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Define a relationship between two schemas using the Schema Registry API

The ability to understand the relationships between your customers and their interactions with your brand across various channels is an important part of Adobe Experience Platform. Defining these relationships within the structure of your Experience Data Model (XDM) schemas allows you to gain complex insights into your customer data.
While schema relationships can be inferred through the use of the union schema and Real-time Customer Profile, this only applies to schemas that share the same class. To establish a relationship between two schemas belonging to different classes, a dedicated relationship field must be added to a source schema, which references the identity of a destination schema.
This document provides a tutorial for defining a one-to-one relationship between two schemas defined by your organization using the Schema Registry API .

Getting started

This tutorial requires a working understanding of Experience Data Model (XDM) and XDM System. Before beginning this tutorial, please review the following documentation:
  • XDM System in Experience Platform : An overview of XDM and its implementation in Experience Platform.
  • Real-time Customer Profile : Provides a unified, real-time consumer profile based on aggregated data from multiple sources.
  • Sandboxes : Experience Platform provides virtual sandboxes which partition a single Platform instance into separate virtual environments to help develop and evolve digital experience applications.
Before starting this tutorial, please review the developer guide for important information that you need to know in order to successfully make calls to the Schema Registry API. This includes your {TENANT_ID} , the concept of "containers", and the required headers for making requests (with special attention to the Accept header and its possible values).

Define a source and destination schema

It is expected that you have already created the two schemas that will be defined in the relationship. This tutorial creates a relationship between members of an organization's current loyalty program (defined in a "Loyalty Members" schema) and their favorite hotels (defined in a "Hotels" schema).
Schema relationships are represented by a source schema having a field that refers to another field within a destination schema . In the steps that follow, "Loyalty Members" will be the source schema, while "Hotels" will act as the destination schema.
In order to establish a relationship, both schemas must have defined primary identities and be enabled for Real-time Customer Profile. See the section on enabling a schema for use in Profile in the schema creation tutorial if you require guidance on how to configure your schemas accordingly.
In order to define a relationship between two schemas, you must first acquire the $id values for both schemas. If you know the display names ( title ) of the schemas, you can find their $id values by making a GET request to the /tenant/schemas endpoint in the Schema Registry API.
API format
GET /tenant/schemas

Request
curl -X GET \
  https://platform.adobe.io/data/foundation/schemaregistry/tenant/schemas \
  -H 'Authorization: Bearer {ACCESS_TOKEN}' \
  -H 'x-api-key: {API_KEY}' \
  -H 'x-gw-ims-org-id: {IMS_ORG}' \
  -H 'x-sandbox-name: {SANDBOX_NAME}' \
  -H 'Accept: application/vnd.adobe.xed-id+json'

The Accept header application/vnd.adobe.xed-id+json returns only the titles, IDs, and versions of the resulting schemas.
Response
A successful response returns a list of schemas defined by your organization, including their name , $id , meta:altId , and version .
{
    "results": [
        {
            "title": "Newsletter Subscriptions",
            "$id": "https://ns.adobe.com/{TENANT_ID}/schemas/192a66930afad02408429174c311ae73",
            "meta:altId": "_{TENANT_ID}.schemas.192a66930afad02408429174c311ae73",
            "version": "1.2"
        },
        {
            "title": "Loyalty Members",
            "$id": "https://ns.adobe.com/{TENANT_ID}/schemas/2c66c3a4323128d3701289df4468e8a6",
            "meta:altId": "_{TENANT_ID}.schemas.2c66c3a4323128d3701289df4468e8a6",
            "version": "1.5"
        },
        {
            "title": "Hotels",
            "$id": "https://ns.adobe.com/{TENANT_ID}/schemas/d4ad4b8463a67f6755f2aabbeb9e02c7",
            "meta:altId": "_{TENANT_ID}.schemas.d4ad4b8463a67f6755f2aabbeb9e02c7",
            "version": "1.0"
        }
    ],
    "_page": {
        "orderby": "updated",
        "next": null,
        "count": 3
    },
    "_links": {
        "next": null,
        "global_schemas": {
            "href": "https://platform-stage.adobe.io/data/foundation/schemaregistry/global/schemas"
        }
    }
}

Record the $id values of the two schemas you want to define a relationship between. These values will be used in later steps.

Define a reference field for the source schema

Within the Schema Registry, relationship descriptors work similarly to foreign keys in relational database tables: a field in the source schema acts as a reference to the primary identity field of a destination schema. If your source schema does not have a field for this purpose, you may need to create a mixin with the new field and add it to the schema. This new field must have a type value of "string".
Unlike the destination schema, the source schema cannot use its primary identity as a reference field.
In this tutorial, the destination schema "Hotels" contains an email field that serves as the schema's primary identity, and therefore will also act as its reference field. However, the source schema "Loyalty Members" does not have a dedicated field to be used as a reference, and must be given a new mixin that adds a new field to the schema: favoriteHotel .
If your source schema already has a dedicated field that you plan to use as a reference field, you can skip ahead to the step on creating a reference descriptor .

Create a new mixin

In order to add a new field to a schema, it must first be defined in a mixin. You can create a new mixin by making a POST request to the /tenant/mixins endpoint.
API format
POST /tenant/mixins

Request
The following request creates a new mixin that adds a favoriteHotel field under the _{TENANT_ID} namespace of any schema it is added to.
curl -X POST\
  https://platform.adobe.io/data/foundation/schemaregistry/tenant/mixins \
  -H 'Authorization: Bearer {ACCESS_TOKEN}' \
  -H 'x-api-key: {API_KEY}' \
  -H 'x-gw-ims-org-id: {IMS_ORG}' \
  -H 'x-sandbox-name: {SANDBOX_NAME}' \
  -H 'content-type: application/json' \
  -d '{
        "type": "object",
        "title": "Favorite Hotel",
        "meta:intendedToExtend": ["https://ns.adobe.com/xdm/context/profile"],
        "description": "Favorite hotel mixin for the Loyalty Members schema.",
        "definitions": {
            "favoriteHotel": {
              "properties": {
                "_{TENANT_ID}": {
                  "type":"object",
                  "properties": {
                    "favoriteHotel": {
                      "title": "Favorite Hotel",
                      "type": "string",
                      "description": "Favorite hotel for a Loyalty Member."
                    }
                  }
                }
              }
            }
        },
        "allOf": [
            {
              "$ref": "#/definitions/favoriteHotel"
            }
        ]
      }'

Response
A successful response returns the details of the newly created mixin.
{
    "$id": "https://ns.adobe.com/{TENANT_ID}/mixins/3387945212ad76ee59b6d2b964afb220",
    "meta:altId": "_{TENANT_ID}.mixins.3387945212ad76ee59b6d2b964afb220",
    "meta:resourceType": "mixins",
    "version": "1.0",
    "type": "object",
    "title": "Favorite Hotel",
    "meta:intendedToExtend": [
        "https://ns.adobe.com/xdm/context/profile"
    ],
    "description": "Favorite hotel mixin for the Loyalty Members schema.",
    "definitions": {
        "favoriteHotel": {
            "properties": {
                "_{TENANT_ID}": {
                    "type": "object",
                    "properties": {
                        "favoriteHotel": {
                            "title": "Favorite Hotel",
                            "type": "string",
                            "description": "Favorite hotel for a Loyalty Member.",
                            "meta:xdmType": "string"
                        }
                    },
                    "meta:xdmType": "object"
                }
            },
            "type": "object",
            "meta:xdmType": "object"
        }
    },
    "allOf": [
        {
            "$ref": "#/definitions/favoriteHotel"
        }
    ],
    "meta:xdmType": "object",
    "meta:abstract": true,
    "meta:extensible": true,
    "meta:containerId": "tenant",
    "meta:tenantNamespace": "_{TENANT_ID}",
    "meta:registryMetadata": {
        "eTag": "quM2aMPyb2NkkEiZHNCs/MG34E4=",
        "palm:sandboxName": "prod"
    }
}

Property
Description
$id
The read-only, system generated unique identifier of the new mixin. Takes the form of a URI.
Record the $id URI of the mixin, to be used in the next step of adding the mixin to the source schema.

Add the mixin to the source schema

Once you have created a mixin, you can add it to the source schema by making a PATCH request to the /tenant/schemas/{SCHEMA_ID} endpoint.
API format
PATCH /tenant/schemas/{SCHEMA_ID}

Parameter
Description
{SCHEMA_ID}
The URL-encoded $id URI or meta:altId of the source schema.
Request
The following request adds the "Favorite Hotel" mixin to the "Loyalty Members" schema.
curl -X PATCH \
  https://platform.adobe.io/data/foundation/schemaregistry/tenant/schemas/_{TENANT_ID}.schemas.533ca5da28087c44344810891b0f03d9 \
  -H 'Authorization: Bearer {ACCESS_TOKEN}' \
  -H 'Content-Type: application/json' \
  -H 'x-api-key: {API_KEY}' \
  -H 'x-gw-ims-org-id: {IMS_ORG}' \
  -H 'x-sandbox-name: {SANDBOX_NAME}' \
  -d '[
    { 
      "op": "add", 
      "path": "/allOf/-", 
      "value":  {
        "$ref": "https://ns.adobe.com/{TENANT_ID}/mixins/3387945212ad76ee59b6d2b964afb220"
      }
    }
  ]'

Property
Description
op
The PATCH operation to be performed. This request uses the add operation.
path
The path to the schema field where the new resource will be added. When adding mixins to schemas, the value must be "/allOf/-".
value.$ref
The $id of the mixin to be added.
Response
A successful response returns the details of the updated schema, which now includes the $ref value of the added mixin under its allOf array.
{
    "$id": "https://ns.adobe.com/{TENANT_ID}/schemas/2c66c3a4323128d3701289df4468e8a6",
    "meta:altId": "_{TENANT_ID}.schemas.2c66c3a4323128d3701289df4468e8a6",
    "meta:resourceType": "schemas",
    "version": "1.1",
    "type": "object",
    "title": "Loyalty Members",
    "description": "",
    "allOf": [
        {
            "$ref": "https://ns.adobe.com/xdm/context/profile"
        },
        {
            "$ref": "https://ns.adobe.com/xdm/context/profile-person-details"
        },
        {
            "$ref": "https://ns.adobe.com/xdm/context/profile-personal-details"
        },
        {
            "$ref": "https://ns.adobe.com/{TENANT_ID}/mixins/ec16dfa484358f80478b75cde8c430d3"
        },
        {
            "$ref": "https://ns.adobe.com/xdm/context/identitymap"
        },
        {
            "$ref": "https://ns.adobe.com/{TENANT_ID}/mixins/3387945212ad76ee59b6d2b964afb220"
        }
    ],
    "meta:containerId": "tenant",
    "meta:class": "https://ns.adobe.com/xdm/context/profile",
    "meta:abstract": false,
    "meta:extensible": false,
    "meta:tenantNamespace": "_{TENANT_ID}",
    "imsOrg": "{IMS_ORG}",
    "meta:extends": [
        "https://ns.adobe.com/xdm/context/profile",
        "https://ns.adobe.com/xdm/data/record",
        "https://ns.adobe.com/xdm/context/identitymap",
        "https://ns.adobe.com/xdm/common/extensible",
        "https://ns.adobe.com/xdm/common/auditable",
        "https://ns.adobe.com/xdm/context/profile-person-details",
        "https://ns.adobe.com/xdm/context/profile-personal-details",
        "https://ns.adobe.com/{TENANT_ID}/mixins/ec16dfa484358f80478b75cde8c430d3",
        "https://ns.adobe.com/{TENANT_ID}/mixins/61969bc646b66a6230a7e8840f4a4d33"
    ],
    "meta:xdmType": "object",
    "meta:registryMetadata": {
        "repo:createdDate": 1557525483804,
        "repo:lastModifiedDate": 1566419670915,
        "xdm:createdClientId": "{API_KEY}",
        "xdm:lastModifiedClientId": "{CLIENT_ID}",
        "eTag": "ITNzu8BVTO5pw9wfCtTTpk6U4WY="
    }
}

Create a reference identity descriptor

Schema fields must have a reference identity descriptor applied to them if they are being used as a reference from other schemas in a relationship. Since the favoriteHotel field in "Loyalty Members" will refer to the email field in "Hotels", email must be given a reference identity descriptor.
Create a reference descriptor for the destination schema by making a POST request to the /tenant/descriptors endpoint.
API format
POST /tenant/descriptors

Request
The following request creates a reference descriptor for the email field in the destination schema "Hotels".
curl -X POST \
  https://platform.adobe.io/data/foundation/schemaregistry/tenant/descriptors \
  -H 'Authorization: Bearer {ACCESS_TOKEN}' \
  -H 'x-api-key: {API_KEY}' \
  -H 'x-gw-ims-org-id: {IMS_ORG}' \
  -H 'x-sandbox-name: {SANDBOX_NAME}' \
  -H 'Content-Type: application/json' \
  -d '{
    "@type": "xdm:descriptorReferenceIdentity",
    "xdm:sourceSchema": "https://ns.adobe.com/{TENANT_ID}/schemas/d4ad4b8463a67f6755f2aabbeb9e02c7",
    "xdm:sourceVersion": 1,
    "xdm:sourceProperty": "/_{TENANT_ID}/email",
    "xdm:identityNamespace": "Email"
  }'

Parameter
Description
@type
The type of descriptor being defined. For reference descriptors the value must be "xdm:descriptorReferenceIdentity".
xdm:sourceSchema
The $id URL of the destination schema.
xdm:sourceVersion
The version number of the destination schema.
sourceProperty
The path to the destination schema's primary identity field.
xdm:identityNamespace
The identity namespace of the reference field. This must be the same namespace used when defining the field as the schema's primary identity. See the identity namespace overview for more information.
Response
A successful response returns the details of the newly created reference descriptor for the destination schema.
{
    "@type": "xdm:descriptorReferenceIdentity",
    "xdm:sourceSchema": "https://ns.adobe.com/{TENANT_ID}/schemas/d4ad4b8463a67f6755f2aabbeb9e02c7",
    "xdm:sourceVersion": 1,
    "xdm:sourceProperty": "/_{TENANT_ID}/email",
    "xdm:identityNamespace": "Email",
    "meta:containerId": "tenant",
    "@id": "53180e9f86eed731f6bf8bf42af4f59d81949ba6"
}

Create a relationship descriptor

Relationship descriptors establish a one-to-one relationship between a source schema and a destination schema. Once you have defined a reference descriptor for the destination schema, you can create a new relationship descriptor by making a POST request to the /tenant/descriptors endpoint.
API format
POST /tenant/descriptors

Request
The following request creates a new relationship descriptor, with "Loyalty Members" as the source schema and "Legacy Loyalty Members" as the destination schema.
curl -X POST \
  https://platform.adobe.io/data/foundation/schemaregistry/tenant/descriptors \
  -H 'Authorization: Bearer {ACCESS_TOKEN}' \
  -H 'x-api-key: {API_KEY}' \
  -H 'x-gw-ims-org-id: {IMS_ORG}' \
  -H 'x-sandbox-name: {SANDBOX_NAME}' \
  -H 'Content-Type: application/json' \
  -d '{
    "@type": "xdm:descriptorOneToOne",
    "xdm:sourceSchema": "https://ns.adobe.com/{TENANT_ID}/schemas/2c66c3a4323128d3701289df4468e8a6",
    "xdm:sourceVersion": 1,
    "xdm:sourceProperty": "/_{TENANT_ID}/favoriteHotel",
    "xdm:destinationSchema": "https://ns.adobe.com/{TENANT_ID}/schemas/d4ad4b8463a67f6755f2aabbeb9e02c7",
    "xdm:destinationVersion": 1,
    "xdm:destinationProperty": "/_{TENANT_ID}/email"
  }'

Parameter
Description
@type
The type of descriptor to be created. The @type value for relationship descriptors is "xdm:descriptorOneToOne".
xdm:sourceSchema
The $id URL of the source schema.
xdm:sourceVersion
The version number of the source schema.
xdm:sourceProperty
The path to the reference field in the source schema.
xdm:destinationSchema
The $id URL of the destination schema.
xdm:destinationVersion
The version number of the destination schema.
xdm:destinationProperty
The path to the reference field in the destination schema.

Response

A successful response returns the details of the newly created relationship descriptor.
{
    "@type": "xdm:descriptorOneToOne",
    "xdm:sourceSchema": "https://ns.adobe.com/{TENANT_ID}/schemas/2c66c3a4323128d3701289df4468e8a6",
    "xdm:sourceVersion": 1,
    "xdm:sourceProperty": "/_{TENANT_ID}/favoriteHotel",
    "xdm:destinationSchema": "https://ns.adobe.com/{TENANT_ID}/schemas/d4ad4b8463a67f6755f2aabbeb9e02c7",
    "xdm:destinationVersion": 1,
    "xdm:destinationProperty": "/_{TENANT_ID}/hotelId",
    "meta:containerId": "tenant",
    "@id": "76f6cc7105f4eaab7eb4a5e1cb4804cadc741669"
}

Next steps

By following this tutorial, you have successfully created a one-to-one relationship between two schemas. For more information on working with descriptors using the Schema Registry API, see the Schema Registry developer guide . For steps on how to define schema relationships in the UI, see the tutorial on defining schema relationships using the Schema Editor .