Grid Computing, B. Wilkinson, 20046c.1 Globus III - Information Services

Grid Computing, B. Wilkinson, 20046c.2 Resource Discovery Critical in a grid to be able to discovery what resources are available and what are the options. For compute resources, information can be hardware details and software details, and dynamically changing information such as load.

Grid Computing, B. Wilkinson, 20046c.3 Typical Details Compute resources: –CPU vendor, type, speed, cache sizes,... –Memory type, size, speed,... –Disk space … Network resources –Network bandwidth –Latency –Topology –Protocols,...

Grid Computing, B. Wilkinson, 20046c.4 Compute Resource Software Details IP address Software available Operating System version number Resource manager,...

Grid Computing, B. Wilkinson, 20046c.5 Static and Dynamic data Information is always subject to change and old. Some information changes naturally, such as load information.

Grid Computing, B. Wilkinson, 20046c.6 Centralized Information System Clients Resources Periodically update LDAP server information Clients query for current information LDAP Server “push” LDAP Lightweight Directory Access Protocol

Grid Computing, B. Wilkinson, 20046c.7 Disadvantages Does not scale well as number of resources grows Commercial LDAP services optimized for read operations, not good with frequent writes. System fails if LDAP server down

Grid Computing, B. Wilkinson, 20046c.8 Globus Grid Information Service Monitoring and Directory Service (MDS) Based upon LDAP. Originally called “Metacomputing Directory Service” - renamed MDS-2 uses a distributed organization.

Grid Computing, B. Wilkinson, 20046c.9 MDS-2 Consisting of two types of service: Grid Resource Information Service (GRIS) Grid Index Information Service (GIIS)

Grid Computing, B. Wilkinson, 20046c.10 Grid Resource Information Service (GRIS) Associated with each resource. Answers queries from client/user about the particular resource. Accesses an “information provider” deployed on that resource for requested information.

Grid Computing, B. Wilkinson, 20046c.11 Queries “White pages” –Resource information e.g. How much memory does machine have “Yellow” pages –Resource options e.g. Which queues allow large jobs.

Grid Computing, B. Wilkinson, 20046c.12 Grid Index Information Service (GIIS) A directory service that collects (‘pulls”) information for GRIS’s. A “caching” service. Provides indexing and searching functions.

Grid Computing, B. Wilkinson, 20046c.13 Overall Structure Clients Resources GIIS information as needed Clients query resource GRIS directly for current information GIIS “pull” GRIS Clients makes indirect query to GIIS

Grid Computing, B. Wilkinson, 20046c.14 Scaling Can have multiple GIIS’s in various configurations Configuration can take into account virtual organizations

Grid Computing, B. Wilkinson, 20046c.15 Accessing Information GT3 command: grid-info-search with various flags to specify host, port, etc.: -h MDS server -p MDS port -b Search start point -T LDAP query time out

Grid Computing, B. Wilkinson, 20046c.16 Example grid-info-search -x -h hot.mcs.anl.gov -p b “Mds-Vo-name=local, o=Grid” Produces: dn: Mdss-Host-hn=hot.mcs.gove, Mds-Vo- name=local, o=grid Mds-CPU-speedMhz: 866 Mds-Memory-Ram-Total-freeMB: 304 Mds-CPU-Free-5minX100: 134. From “Grid Computing” by A. Abbas, page 204.

Grid Computing, B. Wilkinson, 20046c.17 LDAP Browser/Editor Java Commodity Grid (CoG) Kit has a LDAP Browser/Editor

Grid Computing, B. Wilkinson, 20046c.18 From “Grid Computing” by A. Abbas, page 202. LDAP Browser/Editor

Grid Computing, B. Wilkinson, 20046c.19 Security MDS 2.1 has PKI security for GSI mutual authentication

Grid Computing, B. Wilkinson, 20046c.20 LDAP Exercise Go to Globus subdirectory called ldap Follow instructions in README file

Grid Computing, B. Wilkinson, 20046c.21 Discovering Grid Services MDS, as described, is only for discovery hardware resources, not the actual grid services one might want. In a service oriented architecture, services are “published” in a registry so that they can be found.

Grid Computing, B. Wilkinson, 20046c Find 3. Bind 1. Publish Service-Oriented Architecture Service requester Service registry Service provider

Grid Computing, B. Wilkinson, 20046c.23 UDDI (Universal Description, Discovery, and Integration) Web services often use UDDI registries. UDDI designed to support business services. Information can be classified as: –White pages -- company contact information,... –Yellow pages -- Web service description –Green pages -- Technical information about Web Service

Grid Computing, B. Wilkinson, 20046c.24 Web Services From

Grid Computing, B. Wilkinson, 20046c.25 Accessing Grid Services GT 3 provides an “index service” (as a higher level service) to access service data provided with grid service. Service data can includes both hardware and software details of service.

Grid Computing, B. Wilkinson, 20046c.26 GT3 Index Service From “Grid Computing” by J. Joseph and C. Fellenstein, page 340.

Grid Computing, B. Wilkinson, 20046c.27 Service Data Information about service provided in service data elements (SDEs) as part of the GWSDL file. The GWSDL file defines service interface (see assignment 2), and SDEs are added to this.

Grid Computing, B. Wilkinson, 20046c.28 Types of Service Data Elements State Information -- results, previous results, run time information, … Service Metadata -- system data, supported interfaces, cost of using service,...

Grid Computing, B. Wilkinson, 20046c.29 Client Accessing Service Data Done through grid service methods.

Grid Computing, B. Wilkinson, 20046c.30 Changes to Grid service Done through “notification” mechanism whereby client subscribes to mechanism and is notified of changes.

Grid Computing, B. Wilkinson, 20046c.31 Derived from The Globus Toolkit 3 Programmer’s Tutorial” by Borja Sotomayor, 2004, page 65. addListener to subscribe notifyChange when change occurs deliverNotification to notify subscribers

Grid Computing, B. Wilkinson, 20046c.32 More Information “The Globus Toolkit 3 Programmer’s Tutorial” by Borja Sotomayor, 2004, Chapter 5 and Chapter 6. Gives sample code.