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Key-Value Pair Property Bag Extensiblity Mechanism

Introduction

• Original RT request: https://rt.egi.eu/rt/Ticket/Display.html?id=3764
• Sites and Services can be extended so that they can define an optional set of custom key-value pairs (akin to GLUE2 ext mech).
• The 'get_service_endpoint' and 'get_site' PI methods use the ‘extensions’ query parameter to filter sites/services by required key/value pair.
• This is not yet in production and needs a thorough period of testing first.
• Bugs are likely at this stage.
• The extensions parameter only supports basic query syntax (e.g. no nesting of sub-queries and negation).
• It is probable that the query syntax will change before the final version is released.
• The results of the get_site and get_service_endpoint PI queries nest new <EXTENSIONS> elements.

PI Examples

The URL query could be parameterised with a known GET request paramter (e.g. 'extensions') with a LDAP syntax query string for the value, eg: This extensions parameter allows you to supply an LDAP styled query to further filter your site and endpoint results. For example:

?method=get_site&extensions=(VO=Alice)

Will return all sites that define VO with a value of Alice. A wildcard could also be used:

?method=get_site&extensions=(VO=*)

Will return all sites that define VO as a key property with any value. Comma separated lists of values are also supported:

?method=get_service_endpoint&extensions=(CPU_HS01_HOUR=1,2,3,4,5)

This will return any services that define a CPU_HS01_HOUR with a value of 1, 2, 3, 4, or 5. Extensions also supports OR/AND operators. This can be used to search against multiple key values eg:

?method= get_service_endpoint&extensions=(AND(CPU_HS01_HOUR=1)(CPU_HS02_HOUR=2))

This will return services that define both CPU_HS01_HOUR with a value or 1 and CPU_HS02_HOUR with a value of 2. The same query can also be performed with OR:

?method= get_service_endpoint&extensions=(OR(CPU_HS01_HOUR=1)(CPU_HS02_HOUR=2))

This can then be used to find sites or service endpoints that all define the same group of key values:

?method=get_site&extensions=(AND(VO=Alice,Atlas,CMS,LHCB))

The extensions parameter can also be used in conjunction with the existing parameters previously supported:

?method=get_site&extensions=(OR(VO=Alice,Atlas,CMS,LHCB))&scope=EGI&roc=NGI_UK

These are currently in testing and can be viewed on the GocDB test server:

https://gocdb-test.esc.rl.ac.uk/v5_pi/public/?method=get_site&extensions=(VO=*)

https://gocdb-test.esc.rl.ac.uk/v5_pi/public/?method=get_site&extensions=(AND(VO=Alice,LHCB))

https://gocdb-test.esc.rl.ac.uk/v5_pi/public/?method=get_site&extensions=(OR(VO=CMS,LHCB,Atlas,Alice))

https://gocdb-test.esc.rl.ac.uk/v5_pi/public/?method=get_service_endpoint&extensions=(CPU_HS01_HOUR=*)

https://gocdb-test.esc.rl.ac.uk/v5_pi/public/?method=get_service_endpoint&extensions=(OR(CPU_HS01_HOUR=*)(CPU_HS02_HOUR=5))

https://gocdb-test.esc.rl.ac.uk/v5_pi/public/?method=get_service_endpoint&extensions=(AND(CPU_HS01_HOUR=*)(CPU_HS02_HOUR=5))

https://gocdb-test.esc.rl.ac.uk/v5_pi/public/?method=get_service_endpoint&extensions=(CPU_HS01_HOUR=*)&sitename=RAL-LCG2

Note:

• The extent to which the ldap syntax query string would be supported will have to be explored. A simplified version including only exact pattern matches and simple wildcards may cover most use cases.
• The property bags may only be applied to a subset of entities and PI queries.

Sample PI XML Output

<?xml version="1.0" encoding="UTF-8"?>
<results>
	<SITE ID="259" PRIMARY_KEY="458G0" NAME="NGS-HECTOR">
		<PRIMARY_KEY>458G0</PRIMARY_KEY>
		<SHORT_NAME>NGS-HECTOR</SHORT_NAME>
		<OFFICIAL_NAME>HeCTOR, UK National Supercomputing Service
		</OFFICIAL_NAME>
		<SITE_DESCRIPTION>Pending</SITE_DESCRIPTION>
		<GOCDB_PORTAL_URL>
			https://127.0.0.1/DoctrineP/index.php?Page_Type=Siteampid=259
		</GOCDB_PORTAL_URL>
		<HOME_URL>www.hector.ac.uk</HOME_URL>
		<CONTACT_EMAIL>support@hector.ac.uk</CONTACT_EMAIL>
		<CONTACT_TEL>0131-650 5029</CONTACT_TEL>
		<COUNTRY_CODE>GB</COUNTRY_CODE>
		<COUNTRY>United Kingdom</COUNTRY>
		<ROC>NGI_UK</ROC>
		<SUBGRID>NGS</SUBGRID>
		<PRODUCTION_INFRASTRUCTURE>Production</PRODUCTION_INFRASTRUCTURE>
		<CERTIFICATION_STATUS>Uncertified</CERTIFICATION_STATUS>
		<TIMEZONE>UTC</TIMEZONE>
		<CSIRT_EMAIL>helpdesk@hector.ac.uk</CSIRT_EMAIL>
		<DOMAIN>
			<DOMAIN_NAME>hector.ac.uk</DOMAIN_NAME>
		</DOMAIN>
		<EXTENSIONS>
			<EXTENSION>
				<LOCAL_ID>24</LOCAL_ID>
				<KEY>VO</KEY>
				<VALUE>LHCB</VALUE>
			</EXTENSION>
			<EXTENSION>
				<LOCAL_ID>21</LOCAL_ID>
				<KEY>VO</KEY>
				<VALUE>Alice</VALUE>
			</EXTENSION>
			<EXTENSION>
				<LOCAL_ID>22</LOCAL_ID>
				<KEY>VO</KEY>
				<VALUE>Atlas</VALUE>
			</EXTENSION>
			<EXTENSION>
				<LOCAL_ID>23</LOCAL_ID>
				<KEY>VO</KEY>
				<VALUE>CMS</VALUE>
			</EXTENSION>
		</EXTENSIONS>
	</SITE>
</results>

Potential Use Cases

A number of potential use cases have been reported (https://rt.egi.eu/rt/Ticket/Display.html?id=3764), including:

• Specifying service access protocol.
• Defining custom monitoring parameters.
• Defining custom functionality/capability flags supported by a service (this may be related to MPI in EGI requirements, see: https://documents.egi.eu/public/RetrieveFile?docid=1260&version=3&filename=VT-MPI_Report_v3_final.pdf and https://rt.egi.eu/rt/Ticket/Display.html?id=3396).

Issues

There is the potential for proliferation of key-value pairs that should instead be recorded in fields/properties as part of the data model.