GCat Service

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Revision as of 19:18, 29 November 2018 by Luca.frosini (Talk | contribs) (→‎HTTP Statuses)

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The gCube Science Catalogue Service is a RESTful web service based on the principles defined in gCube Catalogue

Request

URL

The URL used to interact with the Science Catalogue Service is composed of two parts:

  • Base Service URL (e.g. https:/catalogue.d4science.org/science-catalogue)
  • Specific API (e.g. /organizations)

D4Science infrastructure uses cloud facilities allowing to replicate a service to achieve failover and load balancing.

Science Catalogue Service instances can be deployed and undeployed dynamically. For such a reason the Base Service URL MUST NOT be hard-cabled in the code because it can change over time.

To dynamically discover the Base Service URL please use the information system.

You need to discover gCore Resource having:

  • class : DataCatalogue
  • name : science-catalogue

HTTP Headers

gCube Authorization Token

Any request performed to Science Catalogue MUST contains the gCube Authorization Token.

This is done using the HTTP Header gcube-token 

gcube-token: YOUR-TOKEN

The gcube-token HTTP header acts as the standard Authorization HTTP header. Plese note that Authorization HTTP header cannot be used in place of gcube-token HTTP header.

Retrieve your gCube Authorization Token

the gCube Authorization Token is a UUID bound to yourself and a given Infrastructure context. To retrieve it, you just need to go to a VRE for which you are interested and use the Authorisation Options portlet (see below)

Authorisation option.png

Click on Show button and select the token.

Content Type

Any request must contain the indication of the interested content type.

For any operation returning a result, the client must specify the Accept HTTP Header. 

Accept: application/json

For any operation sending content to the service, it is necessary to specify the Content-Type HTTP Header. 

Content-Type: application/json

Actually, the service accepts and returns only JSON objects.

Except for a profile which can be also requested in XML.

HTTP Statuses

Any successful operation returns 200 OK status code except for create operation which return 201 Created.

The most common error status a client can obtain are

The response contains the Allow HTTP Header indicating the supported HTTP method for such URL https://tools.ietf.org/html/rfc7231#section-7.4.1;

A complete list of HTTP Status can be found here: https://httpstatuses.com/

You can report a 500 Internal Server Error the ticketing system. Please use this checklist before reporting an error:

  • replicate the request
  • the failure could be temporal due to network error, server issue so please retry the request after a certain amount of time
  • indicate how to replicate the error
  • indicate the time when the error occurred (this simplify the identification of the issue)

HTTP Methods

To be RESTful compliant Science Catalogue uses standard HTTP Methods to perform a listing of collections and CRUD (Create Read Update Delete) operations on instances.


Operation HTTP Method URL Success HTTP Status
Supported Methods OPTIONS /{COLLECTION} 200 OK
(Supported HTTP Methods in Allow HTTP Header)
List GET /{COLLECTION} 200 OK
Create POST /{COLLECTION} 201 Created
Supported Methods OPTIONS /{COLLECTION}/{INSTANCE_ID} 200 OK
(Supported HTTP Methods in Allow HTTP Header)
Read GET /{COLLECTION}/{INSTANCE_ID} 200 OK
Update PUT /{COLLECTION}/{INSTANCE_ID} 200 OK
Patch PATCH /{COLLECTION}/{INSTANCE_ID} 200 OK
Delete DELETE /{COLLECTION}/{INSTANCE_ID} 200 OK
Purge PURGE /{COLLECTION}/{INSTANCE_ID} 200 OK
Purge DELETE /{COLLECTION}/{INSTANCE_ID}?purge=true 200 OK


Where:

  • {COLLECTION} is the plural name of the entity type
  • {INSTANCE_ID} is an identification which enables to univocally identify the instance in the collection

You can find more information about this at https://restfulapi.net/http-methods/


PURGE Method is not a standard HTTP Method but is a widely used in service which requires this action (e.g. Varnish, Squid)


The Science Catalogue provide support for this method but to support a wider range of clients it also provides the Purge action via DELETE with the additional get parameter 
purge=true

Collections

Group Collection

Operation HTTP Method URL
List GET /groups
Create POST /groups
Read GET /groups/{NAME}
Update PUT /groups/{NAME}
Patch PATCH /groups/{NAME}
Delete DELETE /groups/{NAME}
Purge PURGE /groups/{NAME}
Purge DELETE /groups/{NAME}?purge=true

Item Collection

Operation HTTP Method URL
List GET /items
Create POST /items
Read GET /items/{NAME}
Update PUT /items/{NAME}
Delete DELETE /items/{NAME}
Purge PURGE /items/{NAME}
Purge DELETE /items/{NAME}?purge=true

Resource Collection

Operation HTTP Method URL
List GET /items/{NAME}/resources
Create POST /items/{NAME}/resources
Read GET /items/{NAME}/resources/{ID}
Update PUT /items/{NAME}/resources/{ID}
Delete DELETE /items/{NAME}/resources/{ID}

License Collection

Operation HTTP Method URL
List GET /licenses

Organization Collection

Operation HTTP Method URL
List GET /organizations
Create POST /organizations
Read GET /organizations/{NAME}
Update PUT /organizations/{NAME}
Patch PATCH /organizations/{NAME}
Delete DELETE /organizations/{NAME}
Purge PURGE /organizations/{NAME}
Purge DELETE /organizations/{NAME}?purge=true

User Collection

Operation HTTP Method URL
List GET /users
Create POST /users
Read GET /users/{NAME}
Update PUT /users/{NAME}
Delete DELETE /users/{NAME}

Profile Collection

Operation HTTP Method URL
List GET /profiles
Read GET /profiles/{NAME}

A profile is defined using XML. It is possible to get the original XML definition using 'Accept' HTTP Header. 

Accept : application/xml

instead of 

Accept : application/json

Namespace Collection

Operation HTTP Method URL
List GET /namespaces
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