Directory UMM :Networking Manual:computer_network_books:

COM, DCOM

COM, DCOM

and

and

Software Components

Software Components

Nat Brown

Nat Brown

COM Program Management

COM Program Management

Microsoft Corporation

Microsoft Corporation

natbro@microsoft.com

Agenda

Agenda



What are COM and DCOM?

What are COM and DCOM?



What’s right with COM

What’s right with COM



What’s wrong with CORBA / IIOP

What’s wrong with CORBA / IIOP



Interesting COM Research Topics

Interesting COM Research Topics

The COM Programming

The COM Programming

Model

Model

A scalable programming model

A scalable programming model

Client

Client

Component

Component



In the same

In the same

process

process



Fast, direct

Fast, direct

function calls

function calls

Client

Client

COM

COM

Component

Component

Client Process

Client Process Server ProcessServer Process



On the same

On the same

machine

machine



Fast, secure IPC

Fast, secure IPC



Across machines

Across machines



Secure, reliable

Secure, reliable

and flexible

and flexible

DCE-RPC based

DCE-RPC based

DCOM

DCOM

protocol

protocol

COM

COM

DCE

RPC

Client

Client

Server Machine

Server Machine

Client Machine

Client Machine

COM

Client Machine

Server Machine

DCOM Architecture

DCOM Architecture

Flexible and extensible

Flexible and extensible

Pluggable Transports

Pluggable Transports

TCP, UDP

TCP, UDP

IPX, SPX

IPX, SPX

HTTP

HTTP

D

C

O

M

Msg-Q

Msg-Q

Clients

Clients

D

C

O

M

Server Machine

Client Machine

DCOM Architecture

DCOM Architecture

Flexible and extensible

Flexible and extensible

Pluggable Security

Pluggable Security

TCP, UDP

TCP, UDP

IPX, SPX

IPX, SPX

HTTP

HTTP

D

C

O

M

Falcon

Falcon

Clients

Clients

NT4 Security

SSL/

Certificates

NT Kerberos

DCE Security

D

D

C

C

O

O

M

M

DCOM Architecture

DCOM Architecture

Efficient and scalable

Efficient and scalable

Server

Server

Client

Client

Client

Client



Multiplexing

Multiplexing

- Single Port per-protocol, per

- Single Port per-protocol, per

server process, regardless of # of objects

server process, regardless of # of objects



Scalable

Scalable

- Connection-Less Protocols like

- Connection-Less Protocols like

UDP Preferred

UDP Preferred



Established Connection-Oriented (TCP)

Established Connection-Oriented (TCP)

Sessions

Server Machine

Server Machine

Client Machine

Client Machine

DCOM Architecture

DCOM Architecture

Efficient and scalable

Efficient and scalable

Server

Server

Client #1

Client #1

Client #2

Client #2



Low Bandwidth

Low Bandwidth



Header is 28 bytes over DCE-RPC

Header is 28 bytes over DCE-RPC



Keep-Alive Messages bundled for all connections

Keep-Alive Messages bundled for all connections

between

between

Machines

Machines

Keep-Alive Traffic

Keep-Alive Traffic

for all connections

for all connections

Lo

gi

ca

l “

Co

nn

ec

tio

ns

”

Lo

gi

ca

l “

Co

nn

ec

tio

ns

”

or

“S

es

si

on

s”

or

“S

es

si

What’s Right with COM

What’s Right with COM



Focus is on binary object standard

Focus is on binary object standard

and scalable/fine-grained

and scalable/fine-grained

component re-use

component re-use



Concreteness and depth of

Concreteness and depth of

definition, for example security,

definition, for example security,

lifetime management, activation,

lifetime management, activation,

installation & deployment

installation & deployment

What’s Wrong with

What’s Wrong with

CORBA/IIOP

CORBA/IIOP



Focus is on cross-node or network

Focus is on cross-node or network

reuse/integration

reuse/integration

–

in practice useful for vertical solutions, not

in practice useful for vertical solutions, not

horizontal reuse/integration

horizontal reuse/integration



Incomplete specification

Incomplete specification

–

marshaling format of certain types of data-

marshaling format of certain types of

data-structures

structures

–

implications of lack of services (e.g. Naming,

implications of lack of services (e.g. Naming,

Events, Lifetime management)

Events, Lifetime management)

COM Research Areas

COM Research Areas



High-Level Language Integration

High-Level Language Integration



Application Management

Application Management



Ease-of-use

Ease-of-use

Language Integration

Language Integration



Re-Use Mechanisms

Re-Use Mechanisms

–

Inheritance, Containment, Delegation, Aggregation

Inheritance, Containment, Delegation, Aggregation

–

“

“

Interception”

Interception”



Constructs of modern OO languages

Constructs of modern OO languages

–

classes, fields, exceptions

classes, fields, exceptions



Constructs of modern 4GL/RAD tools

Constructs of modern 4GL/RAD tools

–

data-binding

data-binding

–

auto-persistence, -everything

auto-persistence, -everything

Application Management

Application Management



Distribution of Code + Data +

Distribution of Code + Data +

Configuration Information

Configuration Information



Security and Security Delegation

Security and Security Delegation

–

Security “roles” and re-use of

Security “roles” and re-use of

components

components



Performance Monitoring

Performance Monitoring

Ease-of-Use

Ease-of-Use



What’s the next programming

What’s the next programming

model layer to vastly improve

model layer to vastly improve

ease-of-use?

ease-of-use?

–

Transactions?

Transactions?

Ease-of-Use: First Steps

Ease-of-Use: First Steps

Clients

Clients

Server

Server

Network

Network

Thread Pool

Thread Pool

Queue

Queue

Connections

Connections

Context

Context

Security

Security

Shared Data

Shared Data

Receiver

Receiver

Synchronization

Synchronization

Service Logic

Service Logic

C

o

n

fig

u

ra

tio

n

C

o

n

fig

u

ra

tio

n

M

a

n

ag

em

e

n

t

M

a

n

ag

em

e

n

t

Server

Server

Thread Pool

Thread Pool

Queue

Queue

Connections

Connections

Context

Context

Security

Security

Shared Data

Shared Data

Receiver

Receiver

Synchronization

Synchronization

Service Logic

Service Logic

C

o

n

fig

u

ra

tio

n

C

o

n

fig

u

ra

tio

n

M

a

n

ag

em

e

n

t

M

a

n

ag

em

e

n

t

MTS = easier

Reference Material

Reference Material

 [Box1 97][Box1 97]

D. Box, Q&A ActiveX/COM,

D. Box, Q&A ActiveX/COM, Microsoft Systems JournalMicrosoft Systems Journal, March 1997, pp. 93-105., March 1997, pp. 93-105.  [Box2 97][Box2 97]

D. Box, Q&A ActiveX/COM,

D. Box, Q&A ActiveX/COM, Microsoft Systems JournalMicrosoft Systems Journal, July 1997, pp. 93-108., July 1997, pp. 93-108.  [Brockschmidt 93]_{[Brockschmidt 93]}

K. Brockschmidt,

K. Brockschmidt, Inside OLE 2Inside OLE 2, Redmond, Washington: Microsoft Press, 1993., Redmond, Washington: Microsoft Press, 1993.  [Brown 96]_{[Brown 96]}

N. Brown, C. Kindel, Distributed Component Object Model Protocol -- DCOM/1.0

N. Brown, C. Kindel, Distributed Component Object Model Protocol -- DCOM/1.0

http://ds1.internic.net/internet-drafts/draft-brown-dcom-v1-spec-01.txt

http://ds1.internic.net/internet-drafts/draft-brown-dcom-v1-spec-01.txt

 [Chappell 96]_{[Chappell 96]} D. Chappell,

D. Chappell, Understanding ActiveX and OLEUnderstanding ActiveX and OLE, Redmond, Washington: Microsoft Press, 1996., Redmond, Washington: Microsoft Press, 1996.  [COM 95] The Component Object Model Specification, [COM 95] The Component Object Model Specification,

http://www.microsoft.com/oledev/olecom/title.htm

http://www.microsoft.com/oledev/olecom/title.htm

 [DCE 95]_{[DCE 95]}

AES/Distributed Computing - Remote Procedure Call, Revision B, Open Software Foundation,

AES/Distributed Computing - Remote Procedure Call, Revision B, Open Software Foundation,

http://www.osf.org/mall/dce/free_dce.htm

http://www.osf.org/mall/dce/free_dce.htm

 [Rogerson 96]_{[Rogerson 96]} D. Rogerson,

D. Rogerson, Inside COMInside COM, Redmond, Washington: Microsoft Press, 1996., Redmond, Washington: Microsoft Press, 1996.  [Wang 97]_{[Wang 97]}

Y. M. Wang, COM/DCOM Resources,

Y. M. Wang, COM/DCOM Resources,

http://www.research.att.com/~ymwang/resources/resources.htm