irods_testbench_training_python_bash/client_metadata_example

Example client side iRODS rule to show metadata operations

• The rule requires the local host be connected/authenticated to iRODS server with the appropriate ~/.irods directory and contained connection profile
• The rule does not require any input
• The rule is written in the iRODS native rule engine language
• The rule is intended to be run client side only, most functions and microservices will work in server side rules, some will not
• The rule intends to assist users with common metadata manipulation tasks
• To augment existing workflow scripts, the user could call their custom metadata rule passing an iRODS data-object as INPUT

Run the rule

• remove the data-object generated from iRODS rule irm test.txt
• clear the trash to ensure there is no history of the data-object irmtrash
• run the rule, pass -t for test mode,-F for file (data-object), specify the rule engine with -r (this is only required if multiple rule engines are present on the server - such as the python rule engine) irule -r irods_rule_engine_plugin-irods_rule_language-instance -F ~/test-meta.r
• check test.txt now exists ils test.txt
• check metadata of test.txt, -d for file (data-object) imeta ls -d test.txt
• the rule output should resemble

a = 10
zebra = horse
hula = dance
art = crayon
timestamp = 2021-06-30.12:09:54
a || 10
zebra || horse
hula || dance
art || crayon
timestamp || 2021-06-30.12:09:54
a
zebra
hula
art
timestamp
1: a = 10
1: zebra = horse
1: hula = dance
1: art = crayon
1: timestamp = 2021-06-30.12:09:54
2: a = 5
2: zebra = horse
2: no match
2: no match
2: timestamp = 2021-06-30.12:09:54
3: AND a = 10
3: zebra = horse
3: art = crayon
3: timestamp = 2021-06-30.12:09:54
4: collection exists: /OCF/home/rods true
4: file created: /OCF/home/rods/test.txt
4: metadata to keep on /OCF/home/rods/test.txt, a=10
4: metadata to keep on /OCF/home/rods/test.txt, art=crayon
4: metadata to remove from /OCF/home/rods/test.txt, hula=dance
4: metadata to remove from /OCF/home/rods/test.txt, timestamp=2021-06-30.12:09:54
4: metadata to remove from /OCF/home/rods/test.txt, zebra=horse
4: year: 2021
4: file: test.txt created between 2020 - 2030
5: writeoff: catC saab £1200

What does the script do?

• creates a metadata array like object from a delimited string of key value pairs
• adds key value pairs to the metadata object
• finds values from keys and keys from values
• example of conditional behaviour based upon key value match
• tests for existence of file in iRODS
• add/remove metadata conditionally where file (data-object) iRODS exists
• creates a file (data-object) in iRODS with simple string content, the file did not pre-exist on a local filesystem
• convert metadata object to metadata structure and apply to iRODS file (data-object)
• use inbuilt function to list iRODS path (collection) and iRODS file (data-object) from a full iRODS path (ZONE + collection + data-object)
• perform SQL like query against the iCAT database to find a file (data-object) with specific keys or values, output specific metadata keys to metadata structure from query result
• loop metadata structure conditionally and remove unwanted key value pair
• remove key value pair without looping using more recent inbuilt function
• use inbuilt function to get and format date/time, use inbuilt split function to create year/month/day key value pairs
• accociate metadata structure directly to an iRODS file (data-object)
• perform SQL like query against the iCAT database to find a file (data-object) with a key value between a range of values
• illustrate usage of the new microservice msiModAVUMetadata to perform all metadata operations that previously required many intermediatory steps
• car lot example, use existing metadata to decide if a car is to sell or writeoff, the new unit attribute of a key value pair is used more granular metadata evaluation