Uniform Resource Name (URN) In Ajanta, A Mobile Object Environment

Plan B Project Report

By Tanvir Ahmed

Advisor: Prof. Anand Tripathi

Ajanta Programming Environment

Name-registry

Agent-server

Agent

Domain B

Agent migration

Domain C

Domain A

NR1

NR3

NR2

Name registry Interaction

MOBILE OBJECT NAMERequirements

– Location independent– Global uniqueness and scope– Persistent– Maps to location (URL) or characteristics of

an object– Name assignment can be delegated– Autonomy of name assignment and name-

resolution

URN Syntax<URN> ::= "urn:" <NID> ":" <NSS>

– NID: Namespace Identifier– NSS: Namespace Specific String

Ajanta URN– urn:ans:umn.edu/tahmed/Resource

• umn.edu = Creation Domain• tahmed = Naming Authority • Resource = A string name in this name-space

Functional RequirementsQuery and Update calls

• lookup(), bind(), rebind()

Fine and coarse grained APIs • Coarse: bind(), lookup()• Fine: getURL(), getVerifyKey()

Object type specific interfaces• Agent: rebindAgentServer()

Client to Name-registry APIs, Name-registry to Name -registry system interfaces

Security RequirementClient/Server Authentication

– Authentication of application level names

Access control on Name Registry entries– Read: all– Write/Update: Specific Principals

Access control on name space– Create-Name: Specific Principals

Name CreationName-Registry Boots, administrator “Admin”

– Admin = urn:ans:umn.edu/Admin– Name Registry = urn:ans:umn.edu

“Admin” adds user “Usr”– urn:ans:umn.edu/Usr

“Usr” registers an agent-server “AS”– urn:ans:umn.edu/Usr/AS

“AS” registers an agent “Ag”– urn:ans:umn.edu/Usr/AS/Ag

Access Control & Delegation(1)

URN ACL Owner Principals withUpdatePermission

Principals withCreate NamePermission

1 umn.edu/Admin umn.edu/Admin umn.edu/Admin umn.edu/Admin

2 umn.edu umn.eduumn.edu/Admin

umn.eduumn.edu/Admin

umn.eduumn.edu/Admin

3 umn.edu/Usr umn.edu/Usrumn.edu/Admin

umn.edu/Usrumn.edu/Admin

umn.edu/Usrumn.edu/Admin

“Update” permission can modify an Entry.

“Create Name” permission can create names under this name-space.

ACL owners can add/delete ACL entries.

Access Control & Delegation(2)

URN ACL Owner Principals withUpdatePermission

Principals withCreate NamePermission

a umn.edu/U/AS1/Ag umn.edu/U/AS1/Agumn.edu/U/AS1

umn.edu/U/AS1/Agumn.edu/U/AS1

umn.edu/U/AS1/Agumn.edu/U/AS1

b umn.edu/U/AS1/Ag umn.edu/U/AS1/Agumn.edu/U/AS1

umn.edu/U/AS1/Agumn.edu/U/AS1umn.edu/U/AS2

umn.edu/U/AS1/Agumn.edu/U/AS1umn.edu/U/AS2

c umn.edu/U/AS1/Ag umn.edu/U/AS1/Agumn.edu/U/AS1

umn.edu/U/AS1/Agumn.edu/U/AS1umn.edu/U/AS3

umn.edu/U/AS1/Agumn.edu/U/AS1umn.edu/U/AS3

a. Agent Ag is registered by agent-server AS1

b. Agent Ag migrates to Agent-server AS2

c. Agent Ag migrates to Agent-server AS3

Access Control & Delegation(3)

URN ACL Owner Principals withUpdate Permission

Principals withCreate NamePermission

umn.edu/U/AS1/Ag/C

umn.edu/U/AS1/Ag/Cumn.edu/U/AS1/Agumn.edu/U/AS3

umn.edu/U/AS1/Ag/Cumn.edu/U/AS1/Agumn.edu/U/AS3

umn.edu/U/AS1/Ag/Cumn.edu/U/AS1/Agumn.edu/U/AS3

Agent Ag, residing on agent-server AS3Ag creates a child agent C Agent-Server AS3, binds C

Name Resolution: UpdateName-registry Administrator adds Alice’s URN and Public Keys

3. bind({Alice, SigA(Nnr)}, AS)

2. Tkt={NR, SigNR(Na), Nnr}

1. authenticate(Alice , Na)

Name RegistryAgent Server

Alice

AS

NR

Alice registers Agent-Server AS

Name Resolution: Update(2)Agent Ag is created and registered by AS1

bind

Ag

AS1

NR1NREntry

urn = NR1/AS1/Agserver URN = AS1acl = { Owner =Ag, AS1; Update =Ag, AS1; Create-Name = Ag, AS1;}

Domain A

Domain B

rebindAgentServer

NR1

NR2

NREntry

urn = NR1/AS1/Agserver URN = AS2acl = { Owner =Ag, AS1; Update =Ag, AS1, AS2; Create-Name=Ag,AS1,AS2}

AS2

AS1

Name Resolution: Update(3)

Name-registry

Agent-server

Agent

Agent Ag migrates to AS2

Ag

Name Resolution: Update(4) Agent Ag is migrates to AS3. Ag’s creation domain NR1

NR2

NREntry

urn = NR1/AS1/Agserver URN = AS3acl = { Owner =Ag, AS1; Update =Ag, AS1, AS3; Create-Name=Ag,AS1,AS3}

AS2

Domain B

Domain A

1.rebindAgentServer

NR1

Name-registry

Agent-server

Agent

NR3

Domain C

AS3

2.rebindAgentServer

Ag

Name Resolution: Lookup(1)

Valid entry present

Cached entry present

Entry not present

Agent-server AS1 lookups a valid entry “NR1/X” present in the local name-registry, NR1

BEFORE AFTER

NR1

AS1

NR1

AS1

Name Resolution: Lookup(2)

Valid entry present

Cached entry present

Entry not present

Mobile Agent entries are not cached

BEFORE AFTER

NR2NR1

AS1

2.lookup

1.lookup

3.return

4 .return

NR1

AS1

NR2

AS1 lookups an agent “NR2/X/X/Ag” not present in NR1

Name Resolution: Lookup(3)

Valid entry present

Cached entry present

Entry not present

AS1 lookups an non-agent entry “NR2/X/AS2”, not present in NR1. After lookup the entry is cached.

BEFORE AFTER

NR2NR1

AS1

2.lookup

1.lookup

3.return

4 .return

NR1

AS1

NR2

Name Resolution: Lookup(3)

Valid entry present

Cached entry present

Entry not present

AS1 lookups the cached non-agent entry in NR1. NR1 updated its cache.

BEFORE AFTER

NR2NR1

AS1

3.lookup

1.lookup

4.return

2 .return

NR1

AS1

NR2

ConclusionWhat is done

– Basic Client to Name-Registry APIs – Name-Registry to Name-Registry System

Interfaces– Client/Server Authentication– Access-Control on Name-Registry Entries– Access-Control on Name-Space– Name Space Delegation– Administrative Utility to Add User and to Add

Name-Registry

ConclusionPossible Future Work

– Introduce the concept of “Subscriber”.– Multiple (K > 1) Name-Registries to maintain a

name.– Map the name-resolution task to Agent Paradigm.

Sent an agent to a Name-Server to get service.