MarketNet Directory Services MDS

1
MarketNet Directory Services (MDS)

• Weibin Zhao
• Henning Schulzrinne
• Department of Computer Science
• Columbia University

2
Background

• Directory Services
• lookup/mapping white page, yellow page
• reverse lookup/mapping DNS (domain name vs. IP)
• attribute-based lookup/mapping LDAP, SLP
• Components
• client
• server
• database
• protocol

3
MDS Market-based Directory Services

• Design Goals
• survivability adjust gracefully to service
  dynamic change and resource loss
• dynamic update price advertisement
• scale to large systems
• Some Critical Issues
• data organization, distribution, replication
• access control
• scalability

4
MDS Design

• Approaches
• use existing directory services as building
  block SLP
• low-cost, widely accepted, reuse for other
  systems
• enhance reliability and scalability
• Out contributions
• define scheme for interaction of SLP directory
  servers
• Mesh-enhanced Service Location Protocol (mSLP)
• standalone and integrated implementation Java
• Internet draft being considered for RFC

5
Architecture
Service
Application
User Agent
Service Agent
Query
Registration
Interaction
Directory Agent
Directory Agent
6
Service Registration

• Service Description
• URL
• attributes-value pairs can be in different
  languages
• service type lpr, bank
• service scope Columbia-CS, Amazon
• Service Registration
• lifetime
• full or incremental registration
• Service Deregistration
• deregister whole service or individual attributes

7
Service Query

• Query Service Type
• list available service types in given scope
• Query Service URL
• given attribute description, find matched URLs
• Query Attributes
• list all or part attributes for given URL or
  service type

8
Directory Agent (DA) Discovery

• Active Discovery
• multicast special service query
• service-type directory-agent
• Passive Discovery
• listen to DA multicast advertisement
• Other Methods
• Static configuration
• DHCP

9
DA Interaction

• Peering DA Architecture
• peer DAs share service scopes
• more than one DA for each scope
• peer DAs maintain same data for common scopes
• Two Issues
• group membership management
• data exchange management

10
DA Set Membership Management

• Learning of New Peers
• DA multicast, static configuration, DHCP
• exchange common peer list (CPL) with peers
• forward DA advertisement
• send unsolicited DA advertisement to peer
• Keeping Peer Relationship
• keep-alive message
• Removal of Peers
• peer shut-down
• keep-alive timeout (peer failure, network
  separation)

11
Data Exchange Management

• Initial Data Exchange
• pull model download data from new peers
• optimize data download
• Forward New Service Registration
• push model
• one-hop forwarding full mesh connection

(a)
(a,c)
(c)
DA1 (a,b)
DA3 (a,c)
DA2 (b,c)
(a,b)
(a,c)
(b,c)
(a,c)
DA4 (a,b,c)
SA
(a,b)
(c)
12
Protocol Design

• Mesh-Control Message (MeshCtrl)
• peering connection notification
  (Pconn_Notification)
• common peer notification (Cpeer_Notification)
• get requested data (Get_Rdata)
• requested data end (Rdata_End)
• keep alive (Keep_Alive)
• Mesh-Forwarding Extension (MeshFwd)
• Action-ID Rqst_Forward, No_Forward
• SA registration timestamp

13
Message Flows
(1) DAAdvert
DA1
DA2
(2) create a peering connection
(3) Pconn_Notification MeshCtrl
(4) unsolicited DAAdvert
(5) Cpeer_Notification MeshCtrl
(5) Cpeer_Notification MeshCtrl
(6) Get_Rdata MeshCtrl
(7) requested data in SrvReg(s)
(8) Rdata_End MeshCtrl
(6) Get_Rdata MeshCtrl
(7) requested data in SrvReg(s)
(8) Rdata_End MeshCtrl
(9) forward SrvReg/SrvDeReg(s)
(9) forward SrvReg/SrvDeReg(s)
(10) Keep_Alive MeshCtrl(s)
(10) Keep_Alive MeshCtrl(s)
14
Demo

• Survivability in case of failure
• DA crash
• network separation
• peer DAs handle DA failure (keep-alive timeout)
• client (SA/UA) handle DA failure (response
  timeout)
• Optimize data download scheme
• Forward new service registration

15
Conclusions

• MDS
• a robust distributed directory services
• serve general purpose or customized applications
• fully implemented in Java, open source software
• submitted Internet draft to standardize protocol
• Future work
• advance mSLP to RFC
• Thank you!