Object Services and Consulting, Inc. Craig Thompson 972-379-3320 August 31, 1998 © Copyright 1998...

Object Services and Consulting, Inc.

Craig Thompson 972-379-3320 August 31, 1998 © Copyright 1998 Object Services and Consulting, Inc. All rights reserved.© Copyright 1998 Object Services and Consulting, Inc. All rights reserved.

StrawmanAgent Reference Architecture

(DARPA ISO coABS Program - Draft 8-31-98)

Craig ThompsonObject Services and Consulting, Inc. (OBJS)[email protected], http://www.objs.com



DARPA coABS Objectives

DoD Problem

• Joint Vision 2010• ABIS Study• DARPA ISO next generation architecture

The Vision

• networked society where every software artifact, information source, and device is connected and running in parallel

• intelligent automation-- application connectivity where networks of agents self-organize at run-time

• scaleable, evolvable, reliable, secure, survivable, ...

The Challenges

• what is an agent - an object with an attitude• control and complexity - agent, ensemble and system behavior that is predicable

and bounded• scalability and pervasiveness - agents for the masses



Object Component Agent ?

• state• behavior• encapsulation• inheritance

• reflection• packaging• serialization• repository

• TBD

Passing the Agent Test

What is an Agent?

deconstructionist view:agents augment objects with additional capabilities

• ACL• process inside• agent framework• planning• mobility• rules• …• goal/task-oriented• autonomous• ontologies• collaborative/teams



• software that acts as a human’s agent to provide some service or function in an intelligent manner

• modular software that exhibits some of these properties: autonomy, mobility, intelligence

• objects with an attitude -- component software constructed according to certain principles and/or mechanisms, e.g., objects that use an ACL to communicate, objects that make use of a planner, …

• more definitions at:http://www.geocities.com/ResearchTriangle/Thinktank/4633/Agents_definition.html

What is an agent?



The presentation consists of a list of views of the Agent Reference Architecture



Operational Payoff View

“Make it so!”WarfighterINTERNET

UserAgent

TaskAgent

InfoAgent

ProcessAgent

Agent systems offer the potential for rapid comprehensive response and adaptation to the dynamic battlefield.

what the end-user sees



Target operational requirements:

• Humans and agents connect to the agent grid anytime from anywhere and get the information and capability they need. Enable teams led by humans and staffed by agents.

• Intelligent automation -- easier application connectivity where networks of agents self-organized at run-time. Reduce the 60% of time in command and control systems spent manipulating stovepipes; incrementally replace stovepipes.

• Connect the $40B worth of DoD equipment that currently only interoperates with one or two other components, permitting better knowledge sharing. Another example is a process improvement in factory 1 is broadcast immediately to factories 2..N.

• Agent-enable object and web applications to reconfigure as new data and function is added to the system. Add capability modularly. Stable, scaleable, evolvable, reliable, secure, survivable, ...

• Scale to millions of agents so agents are pervasive and information and computation is not restricted to machine or organization boundaries.

• Survivable so if one agent goes down, another takes its place;

Requirements View



AdaptiveAdaptiveto uncertainty and change

Agents are goal directedand act on theirown performing

tasks on your behalf

Agents coordinate and negotiate to achieve

common goals

Agents moveto where they

are needed

AutonomousAutonomousproactive

MobileMobile InteroperateInteroperate

Agents interoperatewith humans, other, legacy systems, and information sources

Agents dynamically adaptto and learn abouttheir environment

CooperativeCooperativeself-organizing

delegation

socialpersonality

socialpersonality

Characteristics of Agents



Agents + the Global Grid

Server

Server

D ataService

D ataService

Server

Server

D ataService

D ataService

AA

A

A

A

AA

A

A

A

A

A

A

A

AA

A

A

A

AA

A

A

A

A

A

A

A

A

A

AA

Server

Server

ComponentLibrary

ComponentLibrary

Agent Grid - System Concept View



agent properties & kinds• communication

capability• computation capability• by role in system

• information agent• data sources

• interface agent• NL• fisheye view

• task agent• web agent• middleware agent

• mobile agent, itinerary• social, personality,

motivation, forgetting• intelligent agent

distributionmessaging svcs*agent life cycle* - start, stop,

checkpoint, name service**event monitoringleasing, compensationcatalog services*, registry/repository* register*, offer/accept/decline publish*, subscribe* trading*, matchmaking, advertising*, negotiating*, brokering*, yellow pages*security** authenticate* encrypt access control lists* firewall* CIA model agent suspectstransactionspersistence*query, profile (of metadata)*data fusionreplication* groups multicast(scarce) resource mgmt*,

allocate*, deallocate*, monitor*,

local, global optimization, load balancing*, negotiation for resources*

schedulingtime, geo-locationrules, constraintsplanning*property listversioning, config

Agent Ontology View (aka Functional/Compositional View)

speech acts*: ACL* - KQML, FIPA ACL, OAA ICL

planning*• reactive*• goal interactions*• discrete vs continuous*• constraints• iterative, revision• workflow

systemicgrid features

common services

AGENT SYSTEM• single vs. multi-agentAGENT SYSTEM• single vs. multi-agent

ensembles• # of agents*• teams, peers,

contracting,• org. responsibility• roles, capabilities,• mutual beliefs• hierarchy*• conversational

policies*

scalability*

policy*, management• resource dial

survivability

evolvability

reliabile*

licensing & cost

QoS*• accuracy• priorities

GRID

time-constrained*

control*, coordination*,multi-agent synchronization• cooperation, competition

adaptation, evolution*via market model, ...

federates

infrastructureprimitives• reflection• serialization• threads• interceptors• proxies• filters• multicast • wrappers

• legacy sys• data sources

ONTOLOGY**• ontolingua, OKBC• metadata representations

• interests, locations, availability, capability, price/cost

• XML and web object models

I*3BADDAICE

IA

EDCS

Quorum

OMGJTFJini

ALP, HLA, IA

Architecture Principle: separation of concernsdeconstructionist view - what can you take away

and still have an agent system

secure*, trust

societies• closed vs. open,

communities of interest

learning• by example• ...

mobility**

heterogeneous*• computing environ. • agent systems• ACLs• content languages• ontologies• policies• services• open world

assumption

autonomousdecentralized*

* = Architecture WG in Pittsburg* = Control WG in Pittsburg* = Interoperability WG in Pittsburgred = Sun Jini green = other DARPA programs

content languages• KIF, FOL, IDL,

RDF

missing• views• MOP

More common services

instrumenting, loggingcachingqueuingrouting, reroutingpedigree, drill downtranslation*...

DDB



Information Access Framework• heterogeneous data sources and domain object models

• properties: • LAN or WAN at known location or dynamically available

• relational • Oracle, Sybase, Informix, ODBC, JDBC

• OODB • information retrieval • simulators • geographical informaiton systems • semi structured sources

• html, xml , other formatted sources, image • information integration services

• data source wrappers • ifilter, subscribe, notify, monitor, push, pull

• persistence • replication • caching • query decomposition

• multi tier queries - get info from one source to complete query • source discovery

• trader, brokering, yellow pages, matchmaking • source selection • transformation, translation services, semantic integration and transformation, includes• unit conversion • domain and ontology services

• term translation , correlation services, name/place • query translation (e.g., from OQL to SQL )• fusing • stream • reflection

• control • properties

• binding time ... • indexing • working in parallel • iterative query reformulaiton • change propagation

• if data sources change (alternate source) • if query changes

• context of query • statically • dynamically - specified in plan, case-based reasoning, workflow

• metrics • operation effectiveness - info quality, timliness and cost of retrieval • breadth of coverage - completeness, data source complexity • maintenance or evolution over time

• cost in labor hours

• metadata properties • operations covered

• query only vs update too • data access systemic properties

• scaleable • plug and play, open, component-based • transparency of data location, access langauge, and protocol

• user queries • static set vs dyanamic and frequently changing based on user task and need

• distributed • all local to user machine, distributed on LAN, on WAN

• how homogeneous is content • uniform across all sources • unique per source • overlapping sources • partially redundant w inconsistencies • incomplete

• homogeneity of information sources • all in same query language • syntatic differences • multiple kinds

• source size - # of entity types • 10, 50, >50

• semantic impedence w user • no vs all query term translation

• source responsiveness • quick (<10 sec; medium - up to 60 sec; slow - <3 min; very slow - <3 min; batch• overnite; unreliable

• cost • availability, permission, quality, quantity, capabilities, type, • synchrony

• synchronous query and response • asynchronous • interuptable

• desired response control • all answers at once • client controls • server controls • top N answers

• requence of data source changes • never, seldom (<1/yr); often >1/mo; continuous - real-time feed

• frequency of user query changes • never, seldom (<1/yr); often >1/mo



Relevant Theories View

• speech acts, conversations/dialogs• ontologies• game theory• economic markets• patterns and protocols• planning & case-based reasoning• learns• KBMS• OO middleware service architectures (OMA/ORB)• Web architectures• distributed AI • workflow• dynamic DBMS• simulation• architecture description languages• network management• QoS• ...

* = Architecture WG in Pittsburg



Grid Federation View

coABS gridBorg collectiveALP clusterHLA federationDDB geolocationIA enclaveswarmdomaincontrol regimesmart spaceJini

• enter and leave• proxies• services• policies



OMG

ALP

I*3/BADD/AICE

HLA

DCOM

FIPA

W3C/Web

Jini

Related Technology/Community View

Some relevant technologies and communities

HPKB

… we don’t want to invent yet another architectureso the architecture views must not just concatenate to each other.

HTTP-NG

DDB

digital libraries

Quorum

WfMC

ODP



Agent Architecture Issues

• What are agents? - code and data packets that are autonomous, adaptive, cooperative, mobile, interoperable … We want all these properties in future agent-based systems. We need experience building systems with these properties.

• Pervasiveness - How do we insure that the architecture stays lite-weight for wide-spread adoption. • Embracing heterogeneity - We must piggyback agent systems on already pervasive infrastructure like ORBs, the

Web, email, and DBMS systems. We must identify the specific kinds of heterogeneity we want agent system architectures to support.

• Separation of concerns• agent-agent separation - can agents access each other’s state directly• agent-service separation - do agents implement the long list of services that the grid provides or is that done via

underlying component-based middleware? • grid-agent separation - agents are autonomous but they cooperate and compete for resources within the

software grid. The grid provides some global systemic properties and some basic shared services. Is there an explicit grid or is it implicit in the way agents interact with each other? Are some “services” (like planning) optionally distributed into agents or are they available from the grid’s planing service? Can new services be autoloaded into a grid that does not have them?

• Semantic interoperability, ontology - do ontologies scale? How do they extend class libraries?• Licensing - Agents, data sources, and component software need an economic model so broad communities can get

value from them. A model of licensing might be critical to success in the large.• Agent communication language (ACL) - Is the ACL compositional and extensible so one can define new speech acts

from existing ones? How many speech acts is enough? 20 or 5000?• Control points - where are the control points where different control algorithms might be substituted into the

architecture• Grid federation issues - How are software grids federated - flat versus hierarchical models? If different grids contain

different policy choices or different services, how does that affect agents communicating across grid boundaries? Can we add new services and -ilities to a grid once it is deployed? how transparent is addition or subtraction of services and ilities

• Coordination - Insure Agent Reference Architecture augments DARPA ISO ATAIS architecture. Provide template for next generation unified OMG, FIPA, and W3C agent standards. Insure that reference implementations (toolkits) exist and are widely available.



BACKUP



Purpose of this presentation• to provide a number of views of a generic Agent Reference Architecture

What is a Reference Architecture• its a meta-architectural blueprint for a family of concrete architectures that may appear in implemented

systems, providing a collection of the component parts of the architecture, how they can fit together, and any constraints on how they fit. A litmus test for a good reference architecture is that it covers actual systems and provides a way to reason about missing pieces, subarchitectures that make sense, interdependencies of parts, and how the architecture relates to other nearby architectures.

What should an Agent Reference Architecture do?• help people understand the scope and value-added of agent systems so they can realize their potential more

quickly (agents for the masses)• explain the principle components of Agent Systems and their interactions• explain how agent architecures solve DoD problems• explain how agent systems complement OMA, HLA, Web, DBMS, and other important system architectures,

also including AITS/NGII/NGA• identify missing components• identify what parts of the architecture already exist in COTS and GOTS, what parts are already prototyped,

and what parts are still needed. Map the coABS investment and what industry will do.• identify research issues (e.g., agent control, agent interoperability)• explain how to scale agent systems; also how to insure systemic properties of agent systems• identify candidate standards and a roadmap for adoption working with industry relevant consensus bodies

Status• this is a first draft and only covers some of the areas above. Textual notes augment this .ppt presentation.

Towards an Agent Reference Architecture



Architecturecodify design of agent architecture,

esp. grid properties and serviceswhat it means to be agent-ready

Interoperabilityallow many kinds of agent

systems to interoperate naming, ACL, KIF, ontology

conversation policies, federation

Controlsmooth grid policy mgmt

how agent groups coordinateplanning, teams

Challenge ProblemDoD Domain: NEO Non-combatant evacuation order

quick insertion of temporary forcelots of uncertaintymost prevalent op

DARPA coABS Working Groups



level 3: participant level

• user interface technologies

• domain entities like humans and simulated tanks

level 2: common apps -

level 1: control services -

level 0: network and connectivity -

By Level in System *

* = used in 8/20 coABS chairs telecon



CONCEPT ORGANIZATIONALMODELS AND

PATTERNS

AGENTCOMMUNICATION

LANGUAGE

ONTOLOGY ANDKNOWLEDGE

REPRESENTATIONSYSTEMS

STANDARDSACTIVITIES

INFRA-STRUCTURE

DISTRIBUTEDPROCESSING

APPLICATIONAREAS

Autonomous Broker ARCOL CYC Agent Interop Auditing ATP Critics

Benevolence Active Object FIPA97 ACL GFP / OKBC FIPA Authorization CORBA Commerce

Collaborative Adapter KQML GKB MAF Broker DCOM Design Eng

Coordination Contract-Net KQML97 JOE Collaboration HTTP Discovery

Learning Economy KQML-LITE KADS I+II ConfigurationMngmt

IIOP Eager Assistant

Mobile Federation KIF Debugging JAVA/RMI Filters

Pro-active Mediator K-ONTOLOGIES Human AgentInteraction

KTP Guides

Rationality Negotiator LOOM Life Cycle OTP InformationMediator

Reactivity Reasoner ONTOLINGUA Location{Geo/Logical}

RPC KnowledgeMining

Social Societies ONTOSAURUS Naming/Directory

KnowledgeMngmt

Veracity PIF Ontology Memory Aids

PSL Persistence NetworkManagement

SHADE Place ResourceTranslation

SHELLEY Resource Mng SituationMonitoring

RDF Routing Workflow

SecurityTime

TransactionPaymentFigure 1. Software Agent Systems Framework

(from Alan Piszcz, MITRE)

Other Architecture Views



Agent

Agent Communication Channel (ACC)

AgentTrigger

Services(ATS)

AgentPersistence

Service(APS)

AgentCommunication

Language(ACL)

Application/MissionSoftware

AgentOntologyService(AOS)

AgentWrapper

(AW)

Agent

AgentCommunication

Language(ACL)

MappingProtocol

(HTTP,ORB)

RDBMS

WWWServer

FIPA Specification

Application Specific Software

Non-FIPA service

DirectoryFacilitator

(DF)

AgentManagement

System(AMS)

AgentResource

Broker(ARB)

Agent Based DynamicVirtual Private Network

Provisioning

PersonalCommunication

Agent(PCA)

ServiceProvider

Agent(SPA)

NetworkProvider

Agent(NPA)

Figure 2. Agent Platform Reference Architecture

(from Alan Piszcz, MITRE)

Other Architecture Views



Other Architectural Views

Views Missing from this presentation

• review and refine all mapping• identify additional requirements and map these to the Agent Reference Architecture • identify additional issues and resolve issues• recurse on sub-reference models for services and capabilities -or- point to existing

specifications from FIPA, OMG, or the agent community• identify mappings from the Agent Reference Architecture to OMG OMA, HLA, etc. to

see the value added• a mapping to implementations available as COTS or GOTS • a mapping of coABS projects and components to other agent reference architecture views• a priority view of components needed first, second, … by potential providers• a roadmap for standards to complement FIPA’s and OMG’s (work through these groups)



Architecture Issues

• requirements - from the point of view of DoD applications, what do we expect from agent technology. There are many answers:

• replace stovepipe systems with more reliable, scalable, survivable, evolvable, adaptable systems. Make it much easier to snap together future systems to meet flexible needs in uncertain environments

• reduce complexity - simplify agent technology so it is useful to the masses• solve data blizzard, information starvation problemsWe need to write these down and then provide mappings to agent architecture capabilities that make these

domain capabilities possible.• avoid yet-another-architecture - the agent reference architecture cannot be a wholly different architecture than

near-by relatives. It should overlay or augment architectures like ORBs, Web, HLA, Jini, ODP, Quorum, AICE, ALP. Or it may be that it provides local agent architectures that can interoperate.

• what are agents? - thin, thick, smart, dump, mobile, stationary, chatty, objects that use ACLs to communicate, … We must tease these (possibly orthogonal) properties apart and understand what our technology is adding to the picture. Especially if we want a large body of industry and DoD to adopt this next generation technology. Related:

• criterial characteristics, minimal, maximal, lite or heavy weight - Are there criterial properties of agent based systems? is there any minimal or maximal set of properties that we can agree on for something to be an agent-based system. Is it based on technical mechanisms (e.g., makes use of an ACL) or just any system with (some of) these properties: autonomy, adaptive, cooperative, mobile, interoperable. How can we keep the architecture lite weight and still accommodate all the services?

• grid-agent separation - agents are autonomous but they cooperate and compete in some context which we are terming the grid. The grid provides some global systemic properties and some basic shared services.

• are agents really autonomous (including being independent of the grid)?• is there an explicit grid or is it implicit in the way agents interact with each other?• are some “services” (like planning) optionally distributed into agents or are they available from the grid’s

planing service. Does this matter?• is there a maximal or minimal (lite-weight) grid and what happens if agents interoperate that come from

differently configured grids?• do agents ask other agents for their properties and grid capabilties• can new services be autoloaded into a grid that does not have them?



• agent-agent separation - can agents access each other’s state directly• agent-service separation - how are agents and services related? For instance, do agents implement the long list of

services that the grid provides or is that underlying component software? Does each agent contain a planner or is a planning service global to a collection of services? It might be a wave-particle distinction.

• embracing heterogeneity - it is clear we must do this if agents will live in internet settings. But we also cannot expect systems to work with complete heterogeneity. The Web works partly because widespread agreement on HTTP, HTML, XML, .. and DBMSs work because of SQL and related standards. So we must identify the specific kinds of heterogeneity we want agent system architectures to support. It is not enough to say we are embracing heterogeneity.

• semantic interoperability, ontology - how far beyond the standard OO class model or DBMS schema do ontologies go; do they scale (most ontologies are pretty narrow), specifically which interoperability problems are solved

• licensing - like many grid services, licensing’s degenerate form is no licensing. But agents and component software cannot succeed without an economic model that makes broad communities get value from them. One way to do this is via licensing space on your machine, capabilities and services, data sources, … A model of licensing might be critical for coABS to succeed in the large.

• Agent Communication Language (ACL)• is the ACL compositional and extensible so one can define new speech acts from existing ones?• How many speech acts is enough? 20 or 5000?

• control points - where are the control points where different control algorithms might be substituted into the architecture

• grid federation issues • how are grids federated - flat model, hierarchical• if different grids contain different policy choices or different services, how does that affect agents communicating

across grid boundaries?• can we add new services and -ilities to a grid once it is deployed? how transparent is addition or subtraction of

services and ilities

Architecture Issues

There are many other issues!They are worth listing.



Challenges

Challenges for DARPA/ISO Next Generation Architecture • What can coABS build on from other DARPA programs? Are reference architectures,

service specs, common schema, data sources, reference implementations readily available in the NGA repository for plug-and-play? How about implementation guidance?

• What is our plan to transfer DARPA/ISO NGA architecture, specs, and implementations inside DARPA and outside to industry via standards and products?

• How do we insure lite-weight meta architectures that are still evolvable?

Challenges for coABS• Risks: silver bullet, overpromising, pin-down coABS unique contribution, do planning

techniques scale for Internet and programming language communities?• Define agent functions, keep complexity manageable for the programmer in the street.

Insure the systems are implementable via prototyping; share toolkits where possible; build on COTS and GOTS where possible.

• Coordinate with DDB, AICE, and Quorum on design of an open decentralized global grid. Borrow and unify ideas of clusters, federates, enclaves from OMG, ALP, HLA, IA, Jini. Unify agent architecture with HLA, Web, ORB, workflow, ...

• Insure coABS reference architecture provides template for next generation unified OMG, FIPA, and W3C standards and that reference implementations (toolkits) exist and are widely available.

• How do we foster an economy of componentized agent software?• micro licensing component software and leasing resources across the network • crossing organizational boundaries so the net is the DBMS, the net is the computer • how to populate space with 100,000 advertisements?

Object Services and Consulting, Inc. Craig Thompson 972-379-3320 August 31, 1998 © Copyright 1998...

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Transcript of Object Services and Consulting, Inc. Craig Thompson 972-379-3320 August 31, 1998 © Copyright 1998...