
Co
mm
on
Lan
gu
age R
un
time
Co
mm
on
Lan
gu
age R
un
time
Base C
lass Lib
raryB
ase Class L
ibrary
AD
O.N
ET
and
XM
LA
DO
.NE
T an
d X
ML
AS
P.N
ET
AS
P.N
ET
Web
Fo
rms W
eb S
ervicesW
eb F
orm
s Web
Services
Mo
bile In
ternet T
oo
lkitM
ob
ile Intern
et To
olkit
Win
do
ws
Win
do
ws
Fo
rms
Fo
rms
Co
mm
on
Lan
gu
age S
pecificatio
nC
om
mo
n L
ang
uag
e Sp
ecification
VB
VB
C+
+C
++
C#
C#
JScrip
tJS
cript
J#J#
Visual Studio.NET Visual Studio.NET
Framew
ork, Languages, And Tools
Languages•
The .NET Platform
is language neutral–
All .N
ET languages are first class players–
You can leverage your existing skills
•Com
mon language specification
–Set of features guaranteed to be in all languages
•W
e are providing–
Visual Basic
®, C++, C#, J#, JScript ®
•Third-parties are building–
APL, CO
BOL, D
elphi, Pascal, Eiffel, Haskell, M
L,O
beron, Perl, Python, Scheme, Sm
alltalk…
Standardization•
A subset of the .N
ET Framew
ork and C#subm
itted to ECMA
–A
dopted as International standards inD
ec. 2001–
In the ISO fast-track process now
–Co-sponsored w
ith Intel, Hew
lett-Packard•
Comm
on language infrastructure–
Based on comm
on language runtime and base
framew
ork–
Layered into increasing levelsof functionality
Summ
ary•
The .NET Fram
ework
–D
ramatically sim
plifies development and
deployment
–U
nifies programm
ing models
–Provides robust and secure executionenvironm
ent–
Supports multiple program
ming languages
DEV
349The M
icrosoft .NET
component m
odelBertrand M
eyerProfessor of Softw
are Engineering, ETH Zürich
Scientific advisor, Eiffel Software, Santa Barbara
Execution scheme under .N
ET
IL code(plus
metadata)
Loader
Managed code
Unjittedroutine call
Execution
Language compilers
JIT + verifier
EiffelVB
C++C#
.NET languages
The basic .NET com
ponent unitResult of com
pilation is an assembly
Assem
bly is a set of classesU
nit of:•
Delivery and deploym
ent•
Nam
ing (through namespaces)
•Security (level for granting perm
issions)•
Versioning &
side-by-side execution
Self-documenting through “m
anifest”
The Single Product Principle
•There is one product: SO
FTWA
RE
Eiffel: use single, seamless notation
throughout the development cycle
Rely on tools to produce documentation
Maintain just one product!
Single Product Principle in .NET
•It’s all in the metadata!
Definition:
•M
etadata is information about a m
odule’sexternal properties, not necessarily neededfor executing the m
odule, but retained aftercom
pilation along with the binary code
Examining an assem
bly with ildasm
How
is the metadata stored?
•Stuffed into PE (Portable Executable)form
at•
To Window
s, result of compiling an
assembly looks like ordinary binary
(*.dll or *.exe), but contains all kindsof supplem
entary information
•W
ill execute on .NET only
The Portable Executable (PE) format
Execution model: the role of
metadata
IL code(plus
metadata)
Loader
Managed code
Unjittedroutine call
Execution
Language compilers
JIT + verifier
EiffelVB
C++C#
.NET languages
Metadata contents
•M
anifest: assembly description
–N
ame, version, culture
–Security properties: N
eeded permissions
–Public key if present
–D
ependencies on other assemblies
•List of classes
•For each class:–
Features: methods, fields, properties, events
–Signatures (argum
ent and result types) of each–
Interfaces it implem
ents•
Custom
attributes (see next)
Working w
ith metadata
Letting a program access m
etadata:•
Use System
.Reflection
Examining m
etadata interactively:•
Use ILD
asmC
an convert metadata to:
•X
ML
•C
OM
type libraries (regasm)
To produce metadata:
•U
se System.R
eflection.Emit
.NET com
ponent model
•Single product principle: full reflectivity;assem
blies are self-documenting
•(G
roups of) classes directly yield components
•N
o extra plumbing
•N
o IDL
•Full application of O
bject-Oriented principles
•M
ulti-language interoperability
