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DIDA, a Distributed Discovery Architecture for Grid Environments

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DIDA, a Distributed Discovery Architecture for Grid Environments Carlos de Alfonso Miguel Caballer Vicente Hern ndez Universidad Polit cnica de Valencia – PowerPoint PPT presentation

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Title: DIDA, a Distributed Discovery Architecture for Grid Environments


1
DIDA, a Distributed Discovery Architecture for
Grid Environments
  • Carlos de Alfonso
  • Miguel Caballer
  • Vicente Hernández
  • Universidad Politécnica de Valencia

2
Index
  • Index
  • Background
  • eGovernment framework
  • Administration features
  • The citizen in the administration
  • Grid Technology
  • gCitizen project
  • Discovery Architecture
  • Service Naming
  • Service Discovery
  • Service Discovery in GT4
  • Design of a Service Discovery System
  • DIDA
  • DIDA Architecture
  • Distributed Discovery Services
  • FADA Topology

3
Background
  • Administration
  • Organized in different units and levels
  • State
  • Region
  • Local
  • Different specialised unit in each level.
  • Despite its heterogeneity the citizen should have
    a unique vision.
  • Should not have to know the internal operation
    complexity
  • Simple and effective interaction

4
Background
  • The Citizen in the Administration
  • Citizen is the aggregation of information
    belonging to the administrative units.
  • This data dispersion produces some problems
  • Not consolidated data
  • Different names for semantically equal data
  • etc.

5
Background
  • Features of the information in the Administration
  • Geographically distributed
  • Different units located in different places.
  • Security
  • Only some people is allowed to read or modify the
    data.
  • Privacy
  • The information must be protected on access and
    transmission.
  • Ubiquitous access
  • Despite the geographical distribution the access
    must be granted.
  • Interoperability
  • Among systems, for enabling the collaboration.
  • Scalability
  • The system must enable the addition of new
    components efficiently.

6
Grid Technology
  • Grid Technology Provides some of the required
    features
  • Security, Transparency, Ubiquitous access,
    Scalability,
  • GT4 implementation of the WSRF standard selected
  • Not all the needed functionality is provided
  • The service oriented programming model enables to
    develop some services over the middleware.
  • Log System
  • Service Discovery System
  • Distributed Authorisation

7
gCitizen Project
  • Creation of a grid middleware for eGovernment.
  • Flexible and scalable prototype of a grid
    citizen
  • System integration project using grid technology.
  • Not invasive for the current systems.

8
Discovery Architecture
  • Main issue Discover services
  • System visibility
  • Any service should be searchable
  • Connectivity failure detection
  • Components
  • Service Naming
  • Identify the services in the system
  • Discovery System
  • Find the services using the naming defined

9
Service Naming
  • WSRF uses URI as service identifier
  • Location dependent.
  • Redundancy
  • Not transparent
  • Changing the location of service implies a
    identifier change.
  • Not enable Mobility
  • Needed Features
  • Location independent
  • Show the hierarchy of the administration
  • Levels
  • Departments

10
Service Naming
  • Design of a Service Naming system based on DNs
  • DNs are used to identify users and host in grid
    environments
  • Location independent
  • Service Mobility
  • A service can change its location maintaining the
    DN
  • Transparent Redundancy
  • Different physical services can have the same DN
  • Represented as a Resource Property
  • The hierarchy of the DN will place the service
    inside the context of the gCitizen system.

11
Service Naming
  • Schema proposed
  • Country Name (C)
  • Region Name (A)
  • State or Province Name (ST)
  • Locality (L)
  • Organization Name (O)
  • Organizational Unit Name (OU)
  • Common Name (CN)
  • Example
  • /CES/AC. Valenciana/STValencia/LValencia/OAyt
    o. Valencia/OUInformática/CNPadrón

12
Service Discovery in GT4
  • Based on the use of Index Services
  • Services deployed that enable to index other
    services
  • Search by means of Resource Properties
  • Published in XML
  • Using XPath
  • Hierarchical structure
  • All the information only accessible on top level
    IS.
  • Not ubiquitous access
  • Central point of failure

13
Design of a Service Discovery System
  • Objectives
  • Completely Distributed
  • Not use a central point of information
  • Ubiquitous access
  • Enable to access the information from different
    points.
  • Transparency
  • All the possible complexity of the system must be
    hided to the user.
  • Scalability
  • Enable to add components to the system easily
  • Fault tolerance
  • The failure of one component must not affect the
    whole system.
  • Detection of the failure of one component

14
Distributed Discovery Architecture
  • Built up on the Globus Toolkit 4 Index Services
  • Services are indexed in the ISs
  • Every entity will have an IS
  • Use XPath as query language
  • Link the ISs to create a vision of a unique
    Virtual Server
  • Avoiding cascade node organizations

15
DIDA Architecture
  • Use FADA to create the view of a virtual server.
  • Distributed directory of services
  • The ISs are registered into a set of FADA nodes.
  • FADA nodes distributed across the system.
  • Each FADA node know about its neighbours.
  • Fault tolerance

16
FADA Network Topology
  • The FADA topology is Scale-Free network
  • Few highly connected hubs
  • Affect the whole system
  • Many nodes with few connections
  • Not affect whole system
  • Proposed a 2-Regular topology
  • 2 kind of links
  • Strong create the 2-Regular graph.
  • FADA node know 2 neighbours
  • Weak some additional links.
  • If one node fails the connectivity of the system
    is assured.
  • The fault of one component is detected

17
Distributed Discovery Services
  • Entry points to the discovery system
  • Every entity has to deploy the DDS.
  • Ubiquitous access
  • All the users of the entity must know the
    location.
  • Implemented as WSRF services
  • Uses XPath as query language
  • Knows some FADA nodes
  • Transparency
  • The client query the service and get the results.

18
Distributed Discovery Services
  • UML Interaction Diagram of DDS

19
Conclusions
  • eGovernment
  • New field for grid technology.
  • Grid as integration information system.
  • Used GT4 as WSRF implementation
  • Provides some interesting features, but have some
    lacks.
  • New service naming based on DN
  • Location independent
  • Discovery Service
  • Based on IS of GT4 Discovery Service
  • Linked using FADA network to create a virtual
    server
  • Totally distributed without a central point
  • Use a 2-Regular topology
  • More topologies must be studied
  • Cache of neighbour services
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