COM+ and MSMQ

Srinivasan.G

Windows DNAA comprehensive

platform scaling from the department to the

Internet

External

Application

s

Legacy

Systems

Database

s

Thin

Client

Rich

Client

Keys to Windows DNA

●Three-tier Application Architecture

okey for scalable, distributed applications

●Cooperating Components

oreusable, binary, pieces of software that provide

services

okey to incremental, flexible development

●Enablers

oTools

oMiddleware ⇨ Application Services

oInteroperability

Non-Functional Requirements

●Performance Requirements

oResponse time

oNumber of clients

oAvailability

●Deployment Constraints

oExisting databases & applications

oTopology

●Security Requirements

oData protection

oUser authorization

●Transaction & Workflow Constraints

Application Services

●COM+

oRuntime environment for COM components

oDeclarative, rich infrastructure

oDistributed Transaction Coordinator (DTC)

oAdministration tool

●Microsoft Message Queue Server (MSMQ)

oRich messaging programming model

and infrastructure

oFlexible; e.g., exactly once, guaranteed delivery

Collaboration via MSMQ

Presentation Business Data

Win32

MSMQ

COM+ application

Presentation Business Data

SQL

Server

Win32

COM+

DCOM

ADO

Business

Object

Data

Objec

t

Component Design vs OOA/D

●Component design and OOA/D are

different

●OOA/D focuses on modeling ‘things’

●Component design focuses more on

services

●OOA/D/P is often used to implement

components but not sufficient

●Pure object designs aren’t always good

component designs

COM Programming ModelObjects

and Interfaces

Component

Client

Class

Factory

IClassFactory

IUnknown

Registration

Packaging

Object

IClassFactory

COM+: Simple, Powerful

Architecture

Context

CreateInstance

…

OK: SetComplete

…

Err: SetAbort

Attrib

utes

IUnknow

n

COM+ Model Benefits

●Simplification through reduction

oIncrease abstraction

o“Zero plumbing”

●Simple programming model

oClients: Create, use, release

oServers: Do work

●Simple, extensible architecture

oInterceptors

COM+ Model Benefits

●The glue in Windows DNA

oComponent Model + Services

oLanguage agnostic

oOnline & offline

oCentralized & distributed

oWeb & client-server

COM+ Features

●Servers

●Transactions

●Security

●Administration

●Load Balancing

●Queued Components

●Events

Problem: Server Programming is

Difficult●Difficult to write servers

oThreading

oConcurrency

oProcess Management

oN-Tier Complexity

oDeployment

COM+: Servers Made Easy

●Design components as a client application

oSingle user, single thread, no process concern

●Write components in ANY language

oVB, VJ, VC, Cobol, whatever

●Deploy as 1, 2, 3 or N-tier Application

oDrag and drop simplicity

Problem: Security Is Complicated

●Many different users sharing the same

components

●Different users require different security

solutions

●Distributed applications

COM+: Role-based Security

●Role-based security

●Method-level security

●Context ‘flows’ the security information

●Abstracts security settings

oEasier for the user

Problem: Management is Difficult

●Managing hundreds or thousands of

clients

●Managing tens or hundreds of servers

●Monitoring System Activity

●GUIs are too laborious for large systems

COM+: Administration

●MMC Snap In - Easy to Use

●Scriptable Interfaces - Full function

●System events are logged for Measuring

Monitoring and Metering

Component Services

●Components can be decorated with

attributes

odeclarative

oconfigurable

Problem: Continue to Work When Servers are

Unavailable

Problem: Smooth the Demand of Your system

●Different components are needed for

connected and disconnected versions of

the same application

●Deployment of two applications is difficult

●No way to govern system load for

consistent server performance

●Scale limitations

COM+: Queued Components

●Based on unification of objects,

transactions, and messaging

oDeferred obj execution

oAutomatic transactions

●Unifies connected / disconnected

application design

●Increases scalability / availability

Problem: Customers Want to Add

machines to increase Performance

●Small servers are dropping down in prices

●Distribute system load across systems

with no changes to the application (client

OR server)

●Increase availability

COM+: Load Balancing

●Transparent to clients

●Controlled via Admin

oReplicated Automatically

●Simple routing

oDesigned for extensibility

●Single router per application cluster

oRouter can fail over via resource cluster

Dynamic Load Balancing

●In addition to static load balancing or DNS

round-robin, COM+ provides dynamic load

balancing

oUses response time algorithm

oLoad balance on creation only

●Use to improve scalability, availability

●Most COM+ components are load-

balanceable

oBeware of machine affinities

Object Pooling

●COM+ supports pooling

●Lets you build a homogeneous pool of objects

oPer-process

oObjects can not have thread-affinity

oPool can be initialized in the background

oPool sizes set administratively

●Use to govern the maximum number of objects

created

●May be useful if construction costs are high

oTest to see if you get a performance benefit

Problem: Proprietary Event

Services●Enterprise applications need event

services

oNotify other components that something

‘interesting’ has happened

●Customers forced to design and

implement their own solutions

●Integration with other application

events becomes difficult

COM+ Event Services

●Publish and subscribe model

●Late bound design

●Notifications sent by COM

Publisher

Event

Database

Subscriber

Event Service Subscriber

Subscriber

Administration