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#! /usr/bin/env python
import arc
import sys
import os
def retrieve(uc, endpoints):
# The ComputingServiceRetriever needs the UserConfig to know which credentials
# to use in case of HTTPS connections
retriever = arc.ComputingServiceRetriever(uc, endpoints)
# the constructor of the ComputingServiceRetriever returns immediately
sys.stdout.write('\n')
sys.stdout.write("ComputingServiceRetriever created with the following endpoints:\n")
for endpoint in endpoints:
sys.stdout.write("- %s\n"%endpoint.str())
# here we want to wait until all the results arrive
sys.stdout.write("Waiting for the results...\n")
retriever.wait()
return retriever
def example():
# Creating a UserConfig object with the user's proxy
# and the path of the trusted CA certificates
uc = arc.UserConfig()
uc.ProxyPath("/tmp/x509up_u%s" % os.getuid())
uc.CACertificatesDirectory("/etc/grid-security/certificates")
# Query registriy (index server) for Computing Services
registries = [
arc.Endpoint("nordugrid.org", arc.Endpoint.REGISTRY, "org.nordugrid.archery")
]
retriever = retrieve(uc, registries)
# The retriever acts as a list containing all the discovered ComputingServices:
sys.stdout.write("Discovered ComputingServices: %s\n"%(", ".join([service.Name for service in retriever])))
# Get all the ExecutionTargets on these ComputingServices
targets = retriever.GetExecutionTargets()
sys.stdout.write("Number of ExecutionTargets on these ComputingServices: %d\n"%len(targets))
# Query the local infosys (COMPUTINGINFO) of computing elements
computing_elements = [
# for piff, we specify that we want to query the LDAP GLUE2 tree
arc.Endpoint("piff.hep.lu.se", arc.Endpoint.COMPUTINGINFO, "org.nordugrid.ldapglue2"),
# for pgs03, we don't specify the interface, we let the system try all possibilities
arc.Endpoint("pgs03.grid.upjs.sk", arc.Endpoint.COMPUTINGINFO)
]
retriever2 = retrieve(uc, computing_elements)
# Get all the ExecutionTargets on these ComputingServices
targets2 = retriever2.GetExecutionTargets()
sys.stdout.write("The discovered ExecutionTargets:\n")
for target in targets2:
sys.stdout.write("%s\n"%str(target))
# Query both registries and computing elements at the same time:
endpoints = [
arc.Endpoint("arc-emi.grid.upjs.sk/O=Grid/Mds-Vo-Name=ARC-EMI", arc.Endpoint.REGISTRY),
arc.Endpoint("piff.hep.lu.se", arc.Endpoint.COMPUTINGINFO, "org.nordugrid.ldapglue2")
]
retriever3 = retrieve(uc, endpoints)
sys.stdout.write("Discovered ComputingServices: %s\n"%(", ".join([service.Name for service in retriever3])))
# wait for all the background threads to finish before we destroy the objects they may use
import atexit
@atexit.register
def wait_exit():
arc.ThreadInitializer().waitExit()
# arc.Logger.getRootLogger().addDestination(arc.LogStream(sys.stderr))
# arc.Logger.getRootLogger().setThreshold(arc.DEBUG)
# run the example
example()
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