GOCDB/PI/Technical Documentation

GOCDB Programmatic Interface

Important information about using the GOCDBPI

Releases, changes and announcements

All client tool using GOCDB should register someone to the GOCDB discussion mailing list: gocdb-discuss_at_mailtalk.ac.uk. Releases, new features, changes in methods and general announcements related to this interface are made on this list.

If your application is using the GOCDB Programmatic interface please request to join this mailing list by sending us a mail to gocdb-admins@mailtalk.ac.uk.

Interface description

Interface type

GOCDB Programmatic Interface is a REST (Representational State Transfer) based interface over https. The use of https guarantees URLs are properly secured when transiting. Some of the methods are nonetheless public and don't require client side authentication (see #Data protection and access).

Entry point

Enter GOCDB here https://goc.gridops.org/ or directly at https://goc.gridops.org/portal/ to browse the global EGI information or at https://gocdb4.esc.rl.ac.uk/portal to update information.

Entry point for every single method is given on method definition pages listed below.

Outputs

Output format is XML. Calling any implemented method will return you a valid DOM document that can be parsed by any tool on client side.

Schemas

The associated XML schema for each method is available by calling the method with "&output=xmlschema", e.g. https://goc.gridops.org/gocdbpi/private/?method=get_site&output=xmlschema

Data protection and access

Protection levels

There are currently 3 protection levels for all methods of the interface

• Level 1: public methods (no critical information, no mail, no personal details)
• Level 2: protected methods (contain mails or personal details)
• Level 3: private methods (contains security or critical information)

Methods at level 1 are available without restrictions. Level 2 requires client to present a valid recognized X509 certificate (reference CA list is the officially agreed EGEE/LCG EUGridPMA list). Level 3 requires client to present a known, registered certificate (certificate DN needs to be stored on GOCDB side for authentication)

How to gain access?

If you need to access protected methods, a valid certificate will be enough. If you need to access private methods, please send a mail to gocdb-admins@mailtalk.ac.uk, indicating:

• Your name and affiliation
• The name and purpose of the tool that need to access the data
• certificate DN of the machine(s) that will retrieve the information
• An e-mail contact for your application, that will be subscribed to the GOCDB-discussion and announcement mailing list if it is not already there.

Available methods

Method name	type	description	Protection level
get_site	read - generic	Returns site information including contacts, grouped by site	2
get_site_list	read - generic	Returns a list of sites with minimal associated information	1
get_site_contacts	read - generic	Returns a list of persons (and associated info) having a role at site level, grouped per site	2
get_site_security_info	read - generic	Returns security contact information for sites	3
get_ngi_list	read - generic	Returns a list of NGIs with minimal associated information	1
get_subgrid_list	read - generic	Returns a list of Subgrids (i.e. registered sub-parts of an NGI) with minimal associated information	1
get_ngi_contacts	read - generic	Returns NGI contact details, including NGI contact mail address and list of NGI staff	2
get_egi_contacts	read - generic	Returns a list of contacts for staff that have a role a EGI level	2
get_downtime	read - generic	Returns a list of EGI downtimes for sites and nodes	1
get_node [unsupported]	read - generic	Returns a list of nodes with associated information and affiliation	1
get_service_endpoint	read - generic	Returns a list of service endpoints (single node x single service) and associated information	1
get_service_types	read - generic	Returns a list of valid service types and associated description	1
get_user	read - generic	Returns a user or a list of users with associated details and roles	2
get_downtime_to_broadcast	read - dedicated	Returns the list of downtimes recently declared with notification settings for CIC portal downtime notification service	2

Note about parameters:

• Unless otherwise stated, all parameters are optional. If no parameter is given, all methods will return results with the wider scope possible.
• It is possible to combine parameters, for example: ?method=get_site&country=Italy&certification_status=Certified&production_status=Production

Client code examples

Simple data retrieval using wget

If getting the data locally is what you're after, a simple cron job retrieving data via wget might do the trick.

• Public methods: You do not need any client certificate, so a simple wget instruction should work:

$ wget --no-check-certificate -O result.xml 'https://goc.gridops.org/gocdbpi/public/?method=get_site_list&sitename=RAL-LCG2'

--no-check-certificate option might be needed to avoid server verification. Note also that URL should be encapsulated into single quotes.

• Protected and private methods: Here you will need authentication, which can be done through wget as shown in next example:

$ wget --certificate=cert.pem --private-key=cert.key.pem --private-key-type=PEM --ca-directory=/etc/grid-security/certificates/ -O result.xml 'https://goc.gridops.org/gocdbpi/private/?method=get_site&sitename=RAL-LCG2'

Note that if you don't specify the --ca-directory option, SSL handshake may fail as server cert cannot be checked.

Note: examples are shown using wget-10.2. Some discrepencies are observed between version so check wget help for correct options. Bugs and weird behaviour have also been observed for wget with a version older than 10.

Perl example

Provided by Emir Imamagic, SRCE. This code is used by NCG

The 3 following examples are GOCDB modules in perl which use LWP::UserAgent for accessing PI and XML::DOM for parsing the data. Data is used to fill internal NCG structure.

• Get site list (public method)
• Get service endpoints (public)
• Get site contacts (protected)

Nagios plugin nagios-gocdb-downtime is used for retrieving downtimes and pushing them to Nagios via GridMon::Nagios module:

• nagios-gocdb-downtime

note: Full code is available from EGEE SA1 Source code repository

PHP example

Provided by Guillaume Cessieux, CC-IN2P3. This code is used by ENOC

The following example shows a simple PHP class with methods used to retrieve and parse XML data from GOCDB-PI using PHP curl and simplexml

• ENOC interface to GOCDB

Python example

Provided by Giuseppe Misurelli, CNAF-INFN

The following example is a Python client that queries the GOCDB programmatic interface, retrieves info about downtimes for a top entity region using curl, parses xml output with the xml.dom.minidom module and stores data into a MySQl db.

• Get_downtimes_python_example.tar.gz

New requests and improvements

Requests on GOCDB-PI can take the form of:

• Change request to an existing method
• Request for new generic methods
• Request for tool specific methods

Such requests are logged in GOCDB task tracker in Savannah. To make a new request, please submit an item in our Savannah wish list.