Hartmut Kaiser GAT - The Grid Application Toolkit Abstracting the Grid for Application Programmers Hartmut Kaiser MPI for Gravitational Physics, Albert-Einstein-Institut, Golm Tom Goodale, Thilo Kielmann, Gabrielle Allen Edward Seidel, André Merzky, Kelly Davis The GridLab Project

Hartmut Kaiser COST D23 Tutorial on Grid Computing 24th/25th October 2004, Manno, 2 Outline Introduction Why another Grid-API? What does it offer/solve? Simple samples Architecture / Implementation In depth course through API groups File Management, File Stream Management, Logical File Management Advert Service Management Job Management Conclusions

Hartmut Kaiser COST D23 Tutorial on Grid Computing 24th/25th October 2004, Manno, 3 Why another Grid-API? The situation today: Grids: everywhere Supposedly. At least many projects Grid applications: nowhere Almost. At least our experience that this is difficult, GGF APPS group Why is this? Application programmers accept the Grid as a computing paradigm only very slowly. Problems: (multifold and often cited - amongst others) Interfaces are NOT simple (see next slides...) Typical Globus code... ahem... Different and evolving interfaces to the ’Grid’ Versions, new services, new implementations, WSDL does not solve all problems at all Environment changes in many ways Globus, grid members, services, network, applications,...

Hartmut Kaiser COST D23 Tutorial on Grid Computing 24th/25th October 2004, Manno, 4 Copy a File: Globus GASS if (source_url.scheme_type == GLOBUS_URL_SCHEME_GSIFTP || source_url.scheme_type == GLOBUS_URL_SCHEME_FTP ) { globus_ftp_client_operationattr_init (&source_ftp_attr); globus_gass_copy_attr_set_ftp (&source_gass_copy_attr, &source_ftp_attr); } else { globus_gass_transfer_requestattr_init (&source_gass_attr, source_url.scheme); globus_gass_copy_attr_set_gass(&source_gass_copy_attr, &source_gass_attr); } output_file = globus_libc_open ((char*) target, O_WRONLY | O_TRUNC | O_CREAT, S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP); if ( output_file == -1 ) { printf ("could not open the file \"%s\"\n", target); return (-1); } /* convert stdout to be a globus_io_handle */ if ( globus_io_file_posix_convert (output_file, 0, &dest_io_handle) != GLOBUS_SUCCESS) { printf ("Error converting the file handle\n"); return (-1); } result = globus_gass_copy_register_url_to_handle ( &gass_copy_handle, (char*)source_URL, &source_gass_copy_attr, &dest_io_handle, my_callback, NULL); if ( result != GLOBUS_SUCCESS ) { printf ("error: %s\n", globus_object_printable_to_string (globus_error_get (result))); return (-1); } globus_url_destroy (&source_url); return (0); } int RemoteFile::GetFile (char const* source, char const* target) { globus_url_t source_url; globus_io_handle_t dest_io_handle; globus_ftp_client_operationattr_t source_ftp_attr; globus_result_t result; globus_gass_transfer_requestattr_t source_gass_attr; globus_gass_copy_attr_t source_gass_copy_attr; globus_gass_copy_handle_t gass_copy_handle; globus_gass_copy_handleattr_t gass_copy_handleattr; globus_ftp_client_handleattr_t ftp_handleattr; globus_io_attr_t io_attr; int output_file = -1; if ( globus_url_parse (source_URL, &source_url) != GLOBUS_SUCCESS ) { printf ("can not parse source_URL \"%s\"\n", source_URL); return (-1); } if ( source_url.scheme_type != GLOBUS_URL_SCHEME_GSIFTP && source_url.scheme_type != GLOBUS_URL_SCHEME_FTP && source_url.scheme_type != GLOBUS_URL_SCHEME_HTTP && source_url.scheme_type != GLOBUS_URL_SCHEME_HTTPS ) { printf ("can not copy from %s - wrong prot\n", source_URL); return (-1); } globus_gass_copy_handleattr_init (&gass_copy_handleattr); globus_gass_copy_attr_init (&source_gass_copy_attr); globus_ftp_client_handleattr_init (&ftp_handleattr); globus_io_fileattr_init (&io_attr); globus_gass_copy_attr_set_io (&source_gass_copy_attr, &io_attr); &io_attr); globus_gass_copy_handleattr_set_ftp_attr (&gass_copy_handleattr, &ftp_handleattr); globus_gass_copy_handle_init (&gass_copy_handle, &gass_copy_handleattr);

Hartmut Kaiser COST D23 Tutorial on Grid Computing 24th/25th October 2004, Manno, 5 Copy a File: CoG/RFT TransferRequestType transferRequest = new TransferRequestType (); transferRequest.setTransferArray (transfers1); int concurrency = Integer.valueOf ((String)requestData.elementAt(6)).intValue(); if (concurrency > transfers1.length) { System.out.println ("Concurrency should be less than the number" "of transfers in the request"); System.exit (0); } transferRequest.setConcurrency (concurrency); TransferRequestElement requestElement = new TransferRequestElement (); requestElement.setTransferRequest (transferRequest); ExtensibilityType extension = new ExtensibilityType (); extension = AnyHelper.getExtensibility (requestElement); OGSIServiceGridLocator factoryService = new OGSIServiceGridLocator (); Factory factory = factoryService.getFactoryPort (new URL (source_url)); GridServiceFactory gridFactory = new GridServiceFactory (factory); LocatorType locator = gridFactory.createService (extension); System.out.println ("Created an instance of Multi-RFT"); MultiFileRFTDefinitionServiceGridLocator loc = new MultiFileRFTDefinitionServiceGridLocator(); RFTPortType rftPort = loc.getMultiFileRFTDefinitionPort (locator); ((Stub)rftPort)._setProperty (Constants.AUTHORIZATION, NoAuthorization.getInstance()); ((Stub)rftPort)._setProperty (GSIConstants.GSI_MODE, GSIConstants.GSI_MODE_FULL_DELEG); ((Stub)rftPort)._setProperty (Constants.GSI_SEC_CONV, Constants.SIGNATURE); ((Stub)rftPort)._setProperty (Constants.GRIM_POLICY_HANDLER, new IgnoreProxyPolicyHandler ()); int requestid = rftPort.start (); System.out.println ("Request id: " + requestid); } catch (Exception e) { System.err.println (MessageUtils.toString (e)); } package org.globus.ogsa.gui; import java.io.BufferedReader; import java.io.File; import java.io.FileReader; import java.net.URL; import java.util.Date; import java.util.Vector; import javax.xml.rpc.Stub; import org.apache.axis.message.MessageElement; import org.apache.axis.utils.XMLUtils; import org.globus.* import org.gridforum.ogsi.* import org.gridforum.ogsi.holders.TerminationTimeTypeHolder; import org.w3c.dom.Document; import org.w3c.dom.Element; public class RFTClient { public static void copy (String source_url, String target_url) { try { File requestFile = new File (source_url); BufferedReader reader = null; try { reader = new BufferedReader (new FileReader (requestFile)); } catch (java.io.FileNotFoundException fnfe) { } Vector requestData = new Vector (); requestData.add (target_url); TransferType[] transfers1 = new TransferType[transferCount]; RFTOptionsType multirftOptions = new RFTOptionsType (); multirftOptions.setBinary (Boolean.valueOf ( (String)requestData.elementAt (0)).booleanValue ()); multirftOptions.setBlockSize (Integer.valueOf ( (String)requestData.elementAt (1)).intValue ()); multirftOptions.setTcpBufferSize (Integer.valueOf ( (String)requestData.elementAt (2)).intValue ()); multirftOptions.setNotpt (Boolean.valueOf ( (String)requestData.elementAt (3)).booleanValue ()); multirftOptions.setParallelStreams (Integer.valueOf ( (String)requestData.elementAt (4)).intValue ()); multirftOptions.setDcau(Boolean.valueOf( (String)requestData.elementAt (5)).booleanValue ()); int i = 7; for (int j = 0; j < transfers1.length; j++) { transfers1[j] = new TransferType (); transfers1[j].setTransferId (j); transfers1[j].setSourceUrl ((String)requestData.elementAt (i++)); transfers1[j].setDestinationUrl ((String)requestData.elementAt (i++)); transfers1[j].setRftOptions (multirftOptions); }

Hartmut Kaiser COST D23 Tutorial on Grid Computing 24th/25th October 2004, Manno, 6 Copy a File: GAT/C #include GATResult RemoteFile_GetFile (GATContext context, char const* source_url, char const* target_url) { GATStatus status = 0; GATLocation source = GATLocation_Create (source_url); GATLocation target = GATLocation_Create (target_url); GATFile file = GATFile_Create (context, source, 0); if (source == 0 || target == 0 || file == 0) { return GAT_MEMORYFAILURE; } if ( GATFile_Copy (file, target, GATFileMode_Overwrite) != GAT_SUCCESS ) { GATContext_GetCurrentStatus (context, &status); return GATStatus_GetStatusCode (status); } GATFile_Destroy (&file); GATLocation_Destroy (&target); GATLocation_Destroy (&source); return GATStatus_GetStatusCode (status); }

Hartmut Kaiser COST D23 Tutorial on Grid Computing 24th/25th October 2004, Manno, 7 Copy a File: GAT/Python import GAT def copyfile(context, source_url, target_url): try: file = GAT.File(context, GAT.Location(source_url)) file.Copy(GAT.Location(target_url)) return GAT.SUCCESS except GAT.Status, err: print err.args[0].message print err.args[0].traceback return err.args[0].errcode

Hartmut Kaiser COST D23 Tutorial on Grid Computing 24th/25th October 2004, Manno, 8 Copy a File: GAT/C++ #include GAT::Result RemoteFile::GetFile (GAT::Context context, std::string source_url, std::string target_url) { try { GAT::File file (context, source_url); file.Copy (target_url); } catch (GAT::Exception const &e) { std::cerr << "Some error: " << e.what() << std::endl; return e.Result(); } return GAT_SUCCESS; }

Hartmut Kaiser COST D23 Tutorial on Grid Computing 24th/25th October 2004, Manno, 9 Copy a File: GAT/C++ #include GAT::Result RemoteFile::GetFile (GAT::Context context, std::string source_url, std::string target_url) { try { GAT::File file (context, source_url); file.Copy (target_url); } catch (GAT::Exception const &e) { std::cerr << e.what() << std::endl; return e.Result(); } return GAT_SUCCESS; }

Hartmut Kaiser COST D23 Tutorial on Grid Computing 24th/25th October 2004, Manno, 10 Code Statistics Language Cleanup 1130 Action 2530 Init Lines total C++ GAT C GATCoGGASSCode

Hartmut Kaiser COST D23 Tutorial on Grid Computing 24th/25th October 2004, Manno, 11 Dynamic Middleware Globus, Unicore, my_service, your_service,... The same functionality has different interfaces all over the place. But you don't want to recompile your app every time, not to speak of recoding... WSDL does not mean end of all problems (see CoG code), but begin of new ones... - on application level, WSDL is not trivial enough Restricting yourself to Globus does not help either: version changes every couple of months (2.4.x, 3.2.y, 4.a.b) and gets bug fixes. Changes often are MAJOR - we have seen a number of them over the last couple of years... The application that runs today will fail tomorrow! Right now, it is basically impossible for a programmer to focus on the science, not on IT (i.e. Grid) problems.

Hartmut Kaiser COST D23 Tutorial on Grid Computing 24th/25th October 2004, Manno, 12 Dynamic Grids Services (and interfaces) get exchanged (“upgraded”) on regular basis That is related to the point above, but also a social problem! Institutions (resources, services, applications) join/leave YOUR grid without (much) notice. The grid is designed to ease and simplify that kind of fluctuation - its not a bug, its a feature! But the applications are not able to make use of that feature right now … The Grid changes AT RUNTIME – services go down, resources get busy/free, disks and storage nodes are empty/full,... THINGS CONSTANTLY CHANGE. Today Grid middleware allows to cope with that, but utilizing that in an intelligent way is a major programming effort, and blows the application with code that needs constant maintenance... Applications need LOTS of code for handling transient problems. Most applications share most of these problems, but code reuse is difficult/impossible. We can reuse the Globus libraries, right, but isn't every project re-inventing its own abstraction layer for these? In our experience/projects: they do! Aren’t we all re-inventing abstraction layers for this?

Hartmut Kaiser COST D23 Tutorial on Grid Computing 24th/25th October 2004, Manno, 13 Simplicity! The key objective for application programmers Remember: an applications programmer is a physicist, chemist, linguist, medical Simple API’s should: be easy to use Simple, finite, consistent API which allows error tracing be invariant: make upgrades really, really simple Well defined API which rarely changes. Implementation which allows dynamic exchange of key elements and provides runtime abstractions. avoid refactoring/recoding/recompilation Same applications runs today and tomorrow; here and there; on Globus and Unicore; on Globus and Globus 2.4; on Linux and on Mac; local and on grid; focus on well-known programming paradigms (e.g., for a file provide a file API – without services to services to files...) Files are best example: expect open, close, read, write, seek. Do not introduce fancy things like the need to ask a service discovery service to tell me the location of an service which is able to tell me the location of my file...

Hartmut Kaiser COST D23 Tutorial on Grid Computing 24th/25th October 2004, Manno, 14 What Applications want...and what they GAT: Enough of 'we want this' and 'we don’t want that' - you got the picture, right? So, here is what we do: An API that allows to implement basic Grid use cases Stay simple! As simple as possible! But not simpler! Focus on applications, and scientists, rather than Grid nerds As you and me Next slides will give an overview of what we think is essential, and how we envision usage of that. Remind: this is version 1 - our first shot - we know its not perfect, but we are converging to something we can work with already.

Hartmut Kaiser COST D23 Tutorial on Grid Computing 24th/25th October 2004, Manno, 15 GAT API Scope Files Monitoring and Events Resources, Jobs Information Exchange Utility classes (error handling, security, preferences...) NOTHING ELSE

Hartmut Kaiser COST D23 Tutorial on Grid Computing 24th/25th October 2004, Manno, 16 API: Sub Systems The pipe stuff in the file subsystem is 'historical‘, pipe is VERY simple - we don't do real communication and data exchange a la MPI! The actual API is somewhat larger (especially the resource part): 34 objects as opposed to 27 shown here. BUT THAT’S IT!!!

Hartmut Kaiser COST D23 Tutorial on Grid Computing 24th/25th October 2004, Manno, 17 Examples in GAT Read remote physical file Read a logical file Spawn a Subtask Migrate a Subtask

Hartmut Kaiser COST D23 Tutorial on Grid Computing 24th/25th October 2004, Manno, 18 Read a remote physical File try { char data[25]; GAT::FileStream file (context, source_url); file.seek (100, SEEK_SET); file.read (data, sizeof(data)); } catch (GAT::Exception const &e) { std::cerr << "Some error: " << e.what() << std::endl; return e.Result(); } Well known paradigm. Whatever service/lib/... implements that, the programmer does not know (no reference to Globus... ) Whatever the URL/protocol (ftp://, gsiftp://, file://) no code changes! No service specific parameter settings (can be drawback BUT SIMPLIFIES)

Hartmut Kaiser COST D23 Tutorial on Grid Computing 24th/25th October 2004, Manno, 19 Read a logical file try { GAT::LogicalFile logical_file (context, name); std::list files = logical_file.get_files(); files.front().Copy(dest_url); } catch (GAT::Exception const &e) { std::cerr << "Some error: " << e.what() << std::endl; return e.Result(); } SAME paradigm + 'private name space‘ URL Unknown! Service unknown! complete abstraction ==> Virtualization! Still simple

Hartmut Kaiser COST D23 Tutorial on Grid Computing 24th/25th October 2004, Manno, 20 Spawn a Subtask GAT::Table sdt; sdt.add ("location", "/bin/date"); GAT::Table hdt; hdt.add ("machine.type", "i686"); GAT::SoftwareDescription sd (sdt); GAT::HardwareResourceDescription hrd (hdt); GAT::JobDescription jd (context, sd, hrd); GAT::ResourceBroker rb (context, prefs); GAT::Job j = rb.submit (jd);

Hartmut Kaiser COST D23 Tutorial on Grid Computing 24th/25th October 2004, Manno, 21 Migrate a Subtask GAT::Table sdt; sdt.add ("location", "/bin/sleep"); sdt.add ("arguments", "36000"); GAT::Table hdt; hdt.add ("machine.type", "i386"); GAT::SoftwareDescription sd (sdt); GAT::HardwareResourceDescription hrd (hdt); GAT::JobDescription jd (context, sd, hrd); GAT::ResourceBroker rb (context, prefs); GAT::Job job = rb.submit (jd); hdt.add ("machine.name", "fs0.das2.cs.vu.nl"); std::list resources = rb.find_resources (hrd); job.Migrate (resources[0]); if (GATJobState_Running == job.GetState ()) job.Stop ();

Hartmut Kaiser COST D23 Tutorial on Grid Computing 24th/25th October 2004, Manno, 22 API Status Version: 1.1 – currently converging towards 1.2 Is object oriented, but language neutral Defines syntax and semantics of GRID access Specification is open process Hopefully gets input from many communities Will evolve along with the findings of GGF’s new SAGA-WG (Simple APIs for Grid Applications)

Hartmut Kaiser COST D23 Tutorial on Grid Computing 24th/25th October 2004, Manno, 23 Architecture API is a very thin layer, provides no capabilities by itself (bind to the Grid-Environment) Adaptors implement capabilities mirroring the API Engine mediates between API and adaptors: switch adaptors at runtime (shared libraries) error tracing and fallback mechanisms (default local adaptor set) CPI is also well defined - adaptors are interchangeable

Hartmut Kaiser COST D23 Tutorial on Grid Computing 24th/25th October 2004, Manno, 24 Architecture

Hartmut Kaiser COST D23 Tutorial on Grid Computing 24th/25th October 2004, Manno, 25 Implementation (Engine) C version fully implemented C++ wrapper to C fully implemented Python wrapper to C fully implemented Java version fully implemented Fortran, Perl (wrappers to C) to follow (SWIG?) Focus: portability, lightness, flexibility, adaptivity

Hartmut Kaiser COST D23 Tutorial on Grid Computing 24th/25th October 2004, Manno, 26 Implementation (Adaptors) Full set of local adaptors implemented (contained in the download) Couple of ‘external’ adaptors implemented as well (GridLab services, Globus) Lot of adaptors currently under development (DRMAA, GRAM, Curl/wget etc.)

Hartmut Kaiser COST D23 Tutorial on Grid Computing 24th/25th October 2004, Manno, 27 File Management: Outline File Package Overview The GATFile class Code Example Exercise

Hartmut Kaiser COST D23 Tutorial on Grid Computing 24th/25th October 2004, Manno, 28 File Package Overview File Management The File Package allows application programmers to manipulate Files in a “Grid” environment. …and contains a single class!

Hartmut Kaiser COST D23 Tutorial on Grid Computing 24th/25th October 2004, Manno, 29 File Management File Package The GATFile class copies, moves, deletes, examines …files

Hartmut Kaiser COST D23 Tutorial on Grid Computing 24th/25th October 2004, Manno, 30 File Management Code sample …/GATEngine/C-Reference/examples/ example_03_-_file_size.c Examine the code Exercise Modify example_03_-_file_size.c to delete a file instead of getting its length GATResult GATFile_Delete(GATFile_const file);

Hartmut Kaiser COST D23 Tutorial on Grid Computing 24th/25th October 2004, Manno, 31 FileStream Management: Outline FileStream Package Overview GATFileStream class Code Example Exercise

Hartmut Kaiser COST D23 Tutorial on Grid Computing 24th/25th October 2004, Manno, 32 FileStream Management Stream Package Overview The Stream Package allows Application programmers to stream data to and from remote or local processes and to stream data to and from remote or local files. … and consists of various classes and interfaces.

Hartmut Kaiser COST D23 Tutorial on Grid Computing 24th/25th October 2004, Manno, 33 FileStream Management FileStream Package Overview We’ll cover only GATFileStream.

Hartmut Kaiser COST D23 Tutorial on Grid Computing 24th/25th October 2004, Manno, 34 FileStream Management Stream Package GATFileStream class streams data to/from a file

Hartmut Kaiser COST D23 Tutorial on Grid Computing 24th/25th October 2004, Manno, 35 FileStream Management Code sample …/GATEngine/C-Reference/examples/ example_20_-_filestream_simple.c Examine the code Exercise Modify example_20_-_filestream_simple.c to write your name, say, to file. GATResult GATFileStream_Write(GATFileStream stream, void const *buffer, GATuint32 buffersize, GATuint32 *written_bytes);

Hartmut Kaiser COST D23 Tutorial on Grid Computing 24th/25th October 2004, Manno, 36 LogicalFile Management: Outline LogicalFile Package Overview GATLogicalFile class Code Example

Hartmut Kaiser COST D23 Tutorial on Grid Computing 24th/25th October 2004, Manno, 37 LogicalFile Management LogicalFile Package Overview The LogicalFile Package exists to replicate files which are identical, but dispersed geographically in an efficient manner. …and consists of a single class!

Hartmut Kaiser COST D23 Tutorial on Grid Computing 24th/25th October 2004, Manno, 38 LogicalFile Management LogicalFile Package GATLogicalFile class replicates files in a “Grid” environment

Hartmut Kaiser COST D23 Tutorial on Grid Computing 24th/25th October 2004, Manno, 39 LogicalFile Management Code sample …/GATEngine/C-Reference/examples/ example_31_-_logicalfile_ops.c Examine the code

Hartmut Kaiser COST D23 Tutorial on Grid Computing 24th/25th October 2004, Manno, 40 Advert Management Advert Package Overview GATInterface_IAdvertisable GATAdvertService class Code Example

Hartmut Kaiser COST D23 Tutorial on Grid Computing 24th/25th October 2004, Manno, 41 Advert Management Advert Package Overview The Advert Package allows an application to persistently store objects (advertisables), query such stored advertisables, and move them across machine and language boundaries. … and consists of only one class and one interface.

Hartmut Kaiser COST D23 Tutorial on Grid Computing 24th/25th October 2004, Manno, 42 Advert Management Advert Package GATInterface_IAdvertisable The interface GATInterface_IAdvertisable marks objects capable of being persisted in a GATAdvertService, it’s similar to Java’s serilizable.

Hartmut Kaiser COST D23 Tutorial on Grid Computing 24th/25th October 2004, Manno, 43 Advert Management Advert Package GATAdvertService - Stores advertisables and allows one to query for these advertisables across machine boundaries.

Hartmut Kaiser COST D23 Tutorial on Grid Computing 24th/25th October 2004, Manno, 44 Advert Management Code sample …/GATEngine/C-Reference/examples/ example_31_-_advertservice_ops.c Examine the code

Hartmut Kaiser COST D23 Tutorial on Grid Computing 24th/25th October 2004, Manno, 45 Job Management: Outline Job Package Overview GATResourceDescription’s GATResource’s GATResourceBroker GATSoftwareDescription GATJobDescription GATJob Code Example

Hartmut Kaiser COST D23 Tutorial on Grid Computing 24th/25th October 2004, Manno, 46 Job Management Job Package Overview The Job Package allows an application to obtain resource, reserve resources, and submit and manage jobs. …and consists of many classes and interfaces.

Hartmut Kaiser COST D23 Tutorial on Grid Computing 24th/25th October 2004, Manno, 47 Job Management Job Package GATResourceDescriptions A GATHardwareResourceDescription describes a hardware resource, such as a i686 box with 1GB of memory. A GATSoftwareResourceDescription describes a software resource, such as an OS.

Hartmut Kaiser COST D23 Tutorial on Grid Computing 24th/25th October 2004, Manno, 48 Job Management Job Package: GATResources A GATHardwareResource represents a hardware resource, such as a i686 box with 1GB of memory. A GATSoftwareResource represents a software resource, such as a running OS.

Hartmut Kaiser COST D23 Tutorial on Grid Computing 24th/25th October 2004, Manno, 49 Job Management Job Package GATResourceBroker A GATResourceBroker instance is able to broker resources, it can find or reserve resources; also, it can submit jobs to such resources.

Hartmut Kaiser COST D23 Tutorial on Grid Computing 24th/25th October 2004, Manno, 50 Job Management Job Package GATSoftwareDescription A GATSoftwareDescription instance describes an executable, for example /bin/date

Hartmut Kaiser COST D23 Tutorial on Grid Computing 24th/25th October 2004, Manno, 51 Job Management Job Package GATJobDescription A GATJobDescription instance describes a job which can be executed. It includes a description of the hardware and software for the job.

Hartmut Kaiser COST D23 Tutorial on Grid Computing 24th/25th October 2004, Manno, 52 Job Management Job Package GATJob A GATJob represents a job that has been submitted to a resource management system.

Hartmut Kaiser COST D23 Tutorial on Grid Computing 24th/25th October 2004, Manno, 53 Job Management Code sample …/GATEngine/C-Reference/examples/ example_60_-_job_submit.c Examine the code example_60_-_job_submit /bin/date

Hartmut Kaiser COST D23 Tutorial on Grid Computing 24th/25th October 2004, Manno, 54 Utility Classes Additional utility classes GATList, GATTable etc. Data structures, specifc to language binding GATSecurityContext Security related operations GATStatus Error handling

Hartmut Kaiser COST D23 Tutorial on Grid Computing 24th/25th October 2004, Manno, 55 Open problems Memory management is very tedious User has to do a lot by himself Track all GAT object instance copies Free all GAT object instances Call constructor and destructor Error handling is complicated (even with macros) Always check for error codes, cluttered code. All of these problems are solved by the C++ and Python wrappers Asynchronicity is (almost) completely missing Engine is not thread safe as of today (C-implementation)

Hartmut Kaiser COST D23 Tutorial on Grid Computing 24th/25th October 2004, Manno, 56 Current activities SAGA (Simple API for Grid Applications) draft will be presented at the next GGF GAT and the Globus-CoG will be used as inputs to the work of SAGA-RG Application/Vendor interest increasing (EGEE, Vienna Uni, CUT, KISTI, LSU, Intel, HP, Platform...) Merge of the Java-GAT and Globus-CoG planned Adaptor writing has been accepted in community

Hartmut Kaiser COST D23 Tutorial on Grid Computing 24th/25th October 2004, Manno, 57 Conclusions The GAT provides a simple and stable API to various Grid environments It is used as a prototype implementation for the ongoing standardization process at the SAGA WG of the GGF Downloads: Currently, snapshots available for GAT V1.1 GAT 1.2, available in early December 2004 Platforms: Linux, Windows, Mac OS X, SGI Irix, True64 UNIX Support via mailing list