1. 1SIAC 2000, Wright State University, August 21, 2000 1 Wisdom consists of knowing when to avoid perfection. -Horowitz Tuesday, February 24, 2009

2. The Globus Project Infrastructure for Computational Grids The Globus Project Team http://www.globus.org/

3. 3SIAC 2000, Wright State University, August 21, 2000 Session Goals Provide an introduction to…  computational grids  the capabilities of the Globus Toolkit  pragmatic issues with grids & Globus Enable attendees to…  start building grids using the Globus Toolkit  start building & using grid applications

4. 4SIAC 2000, Wright State University, August 21, 2000 Overview Introduction to computational grids Introduction to the Globus Toolkit  Portability  Security  Information services  Resource management  Data management  Communication Case studies Other Globus services, and future directions

5. 5SIAC 2000, Wright State University, August 21, 2000 What is a computational grid? A pool of computational resources that can be “plugged into” via standard interfaces. Processors Data storage devices Instruments As the power grid is to electrical power, and the telephone grid is to voice communication, so will the computational grid be for computation.

6. 6SIAC 2000, Wright State University, August 21, 2000 Computational Collaboration 1975-1995: Collaboration  We work together, but use our own unique systems.  It’s hard to share data, computing power, instrumentation. 1995-2005: Virtual Organizations  We build systems that combine our resources with those of our collaborators.  We learn how to manage the heterogeneity of systems, management, and users. 2005-?: Computational Grid  Computation is a commodity, that can be bought and sold by anyone.  Computational services use standard interfaces.  Organizations and individuals typically don’t need to build their own computing infrastructures.

7. 7SIAC 2000, Wright State University, August 21, 2000 Why do we need the Grid? The Grid will enable applications that include people, computers, databases, instruments, etc.  Online instruments  Collaborative engineering  Parameter studies  Browsing of remote datasets  Use of remote software  Data-intensive computing  Very large-scale simulation

8. 8SIAC 2000, Wright State University, August 21, 2000 tomographic reconstruction real-time collection wide-area dissemination desktop & VR clients with shared controls Advanced Photon Source Online Instruments archival storage DOE X-ray source grand challenge: ANL, USC/ISI, NIST, U.Chicago

9. 9SIAC 2000, Wright State University, August 21, 2000 Collaborative Engineering CAVERNsoft: UIC, Electronic Visualization Laboratory Manipulate shared virtual space, with  Simulation components  Multiple flows: Control, Text, Video, Audio, Database, Simulation, Tracking, Haptics, Rendering Issues:  (un)reliable uni/multicast  Security  Reservation & QoS

10. 10SIAC 2000, Wright State University, August 21, 2000  Control  Text  Video  Audio  Database Tele-immersion “5 Gflop/sec, flowspecs, design db” Multiple access modalities Multiple flows  Simulation  Tracking  Haptics  Rendering Leigh et al: UIC, Electronic Visualization Laboratory

11. 11SIAC 2000, Wright State University, August 21, 2000 Distributed Supercomputing Issues:  Resource discovery, scheduling  Configuration  Multiple comm methods  Message passing (MPI)  Scalability  Fault tolerance NCSA Origin Caltech Exemplar Argonne SP Maui SP SF-Express Distributed Interactive Simulation: Caltech, USC/ISI

12. 12SIAC 2000, Wright State University, August 21, 2000 High-Throughput Computing Nimrod-G: Monash University Cost Deadline Available Machines Schedule many independent tasks  Parameter studies  Data analysis Issues:  Resource discovery  Data Access  Scheduling  Reservatation  Security  Accounting  Code management

13. 13SIAC 2000, Wright State University, August 21, 2000 Examples:  Problem solving env. for computational chemistry  Application web portals Issues:  Remote job submission, monitoring, and control  Resource discovery  Distributed data archive  Security  Accounting Problem Solving Environments ECCE’: Pacific Northwest National Laboratory

14. 14SIAC 2000, Wright State University, August 21, 2000 The Grid “Dependable, consistent, pervasive access to [high-end] resources” Dependable: Can provide performance and functionality guarantees Consistent: Uniform interfaces to a wide variety of resources Pervasive: Ability to “plug in” from anywhere

15. 15SIAC 2000, Wright State University, August 21, 2000 Early Steps Toward the Grid Metacomputing: late 80s  Focus on distributed computation Gigabit testbeds: early 90s  Research, primarily on networking I-WAY: 1995  Demonstration of application feasibility NFS PACIs (National Technology Grid): 1998 NASA Information Power Grid: 1999 DOE ASCI DISCOM DRM: 1999 European Grid: 2000

16. 16SIAC 2000, Wright State University, August 21, 2000 Technical Challenges Complex application structures that combine aspects of parallel, multimedia, distributed, collaborative computing Resource characteristics that vary dynamically in both time and space. Requirements for guaranteed high “end to end” performance, despite heterogeneity and lack of global control. Desire to retain local policies for security, fees, usage restrictions, management, and technical standards.

17. 17SIAC 2000, Wright State University, August 21, 2000 Domain 2 Domain 1 Authenticate once Specify simulation (code, resources, etc.) Locate resources Negotiate authorization, acceptable use, etc. Acquire resources Initiate computation Steer computation Access remote datasets Collaborate on results Account for usage Issues

18. 18SIAC 2000, Wright State University, August 21, 2000 Architectural Approaches Distributed systems: DCE, CORBA, Jini, etc.  Rich functionality eases app development  Complexity hinders deployment especially in absence of global control  Performance difficulties Internet/Web Protocols and Tools  Simple protocols facilitate deployment  Missing functionality hinders app development  Performance difficulties

19. 19SIAC 2000, Wright State University, August 21, 2000 Standards & Commodity Tech Where appropriate, exploit standards and commodity technology in core infrastructure  LDAP, SSL/TLS, X.509, GSS-API, HTTP, FTP, XML, SOAP, etc.  Provides leverage Interface with other common standards  CORBA, Java/Jini, DCOM, Web, etc  While our core infrastructure may not be built on one of these distributed architectures, we can and must cleanly interface with them

20. 20SIAC 2000, Wright State University, August 21, 2000 The Globus Project Basic research in grid-related technologies  Resource & data management, security, QoS, policy, communication, adaptation, etc. Development of the Globus Toolkit  Core services for grid-enabled tools & applications Construction of production grids & testbeds  Environments in which grid software can be deployed and experiments can be run. Experimentation with real grid applications  Verifying that the grid works and is useful.

21. 21SIAC 2000, Wright State University, August 21, 2000 Grid Services Architecture Applications Grid Services Security Data Management Fault Detection Information Services Resource Management Grid Fabric Data Transport Schedulers Control Interfaces Operating Systems Application Toolkits Data Intensive Remote VisualizationCollab Design High ThroughputRemote Control Portability Instrumentation QoS Services High Energy Physics Data Analysis Climate Studies Collab Engineering Online Instrumentation Message Passing

22. 22SIAC 2000, Wright State University, August 21, 2000 Globus Project Participants Globus Project is a large community effort  Globus Toolkit core development Argonne, USC/ISI, NCSA, SDSC  Globus Toolkit contributors NASA, DOE ASCI DRM (SNL, LBNL, LLNL), Raytheon, and numerous others  Collaborators University, lab, industrial, and international partners spanning many scientific and engineering disciplines Active in Grid Forum  http://www.gridforum.org

23. 23SIAC 2000, Wright State University, August 21, 2000 Globus Approach A toolkit and collection of services addressing key technical problems  Modular “bag of services” model  Not a vertically integrated solution  General infrastructure tools (aka middleware) that can be applied to many application domains Inter-domain issues, rather than clustering  Integration of intra-domain solutions Distinguish between local and global services

24. 24SIAC 2000, Wright State University, August 21, 2000 Globus Hourglass Focus on architecture issues  Propose set of core services as basic infrastructure  Use to construct high-level, domain-specific solutions Design principles  Keep participation cost low  Enable local control  Support for adaptation  “IP hourglass” model Diverse global services Core Globus services Local OS A p p l i c a t i o n s

25. 25SIAC 2000, Wright State University, August 21, 2000 Technical Focus & Approach Enable incremental development of grid-enabled tools and applications  Model neutral: Support many programming models, languages, tools, and applications  Evolve in response to user requirements Deploy toolkit on international-scale production grids and testbeds  Large-scale application development & testing Information-rich environment  Basis for configuration and adaptation

26. 26SIAC 2000, Wright State University, August 21, 2000 Layered Architecture Applications Grid Services GRAM GSI HBM Nexus globus_io Grid Fabric LSF CondorMPI NQEPBS TCP NTLinux UDP Application Toolkits DUROCglobusrunMPICH-GNimrod/GCondor-GHPC++ GlobusViewWeb Portals GASS Solaris DiffServ GSI-FTP MDS

27. 27SIAC 2000, Wright State University, August 21, 2000 Globus Toolkit Grid Services Security (GSI) Information services (MDS) Resource management (GRAM) Data management (GASS, GSI-FTP, replicas) Communication (globus_io, Nexus) Fault detection (HBM) Portability (globus_dc, globus_thread)

28. 28SIAC 2000, Wright State University, August 21, 2000 Other Globus Project Grid Services Coming Soon  Data transfer (GSI-FTP)  Replica Management http://www.globus.org/datagrid Experimental Prototypes  Advanced Reservations & QoS (GARA)  Distributed Events & Logging

29. 29SIAC 2000, Wright State University, August 21, 2000 Sample of High-Level Services Resource brokers and co-allocators  DUROC, HTB, Nimrod/G, Condor-G, ASCI DRM Communication & I/O libraries  MPICH-G, PAWS, RIO (MPI-IO), PPFS, MOL Parallel languages  HPC++, CC++ Collaborative environments  CAVERNsoft, ManyWorlds Others  MetaNEOS, NetSolve, LSA, AutoPilot, WebFlow

30. 30SIAC 2000, Wright State University, August 21, 2000 Condor-G: Condor for the Grid Condor is a high-throughput scheduler Condor-G uses Globus Toolkit libraries for:  Security (GSI)  Managing remote jobs on Grid (GRAM)  File staging & remote I/O (GSI-FTP) Grid job management interface & scheduling  Robust replacement for Globus Toolkit programs Globus Toolkit focus is on libraries and services, not end user vertical solutions  Supports single or high-throughput apps on Grid Personal job manager which can exploit Grid resources

31. 31SIAC 2000, Wright State University, August 21, 2000 Production Grids & Testbeds Production deployments underway at:  NSF PACIs (National Technology Grid)  NASA Information Power Grid  DOE ASCI  European Grid Research testbeds  EMERGE: Advance reservation & QoS  GUSTO: Globus Ubiquitous Supercomputing Testbed Organization  Particle Physics Data Grid  Earth Systems Grid

32. 32SIAC 2000, Wright State University, August 21, 2000 Production Grids & Testbeds NASA’s Information Power Grid The Alliance National Technology Grid GUSTO Testbed

33. 33SIAC 2000, Wright State University, August 21, 2000 Application Experiments Computed microtomography (ANL, ISI)  Real-time, collaborative analysis of data from X- Ray source (and electron microscope) Hydrology (ISI, UMD, UT; also NCSA, Wisc.)  Interactive modeling and data analysis Collaborative engineering (“tele-immersion”)  CAVERNsoft @ EVL OVERFLOW (NASA)  Large CFD simulations for aerospace vehicles

34. 34SIAC 2000, Wright State University, August 21, 2000 Application Experiments Distributed interactive simulation (CIT, ISI)  Record-setting SF-Express simulation Cactus  Astrophysics simulation, viz, and steering  Including trans-Atlantic experiments Particle Physics Data Grid  High Energy Physics distributed data analysis Earth Systems Grid  Climate modeling data management

35. 35SIAC 2000, Wright State University, August 21, 2000 Where Are We? (August 2000) Research is focused on data management, resource management, and web portals. Globus Toolkit v4 has been released.  Runs on most versions of Unix, Win32 clients. Production deployment is underway.  NSF PACIs, NASA IPG, DOE ASCI DRM Many research applications and tools are using these testbeds. We’re always looking for interesting applications.

36. 36SIAC 2000, Wright State University, August 21, 2000 For More Information on Globus http://www.globus.org/ Papers on most components Tutorials  User, Developer, Administrator Manuals  Quick Start Guide, System Administration Guide Mailing lists  discuss@globus.org, announce@globus.org Software & API documentation Application descriptions Attend Supercomputing 2000 (Nov. 2000)

37. 37SIAC 2000, Wright State University, August 21, 2000 The Grid: Blueprint for a New Computing Infrastructure I. Foster, C. Kesselman (Eds), Morgan Kaufmann, 1999 Available July 1998; ISBN 1-55860-475-8 22 chapters by expert authors including Andrew Chien, Jack Dongarra, Tom DeFanti, Andrew Grimshaw, Roch Guerin, Ken Kennedy, Paul Messina, Cliff Neuman, Jon Postel, Larry Smarr, Rick Stevens, and many others http://www.mkp.com/grids “A source book for the history of the future” -- Vint Cerf

38. 38SIAC 2000, Wright State University, August 21, 2000 Session Approach Five sections, each illustrating a basic Globus service Laboratory material is available to allow practice with the use of each technique  See http://www.globus.org/tutorial/

39. 39SIAC 2000, Wright State University, August 21, 2000 Desktop Supercomputing Seamlessly, from the desktop  Sign-on once  Locate available computers  Start computation on an appropriate system  Monitor progress  Get output files  Manipulate locally E.g. ECCE’, Cactus, Hotpage, Chemical Eng. Workbench, WebFlow, LSA

40. 40SIAC 2000, Wright State University, August 21, 2000 WebFlow Grid Interface Dataflow computing interface to grid computing  Fox, Haupt: Syracuse Globus services for  Authentication  Process creation and management Applications include nanomaterials

41. 41SIAC 2000, Wright State University, August 21, 2000 Application Challenges Security  How do we authenticate ourselves at the remote site? Resource specification  How do we locate and request a resource? Staging of code and data  How do we stage a user’s executables and data to the remote resource? Computation  How do we start & manage computation?

42. 42SIAC 2000, Wright State University, August 21, 2000 Grid Services Single sign-on for all resources  No need for user to keep track of accounts and passwords at multiple sites  No plaintext passwords Uniform interface to various local scheduling mechanisms  PBS, Condor, LSF, NQE, LoadLeveler, fork, etc.  No need to learn and remember obscure command sequences at different sites Support for file staging, remote I/O, etc.

43. 43SIAC 2000, Wright State University, August 21, 2000 Grid Authentication Model Authentication is done on a “user” basis  Single authentication step allows access to all grid resources No communication of plaintext passwords Most sites will use conventional account mechanisms  You must have an account on a resource to use that resource Sites may use “generic” Grid accounts  Not common, but Globus can deal with it

44. 44SIAC 2000, Wright State University, August 21, 2000 Grid Security Infrastructure (GSI) Based on public key technology  Standard X.509 certificate, same as certificates used for the Web Each user has:  a Grid user id (called a Subject Name)  a private key (like a password)  a certificate signed by a Certificate Authority (CA) A “gridmap” file at each site specifies grid-id to local-id mapping

45. 45SIAC 2000, Wright State University, August 21, 2000 Certificate Based Authentication User has a certificate, signed by a trusted “certificate authority” (CA)  Certificate contains users name and public key  Globus project operates a CA User’s private key is used to encode a challenge string Public key is used to decode the challenge  If you can decode it, you know the user Treat your private key carefully!!  Private key is stored in encrypted form

46. 46SIAC 2000, Wright State University, August 21, 2000 User Proxies Minimize exposure of user’s private key A temporary credential for use by our computations  We call this a user proxy certificate  Allows process to act on behalf of user  User-signed user proxy certificate stored in local file Proxy’s private key is not encrypted  Rely on file system security, proxy certificate file must be readable only by the owner

47. 47SIAC 2000, Wright State University, August 21, 2000 Delegation Remote creation of a user proxy Allows remote process to act on behalf of the user Avoids sending passwords or private keys across the network

48. 48SIAC 2000, Wright State University, August 21, 2000 Single sign-on via “grid-id” User User Proxy GlobusCredential Site 1 Kerberos GRAM Process GSI Ticket Site 2 Public Key GRAM GSI Certificate Process Authenticated interprocess communication CREDENTIAL GSSAPI: multiple low-level mechanisms Mutual user-resource authentication Mapping to local ids Assignment of credentials to “user proxies”

49. 49SIAC 2000, Wright State University, August 21, 2000 Globus Authentication Setup Before you can run Globus applications:  Install Globus  Obtain a Grid certificate and key  Set up your environment so Globus knows where to find certificates and keys  Contact sites to set up local accounts and globusmap entries  Create proxy certificate for each application run Documentation  Globus Quick Start Guide (on website)

50. 50SIAC 2000, Wright State University, August 21, 2000 Your New Certificate Certificate: Data: Version: 3 (0x2) Serial Number: 28 (0x1c) Signature Algorithm: md5WithRSAEncryption Issuer: C=US, O=Globus, CN=Globus Certification Authority Validity Not Before: Apr 22 19:21:50 1998 GMT Not After : Apr 22 19:21:50 1999 GMT Subject: C=US, O=Globus, O=NACI, OU=SDSC, CN=Richard Frost Subject Public Key Info: Public Key Algorithm: rsaEncryption RSA Public Key: (1024 bit) Modulus (1024 bit): 00:bf:4c:9b:ae:51:e5:ad:ac:54:4f:12:52:3a:69: b4:e1:54:e7:87:57:b7:d0:61 Exponent: 65537 (0x10001) Signature Algorithm: md5WithRSAEncryption 59:86:6e:df:dd:94:5d:26:f5:23:c1:89:83:8e:3c:97:fc:d8: 8d:cd:7c:7e:49:68:15:7e:5f:24:23:54:ca:a2:27:f1:35:17: NTP is highly recommended

51. 51SIAC 2000, Wright State University, August 21, 2000 “Logging on” to the Grid To run programs, authenticate to Globus: % grid-proxy-init Enter PEM pass phrase: ****** Creates a temporary, short-lived credential for use by our computations Private key is not exposed past grid-proxy-init Options for grid-proxy-init: -hours -bits -help

52. 52SIAC 2000, Wright State University, August 21, 2000 Proxy Information To get proxy information run grid-proxy-info % grid-proxy-info -subject /C=US/O=Globus/O=ANL/OU=MCS/CN=Ian Foster Options for printing proxy information -subject-issuer -type-timeleft -strength-help Options for scripting proxy queries -exists -hours -exists -bits  Returns 0 status for true, 1 for false:

53. 53SIAC 2000, Wright State University, August 21, 2000 Sample Gridmap File # Distinguished name Local # username "/C=US/O=Globus/O=NPACI/OU=SDSC/CN=Rich Gallup” rpg "/C=US/O=Globus/O=NPACI/OU=SDSC/CN=Richard Frost” frost "/C=US/O=Globus/O=USC/OU=ISI/CN=Carl Kesselman” u14543 "/C=US/O=Globus/O=ANL/OU=MCS/CN=Ian Foster” itf Gridmap file maintained by Globus administrator Entry maps Grid-id into local user name(s)

54. 54SIAC 2000, Wright State University, August 21, 2000 Remote Startup Mechanism key cert gatekeeperclient 1. Exchange certificates, authenticate, delegate 2. Check gridmap file 3. Lookup service 4. Run service program (e.g. jobmanager) jobmanager key cert 1. 2. map 4. services 3.

55. 55SIAC 2000, Wright State University, August 21, 2000 Simple job submission globus-job-run provides a simple RSH compatible interface % grid-proxy-init Enter PEM pass phrase: ***** % globus-job-run host program [args] Job submission will be covered in more detail in Part 5

56. 56SIAC 2000, Wright State University, August 21, 2000 Exercise: Sign-On & Remote Process Creation Use grid-proxy-init to create a proxy certificate: % grid-proxy-init Enter PEM pass phrase:......................................+++++.....+++++ Use grid-proxy-info to query proxy: % grid-proxy-info -subject Use globus-job-run to start remote programs: % globus-job-run jupiter.isi.edu /usr/bin/ls -l /tmp

57. 57SIAC 2000, Wright State University, August 21, 2000 Globus Components Being Used GSI: Grid Security Infrastructure  Authenticate to remote system GRAM: Globus Resource Allocation Manager  Create process on remote resource, deal with local resource managers GASS: Global Access to Secondary Storage  Redirect standard output (More on GRAM and GASS later!)

58. 58SIAC 2000, Wright State University, August 21, 2000 Job Submission Interfaces Globus Toolkit includes several command line programs for job submission  globus-job-run: Interactive jobs  globus-job-submit: Batch/offline jobs  globusrun: Flexible scripting infrastructure Others are building better interfaces  General purpose Condor-G, PBS, GRD, Hotpage, etc  Application specific ECCE’, Cactus, Web portals

59. 59SIAC 2000, Wright State University, August 21, 2000 globus-job-run For running of interactive jobs Additional functionality beyond rsh  Ex: Run 2 process job w/ executable staging globus-job-run -: host –np 2 –s myprog arg1 arg2  Ex: Run 5 processes across 2 hosts globus-job-run \ -: host1 –np 2 –s myprog.linux arg1 \ -: host2 –np 3 –s myprog.aix arg2  For list of arguments run: globus-job-run -help

60. 60SIAC 2000, Wright State University, August 21, 2000 globus-job-submit For running of batch/offline jobs  globus-job-submitSubmit job Same interface as globus-job-run Returns immediately  globus-job-statusCheck job status  globus-job-cancelCancel job  globus-job-get-outputGet job stdout/err  globus-job-cleanCleanup after job

61. 61SIAC 2000, Wright State University, August 21, 2000 globusrun Flexible job submission for scripting  Uses an RSL string to specify job request  Contains an embedded globus-gass-server Defines GASS URL prefix in RSL substitution variable: (stdout=$(GLOBUSRUN_GASS_URL)/stdout)  Supports both interactive and offline jobs Complex to use  Must write RSL by hand  Must understand its esoteric features  Generally you should use globus-job-* commands instead

62. 62SIAC 2000, Wright State University, August 21, 2000 Summary Grid Security Infrastructure (GSI) provides single sign-on capability globus-job-run can be used to create a remote process  Difference between schedulers managed by Globus  Strong authentication provided Remote process creation can be added to applications by using Globus services Rest [Self Study]

63. 63SIAC 2000, Wright State University, August 21, 2000 Grid Information Services System information is critical to operation of the grid and construction of applications  How does an application determine what resources are available?  What is the “state” of the computational grid?  How can we optimize an application based on configuration of the underlying system? We need a general information infrastructure to answer these questions

64. 64SIAC 2000, Wright State University, August 21, 2000 Using Information for Resource Brokering “10 GFlops, EOS data, 20 Mb/sec -- for 20 mins” Metacomputing Directory Service GRAM Resource Broker Info service: location + selection Globus Resource Allocation Managers GRAM Fork LSF EASYLL Condor etc. “What computers?” “What speed?” “When available?” “50 processors + storage from 10:20 to 10:40 pm” “20 Mb/sec”

65. 65SIAC 2000, Wright State University, August 21, 2000 Examples of Useful Information Characteristics of a compute resource  IP address, software available, system administrator, networks connected to, OS version, load Characteristics of a network  Bandwidth and latency, protocols, logical topology Characteristics of the Globus infrastructure  Hosts, resource managers

66. 66SIAC 2000, Wright State University, August 21, 2000 Grid Information Service Provide access to static and dynamic information regarding system components A basis for configuration and adaptation in heterogeneous, dynamic environments Requirements and characteristics  Uniform, flexible access to information  Scalable, efficient access to dynamic data  Access to multiple information sources  Decentralized maintenance

67. 67SIAC 2000, Wright State University, August 21, 2000 The Globus Toolkit’s Metacomputing Directory Service (MDS) Information is maintained in a distributed directory.  Information is accessed via a standard protocol  Information is distributed across many servers  Each server can be optimized for particular functions Information comes from many sources.  Information providers and tools  Applications (i.e., users)  Resources that generate info on demand Information is available everywhere.

68. 68SIAC 2000, Wright State University, August 21, 2000 MDS Features White Pages  Look up the IP number, amount of memory, etc., associated with a particular machine Yellow Pages  Search for computers of a particular class or with a particular property Information is dynamic!  In a distributed system, things change without warning.  Information often has an expiration date or other measures of uncertainty.

69. 69SIAC 2000, Wright State University, August 21, 2000 MDS Approach Based on LDAP  Lightweight Directory Access Protocol v3 (LDAPv3)  Standard data model  Standard query protocol Globus specific schema  Host-centric representation Globus specific tools  GRIS, GIIS  Data discovery, publication,… SNMP GRIS NIS NWS LDAP LDAP API Middleware … Application GIIS…

70. 70SIAC 2000, Wright State University, August 21, 2000 LDAP Details Lightweight Directory Access Protocol  Stripped down version of X.500 DAP protocol  Supports distributed storage/access (referrals)  Supports replication  Becoming de facto standard Defines:  Network protocol for accessing directory contents  Information model defining form of information  Namespace defining how information is referenced and organized

71. 71SIAC 2000, Wright State University, August 21, 2000 LDAP Directory Structure Directory contents  Called Object Classes and Entries  What information is stored in directory  Group related information into entries Directory organization  Called Directory Information Tree (DIT)  Objects are organized into tree structure  Position of object in tree uniquely names entry within the server

72. 72SIAC 2000, Wright State University, August 21, 2000 Sample Object Classes Compute Resources  Operating System  Memory Hierarchy  Health and Status Network Interfaces  IP address  Interface types Performance Data  Schedule Jobs  CPU Loads  Network Traffic Resource Managers  Contact strings  Scheduled jobs  Free nodes Software  Configuration  Version Control  Contact information Organizations People

73. 73SIAC 2000, Wright State University, August 21, 2000 LDAP Directory Information Tree Directory entries are organized into a tree.  Called Directory Information Tree (DIT)  Subtrees can be distributed or replicated. Position in tree uniquely names entry within a server. Each object in a server is uniquely determined by its distinguished name (DN).  List of unique attribute names and values along path from root of DIT to object, e.g.:

74. 74SIAC 2000, Wright State University, August 21, 2000 Global Namespace A DN uniquely names an entry within an LDAP server. The host and port uniquely names an LDAP server. An LDAP URL is the combination of these. ldap:// : / LDAP URL can be used as the global name of an entry.

75. 75SIAC 2000, Wright State University, August 21, 2000 MDS Components Uses standard LDAP servers  OpenLDAP, Netscape, Oracle, etc Tools for populating & maintaining MDS  Integrated with Globus Toolkit server release, not of concern to most Globus users  Discover/update static and dynamic info APIs for accessing & updating MDS contents  C, Java, PERL (LDAP API, JNDI) Various tools for manipulating MDS contents  Command line tools, Shell scripts & GUIs

76. 76SIAC 2000, Wright State University, August 21, 2000 Three Classes Of MDS Servers Grid Resource Information Service (GRIS)  Supplies information about a specific resource  Mostly “white pages” lookups Grid Index Information Service (GIIS)  Supplies collection of information which was gathered from multiple GRIS servers  Supports efficient queries against information which is spread across multiple GRIS servers  Mostly “yellow pages” lookups Referral Service  Links together GRIS and/or GIIS servers

77. 77SIAC 2000, Wright State University, August 21, 2000 Grid Resource Information Service GRIS is an LDAP server which runs on each resource.  GRIS runs on a well known port (2135). GRIS provides resource-specific information.  Load, process information, storage information, etc.  GRIS gathers this information on demand with a TTL GRIS supports white & yellow pages queries.  Configuration settings  Capabilities (queues, extra equipment, etc.) GRIS can be configured to register with a GIIS on startup, deregister on shutdown.

78. 78SIAC 2000, Wright State University, August 21, 2000 Grid Index Information Service GIIS describes a class of servers.  Gathers information from multiple GRIS servers.  Each GIIS is optimized for particular queries. Ex1: Which Alliance machines are >16 process SGIs? Ex2: Which Alliance storage servers have >100Mbps bandwidth to host X?  GIIS is similar to web search engines. GIIS can be used to inventory an organization’s resources (“organizational information service”).  The Globus Toolkit includes a GIIS.  Caches GRIS info with long update frequency. Useful for queries across an organization that rely on relatively static information. (Ex1 above.)

79. 79SIAC 2000, Wright State University, August 21, 2000 Referral Service Links together multiple GRIS and/or GIIS servers into a single LDAP namespace Referral servers contain no actual content Current limitations  Requires LDAPv3 referrals  Some LDAP clients to not have good support for referrals  But this is improving… Can be implemented as a GIIS or as a commercial LDAP server.

80. 80SIAC 2000, Wright State University, August 21, 2000 Pulling Together a DIT In order for a GRIS’s content to appear in a GIIS, the GIIS must first find it.  GRISes can register with GIIS during startup.  GIIS can be configured with GRISes’ hostnames.  GIIS can walk a referral tree to find GRISes. MDS can support any of these approaches.  The “right” approach depends on the organization’s requirements.  Can use a combinations of these approaches.  This is the subject of ongoing research.

81. 81SIAC 2000, Wright State University, August 21, 2000 Finding a GIIS How does a user or application find a GIIS server? Options include:  Runs on well-known host/port  Use DNS server records Returns host/port of server for a particular domain  Part of referral tree Recursive: How do you find the referral service?  Indexed by another GIIS Recursive: How do you find the referral service? This is also the subject of ongoing research.

82. 82SIAC 2000, Wright State University, August 21, 2000 Server Registration A GRIS or GIIS server can be configured to (de-)register itself during startup/shutdown  Basic capability that is useful in many scenarios Support for multiple registration protocols  Can register with a GIIS using custom protocol  Can dynamically add itself to a referral tree using LDAPv3 referral protocol Allows for federations of information servers  E.g. Argonne GRIS can register with both Alliance and DOE GIIS servers

83. 83SIAC 2000, Wright State University, August 21, 2000 MDS Tools Java LDAP browser  http://www.mcs.anl.gov/~gawor/ldap Web-based browsers and displays  http://www.globus.org/mds CGI-based MDS browser MDS Object Class Browser Various APIs and search tools Translators from “Globus Object Definition Language”  Commented LDIF - LDAP schema definition  Converts to LDIF, HTML

84. 84SIAC 2000, Wright State University, August 21, 2000

85. 85SIAC 2000, Wright State University, August 21, 2000 MDS Access/Update Commands LDAP defines a set of standard commands ldapsearch, ldapmodify, ldapdelete, etc. We also define MDS-specific commands  grid-info-search, grid-info-create, grid-info-update, grid- info-remove, grid-info-host-search  Routines to ensure data consistency and to insert metadata APIs are defined for C, Java, etc.  C: OpenLDAP client API ldap_search_s(), ldap_modify_s(), …  Java: JNDI

86. 86SIAC 2000, Wright State University, August 21, 2000 Searching an LDAP Database grid-info-search [options] filter [attributes] Default grid-info-search options -h mds.globus.orgMDS server -p 389 MDS port -b “o=Grid” search start point -T 30 LDAP query timeout -s sub scope = subtree alternatives: base : lookup this entry one: lookup immediate children

87. 87SIAC 2000, Wright State University, August 21, 2000 Searching a GRIS Server grid-info-host-search [options] filter [attributes] Exactly like grid-info-search, except defaults: -h localhostGRIS server -p 2135 GRIS port Example: grid-info-host-search –h pitcairn “dn=*” dn

88. 88SIAC 2000, Wright State University, August 21, 2000 Filtering Filters allow selection of object based on relational operators (=, ~=, =)  grid-info-search “cputype=*” Compound filters can be construct with Boolean operations: (&, |, !)  grid-info-search “(&(cputype=*)(cpuload1<=1.0))”  grid-info-search “(&(hn~=sdsc.edu)(latency<=10))” Hints:  white space is significant  use -L for LDIF format required

89. 89SIAC 2000, Wright State University, August 21, 2000 Example: Filtering % grid-info-host-search -L “(objectclass=GlobusSoftware)” dn: sw=Globus, hn=pitcairn.mcs.anl.gov, dc=mcs, dc=anl, dc=gov, o=Grid objectclass: GlobusSoftware releasedate: 2000/04/11 19:48:29 releasemajor: 1 releaseminor: 1 releasepatch: 3 releasebeta: 11 lastupdate: Sun Apr 30 19:28:19 GMT 2000 objectname: sw=Globus, hn=pitcairn.mcs.anl.gov, dc=mcs, dc=anl, dc=gov, o=Grid

90. 90SIAC 2000, Wright State University, August 21, 2000 Example: Attribute Selection % grid-info-host- search -L “(objectclass=*)” dn hn  Returns the distinguished name (dn) and hostname (hn) of all objects  Objects without hn fields are still listed  DNs are always listed dn: sw=Globus, hn=pitcairn.mcs.anl.gov, dc=mcs, dc=anl, dc=gov, o=Grid dn: hn=pitcairn.mcs.anl.gov, dc=mcs, dc=anl, dc=gov, o=Grid hn: pitcairn.mcs.anl.gov dn: service=jobmanager, hn=pitcairn.mcs.anl.gov, dc=mcs, dc=anl, dc=gov, o=Grid hn: pitcairn.mcs.anl.gov dn: queue=default, service=jobmanager, hn=pitcairn.mcs.anl.gov, dc=mcs, dc=anl, dc=gov, o=Grid

91. 91SIAC 2000, Wright State University, August 21, 2000 Example: Discovering CPU Load Retrieve CPU load fields of compute resources % grid-info-search -L “(objectclass=GlobusComputeResource)” \ dn cpuload1 cpuload5 cpuload15 dn: hn=lemon.mcs.anl.gov, ou=MCS, o=Argonne National Laboratory, o=Globus, c=US cpuload1: 0.48 cpuload5: 0.20 cpuload15: 0.03 dn: hn=tuva.mcs.anl.gov, ou=MCS, o=Argonne National Laboratory, o=Globus, c=US cpuload1: 3.11 cpuload5: 2.64 cpuload15: 2.57

92. 92SIAC 2000, Wright State University, August 21, 2000 MDS and Security Authentication is required to perform certain operations (e.g., write operations) Each site has a Directory Manager  cn=Directory Manager, o=Organization, c=US Users registered with the MDS have a DN  cn=Jane Doe, o=Organization, c=US % grid-info-search -D “cn=Jane Doe, o=Organization, c=US” \ -w GSI based authentication coming soon  Working prototype of GSI with OpenLDAP v2

93. 93SIAC 2000, Wright State University, August 21, 2000 Summary MDS provides the information needed to perform dynamic resource discovery and configuration.  This is a critical component of resource brokers! MDS is based on existing directory service standards (LDAPv3). Although MDS is based on the LDAPv3 protocol, we are not tied to commercial LDAP servers.

94. 94SIAC 2000, Wright State University, August 21, 2000 SF-Express Distributed Interactive Simulation P. Messina et al., Caltech Developed at Caltech 100K vehicles (2002 goal) using 13 computers, 1386 nodes, 9 sites Globus mechanisms for  Resource allocation  Distributed startup  I/O and configuration  Fault detection NCSA Origin Caltech Exemplar CEWES SP Maui SP

95. 95SIAC 2000, Wright State University, August 21, 2000 Grid Services Resource Specification: the power to express the required resources and constraints Resource Co-allocation: using resources together simultaneously Executable staging, remote data access and I/O streaming (more on these later) These services should be integrated with higher- level tools  MPICH-G, globus-job-*, Condor, PBS, GRD, etc.

96. 96SIAC 2000, Wright State University, August 21, 2000 Globus Components in Action globus-job-run jobmanager fork P1 P2 gatekeeper jobmanager LSF P1 P2 gatekeeper jobmanager LoadLeveler P1 P2 gatekeeper GRAM

97. 97SIAC 2000, Wright State University, August 21, 2000 Resource Management Resource Specification Language (RSL) is used to communicate requirements The Globus Resource Allocation Manager (GRAM) API allows programs to be started on remote resources, despite local heterogeneity A layered architecture allows application- specific resource brokers and co-allocators to be defined in terms of GRAM services

98. 98SIAC 2000, Wright State University, August 21, 2000 GRAM LSFEASY-LLNQE Application RSL Information Service Local resource managers Broker Co-allocator Building a Resource Broker RSL LDAP RSL Status Globus components

99. 99SIAC 2000, Wright State University, August 21, 2000 Resource Specification Language Common notation for exchange of information between components  Syntax similar to MDS/LDAP filters RSL provides two types of information:  Resource requirements: Machine type, number of nodes, memory, etc.  Job configuration: Directory, executable, args, environment API provided for manipulating RSL

100. 100SIAC 2000, Wright State University, August 21, 2000 RSL Syntax Elementary form: parenthesis clauses  (attribute op value [ value … ] ) Operators Supported:  =, >, != Some supported attributes:  executable, arguments, environment, stdin, stdout, stderr, resourceManagerContact, resourceManagerName Unknown attributes are passed through  May be handled by subsequent tools

101. 101SIAC 2000, Wright State University, August 21, 2000 Constraints: “&” For example: & (count>=5) (count<=10) (max_time=240) (memory>=64) (executable=myprog) “Create 5-10 instances of myprog, each on a machine with at least 64 MB memory that is available to me for 4 hours”

102. 102SIAC 2000, Wright State University, August 21, 2000 Disjunction: “|” For example: & (executable=myprog) ( | (&(count=5)(memory>=64)) (&(count=10)(memory>=32))) Create 5 instances of myprog on a machine that has at least 64MB of memory, or 10 instances on a machine with at least 32MB of memory

103. 103SIAC 2000, Wright State University, August 21, 2000 GRAM Components Globus Security Infrastructure Job Manager GRAM client API calls to request resource allocation and process creation. MDS client API calls to locate resources Query current status of resource Create RSL Library Parse Request Allocate & create processes Process Monitor & control Site boundary ClientMDS: Grid Index Info Server Gatekeeper MDS: Grid Resource Info Server Local Resource Manager MDS client API calls to get resource info GRAM client API state change callbacks

104. 104SIAC 2000, Wright State University, August 21, 2000 Multirequest: “+” A multirequest allows us to specify multiple resource needs, for example + (& (count=5)(memory>=64) (executable=p1)) (&(network=atm) (executable=p2))  Execute 5 instances of p1 on a machine with at least 64M of memory  Execute p2 on a machine with an ATM connection Multirequests are central to co-allocation

105. 105SIAC 2000, Wright State University, August 21, 2000 Co-allocation Simultaneous allocation of a resource set  Handled via optimistic co-allocation based on free nodes or queue prediction  In the future, advance reservations will also be supported globusrun and globus-job-* will co-allocate specific multi-requests  Uses a Globus component called the Dynamically Updated Request Online Co-allocator (DUROC)

106. 106SIAC 2000, Wright State University, August 21, 2000 A Co-allocation Multirequest +( & (resourceManagerContact= “flash.isi.edu:754:/C=US/…/CN=flash.isi.edu-fork”) (count=1) (label="subjob A") (executable= my_app1) ) ( & (resourceManagerContact= “sp139.sdsc.edu:8711:/C=US/…/CN=sp097.sdsc.edu-lsf") (count=2) (label="subjob B") (executable=my_app2) ) Different executables Different counts Different resource managers

107. 107SIAC 2000, Wright State University, August 21, 2000 Job Submission Interfaces Globus Toolkit includes several command line programs for job submission  globus-job-run: Interactive jobs  globus-job-submit: Batch/offline jobs  globusrun: Flexible scripting infrastructure Others are building better interfaces  General purpose Condor-G, PBS, GRD, Hotpage, etc  Application specific ECCE’, Cactus, Web portals

108. 108SIAC 2000, Wright State University, August 21, 2000 globus-job-run For running of interactive jobs Additional functionality beyond rsh  Ex: Run 2 process job w/ executable staging globus-job-run -: host –np 2 –s myprog arg1 arg2  Ex: Run 5 processes across 2 hosts globus-job-run \ -: host1 –np 2 –s myprog.linux arg1 \ -: host2 –np 3 –s myprog.aix arg2  For list of arguments run: globus-job-run -help

109. 109SIAC 2000, Wright State University, August 21, 2000 globus-job-submit For running of batch/offline jobs  globus-job-submitSubmit job Same interface as globus-job-run Returns immediately  globus-job-statusCheck job status  globus-job-cancelCancel job  globus-job-get-outputGet job stdout/err  globus-job-cleanCleanup after job

110. 110SIAC 2000, Wright State University, August 21, 2000 globusrun Flexible job submission for scripting  Uses an RSL string to specify job request  Contains an embedded globus-gass-server Defines GASS URL prefix in RSL substitution variable: (stdout=$(GLOBUSRUN_GASS_URL)/stdout)  Supports both interactive and offline jobs Complex to use  Must write RSL by hand  Must understand its esoteric features  Generally you should use globus-job-* commands instead

111. 111SIAC 2000, Wright State University, August 21, 2000 Brokering via Lowering Resource location by refining a RSL expression (RSL lowering): (MFLOPS=1000)  (& (arch=sp2)(count=200))  (+ (& (arch=sp2) (count=120) (resourceManagerContact=anlsp2)) (& (arch=sp2) (count=80) (resourceManagerContact=uhsp2)))

112. 112SIAC 2000, Wright State University, August 21, 2000 SF-Express Distributed Interactive Simulation P. Messina et al., Caltech Developed at Caltech 100K vehicles (2002 goal) using 13 computers, 1386 nodes, 9 sites Globus mechanisms for  Resource allocation  Distributed startup  I/O and configuration  Fault detection NCSA Origin Caltech Exemplar CEWES SP Maui SP

113. 113SIAC 2000, Wright State University, August 21, 2000 Grid Services Resource Specification and Resource Co-allocation (GRAM) Executable Staging Remote Data Access These services should be integrated with higher- level tools  globus-job-*, Condor, etc.

114. 114SIAC 2000, Wright State University, August 21, 2000 What is GASS? 1.RSL extensions  URLs used to name executables, stdout, stderr 2.A file access API  Replace open/close with globus_gass_open/close; read/write calls can then proceed directly 3.Remote cache management utility

115. 115SIAC 2000, Wright State University, August 21, 2000 GASS Architecture Cache GASS Server HTTP Server FTP Server % globus-gass-cache Remote cache management GRAM GASS file access API &(executable=https://…) RSL extensions main( ) { fd = globus_gass_open(…) … read(fd,…) … globus_gass_close(fd) } 1 2 3

116. 116SIAC 2000, Wright State University, August 21, 2000 GASS File Naming URL encoding of resource names https://quad.mcs.anl.gov:9991/~bester/myjob protocol server address file name Other examples https://pitcairn.mcs.anl.gov/tmp/input_dataset.1 https://pitcairn.mcs.anl.gov:2222/./output_data http://www.globus.org/~bester/input_dataset.2 Currently supports http & https Next release will also support ftp & gsiftp.

117. 117SIAC 2000, Wright State University, August 21, 2000 GASS RSL Extensions executable, stdin, stdout, stderr can be local files or URLs executable and stdin loaded into local cache before job begins (on front-end node) stdout, stderr handled via GASS append mode Cache cleaned after job completes

118. 118SIAC 2000, Wright State University, August 21, 2000 GASS/RSL Example &(executable=https://quad:1234/~/myexe) (stdin=https://quad:1234/~/myin) (stdout=/home/bester/output) (stderr=https://quad:1234/dev/stdout)

119. 119SIAC 2000, Wright State University, August 21, 2000 Example GASS Applications On-demand, transparent loading of data sets Caching of data sets Automatic staging of code and data to remote supercomputers (Near) real-time logging of application output to remote server

120. 120SIAC 2000, Wright State University, August 21, 2000 GASS File Access API Minimum changes to application globus_gass_open(), globus_gass_close()  Same as open(), close() but use URLs instead of filenames  Caches URL in case of multiple opens  Return descriptors to files in local cache or sockets to remote server globus_gass_fopen(), globus_gass_fclose()

121. 121SIAC 2000, Wright State University, August 21, 2000 GASS File Access API (cont) Support for different access patterns  Read-only (from local cache)  Write-only (to local cache)  Read-write (to/from local cache)  Write-only, append (to remote server)

122. 122SIAC 2000, Wright State University, August 21, 2000 Remove cache reference Upload changes Modified no yes globus_gass_open()/close() Download File into cache open cached file, add cache reference URL in cache? no yes globus_gass_open() globus_gass_close()

123. 123SIAC 2000, Wright State University, August 21, 2000 GASS File API Semantics Copy-on-open to cache if not truncate or write-only append and not already in cache Copy on close from cache if not read only and not other copies open Multiple globus_gass_open() calls share local copy of file Append to remote file if write only append: e.g., for stdout and stderr Reference counting keeps track of open files

124. 124SIAC 2000, Wright State University, August 21, 2000 Remote Cache Management Utilities Remote management of caches, for  Prestaging/poststaging of files  Cache cleanup and management Support operations on local & remote caches Functionality encapsulated in a program: globus-gass-cache

125. 125SIAC 2000, Wright State University, August 21, 2000 globus-gass-server Simple file server  Run by user wherever necessary  Secure https protocol, using GSI  APIs for embedding server into other programs Example globus-gass-server –r –w -t  -r: Allow files to be read from this server  -w: Allow files to be written to this server  -t: Tilde expand (~/…  $(HOME)/…)  -help: For list of all options

126. 126SIAC 2000, Wright State University, August 21, 2000 1. Build RSL string 2. Startup GASS server 3. Submit to request 4. Return output jobmanager gatekeeper program GRAM & GASS: Putting It Together stdout GASS server 2 3 globus-job-run RSL string 1 Command Line Args 3 3 4 4 4 4

127. 127SIAC 2000, Wright State University, August 21, 2000 Globus Components In Action Local Machine mpirun globusrun GRAM Client GSI GRAM Client GSI Remote Machine App Nexus AIX PBS MPI grid-proxy-init X509 User Cert User Proxy Cert Machines GRAM Gatekeeper GSI GRAM Job Manager GASS Client Remote Machine App Nexus Solaris Unix Fork MPI GRAM Gatekeeper GSI GRAM Job Manager GASS Client RSL string RSL multi-request RSL single request DUROC GASS Server RSL parser

128. 128SIAC 2000, Wright State University, August 21, 2000 Summary We learned how to dynamically select and configure computations  MDS and DUROC/GRAM enable construction of brokers GASS enables access to remote files and executables Demonstrates the interaction of many Globus components

129. 129SIAC 2000, Wright State University, August 21, 2000 IPC with globus_io TCP, UDP, IP multicast, and File I/O  Familiar socket and file abstractions Asynchronous & synchronous interfaces  Robust implementation & applications Easy to use security, socket options, etc  Turn on security and other options with just a few function calls Designed for Win32 support  Hides difference between socket & file handles  Compatible with completion ports

130. 130SIAC 2000, Wright State University, August 21, 2000 Motivation Numerous modules were using various combinations of TCP, UDP, IP multicast, and file I/O  Write very robust code once, and exploit it throughout In the process, solve other issues:  Win32 portability  Ease of use of security, socket options, QoS

131. 131SIAC 2000, Wright State University, August 21, 2000 Approach Provide familiar socket and file abstractions Provide both synchronous and asynchronous versions of everything  Can easily write code that will not block for anything Handle security, socket options, and QoS through attributes

132. 132SIAC 2000, Wright State University, August 21, 2000 Win32 Unlike Unix, in Win32 “file handles” and “socket handles” are treated differently  Select only works on socket handles  Different Win32 calls for file and socket I/O  globus_io allows us to mask this difference Win 32 “completion ports” give the best I/O performance  globus_io’s asynchronous callback interface matches well with completion ports  globus_callback also designed for this

133. 133SIAC 2000, Wright State University, August 21, 2000 TCP Security Attributes TCP authentication and delegation characteristics  globus_io_attr_set_secure_authentication_mode() GLOBUS_IO_SECURE_AUTHENTICATION_MODE_NONE GLOBUS_IO_SECURE_AUTHENTICATION_MODE_GSSAPI  globus_io_attr_set_secure_delegation_mode() GLOBUS_IO_SECURE_DELEGATION_MODE_NONE GLOBUS_IO_SECURE_DELEGATION_MODE_LIMITED_PROXY GLOBUS_IO_SECURE_DELEGATION_MODE_FULL_PROXY

134. 134SIAC 2000, Wright State University, August 21, 2000 TCP Security Attributes TCP authorization and channel characteristics  globus_io_attr_set_secure_authorization_mode() GLOBUS_IO_SECURE_AUTHORIZATION_MODE_SELF GLOBUS_IO_SECURE_AUTHORIZATION_MODE_IDENTITY GLOBUS_IO_SECURE_AUTHORIZATION_MODE_CALLBACK  globus_io_attr_set_secure_channel_mode() GLOBUS_IO_SECURE_CHANNEL_MODE_CLEAR GLOBUS_IO_SECURE_CHANNEL_MODE_GSI_WRAP GLOBUS_IO_SECURE_CHANNEL_MODE_SSL_WRAP

135. 135SIAC 2000, Wright State University, August 21, 2000 TCP Socket Attributes TCP socket options  globus_io_attr_set_socket_reuseaddr()  globus_io_attr_set_socket_keepalive()  globus_io_attr_set_socket_linger()  globus_io_attr_set_socket_oobinline()  globus_io_attr_set_socket_sndbuf()  globus_io_attr_set_socket_rcvbuf()  globus_io_attr_set_tcp_nodelay()

136. 136SIAC 2000, Wright State University, August 21, 2000 Other Attributes File attributes  globus_io_attr_set_file_type() GLOBUS_IO_FILE_TYPE_TEXT GLOBUS_IO_FILE_TYPE_BINARY Restricting anonymous ports to a particular port range  globus_io_attr_set_tcp_restrict_port() IP multicast  globus_io_attr_set_udp_multicast_loop()  globus_io_attr_set_udp_multicast_ttl()

137. 137SIAC 2000, Wright State University, August 21, 2000 Core Functions Common functions used for all forms of I/O  globus_io_[register]_select()  globus_io_[register]_cancel()  globus_io_[register]_close()  globus_io_[register]_read()  globus_io_[register]_write()  globus_io_[register]_writev()  globus_io_try_{read,write,writev}()  globus_io_get_handle_type()  globus_io_handle_{set,get}_user_pointer()

138. 138SIAC 2000, Wright State University, August 21, 2000 TCP Connection Setup Typical functions for creating TCP connections  globus_io_tcp_create_listener()  globus_io_tcp_[register]_listen()  globus_io_tcp_[register]_accept()  globus_io_tcp_[register]_connect() Setting and getting attributes  globus_io_tcp_set_attr()  globus_io_tcp_get_attr()

139. 139SIAC 2000, Wright State University, August 21, 2000 File Setup Typical functions for establishing file I/O  globus_io_file_open()  globus_io_file_seek()

140. 140SIAC 2000, Wright State University, August 21, 2000 Portability Features A collection of fundamental software modules.  Module activation/deactivation  Portable thread library (POSIX subset)  Thread-safe and portable libc wrappers  Timed and periodic callbacks  Data object and error object management  Modules to manipulate lists, fifos, URLs, … The rest of Globus relies on these features. Developers can (should) use these features for maximum portability and convenience.

141. 141SIAC 2000, Wright State University, August 21, 2000 Activation and Deactivation globus_module_*()  Functions for activation (initialization) and deactivation (shutdown)  Support for multiple independent activations and deactivations of a module through reference counting  Support for dependencies amongst modules  Support for thread-safe initialization  Modules can use atexit()...

142. 142SIAC 2000, Wright State University, August 21, 2000 Threads globus_thread_*(), globus_mutex_*(), globus_cond_*()  Simple POSIX threads (pthreads) subset  Same arguments and semantics as pthreads  Simply change “pthread” to “globus” or “globus_thread” in the function name  Provides portability to pre-standard pthread libraries, and non-pthread based systems  Simple pass-through on systems with standard pthreads  Co-exists with programs using pthreads directly

143. 143SIAC 2000, Wright State University, August 21, 2000 Threaded vs Non-threaded Globus supports pthreads, cthreads, Solaris threads, and sproc. Globus also supports non-threaded applications.  Most thread-related functions are stubbed out.  If you write code carefully which uses the mutex, cond, and thread specific storage functions, if should work both threaded and non-threaded.  Most Globus Toolkit APIs use an event driven approach, which works well with or without threads.

144. 144SIAC 2000, Wright State University, August 21, 2000 globus_libc Wrappers around standard libc functions  Thread safe, even if underlying libc is not Caveat: Application must also use globus_libc to ensure thread safety.  Same interface for threaded and non-threaded POSIX reentrant functions (*_r()) always work. Example: globus_libc_gethostbyname_r()  Fixes or enhances some functions Example: globus_libc_gethostname() tries to figure out a fully qualified hostname despite system configuration.

145. 145SIAC 2000, Wright State University, August 21, 2000 Callbacks Driver for timed and periodic callbacks  globus_callback_register_oneshot()  globus_callback_register_periodic()  globus_callback_unregister()  globus_callback_poll() All modules rely on this for periodic polling Uses threads where possible Uses thread blocking callbacks to guarantee progress even when callback blocks

146. 146SIAC 2000, Wright State University, August 21, 2000 Convenience Modules globus_common also contains a small set of convenience modules  globus_fifo: First-In-First-Out queue  globus_hashtable: Hashtable  globus_list: List functions  globus_symboltable: Symbol table management  globus_url: URL parsing  globus_strptime: Y2K-compliant strptime()  globus_object  globus_error