CX-0120 Short-Term Material Demand Exchange 2.0.0

ABSTRACT

This document defines the standardized exchange of Short-Term Material Demand data within the Catena-X network. With a focus on addressing shortages and enhancing efficiency across supply chains, this standard aims to facilitate the consistent, reliable, and secure transmission of Short-Term Material Demand data among network participants. It serves as a foundational resource for developers, solution providers, and participants in the Catena-X network by offering comprehensive guidance on implementing and adhering to the standardized exchange of Short-Term Material Demand data. The standardization of the customer's Short-Term Material Demand semantics and exchange API enables participants in the supply chain to share information about time-bound Short-Term Material Demand quantities at a customer's site in an interoperable manner. To give additional context and guidance, specific process descriptions with examples are used to convey an understanding of the application.

FOR WHOM IS THE STANDARD DESIGNED

COMPARISON WITH THE PREVIOUS VERSION OF THE STANDARD

Changes:

• integration and usage of digital twins as defined in [CX-0002] Digital Twins in Catena-X
• harmonization of aspect model in accordance with [CX-0126] Industry Core: Part Type
• new specific submodel io.catenax.short_term_material_demand:1.0.0:ShortTermMaterialDemand from io.catenax.material_demand:1.0.0:MaterialDemand
• discontinuation of the proprietary API used in v1.0.0 of this standard
• grammatical, spelling and semantic improvements

New Content:

• added a note on the obligation of standard implementers to make aware that sensitive data is being handled, see [Chapter 2.1.3]

1 INTRODUCTION

In recent years global supply chains have significantly been affected by global crises. Ever-increasing complexity and interdependencies compound this issue. As a result small and medium-sized enterprises as well as large enterprises are exposed to an increased risk of disruptions in their supply chains. To adapt to short-term fluctuations and develop the right countermeasures, it is essential to have sound information about the Short-Term Material Demand of customers.

This document describes and standardizes a common semantic model for the Short-Term Material Demand as well as an associated API to exchange Short-Term Material Demand information between supply chain partners in an interoperable manner. The customer's Short-Term Material Demand is the quantity of a material that a customer requests from a supplier in a time horizon of up to four weeks. It aims to supplement, not to replace or to duplicate, regular and legally binding orders or call-offs between partners and enable customers to provide suppliers with context regarding their demands. It is possible to distinguish in particular between those demands that are critical for the customer's planned production and those that are additional and possibly non-recurring, e.g. for building up safety stocks. Suppliers can use this additional information to better coordinate their own production and demands and to proactively propose solutions in the event of shortages.

Through the adoption of this standard, supply chain partners can efficiently communicate Short-Term Material Demand information, that supports proactive and better-founded decision-making, responsive inventory management, and effective allocation of resources to prevent or mitigate shortages.

1.1 AUDIENCE & SCOPE

This section is non-normative

This standard is relevant for the following roles defined in [CX-OMW]:

• Data Providers willing to provide Short-Term Material Demand data
• Data Consumers interested in requesting and receiving short-term material demand data
• Business Application Providers interested in providing solutions implementing this standard
• Consulting Services Providers interested in supporting companies fulfilling the standard

The scope of this standard is only the Short-Term Material Demand aspect model and API. It describes the exchange of Short-Term Material Demand data through a connector in accordance to [CX-0018].

1.2 CONTEXT AND ARCHITECTURE FIT

The customer's demand is one of the key information a supplier or manufacturer uses to plan his production. The customer order represents this demand towards the supplier or customer. The Short-Term Material Demand is intended to be additional information to evaluate the partners' supply situation. The respective orders or call-offs communicated, are still contractually binding. The actions to take based on the material demand data described in this standard must be aligned between the customer and supplier.

Figure 1 shows the high-level architecture of the Short-Term Material Demand exchange in the Catena-X dataspace and the services that are involved. Both the data consumer and the data provider must be members of the Catena-X network in order to communicate with each other. With the help of the Credential Service and the Identity Access Management (IAM) each participant can authenticate itself, verify the identity of the requesting party and decide whether to authorize the request. The Short-Term Material Demand is provisioned in accordance with [CX-0002].

Figure 1: high-level architecture of the Short-Term Material Demand exchange in the Catena-X

1.3 CONFORMANCE AND PROOF OF CONFORMITY

This section is non-normative

As well as sections marked as non-normative, all authoring guidelines, diagrams, examples, and notes in this specification are non-normative. Everything else in this specification is normative. The key words MAY, MUST, MUST NOT, OPTIONAL, RECOMMENDED, REQUIRED, SHOULD and SHOULD NOT in this document are to be interpreted as described in [BCP 14] [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here. All participants and their solutions will need to prove, that they are conform with the Catena-X standards.

All participants and their solutions will need to prove, that they are conform with the Catena-X standards. To validate that the standards are applied correctly, Catena-X employs Conformity Assessment Bodies (CABs). The proof of conformity for a single semantic model is done according to the general rules for proving the conformity of data provided to a semantic model or the ability to consume the corresponding data. Furthermore, participants agree to follow the normative language of this standardization document and to implement the required API-Endpoints described in Chapter 4.

1.4 EXAMPLES

This section is non-normative

The following example shows a value-only JSON representation of an "Short-Term Material Demand" aspect model. It contains a demand quantity of 180 pieces with a demand category "series" and a demand quantity of 100 pieces with demand category "after-sales" for material with Catena-X ID "urn:uuid:48878d48-6f1d-47f5-8ded-a441d0d879df". Also the customer location varies for the different demand series. This Short-Term Material Demand is the demand that a supplier received from a customer.

{
  "materialGlobalAssetId": "urn:uuid:48878d48-6f1d-47f5-8ded-a441d0d879df",    
  "demandSeries": [
    {
      "lastUpdatedOnDateTime" : "2023-11-05T08:15:30.123-05:00",
      "expectedSupplierLocation": "BPNS8888888888XX",                          
      "demands": [
        {
          "demand": {
            "value": 180,
            "unit" : "unit:piece"
          },
          "day" : "2023-10-09"                       
        }
      ],
      "customerLocation": "BPNS9090909090YY",                                  
      "demandCategory": {
        "demandCategoryCode": "SR99"                                           
      }
    },
    {
      "expectedSupplierLocation": "BPNS8888888888XX",
      "lastUpdatedOnDateTime" : "2023-11-05T08:15:30.123-05:00",
      "demands": [
        {
          "demand": {
            "value": 100,
            "unit" : "unit:piece"
          },
          "day" : "2023-10-09"                       
        }
      ],
      "customerLocation": "BPNS5555555555XX",                                 
      "demandCategory": {
        "demandCategoryCode": "A1S1"                                           
      }
    }
  ]
}

1.5 TERMINOLOGY

This section is non-normative

Name	Abrv.	Description
Business Partner Number	BPN	A BPN is the unique identifier of a partner within Catena-X as defined in [CX-0010].
Business Partner Number Legal Entity	BPNL	A BPNL is the unique identifier of a partner legal entity within Catena-X as defined in [CX-0010].
Business Partner Number Site	BPNS	A BPNS is the unique identifier of a partner site within Catena-X as defined in [CX-0010].
Business Partner Number Address	BPNA	A BPNA is the unique identifier of a partner address within Catena-X as defined in [CX-0010].
Demand		Quantity of a demand for a given time frame. The quantity must be greater than or equal to 0 and less or equal than 999999999999999999.999. It allows up to 12 digits and 3 decimal places.
Demand series		The demands for a dedicated material in a given time period of a given demand rate, distinguished by their demand location and demand category.
Demand category		Classification of demands used for prioritization or allocation.
Order		Request from a customer towards a supplier to manufacture / supply a given quantity of a specific product in a predefined time frame.
Provider		The party providing the Short-Term Material Demand data. This is always the customer.
Consumer		The party requesting and consuming the Short-Term Material Demand data provided by the provider. This is always the Supplier. Additional terminology used in this standard can be looked up in the glossary on the association homepage.
Customer		The recipient of products ordered from / manufactured by a supplier.
Supplier		The supplier / manufacturer of a product.
Stock		Two-way direction of material on stock: - One can have a stock of material which is ready for delivery to customers. - One can have a stock of material which can be used for the own production. Within this document, the term material, product, component or item refers to any kind of product that may be either be used as input or output of the production. Semi-finished goods are not intended to be covered.
Material Number		Unique number of a component or material.
Material		The term material is used as a catalogue item in the meaning of the Industry Core Part Type ([CX-0126]). Whenever referring to material also products, components or items are considered. Semi-finished goods are not intended to be covered.
Digital Twin	DT	Digital representation of an asset that provides data on aspects of the represented data following [CX-0002].
decentralized Digital Twin Registry	dDTR	Component providing registration and discovery API implementations following [CX-0002]. Sometimes referred to without the "decentralized" BUT in Catena-X those are always decentralized.
Asset Administration Shell	AAS	Technical concept for Digital Twins consisting of different standards. Application in Catena-X is described in Digital Twins in Catena-X standard ([CX-0002])
Shell Descriptor		Technical concept of the AAS API describing metadata of an Asset Administration Shell representing a Digital Twin. It holds several identification information and meta-information about which submodels are available and where to get the data from (see [CX-0002], [IDTA-01002-3-0]). There may exist multiple Shell Descriptor for the same represented Asset (see [CX-0126]).
Submodel Descriptor		Technical concept of the AAS API describing metadata of Submodels within a Shell Descriptor (Asset Administration Shell) (see [CX-0002], [IDTA-01002-3-0]).
Specific Asset Ids		Identifiers of the Shell Descriptor (Asset Administration Shell) that refer to common identification data for an asset/material at hand e.g., manufacturer part Id. Common specific asset ids used for identification are described in Industry Core Part Type Standard (see [CX-0126]).
Asset Administration Shell Identifier	AAS ID	Also referred to as Shell Descriptor id, is the technical identifier of the Shell Descriptor.
Global Asset Id		Also referred to as Catena-X Id, is the Catena-X identifier for assets represented by Digital Twins (see [CX-0126]).
Aspect		A domain-specific view on information and functionality associated with a specific Digital Twin with a reference to a concrete Aspect Model (see [CX-0002]). Within Catena-X, an aspect is formally described using the Semantic Aspect Meta Model (see [CX-0003]).
Semantic Id		Identifier including namespace to specify the semantic description of submodels using the Semantic Aspect Meta Model (SAMM). It allows partners to know the exact data format and semantics when e.g., browsing catalogs (see [CX-0003]).
Data Space Protocol	DSP	A set of specifications designed to facilitate interoperable data sharing between entities governed by usage control and based on Web technologies. These specifications define the schemas and protocols required for entities to publish data, negotiate Agreements, and access data as part of a Dataspace. It is governed by the International Data Spaces Association. Connectors compliant to [CX-0018] support the Data Space Protocol.
Shared Asset Approach		Digital twin pattern in which each party has a twin for the same asset (Part Type). They share the same identification data in terms of specific asset IDs and global asset ID. The digital twins do have different technical identifiers.

Table 1: Terminology Short-Term Material Demand Standard

Additional terminology used in this standard can be looked up in the glossary on the association's homepage

2 RELEVANT PARTS OF THE STANDARD FOR SPECIFIC USE CASES

2.1 "SHORT-TERM MATERIAL DEMAND"

2.1.1 LIST OF STANDALONE STANDARDS

The following Catena-X standards are prerequisites for the implementation of this standard and therefore MUST be considered / implemented by the relevant parties specified in each of them.

Number	Standard	Version
[CX-0001]	EDC Discovery API	1.0.2
[CX-0002]	Digital Twins in Catena-X	2.2.0
[CX-0003]	SAMM Aspect Meta Model	1.1.0
[CX-0006]	Registration and initial onboarding	2.0.0
[CX-0010]	Business Partner Number (BPN)	2.0.0
[CX-0018]	Dataspace Connectivity	3.0.0
[CX-0126]	Industry Core Part Type	2.0.0

Table 2: List of mandatory standards

The usage of this standard may be complemented with the following Catena-X standards to further extend the range of shortage prevention possibilities:

Number	Standard	Version
[CX-0118]	Delivery Information Exchange	2.0.0
[CX-0121]	Planned Production Output Exchange	2.0.0
[CX-0122]	Item Stock Exchange	2.0.0
[CX-0145]	Days of Supply Exchange	1.0.0
[CX-0146]	Supply Chain Disruption Notifications	1.0.0

Table 3: List of non-mandatory complementary standards

2.1.2 DATA REQUIRED

No additional data requirements.

2.1.3 ADDITIONAL REQUIREMENTS

CONVENTIONS FOR USE CASE POLICY IN CONTEXT DATA EXCHANGE

In alignment with our commitment to data sovereignty, a specific framework governing the utilization of data within the Catena-X use cases has been outlined. A set of specific policies on data offering and data usage level detail the conditions under which data may be accessed, shared, and used, ensuring compliance with legal standards.

For a comprehensive understanding of the rights, restrictions, and obligations associated with data usage in the Catena-X ecosystem, we refer users to

• the detailed ODRL policy repository [CX-ODRL]. This document provides in-depth explanations of the terms and conditions applied to data access and utilization, ensuring that all engagement with our data is conducted responsibly and in accordance with established guidelines.
• the ODRL schema template. This defines how policies used for data sharing/usage should get defined. Those schemas MUST be followed when providing services or apps for data sharing/consuming.

ADDITIONAL DETAILS REGARDING ACCESS POLICIES

A Data Provider may tie certain access authorizations ("Access Policies") to its data offers for members of Catena-X and one or several Data Consumers. By limiting access to certain Participants, Data Provider maintains control over its anti-trust obligations when sharing certain data. In particular, Data Provider may apply Access Policies to restrict access to a particular data offer for only one Participant identified by a specific business partner number:

• Membership
• BPNL

ADDITIONAL DETAILS REGARDING USAGE POLICIES

In the context of data usage policies (“Usage Policies”), Participants and related services MUST use the following policy rules:

• Use Case Framework (“FrameworkAgreement”)
• at least one use case purpose (“UsagePurpose”) from the above mentioned ODRL policy repository.

Additionally, respective usage policies MAY include the following policy rule:

• Reference Contract (“ContractReference”).

Details on namespaces and ODRL policy rule values to be used for the above-mentioned types are provided via the ODRL policy repository [CX-ODRL].

REMINDER OF ANTITRUST

Notice and/or acknowledgement concepts to raise awareness of antitrust issues during use of this standard are RECOMMENDED, for example through the implementation of a help desk or pop-up info.

2.1.4 DIGITAL TWINS AND SPECIFIC ASSET IDs

This standard builds upon the Industry Core Part Type [CX-0126] and the Digital Twins in Catena-X [CX-0002] standards. It follows the following design patterns:

• Usage of Digital Twins as shared assets to follow a pull approach for data.
• Usage of the specific asset IDs and further identification data for the Digital Twin for the Part Type (see [CX-0126]).
• Provisioning of the PartTypeInformation on supplier side (see [CX-0126]).

Because both parties may provide data regarding different aspects of the same Part Type Twin, they need to use the same identification data to pinpoint it.

• The supplier of the part has a Digital Twin representation and is then able to offer Short-Term Material Demand data to customers.
• The customer, who orders or uses the part, has a Digital Twin representation to offer Short-Term Material Demand data to a supplier.
• Both twins refer to the same asset and provide complementary information. They share the same identification data in two partners' context.
  • The supplier
    • MUST create the Digital Twin first.
    • MUST generate the Catena-X ID and ensure that the customer-specific asset IDs and submodel descriptors are only accessible by the specific customer.
    • MAY use the Digital Twin for multiple customers.
  • The customer
    • MUST create one Digital Twin per supplier.
    • MUST use the Catena-X ID generated by the supplier.

The definition of identification data (Catena-X ID, Asset Administration Shell ID, specific asset ID) MUST follow the Industry Core Part Type [CX-0126]. Refer to Chapter 4.1.2 for further details.

Note: The Part Type Twin's data is considered sensitive. Data providers MUST implement appropriate measures ensuring that competitors-specific asset IDs and/or information about submodels is accessible only to the data consumers it concerns, but not to their competitors.

Figure 2 shows how the shared asset approach is realized. The orange lines show which submodels belong to the respective AAS. All Short-Term Material Demand specific submodels are bound to the specific Part Type's context e.g., meaning that the Short-Term Material Demand aspect is described for the specific catalog item on supplier and customer side represented by the AASs. The orange submodels are the submodels used within this standard's context. The grey submodels are used within the Industry Core [CX-0126](PartTypeInformation, SingleLevelBomAsPlanned, SingleLevelUsageAsPlanned). The blue dashed lines show the references between DTs based on Catena-X UUIDs and BPNL information that may be resolved by the Item Relationship Service (see [CX-0126]).

Figure 2: Conceptual levels of provisioning digital twins in the shared asset approach.

Figure 2 details two conceptual levels:

• The Asset level contains the asset (Industry Core Part Type) represented by a Digital Twin. The latter is provisioned as an Asset Administration Shell (AAS) within the decentralized Digital Twin Registry (dDTR) of the data provider (supplier or customer).
• The Submodel level represents the actual information that are held by a Digital Twin (DT). Those submodels follow the respective definition of the in Semantic Aspect Meta Model (SAMM) format (see Chapter 3). The dDTR only holds metadata about the Submodel (e.g. kind of submodel via semantic ID or connector endpoint information).

3 ASPECT MODELS

This section is normative

3.1 "SHORT-TERM MATERIAL DEMAND" ASPECT MODEL

3.1.1 INTRODUCTION

This section describes the "Short-Term Material Demand" semantic model. It defines the demand of material, product, component or items for a customer. For the complete semantics and detailed description of its properties refer to the SAMM model in Chapter 3.1.5.1.

3.1.2 SPECIFICATIONS ARTIFACTS

The modeling of the semantic model specified in this document was done in accordance to the "semantic-driven workflow" to create a submodel template specification [SMT].

This aspect model is written in SAMM 2.1.0 as a modeling language conformant to [CX-0003] as input for the semantic driven workflow.

Like all Catena-X data models, this model is available in a machine-readable format on GitHub conformant to [CX-0003].

3.1.2.1 SHORT-TERM MATERIAL DEMAND CATEGORY HANDLING

The Material Demand data MUST consider the following demand categories shared with the DCM standard CX-0128. These Demand Categories MAY be used optionally. If no categories are to be used, the value "default" MUST be selected. If different categories apply, it is RECOMMENDED to use them to describe certain use cases such as inventory build-up, logistics optimization or series start-ups. This use case-specific categorization can be an important building block for the supplier to leverage potential in the event of possible bottlenecks or supply gaps. Demand data for demand category "Extraordinary Demand" MAY be set to actively indicate differences between call-offs or orders and the demand derived from the scheduled or planned production.

Demand Category	Description	Demand Category Code (Based on Data Model)
Default	No Assignment	0001
After-Sales	After sales demand of spare parts	A1S1
Series	Dependent demand e.g. production, assembly, raw material	SR99
Phase-In-Period	Ramp up of a new product or new material introduction	PI01
Single-Order	Demand outside the normal spectrum of supply	OS01
Small Series	Short time frame for demand and pose to higher volatility	OI01
Extraordinary Demand	Temporary demand on top of standard demand. Used e.g. in the following scenarios: - logistic optimization (e.g., full use of container) - preventing shortage by building stock (banking) - restocking safety stock	ED01
Phase-Out-Period	Ramp down; Product or material retires from the market	PO01

Table 4: Short-Term Material Demand categories

3.1.3 LICENSE

This Catena-X data model is made available under the terms of the Creative Commons Attribution 4.0 International (CC-BY-4.0) license, which is available at Creative Commons.

3.1.4 IDENTIFIER OF SEMANTIC MODEL

The semantic model has the unique identifier

urn:samm:io.catenax.short_term_material_demand:1.0.0

This identifier MUST be used by the data provider to define the semantics of the data being transferred.

3.1.5 FORMATS OF SEMANTIC MODEL

3.1.5.1 RDF TURTLE

The RDF turtle file, an instance of the Semantic Aspect Meta Model, is the master for generating additional file formats and serializations. It can be found under the following link:

https://github.com/eclipse-tractusx/sldt-semantic-models/blob/main/io.catenax.short_term_material_demand/1.0.0/ShortTermMaterialDemand.ttl

The open source command line tool of the Eclipse Semantic Modeling Framework is used for generation of other file formats like for example a JSON Schema, aasx for Asset Administration Shell Submodel Template or a HTML documentation.

3.1.5.2 JSON SCHEMA

A JSON Schema MUST be generated from the RDF Turtle file. The JSON Schema defines the Value-Only payload of the Asset Administration Shell for the API operation "GetSubmodel".

3.1.5.3 AASX

An AASX file can be generated from the RDF Turtle file. The AASX file defines one of the requested artifacts for a Submodel Template Specification conformant to [SMT].

4 APPLICATION PROGRAMMING INTERFACES

4.1 API USED TO EXCHANGE "SHORT-TERM MATERIAL DEMAND" INFORMATION

As described in Chapter 2.1.4 this standard builds upon the [CX-0002] Digital Twins in Catena-X and [CX-0126] Industry Core Part Type standards. Therefore, the APIs provided by the Digital Twin standard are combined with the part identification defined in the Industry Core standard. This chapter defines how the aforementioned standards and the [CX-0018] standard MUST be used to facilitate the provisioning of Short-Term Material Demand data. The usage of the Discovery Services defined in [CX-0001], [CX-0053] is not mandatory, because this standard assumes an already existing business relationship between the involved parties.

The sequence diagram in Figure 3 provides an overview of the interactions required to register the Part Type Twin following the shared asset approach.

• Steps 1 & 2: Register the dDTR access for the partner at the connector
• Steps 3 & 4: When using the repository pattern, create the submodel (and twin)
• Steps 5 & 6: Register the submodel endpoint for the partner at the connector
• Steps 7 & 8: Register or update the twin Shell Descriptor relying on the registered Connector asset for the submodel endpoint and the identification data of the partners.

Note: This sequence diagram is simplified and does not cover the generation of the Part Type Twin on supplier side and the handling of the identification data needed. Both partners need to create a Part Type Twin of the shared asset as well as provide Short-Term Material Demand data.

Figure 3: Flow to create and register a digital twin

The sequence diagram in Figure 4 provides an overview of the interactions required when a customer (acting as data provider) provisions Short-Term Material Demand data to a supplier (acting as data consumer).

The flow "Supplier reads (updated) Submodel from Customer" visualizes the sequence of calls when consuming data:

• Steps 3 - 8: Contract dDTR usage in the connector.
• Steps 9 - 12: Lookup the Industry Core Part Type Twin for a Part Type based on the common identification data.
• Steps 13 - 18: Read the Shell Descriptor of the Industry Core Part Type Twin to extract the Short-Term Material Demand submodel endpoint (registered at the connector).
• Steps 19 - 24: Contract the Short-Term Material Demand data usage in the connector.
• Steps 25 - 29: Consume and use the Short-Term Material Demand data.

Figure 4: Flow to lookup a digital twin and get a submodel.

Note: Depending on the use of repository patterns and the design of the Digital Twins, the data may be updated manually in the Submodel endpoint.

4.1.1 CONNECTOR DATA ASSET STRUCTURE

The endpoints for the dDTR and the Submodel Endpoint MUST be made available BUT they MUST NOT be directly called data consumer. Rather, for access to dDTRs and Submodels, there MUST be contracts negotiated in accordance with the DSP. Therefore, the endpoints MUST be offered as connector data assets. To make these assets easily identifiable in the connector's catalog, each asset MUST be configured with a set of properties as described in the corresponding sections below.

The following table provides an overview of the connector data assets that the parties MUST offer to be able to provision and/or consume Short-Term Material Demand data.

Party	REQUIRED	Asset	Purpose
Customer	Yes	"Digital Twin Registry"	Allows a consumer to query for Part Type Twins and their Short-Term Material Demand submodels.
Customer	Yes	"Submodel Short-Term Material Demand"	Allows a consumer to read actual Short-Term Material Demand data related to a Part Type Twin.
Supplier	Yes	"Digital Twin Registry"	Allows a consumer to query for Part Type Twins and their Short-Term Material Demand submodels.

Table 5: Connector data assets

In the sections below the asset definitions of the two different kinds of assets are defined.

CONNECTOR DATA ASSET STRUCTURE FOR "Digital Twin Registry"

To allow partners to find the "Short-Term Material Demand" data for a specific Industry Core Part Type Twin, the provider MUST register a connector data asset (see details in [CX-0018]) specifying the address of the Digital Twin Registry of the provider (see [CX-0002]).

The data asset MUST be configured with the set of properties as defined in the table below.

Object	Property	Purpose	Usage & Constraints
	@id	Identifier of the asset	The asset ID MUST be unique and therefore MUST NOT be reused elsewhere.
properties	http://purl.org/dc/terms/type	Defines the "Digital Twin Registry" according to the Catena-X taxonomy.	MUST be set to {"@id": "https://w3id.org/catenax/taxonomy#DigitalTwinRegistry"} to allow filtering the data assets catalog for the respective "Digital Twin Registry".
properties	https://w3id.org/catenax/ontology/common#version	The version of the standard defining the implemented API of the "Digital Twin Registry"	MUST correspond to the version of the standard defining the Interfaces of the "Digital Twin Registry". The value MUST be set to "3.0" for "Digital Twin Registries" used by this standard.
dataAddress	@type	Type of the DataAddress node.	MUST be set to "DataAddress".
dataAddress	baseUrl	Defines the HTTPS endpoint of the corresponding "Digital Twin Registry Endpoint".	The {{ DIGITAL_TWIN_REGISTRY_ENDPOINT }} refers to an URL under which the API of the "Digital Twin Registry" endpoint is available. HTTPS transport protocol MUST be used.
dataAddress	proxyBody	Defines whether the endpoint allows to proxy the HTTPS body	SHOULD be set to "false" to not allow the API endpoint to receive a HTTPS body via the HTTPS request.
dataAddress	proxyMethod	Defines whether the endpoint allows to proxy the HTTPS method	SHOULD be set to "false" to only allow the API endpoint to receive GET requests.
dataAddress	proxyPath	Defines whether the endpoint allows to proxy paths for the URL	MUST be set to "true" to allow the API endpoint to receive appended paths of the HTTPS request.
dataAddress	type	Defines the type of data plane extension handling the data exchange	MUST be set to "HttpData" to provide an API via an HTTPS proxy endpoint.

Table 6: Connector data assets request properties

Additionally security identification information MAY be added to secure the "Decentralized Digital Twin Registry".

When searching the Catalog of a provider, a consumer SHOULD use the following properties AND their values to identify the Data Asset specifying "Digital Twin Registry". In the connector Data Asset descriptions the API version valid for this standard is mentioned for the property https://w3id.org/catenax/ontology/common#version. The requester of a Data Asset MUST be able to handle multiple Data Asset for this endpoint, being differentiated only by the version. The requester SHOULD choose the Data Asset set with the highest compatible version number implemented by themselves. If the requester cannot find a compatible version with their own, the requester MUST terminate the data transfer.

Property	Value
http://purl.org/dc/terms/type	{"@id": "https://w3id.org/catenax/taxonomy#DigitalTwinRegistry"}

Table 7: Connector data assets request properties values.

An example connector data asset definition is given below.

Note: Expressions in double curly braces {{}} must be substituted with a corresponding value.

{
  "@context": {
    "@vocab": "https://w3id.org/edc/v0.0.1/ns/",
    "cx-common": "https://w3id.org/catenax/ontology/common#",
    "cx-taxo": "https://w3id.org/catenax/taxonomy#",
    "dct": "http://purl.org/dc/terms/"
  },
  "@id": "{{CONNECTOR_ASSET_ID}}",
  "properties": {
    "dct:type": {"@id": "cx-taxo:DigitalTwinRegistry"},
    "cx-common:version": "3.0"
  },
  "privateProperties": {
  },
  "dataAddress": {
    "@type": "DataAddress",
    "type": "HttpData",
    "baseUrl": "{{ DIGITAL_TWIN_REGISTRY_ENDPOINT }}",
    "proxyQueryParams": "true",
    "proxyBody": "false",
    "proxyPath": "true",
    "proxyMethod": "false",
  }
}

CONNECTOR DATA ASSET STRUCTURE FOR "Submodel"

To allow partners to receive the "Short-Term Material Demand" data as defined in Chapter 3, the provider MUST register a connector data asset (see details in[ CX-0018]) specifying the address of the submodel endpoint (see [CX-0002]) providing the actual data.

The data asset MUST be configured with the set of properties as defined in the table below.

Object	Property	Purpose	Usage & Constraints
	@id	Identifier of the asset	The asset ID MUST be unique and therefore MUST NOT be reused elsewhere.
properties	http://purl.org/dc/terms/type	Defines the "Submodel API" according to the Catena-X taxonomy.	MUST be set to {"@id": "https://w3id.org/catenax/taxonomy#Submodel"} to allow filtering the data assets catalog for the respective "Submodel API".
properties	https://admin-shell.io/aas/3/0/HasSemantics/semanticId	The semantic identifier of the "Short-Term Material Demand" SAMM.	MUST be set to {"@id": "urn:samm:io.catenax.short_term_material_demand:1.0.0#ShortTermMaterialDemand"} to externally define how the Submodel must be interpreted. MUST NOT be set, if different submodels may be returned by this API.
properties	https://w3id.org/catenax/ontology/common#version	Version of the Submodel Interface Specification	MUST be set to "3.0" in accordance to [CX-0002].
dataAddress	@type	Type of the DataAddress node.	MUST be set to "DataAddress".
dataAddress	baseUrl	Defines the HTTPS Submodel endpoint provisioning the Short-Term Material Demand data	The {{ SUBMODEL_ENDPOINT }} refers to an URL under which the Submodel API Endpoint ([CX-0002]) is available to provide the "Short-Term Material Demand" . HTTPS transport protocol MUST be used.
dataAddress	proxyBody	Defines whether the endpoint allows to proxy the HTTPS body	SHOULD be set to "false" to not allow the API endpoint to receive a HTTPS body via the HTTPS request.
dataAddress	proxyMethod	Defines whether the endpoint allows to proxy the HTTPS method	SHOULD be set to "false" to only allow the API endpoint to receive GET requests.
dataAddress	proxyPath	Defines whether the endpoint allows to proxy paths for the URL	MUST be set to "true" to allow the API endpoint to receive appended paths of the HTTPS request. Setting this parameter depends on the implementation of the submodel lookup.
dataAddress	type	Defines the type of data plane extension handling the data exchange	MUST be set to "HttpData" to provide an API via an HTTPS proxy endpoint.

Table 8: Connector data assets request properties

Additionally security identification information MAY be added to secure the "Submodel API".

When searching the data assets catalog of a provider, a consumer SHOULD use the assetId previously determined via subprotocolBody of the SubmodelDescriptor's endpoint definition of subprotocol type "DSP". Refer to Chapter 4.1.2 for the definition of the subprotocolBody.

Property	Value
https://w3id.org/edc/v0.0.1/ns/id	{{CONNECTOR_ASSET_ID}} specified in the DSP endpoint of the SubmodelDescriptor (see Chapter 4.1.2)

Table 9: Connector data assets request properties values

An example connector data asset definition is given below.

Note: Expressions in double curly braces {{}} must be substituted with a corresponding value.

{
  "@context": {
    "@vocab": "https://w3id.org/edc/v0.0.1/ns/",
    "cx-common": "https://w3id.org/catenax/ontology/common#",
    "cx-taxo": "https://w3id.org/catenax/taxonomy#",
    "dct": "http://purl.org/dc/terms/",    
    "aas-semantics": "https://admin-shell.io/aas/3/0/HasSemantics/"
   },
  "@id": "{{CONNECTOR_ASSET_ID}}",
  "properties": {
    "dct:type": {"@id": "cx-taxo:Submodel"},
    "cx-common:version": "3.0",
    "aas-semantics:semanticId": {"@id": "urn:samm:io.catenax.short_term_material_demand:1.0.0#ShortTermMaterialDemand"}   
  },
  "privateProperties": {
  },
  "dataAddress": {
    "@type": "DataAddress",
    "type": "HttpData",
    "baseUrl": "{{ SUBMODEL_ENDPOINT }}",
    "proxyQueryParams": "false",
    "proxyBody": "false",
    "proxyPath": "true",
    "proxyMethod": "false",
  }
}

4.1.2 INDUSTRY CORE PART TYPE TWIN REGISTRATION AND DEFINITION

4.1.2.1 SHELL DESCRIPTOR REGISTRATION

To allow partners to receive the actual "Short-Term Material Demand" data as defined in Chapter 3, the provider MUST register a Shell Descriptor in the dDTR (see [CX-0002]) so that a partner:

• May lookup the Industry Core Part Type Twin based on known identification data.
• May identify the connector endpoint providing access to the "Short-Term Material Demand" submodel data.

The Shell Descriptors represent each an Industry Core Part Type Twin and MUST follow the rules as defined in Chapter 2.1.4.

The Shell Descriptor MUST be configured with the set of properties as defined in the table below.

Object in ShellDescriptor	Property	Purpose	Usage & Constraints
	id	Defines the technical ID of the Asset Administration Shell representing a partner's twin.	MUST be unique following Industry Core Part Type standard ([CX-0126]) and is a technical Id randomly assigned as multiple Part Type Twins may be created for one Part Type. E.g. this number differs for the twins created at supplier and customer side.
	globalAssetId	Defines the Catena-X ID of the twin.	MUST be aligned with the partner's material. When referring to the same Part Type Twin, the same number MUST be used (see [CX-0126]).
	specificAssetIds	Identifiers that may be used to lookup Part Type Twins.	MUST be set to according to the Industry Core Part Type standard ([CX-0126]). See Table 11 for respective specific asset IDs. The "customerPartId" MUST be set by Customers and SHOULD be set by Suppliers.
submodelDescriptor	id	Technical identifier of a SubmodelDescriptor.	MUST be set to a unique identifier.
submodelDescriptor	semanticId	The semantic identifier of the "Short-Term Material Demand" SAMM.	MUST be set to { "type": "ExternalReference", "keys": [{ "type": "GlobalReference", "value": "urn:samm:io.catenax.short_term_material_demand:1.0.0#ShortTermMaterialDemand" }] } to externally define how the Submodel must be interpreted.
submodelDescriptor > endpoint	interface	Defines the Submodel Interface [CX-0002] and the version.	MUST be set to "SUBMODEL-3.0" to rely on current specification.
submodelDescriptor > endpoint > protocolInformation	href	Defines the direct link to the public API of the connector's data plane with a path that SHOULD be appended by the proxy, if needed.	MUST be set to the public API of the data plane providing the data with the path appended to directly access the submodel.
submodelDescriptor > endpoint > protocolInformation	subprotocol	Defines the usage of the connector based on DSP to access and use the submodel.	MUST be set to "DSP" to define the connector endpoint of the subprotocol.
submodelDescriptor > endpoint > protocolInformation	subprotocolBody	Defines the asset id in the connector and the connector address to access and use the submodel.	MUST be set to "id={{CONNECTOR_ASSET_ID}};dspEndpoint={{SUPPLIER_CONNECTOR_DSP_ENDPOINT}}" to provide the necessary information for contracting the submodel endpoint. Refer to Chapter 4.1.2 for the definition of the asset of the subprotocolBody.

Table 10: Properties relevant for the Shell Descriptor definition

When searching the submodel in the dDTR of a provider, a consumer SHOULD use the specific asset IDs as defined in [CX-0126]. Table 11 gives an overview of the specific asset IDs that the data provider added to the ShellDescriptor so that the data consumer may find the Industry Core Part Type Twin.

Specific Asset Id	Value
digitalTwinType	"PartType". Set to identify twins compliant to the Industry Core Part Type (see [CX-0126]).
manufacturerId	Supplier / Manufacturer partner BPNL (see [CX-0010])
manufacturerPartId	Supplier / Manufacturer partner identification number of the part.
customerPartId	Customer partner identification number of the part.

Table 11: Specific asset IDs of Industry Core Part Type Twins proposed to be used to look up a twin in the dDTR

The Shell Descriptor defines the metadata of the Industry Core Part Type Twin. The following example presents a Shell Descriptor of a customer providing two of its suppliers access to a "Short-Term Material Demand" submodel. For further information on the creation of Part Type Twins, refer to Chapter 2.1.4.

Following [CX-0002], when searching the data assets catalog of a provider, a consumer SHOULD use the assetId determined via subprotocolBody of the SubmodelDescriptor's endpoint definition of subprotocol type "DSP" of the Submodel Descriptor of interest.

Note: Expressions in double curly braces {{}} must be substituted with a corresponding value.

{
  "id": "{{TECHNICAL_TWIN_ID}}",
  "globalAssetId": "{{MATERIAL_NUMBER_CX}}",
  "idShort": "Semiconductor",
  "specificAssetIds": [
    {
      "name": "digitalTwinType",
      "value": "PartType",
      "externalSubjectId": {
        "type": "ExternalReference",
        "keys": [
          {
            "type": "GlobalReference",
            "value": "{{SUPPLIER_BPNL}}"
          },
          {
            "type":"GlobalReference",
            "value":"{{CUSTOMER_BPNL}}"
          }
        ]
      }
    },
    {
      "name": "manufacturerPartId",
      "value": "{{MATERIAL_NUMBER_SUPPLIER}}",
      "externalSubjectId": {
        "type": "ExternalReference",
        "keys": [
          {
            "type": "GlobalReference",
            "value": "{{SUPPLIER_BPNL}}"
          },
          {
            "type":"GlobalReference",
            "value":"{{CUSTOMER_BPNL}}"
          }
        ]
      }
    },
    {
      "name": "manufacturerId",
      "value": "{{SUPPLIER_BPNL}}",
      "externalSubjectId": {
        "type": "ExternalReference",
        "keys": [
          {
            "type": "GlobalReference",
            "value": "{{SUPPLIER_BPNL}}"
          },
          {
            "type":"GlobalReference",
            "value":"{{CUSTOMER_BPNL}}"
          }
        ]
      }
    },
    {
      "name": "customerPartId",
      "value": "{{MATERIAL_NUMBER_CUSTOMER}}",
      "externalSubjectId": {
        "type": "ExternalReference",
        "keys": [
          {
            "type": "GlobalReference",
            "value": "{{SUPPLIER_BPNL}}"
          },
          {
            "type":"GlobalReference",
            "value":"{{CUSTOMER_BPNL}}"
          }
        ]
      }
    }
  ],
  "submodelDescriptors": [
    {
      "id": "e5c96ab5-896a-482c-8761-efd74777ca97",
      "semanticId": {
        "type": "ExternalReference",
        "keys": [
          {
            "type": "GlobalReference",
            "value": "urn:samm:io.catenax.short_term_material_demand:1.0.0#ShortTermMaterialDemand"
          }
        ]
      },
      "endpoints": [
        {
          "interface": "SUBMODEL-3.0",
          "protocolInformation": {
            "href": "{{SUPPLIER_CONNECTOR_DATAPLANE_PUBLIC_API}}/{{PATH_IF_NEEDED}}",
            "endpointProtocol": "HTTP",
            "endpointProtocolVersion": [
              "1.1"
            ],
            "subprotocol": "DSP",
            "subprotocolBody": "id={{CONNECTOR_ASSET_ID}};dspEndpoint={{SUPPLIER_CONNECTOR_DSP_ENDPOINT}}",
            "subprotocolBodyEncoding": "plain",
            "securityAttributes": [
              {
                "type": "NONE",
                "key": "NONE",
                "value": "NONE"
              }
            ]
          }
        }
      ]
    }
  ]
}

4.1.2.2 LOOKING UP A PART TYPE TWIN IN THE DDTR

To query the dDTR of a data provider, after contracting the usage via the data provider's connector (see [CX-0018]), the lookup API (see [CX-0002]) can be used relying on the specific asset IDs defined by the Industry Core Part Type (see [CX-0126]) that can be seen in Table 11 (table of shellDescriptorRegistration with specific asset IDs).

An example call relying on all information is given in the code sample below.

Note: Expressions in double curly braces {{}} must be substituted with a corresponding value.

GET: {{PARTNER_CONNECTOR_DATA_PLANE}}/lookup/shells?assetIds={"name":"digitalTwinType", "value": "PartType"},{"name":"manufacturerPartId", "value": "{{MATERIAL_NUMBER_SUPPLIER}}"},{"name":"manufacturerId", "value": "{{SUPPLIER_BPNL}}"},{"name":"customerPartId", "value": "{{MATERIAL_NUMBER_CUSTOMER}}"}

As a result identifiers of the ShellDescriptors will be returned. With this data, a data provider can read the ShellDescriptor to extract the endpoint data of the data provider. An example is given in the code sample below.

Note: Expressions in double curly braces {{}} must be substituted with a corresponding value.

GET: {{PARTNER_CONNECTOR_DATA_PLANE}}/shell-descriptors/{{AAS_IDENTIFIER}}

4.1.2.3 FETCHING SUBMODEL DATA

To fetch the Short-Term Material Demand Submodel data at the submodel endpoint of a data provider, after contracting the usage via the data provider's connector (see [CX-0018]), the submodel API (see [CX-0002]) can be used.

An example call relying on all information is given in the code sample below.

Note: Expressions in double curly braces {{}} must be substituted with a corresponding value.

GET: {{HREF_PATH}}/$value

5 PROCESSES

This section is normative

The Short-Term Material Demand is intended to provide more details and insights about the customer's demand. It is not meant to replace regular and legally binding orders or call-offs between partners but to offer supplementary information. Therefore the Short-Term Material Demand aspect model provides several categories that may be used to differentiate between different types of demand. The categories originate from the joint use of the aspect model of the Demand and Capacity Standard [CX-0128] and may not necessarily apply. Categories should only be used if they are beneficial for at least one of the partners involved. If in doubt, "Default" SHOULD always be used.

The key purpose of the Short-Term Material Demand is to indicate the actual required quantities that are critical for the customer's planned production. To do so it is RECOMMENDED to use the Categories "Default" or "Series". Quantities deviating from this, e.g. to build up stock or to optimize logistics, SHOULD be mapped to "Extraordinary Demand". All other categories should be selected and used after aligning with the respective partner to ensure a mutual understanding and intention of use.

The following chapter should contribute to the understanding by providing different process representations and examples.

5.1 ACTORS AND ROLES

The following actors and roles occur in the described processes.

Actors	Role	Description
Supplier	The supplier acts as the data consumer in this standard.	Is a business partner that supplies items to a customer. As such, a supplier is interested in detailed information about the customer's Short-Term Material Demand.
Customer	The customer acts as the data provider in this standard.	Is a business partner that procures items from suppliers and provides information about his Short-Term Material Demand.

Table 12: Actors and roles

5.2 PROCESS REPRESENTATIONS

5.2.1 SINGLE SOURCING USING A SINGLE CATEGORY

In this most basic example the customer procures materials from a single supplier to fulfill its demands for a specific material. Also the call-off or order quantities exactly match the quantities that are required for the customer's production on a daily basis.

The following table visualizes the data which may be transferred as Short-Term Material Demand.

Table 13: Single sourcing with one demand category and daily ordering

Another scenario in this context might be that the delivery date stated in the call-off or order does not match the actual expected consumption date for the material.

Table 14: Single sourcing with one demand category and non-daily ordering

The additional information can be e.g. used to smooth out the supplier's production and to jointly agree between partners on a split of the total order quantity across different delivery days. The same applies for a shortage case where the supplier is not able to deliver the ordered quantity on day 1.

5.2.2 SINGLE SOURCING USING MULTIPLE CATEGORIES

Additional information about the customer's Short-Term Material Demand can be provided via categories. The following example shows a scenario where the customer is signaling that the ordered amount of material on day 2 is partially intended to build up safety stock and is not directly related to a planned consumption.

Table 15: Single sourcing with multiple demand categories to signal stock building

With this additional information the supplier can distinguish which quantity is the absolute minimum required to fulfill the customer's production needs and which is e.g., to build up a safety stock or to replenish stock. In the event of a production bottleneck, the supplier can suggest stretching the delivery of the additional parts. The supplier is also informed that this is not a regular increase in demand, which in turn can be used while communicating with its upstream suppliers and may therefore contribute to reduce the bullwhip effect.

In the same manner, the customer can make use of the categories e.g., to indicate that a partial quantity is attributed to logistical optimizations. This might be e.g. due to fixed container sizes. The following example shows a scenario in which one container always carries a batch of 15 pieces.

Table 16: Single sourcing with multiple demand categories to distinguish quantities for logistical optimizations

5.2.3 MULTI-SOURCING WITH MULTIPLE CATEGORIES

A multi-sourcing strategy is a common approach in supply chain management to mitigate supply risks. This means that a customer works with two or more suppliers to procure equivalent materials. However, to use the "Short-Term Material Demand Exchange" standard, participants must comply with legal restrictions, such as competition laws. Furthermore, it is in the interests of the customer not to disclose any company secrets about existing business relationships and their extent with third parties.

Therefore, in case of multi-sourcing, each participant needs to prevent potential prohibited or disadvantageous data leakage during the information provisioning. Any Short-Term Material Demand provided must be partner-specific. In case of multi-sourcing the demand data can be e.g., broken down based on the partner's proportion of the customer's total demand volume. Using supplier-specific material numbers may support the data provisioning system-wise.

In the following example a customer has two suppliers, that are sourced 60% and 40% respectively. Therefore demands need to be split according to the given quota. In addition to the demand directly derived from the customer's material consumption, the customer orders additional material on Day 1 and Day 2 to build up a safety stock.

Table 17: Multi-sourcing with multiple demand categories to signal stock building

6 REFERENCES

6.1 NORMATIVE REFERENCES

Number	Standard	Version
[CX-0001]	EDC Discovery API	1.0.2
[CX-0002]	Digital Twins in Catena-X	2.2.0
[CX-0003]	SAMM Aspect Meta Model	1.1.0
[CX-0006]	Registration and initial onboarding	2.0.0
[CX-0010]	Business Partner Number (BPN)	2.0.0
[CX-0018]	Dataspace Connectivity	3.0.0
[CX-0053]	Discovery Finder and BPN Discovery Service APIs	1.1.0
[CX-0118]	Delivery Information Exchange	2.0.0
[CX-0121]	Planned Production Output Exchange	2.0.0
[CX-0122]	Item Stock Exchange	2.0.0
[CX-0126]	Industry Core Part Type	2.0.0
[CX-0128]	Demand and Capacity Management	2.0.0
[CX-0145]	Days of Supply Exchange	1.0.0
[CX-0146]	Supply Chain Disruption Notifications	1.0.0

6.2 NON-NORMATIVE REFERENCES

This section is non-normative

Context	Link
[CX-OMW]	Catena-X Operating Model Whitepaper. Download from: https://catena-x.net/fileadmin/_online_media_/CX_Operating_Modelv2.1_final.pdf
[CX-ODRL]	Catena-X ODRL Profile repository: https://github.com/catenax-eV/cx-odrl-profile
[RFC2119]	Bradner, S. Key words for use in RFCs to Indicate Requirement Levels. Available online: https://datatracker.ietf.org/doc/html/rfc2119
[RFC8174]	Leiba, B. Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words. Available online: https://datatracker.ietf.org/doc/html/rfc8174
[SMT]	How to create a submodel template specification. Guideline. Download from: https://industrialdigitaltwin.org/wp-content/uploads/2022/12/I40-IDTA-WS-Process-How-to-write-a-SMT-FINAL-.pdf
[IDTA-01002-3-0]	Specification of the Asset Administration Shell Part 2: Application Programming Interfaces. Download from: https://industrialdigitaltwin.org/wp-content/uploads/2023/04/IDTA-01002-3-0_SpecificationAssetAdministrationShell_Part2_API.pdf

6.3 REFERENCE IMPLEMENTATIONS

This section is non-normative

Not applicable

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