Mobile Agents for Database Applications Ludwig Klug Database - - PDF document
DBagents dbagents@scch.at +43 7236 3343 837 www.scch.at Mobile Agents for Database Applications Ludwig Klug Database Agents 1 Ludwig Klug Ludwig works with Agents for more than 1.5 years Technical consultant for Grasshopper
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Database Agents 1
Mobile Agents for Database Applications
Ludwig Klug
DBagents dbagents@scch.at +43 7236 3343 837 www.scch.at
Database Agents 2
Ludwig Klug
■ Ludwig works with Agents for more than 1.5 years ■ Technical consultant for Grasshopper implementations ■ Implementation of DBagents
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Database Agents 3
Building an Agent with Grasshopper
DBagents dbagents@scch.at +43 7236 3343 837 www.scch.at
Database Agents 4
Grasshopper – The Agent Platform
■Producer IKV++ GmbH, Berlin, Germany Partner of GMD FOKUS ■Costs Evaluation free of charge Licenses ~10000 € (for 100 VAR licenses) 3000 € / Year for premium support (answers
within 24 hrs)
Discussion forum (answers usually within 1 week)
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Grasshopper - The Agent Platform
■FIPA and MASIF Extensions One of few agent platforms building on
standards
Extensions realized as Grasshopper
agents
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Grasshopper Security I ■External Security
Protect agents against external threats SSL (e.g., IAIK Implementation)
■Internal Security
Protect platforms against hostile agents Protect agents against hostile platforms Public key encryption (certificates)
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Grasshopper Security II
■ Authorization
Restrict Access to Agency Resources
– Directories – Sockets
Policy Files (for Each Place Separate)
– Current version only allows the same access rights for all agents – Next version: codesource-based access control
■ Missing: Protecting agents against hostile
platforms
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Communication
■ Agent-to-Agent, Agent-to-Platform, Agent- to-Registry ■ Communication Over Proxies ■ Synchronous Communication
Wait for a return value
■ Asynchronous Communication
Do not wait for a return value
■ Broadcasts
Communicate with more object simultaneously
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Grasshopper Agent Model I
■Region Unit of agencies Region registry maintains agent
addresses
■Agency Container for places Usually one agency on one computer
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Grasshopper Agent Model II
■Place Runtime environment for agents ■Agent Code that runs as a thread in a place (Optional) can move between places
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Grasshopper Agent Model III
■What is an agent? Instance of subclass of MobileAgent or
StationaryAgent
Has a unique identifier (IP-address, time,
copy-number)
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Grasshopper Agent Model IV
■MobileAgent Allowed to move PersistentMobileAgent ■StationaryAgent Limited to a single place PersistentStationaryAgent
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Actions
■public void init(Object[] args) Initialization of the agent (agent parameters) Called after the agent is loaded ■public void live() Heart of the agent (agent‘s active behaviour) Only method that MUST be overridden
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Actions
■public void move (GrasshopperAddress location) Migrate to another location ■public void remove()
Destroy an agent.
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Event Handlers
■before/afterMove Called before/after the agent migrates ■before/afterCopy Called before/after the agent is cloned ■beforeRemove Called before the agent is removed
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Example Agency Structure
newyork.scch.at Hagenberg InformationDesk Softwarepark chicago.scch.at Linz InformationDesk Hauptplatz boston.scch.at Wien InformationDesk Stephansplatz
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Creating a Region Registry
■Decide on Which Computer It Should Run Registry is vital
for agencies
Computer should
run permanently
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Creating a Region Registry
■Three Ways To (Configure and) Run an Agency Commandline
argument
Wizard Profile editing ■GUI/TUI option
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Creating the Agencies ■Name of the Agency ■Decide Which Region it Should Belong to ■Access Control ■Security ■Enter Region Address
Format:
socket://chicago:7020/Austria protocol://host:port/region
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Creating Places ■Place InformationDesk is Predefined
Place where every
agent can migrate to
No security limits
Place creation in an agency
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Creating Places ■Create Custom Places
Specify a name Specify security
policy
Place creation in an agency
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3 Ways of Running an Agent ■GUI
In an agency explorer by right-clicking and
selecting "New Agent" on a place's popup menu
■Profile
The
user can define an agent in the configuration window, which is started on initialization of the agency
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3 Ways of Running an Agent ■API
During execution of an agent another agent can
be activated by calling the createAgent-method
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Agent life cycle
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Database Agents 25
Agent@Singapore
Singapore Tokyo Frankfurt Chicago Moscow toVisitVector Singapore here Singapore Tokyo Frankfurt Chicago Moscow visitedVector Singapore creator Agency Singapore Agent Singapore Tokyo Frankfurt Chicago Moscow toVisitVector Singapore here visitedVector Singapore creator Agency Singapore Agent
Agent.move(Tokyo)
Database Agents 26
Agent@Tokyo
Singapore Tokyo Frankfurt Chicago Moscow toVisitVector Singapore here Singapore Tokyo Frankfurt Chicago Moscow visitedVector Singapore creator Agency Singapore Agent Tokyo Frankfurt Chicago Moscow toVisitVector Tokyo here Singapore visitedVector Singapore creator Agency Tokyo Agent
Agent.move(Moscow)
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Agent@Moscow
Singapore Tokyo Frankfurt Chicago Moscow toVisitVector Singapore here Singapore Tokyo Frankfurt Chicago Moscow visitedVector Singapore creator Agency Singapore Agent Tokyo Frankfurt Chicago Moscow toVisitVector Tokyo here Singapore visitedVector Singapore creator Agency Tokyo Agent Frankfurt Chicago Moscow toVisitVector Moscow here Singapore Tokyo visitedVector Singapore creator Agency Moscow Agent
Agent.move(Frankfurt)
Database Agents 28
Agent@Frankfurt
Singapore Tokyo Frankfurt Chicago Moscow toVisitVector Singapore here Singapore Tokyo Frankfurt Chicago Moscow visitedVector Singapore creator Agency Singapore Agent Tokyo Frankfurt Chicago Moscow toVisitVector Tokyo here Singapore visitedVector Singapore creator Agency Tokyo Agent Frankfurt Chicago toVisitVector Frankfurt here Singapore Tokyo Moscow visitedVector Singapore creator Agency Frankfurt Agent
Agent.move(Chicago)
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Agent@Chicago
Singapore Tokyo Frankfurt Chicago Moscow toVisitVector Singapore here Singapore Tokyo Frankfurt Chicago Moscow visitedVector Singapore creator Agency Singapore Agent Tokyo Frankfurt Chicago Moscow toVisitVector Tokyo here Singapore visitedVector Singapore creator Agency Tokyo Agent Chicago toVisitVector Chicago here Singapore Tokyo Moscow Frankfurt visitedVector Singapore creator Agency Chicago Agent
Agent.move(Singapore)
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Agent@Singapore
Singapore Tokyo Frankfurt Chicago Moscow toVisitVector Singapore here Singapore Tokyo Frankfurt Chicago Moscow visitedVector Singapore creator Agency Singapore Agent Tokyo Frankfurt Chicago Moscow toVisitVector Tokyo here Singapore visitedVector Singapore creator Agency Tokyo Agent toVisitVector Singapore here Singapore Tokyo Moscow Frankfurt Chicago visitedVector Singapore creator Agency Singapore Agent
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Agents in Database Systems
DBagents dbagents@scch.at +43 7236 3343 837 www.scch.at
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DBagents ■Basic platform runtime required on each computer Advantages ■Database queries within DBMS ■Searching within network ■Load balancing (not between DB servers but processing at the DB where data is located)
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Solution Concept ■Standard Agent Platform for Transportation
Extend available migration strategies Extend available security solutions Perform non-SQL operations
(e.g., schema export)
Transport query results back
to home agency
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Solution Concept ■Mobile Database Agents
SQL statements SQL scripts Java stored procedures
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Implemented Architecture
miami.scch.at dbag on miami.scch.at Miami MediatorAgents
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Implemented Architecture
miami.scch.at boston.scch.at Boston dbag on chicago.scch.at dbttest on havana.scch.at Miami MediatorAgents UIAgent
NewYork
DBagent Transport Agent
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DBagents Framework
DBagents provides a flexible API to support agent-based
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DBagents Framework ■4 Agent types ■4 Result handlers ■2 Communication modes ■Agent groups support multi-agent transactions ■UI templates for results, logs and migration strategies
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Framework Agent Operations ■SQL
A statement is executed and results are
returned to home
■SQL script
A script is executed and log information is
returned
■Stored procedure installation ■Java stored procedure installation
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Status ■Status
Basic prototype implemented Currently, test scenarios are being
developed
Implementation of CopyAgent in Progress Problem for real-world applications:
– Stability – Security
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Mobile Agents DBagents Distributed Databases