ADAPTABLE SOFTWARE

1
ADAPTABLE SOFTWARE

• ARCHITECTURAL SOLUTIONS THAT ENABLE ADAPTATION
• TO CHANGES IN REQUIREMENTS (MICROKERNEL)
• BY DYNAMICAL CHANGE STRUCTURE AND BEHAVIOR OF
  SOFTWARE (REFLECTION)

2
MICROKERNEL PATTERN

• SEPARATES a Minimal Functional Core (MICROKERNEL)
  from extended functionality provided by
  (INTERNAL SERVERS) and customer-specific parts
  (EXTERNAL SERVERS)
• The MICROKERNEL also provides the sockets for
  plugging in these extensions and coordinating
  their collaboration.

3
EXAMPLE FIPA Architecture

• Describes
• Elements of FIPA agent systems
• Relationships between elements
• Mechanisms for communication and transport
  (communication languages, protocols, network
  services )

• Addresses issues
• Transport mechanisms for messages(RMI, SUNIIOP)
• Mapping specifications to new technologies (XML,
  CORBA, SMTP, web servers)
• Levels of operation which include relationships
  between agents or between agents and platforms

4
FIPA-OS as Microkernel
5
INTELLIGENT AGENTS

• An intelligent agent is a software entity which
  exhibits, in some significant measure, autonomy,
  intelligence, and environmental awareness, and
  which interacts with its environment to achieve
  internal goals. Jennings, 1996
• Co-operation with other agents
• Software Hardware?
• (Agents or Holons or Autonomous XXX?)

6
Architecture
K n o w l e d g e b a s e
Planner
Scheduler
Reasoning engine
Context collector
User profile manager
Context manager
Context parser
Content handler
Context dB
Message generator
ACL parser
Communications
7

• a protocol is a stereotypical dialogue for a
  cooperation framework (e.g. contract net)
• reasoning, deciding and reacting component
• - maintains an agenda containing active scripts
• - a script can be (goal-driven) invoked to
  satisfy an intention or (data-driven) involved
  in response to current situation
• - a filter component which selects scripts to
  execute

8
WHY AGENTS ?

• More usable and understandable structure (e.g.
  spaghetti code vs structure modules).
• (Almost) essential in large distributed systems
  where all subsystems need to be continually
  interchanging information to collectively
  achieve or to maintain some desired state
• (e.g. highly coupled subsystems)
• (cf. human case of multi-disciplinary research
  team)

9
HOLONIC ENTERPRISE
ENTERPRISE
Field Cluster
CC
CC
RESOURCEr
EC
RESOURCE
EC
CC
CE
CE
CE
RESOURCE
CE
CE
CE
EC
CC
CC
ENTERPRISE
RESOURCE
CE
CE
CE
EC
RESOURCE
EC
CE
CE
CE
CE
CE
CE
CC
CC
RESOURCEr
EC
RESOURCE
EC
CC
Dynamic Virtual Cluster
CE
CE
CE
RESOURCEr
CE
CE
CE
EC
CE
CE
CE
Field Cluster
HOLONIC ENTERPRISE AS A HOLARCHY
10
FIPA Kernel

• Includes mandatory agents that manage the
  platform
• AMS (Agent Management System) -- manages the
  creation,deletion,authentication of agents and
  provides a white pages directory service for the
  agents that reside on the platform
• ACC (Agent Communication Channel)-provides the
  foundation for communication between the software
  agents
• DF (Directory facilitator) represents a yellow
  pages directory for agents -has information about
  the agents and the services they offer.

11
Core Platform Functionality(FIPA - mK)

• a collection of services that are closely coupled
• provides an infrastructure where agents are
  deployed
• a FIPA-compliant AP consists of three agentsAMS,
  ACC,DF

12
Agent Management System

• Manages the platform resources
• Has control over access and use of the AP being
  the managing authority of it.
• Supports a set of methods for binding agents to
  platform, providing information about the
  platform capabilities and settings
• Offers white pages services to other agents by
  maintaining an index of agent names that reside
  on an AP and their corresponding addresses.

13
Agent Communication Channel

• The ACC is a low level entity that takes care of
  message routing between agents within an AP to
  agents on other APs.
• It publishes its transport address into a file
  store to a location for other ACCs to locate
• Uses information provided by the Agent Management
  System to direct messages between agents
• Messages addressed to an agent will first be
  sent to an ACC.

14
FIPA-OS as Microkernel
15
Directory Facilitator

• Provides a yellow pages directory to agents
• It must maintain an accurate list of agents with
  the most current information about them
• Agents may register with DF or query it about
  types of services offered by other agents.
• Management actions register, search, modify

16
Message Transport Service

• Provides the ability to send and receive messages
  to and from an Agent implementation
• It has built-in mechanisms for Internal and
  External transport
• It has a split structure composed of different
  service stacks (BufferService, ACCRouterService)

17
INTERNAL SERVER

• Extends the functionality provided by the
  Microkernel (mK)
• Encapsulate some system specifics
• Design Rule Keep the mK as small as possible
• Extended services are activated by the mK as
  needed.
• Example Configuration server for agent profiles

18
FIPA-OS INTERNAL SERVERS

• Agent configuration settings (in form of strings
  in a XML format)
• Contains information or defines
• What MTP (message transport protocol) is used by
  the platform
• Agent name
• Address (location)
• Types of databases to be used for storage
• Profiles are read through parsers

19
INTERNAL VS. EXTERNAL

• Mandatory Functionality - INTERNAL SERVICES
• Agent Shell
• Task Manager
• Conversation Manager
• MTS
• Pluggable Functions - EXTERNAL SERVICES
• MTP
• JESS (Agent Shell)
• Parsers (ACL, XML, RDF)

20
Agent Construction

• FIPA provides a template (Agent Shell - internal
  service!) for building agents.
• A new implemented agent consists of a class that
• extends the FIPAOSAgent class that provides
  methods for registration, message sending,
  setting up tasks and agent shutdown
• contains a number of Task implementations that
  give the functionality of the agent
• contains application specific code for the
  desired behavior within the architecture.

21
FIPA-OS as Microkernel
22
Agent Shell (IS)

• A template provided for agent implementation
• Responsible for loading an agent profile and
  initializing its components
• It creates a MTS (message transport service), a
  Task Manager and a Conversation Manager
• A new agent consists of a class that extends the
  FIPAOSAgent and inherits all its methods among
  which we can find getProfile(),
  registerWithAMS(), shutdown()

23
Agent Shell

• Provides functionalities (Policies) for
• Sending messages
• Retrieving the Agents properties
• Registration with platform
• Setting up the Task
• Shutdown (clean shutdown for all components of an
  agent)

24
Task Manager (IS)

• Splits the functionality of an Agent into small
  units of work (task decomposition)
• The subtasks are reusable as code and easy to
  debug
• Multiple tasks can be executed at once
• Handles task creation and registration

25
FIPA-OS as Microkernel
26
Messages and Tasks

• Multiple conversations can be conducted
  simultaneously given the ability of Task to send
  messages
• A TaskManager coordinates the Tasks inside the
  agents and is built around event-based
  processing.
• Every Task within the TaskManager has a set of
  events of type TaskEvent
• When a new task is created (newTask()) an event
  will be added to the queue of the TaskEvent

27
Messages and Tasks (cont.)

• If messages are constructed with the protocol
  field set to fipa-request, a certain message
  order is reinforced
• Agents are configured to be able to handle all
  message types in that protocol
• Messages sent are part of a Conversation and when
  a Task sends a message, the conversation that
  message is part of is bound to that Task.
• In order to handle messages like request, refuse,
  inform, several methods that take Conversation
  objects as arguments are provided.

28
Constructing a Task

• public class FirstTask extends Task
• public FirstTask(OrderAgent owner)
• public void startTask()
• public void sendRequest( Conversation conv )
• ACLMessage acl getNewConversation(String
  protocol)
• acl.setContent()
• acl.setLanguage()
• acl.setOntology()
• forward(acl)

29
Tasks and Conversations
FIPAOSAgent
ConversationManager
TaskManager
MTS
Task
Conversation
FIPAQuery protocol
TaskEvent
FIPARequest protocol
ConversationUpdateEvent public void
handleRequest(conv)
Other Events
30
Conversation Manager (IS)

• Provides the ability to track conversation state
  and mechanisms for grouping messages of the same
  conversation together (encapsulated as
  Conversation objects that represent individual
  conversations) - e.g. Cooperation Domains
• Ensures that the conversation protocol is being
  followed by the involved parties (agents)
• A Conversation class with various specializations
  is provided to enable the use of different
  protocols

31
Message Transport Protocol

• Internal (RMI)
• Proprietary mechanism
• Efficiency vs. interoperability
• Messages do not need to be prepared before being
  sent

• External (SUNIIIOP)
• Standardized mechanism
• Provides interoperability
• Messages are prepared before being sent

32
Interplatform communication
33
Message Encoding (ES)
34
Agent Languages Agent Languages An agent
language is a language for programming software
or hardware agents or agent systems. It should
provide for at least some structural agent
features and may also allow agency attributes to
be directly programmed. It may be incorporated
in a development environment with user-friendly
editors, browsers, etc. which facilitate the
programming. Most existing agent languages are
deliberative (e.g. AGENTO, PLACA, CONCURRENT
METAM, APRIL, MAIL) often related closely (or
less so) to agent theory and logic. Some agent
languages, e.g. ABLE, are reactive languages.
35
ACL Message structure

• Represents a communicative act (Policy) that can
  be simple (inform ,request,confirm) or composed
  request(propose(action))
• Has its corresponding semantics and protocol
• Contains parametersgtattributes /values
• language representation language for content
• content the information about which a message
  is sent
• receiver agent that receives the message
• protocol interaction protocol used by sender
• ontology ontology to which the content refers to

36
Agent Interactions

• FIPA ACL deals with intention interpretation and
  supports the communication between agents through
  explicit linguistic actions
• The information content transmitted and the
  protocols are those described and defined in FIPA
  specifications
• www.fipa.org

37
ACL - Example

• The information content will be communicated
  through the existing message types.
• Ex (request
• sender OrderAgent
• receiver OperationPlanningAgent
• content(action d (produce 50 parts A (product
  ABC))(due date Dec 12, 2000))
• protocol fipa-request
• reply-with order 132
• )

38
Microkernel Implementation

• 1. Analyze the Application Domain (define
  policies of external servers identify the core
  functionality needed to implement the external
  servers).
• 2. Categorize the services to separate core
  services (microkernel) from internal servers.
• CRITERIA time-critical, hardware-dependent and
  frequently used operations - in microkernel.

39
cont

• RULE Place all resource-management services in
  the mK (e.g. agent management, task management,
  memory management). Also strategies for sharing,
  locking, allocation and de-allocation of
  resources.

40
APPLICATION DOMAIN Supply Chain Management

• Composed of cooperating agents, each performing a
  set of supply chain operations (functions order,
  shipping, receiving, etc.)
• The agents are constructed as computational
  systems that interact across networks
• Agents are deployed on several FIPA platforms
  that already contain the infrastructure (mK) to
  enable the communication between them
• The interactions among agents are managed through
  existing Task and Conversation classes (IS)

41
Agents for Supply Chain Roles and Interactions

• Extending a generic agent framework to an
  integrated supply chain management architecture
  (by implementing new application specific agents)
  implies the identification of the entities
  involved in a supply chain as well as the
  elements that affect the performance of it.
• Elements or roles like inventory control,
  material flows,information storage are embedded
  as abilities into new specialized agents or
  application specific agents which will perform
  the respective activities.
• Other agents with built-in capabilities will
  model the roles played by different parts in a
  supply chain network such as capacity allocation,
  resource management and information exchange.

42
(No Transcript)
43
Agent Definitions

• Order Agent
• - Gets orders from customers
• - Handles requests for changing/ canceling
  orders
• - Transmits the orders to OPAgent
• OperationPlanning Agent
• - Receives orders from Customer through the
  Order Agent
• - Coordinates manufacturers, suppliers,
  transportation, distribution within the
  enterprise to achieve the best possible results
  in terms of customer requirements
• - It monitors the execution of tasks through
  conversations with functional agents within the
  supply chain.

44
Agent Definitions (cont.)

• Shipping Agent
• - Schedules and monitors the performing of
  transportation tasks pertinent to each order as
  requested or specified by the OperationPlanning
  Agent
• - Assigns transportation resources (routes) in
  order to construct the best possible shipping
  schedule.
• Supplier Agent
• - Responsible for scheduling the tasks related
  to product delivery
• - Manages the availability of requested products

45
Agent Implementation

• As part of the SCM architecture we consider some
  functional agents (Supplier and Shipping agents),
  the Operation Planning agent and an Order agent.
• The information content transmitted and the
  protocols are those defined in FIPA language
  specifications

46
Implementation ...

• 4. Find a complete set of operations and
  abstractions needed to define every external
  service (POLICIES).
• 5. Implement each Policy using the services and
  mechanisms that the microkernel provides through
  its interfaces (includes services provided by
  internal servers).
• Determine strategies for communication (request,
  transmission and retrieval of services)

47
Agent Construction

• FIPA provides a template (Agent Shell) for
  building agents.
• A new implemented agent consists of a class that
• extends the FIPAOSAgent class that provides
  methods for registration, message sending,
  setting up tasks and agent shutdown
• contains a number of Task implementations that
  give the functionality of the agent
• contains application specific code for the
  desired behavior within the architecture.

48
Agent Interactions

• FIPA ACL deals with intention interpretation and
  supports the communication between agents through
  explicit linguistic actions
• The information content transmitted and the
  protocols are those described and defined in FIPA
  specifications

49
Agent Interactions (cont..)

• The information content will be communicated
  through the existing message types.
• Ex (request
• sender OrderAgent
• receiver OperationPlanningAgent
• content(action d (produce 50 parts A (product
  ABC))(due date Dec 12, 2000))
• protocol fipa-request
• reply-with order 132
• )

50
EXTERNAL SERVERS (Personality)

• Implement specific views of the application
  domain (as Policies - e.g. Order Policy)

51
Agent Interactions (cont..)

• The receiver (the OperationPlanningAgent) can
  only answer with agree, refuse in the first stage
  given the performatives for the fipa-request
  protocol employed here
• (agree
• sender OperationPlanningAgent
• receiver OrderAgent
• content (produce d (50 parts A (product
  ABC)) (delivery time Jan 15, 2001))
• in-reply-to order 132
• protocol fipa-request

Request
Agree
Refuse
Inform
Failure
52
Messages and Tasks

• Multiple conversations can be conducted
  simultaneously given the ability of Task to send
  messages
• A TaskManager coordinates the Tasks inside the
  agents and is built around event-based
  processing.
• Every Task within the TaskManager has a set of
  events of type TaskEvent
• When a new task is created (newTask()) an event
  will be added to the queue of the TaskEvent

53
Messages and Tasks (cont.)

• If messages are constructed with the protocol
  field set to fipa-request, a certain message
  order is reinforced
• Agents are configured to be able to handle all
  message types in that protocol
• Messages sent are part of a Conversation and when
  a Task sends a message, the conversation that
  message is part of is bound to that Task.
• In order to handle messages like request, refuse,
  inform, several methods that take Conversation
  objects as arguments are provided.

54
Constructing a Task

• public class FirstTask extends Task
• public FirstTask(OrderAgent owner)
• public void startTask()
• public void sendRequest( Conversation conv )
• ACLMessage acl getNewConversation(String
  protocol)
• acl.setContent()
• acl.setLanguage()
• acl.setOntology()
• forward(acl)

55
Tasks and Conversations
FIPAOSAgent
ConversationManager
TaskManager
MTS
Task
Conversation
FIPAQuery protocol
TaskEvent
FIPARequest protocol
ConversationUpdateEvent public void
handleRequest(conv)
Other Events
56
Microkernel Implementation

• 1. Analyze the Application Domain (define
  policies of external servers identify the core
  functionality needed to implement the external
  servers).
• 2. Categorize the services to separate core
  services (microkernel) from internal servers.
• CRITERIA time-critical, hardware-dependent and
  frequently used operations - in microkernel.

57
cont

• RULE Place all resource-management services in
  the mK (e.g. agent management, task management,
  memory management). Also strategies for sharing,
  locking, allocation and de-allocation of
  resources.

58
Implementation...

• 7. Structure the Microkernel (e.g. using the
  Layers Pattern) to separate system-specific from
  system-independent parts. Lower layers hide
  system dependencies from the services that the
  Microkernel exposes publicly. Intermediate layers
  bridge hardware specifics with the gateways
  towards outside processes (the uppermost layer.)

59
Implementation ...

• 4. Find a complete set of operations and
  abstractions needed to define every external
  service (POLICIES).
• 5. Implement each Policy using the services and
  mechanisms that the microkernel provides through
  its interfaces (includes services provided by
  internal servers).
• Determine strategies for communication (request,
  transmission and retrieval of services)

60
FIPA-OS Layers
Layers
Application Agents ACL MTP
Agent Shell
Task/Conv. Manager
Agent Configurator
Directory Facilitator
Agent Management System
MTS
Agent Communication Channel
61
FIPA-OS as Microkernel
62
cont

• Design and Implement the Internal Servers - they
  are accessed exclusively by the mK!!
• Implement External Servers - write the Policies
  that describe the services such that they can be
  implemented using the programming interfaces of
  the mK.
• Implement the Adapters - e.g. can be implemented
  as Proxies representing the external servers (one
  proxy per server).

63
REFLECTION PATTERN
64
(No Transcript)
65
PARTICIPANTS
66
(No Transcript)
67
(No Transcript)
68
(No Transcript)
69
(No Transcript)
70
(No Transcript)
71
(No Transcript)
72
(No Transcript)