An Overview of ActiveX

Charlie KindelArchitect & Chief Technical AdvisorMicrosoft Developer Relations Group

Outline

What is ActiveX?The Component Object ModelCurrent Status

What is ActiveX?

A marketing name for a set of technologies and services, all based on the Component Object Model (COM)

It’s just COM! “DCOM” is just COM with a longer wire

Wanted: Software Components

“Active wave” requires applications, content, operating systems, networking, distributed services to be integrated as never before

Monolithic solutions won’t work No one vendor or one team of programmers can

move fast enough Need to leverage others’ work and to build and

ship smaller pieces incrementally Need to evolve smaller pieces asynchronously

without sacrificing the whole

Solutions… “WOSA” architecture was Microsoft’s 2nd

generation component technology API (often with different “levels”) System (Microsoft) -supplied intermediary DLL

with out-of-band management routines SPI for real components/servers to plug in

“underneath”

Works great (e.g. ODBC) but has crucial limitations No safe decentralized extension or evolution

COM: 3rd Generation Components

Unified programming model Between OS and apps — unification of system

handle-based “objects” and variety of app models Between in-process and remote interaction —

unification of DLLs and RPC

Standards for binary deployment, connection Software pieces or “components” find and connect

to each other through clearly defined interfaces

Solves fundamental problems of software integration, independent evolution

Examples

Manufacturing process controlControls on the Interent/Intranet

clientComponent based server applications

Active Server Pages Microsoft Transaction Server (Viper)

Multi-tier “client/server” applications

3 Tier Client/Server

Third-Tier - Databases, Legacy Data

COM

SNAetc...

CORBA

Mid-Tier - HTTP, Biz Objects, Active Server Pages, Scripting

COM

HTTP

“Desktop” - Compound Documents, Controls, Scripting

ActiveX Builds on COM

COM’s initial thrust: integrating desktop applications with OLE

COM technology is generically useful, being applied to a range of other areas Inherently distributed

1000’s of shipping, commercially available, products.

World class development tools VB, VC, VJ, Delphi, PowerSoft…

Who Benefits?

Independent software vendors Build components in any language, any

development process Sell independently or in bundles No central coordination required

Corporate developers Buy from competitive market rather than build Large projects benefit from component discipline

Anyone doing software integration

COM Architecture

The ModelThe “ORB”The Services

Component Object Model

Components, Components, Components

Binary standardWire-level standard

COM Fundamental PrinciplesWhat the designers of COM were striving for...

Binary components Any programming language Any location (in-process, cross-process,

cross-machine) No centralized authority

Zero sacrifice in-proc performanceSimplest model possible

Enable extensibility and adaptability

COM Principles

Rigorous Encapsulation Black box -- no leakage of

implementation details All object manipulation through strict

interfacesPolymorphism

via multiple interfaces per class “Discoverable”: QueryInterface COM

Object

IUnknown

IRobot

IDispatch

Isn’t COM about “Objects”?

No … COM sets out to solve system software problems that arise when hooking up randomly evolving combinations of binaries

Yes … from the perspective of these new kinds of objects also called “components” Traditional object concepts used (but adapted) to

solve a different (but overlapping) set of requirements in a different problem space

Component services can be called more naturally from O-O languages

Systems OT complements language OT

COM Architecture

ClientClient ComponentComponent

InprocessInprocess

COMCOMrun timerun time

providerproviderSecuritySecurity

RPCRPC

COMCOMrun timerun time

SecuritySecurityproviderprovider RPCRPC

LocalLocal

LPCLPCProtocol stackProtocol stack Protocol stackProtocol stack

DCOM network-DCOM network-protocolprotocol RemoteRemote

Distributed COM

Just COM “with a longer wire”All COM components communicate in the

same way on the same machine

In-process, Out-of-process

across a Local Area Network across a Wide Area Network across the Internet

Same tools, knowledge, code

Distributed COM

Wire Protocol Based on DCE RPC Specification

Interoperable with OSF DCE RPC implementations

We call it “ORPC” Efficient and Scalable Documented in Internet-Draft

ftp://ietf.org/internet-drafts/draft-brown-dcom-v1-spec-01.txt

The COM “ORB”

The “model” is about how the technology is used

The “ORB” is how it’s implemented We call it the COM Runtime

Pluggable Transports

COMCOMClientClient

COM Runtime ArchitectureFlexible and extensible

Component

CO

M R

unti

me

Server MachineClient Machine

TCP, UDP

SPX,IPX

Net BUI

HTTP

“Falcon”CO

M R

unti

me

Proxy

Other Component

Pluggable Security Providers

COMCOMClientClient

COM Runtime ArchitectureFlexible and extensible

Component

CO

M R

unti

me

Server MachineClient Machine

DCE

NT Kerberos

SSL, Certs.

NTLM

CO

M R

unti

me

Proxy

Other Component

ServerServerClientClient

Efficient and Scalable

Multiplexing - Single Port per-protocol, per server process, regardless of # of objects

Scalable - Connection-Less Protocols like UDP Preferred

Established Connection-Oriented (TCP) Sessions Reused by same client

ClientClient

Server MachineServer MachineClient MachineClient Machine

ServerServerClient #1Client #1

Client #2Client #2

Keep-Alive TrafficKeep-Alive Trafficfor all for all

connectionsconnections

Logical

“

Logical

“Connec

tions

Connectio

ns””

or “Ses

sions”

or “Ses

sions”

Efficient and Scalable

Low Bandwidth Header is 28 bytes over DCE-RPC Keep-Alive Messages bundled for all

connections between Machines

COM Runtime Architecture

Secure - Security is designed and built in. Not an option.

Inherently DistributedPluggable

Security Transports

The COM “ORB”

Highly debugged and tuned The COM Runtime first shipped in 1993 Used by 1000s of commercial

applicationsAvailable today on Win95, NT, Solaris

DEC UNIX, HPUX, Linux, MVS, VMS, Mac, and others rolling out this year

The COM “ORB”

Full source code licensable from The Open Group (formerly OSF and X/Open) With conformance test suite

Free! (Built-into Win32 Platforms) No separate client access license or

expensive “developer” version

Structure of the COM “ORB”

The COM Runtime

COM and Distributed COM Registry

Pluggable Security(SSPI)

NTLMKerberos

Pluggable Transports DCE

MS-RPC

TCP UDP IPX SPX HTTP “Falcon”ETC...

Core Services(Automation, Monikers, Storage, ComCat, Data Transfer, IR)

Components and ApplicationsComponents and Applications

Core COM Services

SecurityLifecycle

ManagementType Information

(Interface Repository)

Monikers (Naming)Automation

(Dynamic Invocation)

Data TransferComponent

CategoriesRegistry

COM Summary

The ModelThe “ORB”The Services

So What is ActiveX?

A marketing name for a set of technologies and services, all based on COM (the model, the “ORB”, and the services)

Internet Explorer 3.x/4.xInternet Explorer 3.x/4.x

HTML contentHTML content(text and images)(text and images)

HTTP HTTP serverserver

HTTPHTTP

ActiveX Control ActiveX Control or Java applet or Java applet downloaddownload

ActiveX Control ActiveX Control or Java appletor Java applet

COM objects or COM objects or ActiveX ControlsActiveX Controls

(D)COM(D)COM

COM objects or COM objects or ActiveX ControlsActiveX Controls

ActiveX ScriptActiveX Script

User Experience: How It Works

Active Components

ActiveX Controls Are COM components with “design-time” UI Can be written in C++, Java, VB, Delphi, ... Self-registering Optimized for download and execute

Java applets Simple applications

Work on both Active Client or Server Can talk indirectly over HTTP or directly over COM

Microsoft Java VM

Java VM is a COM component Use Java classes from any

application/language, not just browser/Java Any Java object is a COM object

Automatic integration of Java applets with other languages and scripts Lets Java applets talk to other Java applets Lets Java applets talk to ActiveX

components Gives Java applets access to all PC

functionality

Transaction Server“Viper”

Runtime executionenvironment for server-based components

Extends COM archi-tecture with transactionsemantics

Provides concurrency,multi-threading, queuing, atomicity, etc.

Makes is easy to encapsulate business logic in middle-tier

ActiveX Core Product Status

“D”COM first released in Windows NT 4.0, August 1996

Win95 version released January 1997Solaris 2.x release imminent

Other UNICES, MVS, and VMS to follow

Macintosh version in H1 1997Active Group source licenses available by

mid-1997; DCE integration project by end of 1997

Resources Great Overview Book

Understanding ActiveX and OLE (by David Chappell)

Implementations Win95 version

<http://www.microsoft.com/oledev/> Solaris and other non-Win32 versions

<http://www.sagus.com/>

Technical info <http://www.microsoft.com/workshop/> and

<http://www.microsoft.com/oledev/> Inside COM (by Dale Rogerson)

Mailing list http://www.microsoft.com/workshop/resources/email.htm

Questions?

Thank you!

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