CX-0145 Days of supply Exchange 1.0.0
ABSTRACT
Days of Supply (DoS) in logistics is a critical metric used to estimate how long current inventory levels will last under normal consumption patterns. This calculation is essential in supply chain management as it assists in forecasting when stock replenishment is needed, thereby preventing stock shortages or overstocking. It plays a significant role in ensuring efficient inventory turnover, maintaining a balance between having enough stock to meet demand and avoiding excess inventory that ties up capital.
To effectively address the challenges associated with manual calculation and estimation of Days of Supply, the standardization and interoperable exchange of this data among Catena-X business partners is essential. Establishing a standardized semantic definition to describe Days of Supply and a common API is a fundamental step to enable this exchange and foster compatibility. This approach maximizes the range of solutions available to mitigate potential supply shortages and supports precise inventory planning.
FOR WHOM IS THE STANDARD DESIGNED
COMPARISON WITH THE PREVIOUS VERSION OF THE STANDARD
This is the first version of the standard.
1 INTRODUCTION
In the intricate frameworks of supply chain management and manufacturing, the Days of Supply metric emerges as a critical tool for optimizing inventory levels and ensuring effective planning. It measures how long the current inventory will suffice to meet future demands under the assumption that no additional inventory is received. This key figure, calculated in days, is essential for maintaining efficient inventory turnover and preventing both shortages and excesses that can impact business operations.
Effective monitoring and calculation of Days of Supply are paramount for businesses to anticipate and mitigate potential inventory imbalances. However, accurately capturing and analyzing this data poses a significant challenge, as conventional methods and systems may not offer comprehensive support for this nuanced metric.
The necessity for a standardized and semantically precise definition of Days of Supply cannot be overstated. By establishing clear standards for this metric, supply chain participants can ensure interoperable data exchange, enhancing collaboration and operational efficiency across the board. This initiative not only aids in avoiding inventory-related issues but also contributes to more streamlined and responsive supply chain operations.
The initiative towards standardizing Days of Supply is aimed at providing businesses with the tools they need for more effective inventory and production planning, enabling them to improve process efficiency, minimize risks of inventory mismatches, and bolster overall supply chain resilience.
Days of Supply can be applied in various use cases in logistics and supply chain management:
- Manufacturing Sector : Manufacturers rely on it to maintain adequate levels of raw materials and components, ensuring uninterrupted production lines.
- Retail Industry : Retailers use it to manage inventory levels of fast-moving consumer goods. They can predict when they need to reorder items to avoid stockouts, especially during peak shopping seasons.
- Healthcare and Pharmaceuticals : It's crucial for managing the inventory of medicines and medical supplies, particularly those with short shelf lives or critical to patient care.
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 Days of Supply data
- Data Consumers interested in requesting and receiving Days of Supply 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 Days of Supply aspect model and the corresponding API usage. It describes the exchange of Days of Supply data through a connector compliant with [CX-0018].
1.2 CONTEXT AND ARCHITECTURE FIT
This section is non-normative
In a typical item manufacturing and procurement process, a company determines the need to maintain stock levels to meet demand. As part of this process, Days of Supply typically refers to metrics or details about how long the existing inventory will last to satisfy current demand without additional delivery or production. It includes calculations on the number of days the current inventory is expected to meet demand based on average daily consumption. This metric provides key insights into inventory efficiency and assists in planning reorders to ensure continuous operation and is crucial for maintaining efficient inventory management and ensuring a smooth supply chain.
Within the framework of the Catena-X network, this standard defines the DaysOfSupply aspect model. Its purpose is to establish a consistent and uniform interpretation and handling of Days of Supply among all interested parties, ensuring that this data is understood and managed in the same manner by all stakeholders.
Figure 1 shows the high-level architecture of the Days of Supply exchange in the Catena-X dataspace and the services that are involved. Both the data provider and the data consumer must be members of the Catena-X network in order to communicate with each other. With the help of 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 Days of Supply data is provisioned in accordance with [CX-0002].
Figure 1: High-level architecture of the Days of Supply in the Catena-X
1.3 CONFORMANCE AND PROOF OF CONFORMITY
This section is non-normative
The 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. 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
The following JSONs provide an example of the value-only serialization of the "Days Of Supply" aspect model for Days of Supply for one (see example one) and multiple days of supply (see example too).
Value-only JSON serialization of the with present day values of days of supply - "DoS for one day only".
{
"materialGlobalAssetId": "urn:uuid:48878d48-6f1d-47f5-8ded-a441d0d879df",
"allocatedDaysOfSupply": [
{
"stockLocationBPNA": "BPNA1234567890ZZ",
"lastUpdatedOnDateTime": "2023-04-28T14:23:00.123456+14:00",
"amountOfAllocatedDaysOfSupply": [
{
"date": "2024-01-01T14:23:00+01:00",
"daysOfSupply": 3.51
}
],
"stockLocationBPNS": "BPNS1234567890ZZ"
}
],
"direction": "INBOUND"
}
Value-only JSON serialization of the with present day and two additional consecutive dates paired with days of supply values - "DoS for multiple days".
{
"materialGlobalAssetId": "urn:uuid:48878d48-6f1d-47f5-8ded-a441d0d879df",
"allocatedDaysOfSupply": [
{
"stockLocationBPNA": "BPNA1234567890ZZ",
"lastUpdatedOnDateTime": "2023-04-28T14:23:00.123456+14:00",
"amountOfAllocatedDaysOfSupply": [
{
"date": "2024-02-01T14:23:00+01:00",
"daysOfSupply": 3.51
},
{
"date": "2024-02-02T14:23:00+01:00",
"daysOfSupply": 4.25
},
{
"date": "2024-02-03T14:23:00+01:00",
"daysOfSupply": 2.78
}
],
"stockLocationBPNS": "BPNS1234567890ZZ"
}
],
"direction": "INBOUND"
}
1.5 TERMINOLOGY
This section is non-normative
Name | Abrev. | 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 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]. |
Direction | / | Direction of the stock from data provider perspective. |
Date | / | Date refers to the specific calendar day (current or projected) associated with the measured (or expected) inventory level. It serves as a timestamp for calculating Days of Supply, indicating when the inventory count was taken or projected. |
Days of Supply | DoS | Amount of days, before the current stock is expected to be exhausted. Days of supply of a customer: Number of days where; (Stock) - Σ(daily Demand) >= 0 Days of supply of a supplier: Number of days where; (Stock) - Σ(daily Outgoing Shipments) >= 0 |
Allocated Days of Supply | / | Defines the number of days with allocated supply for an item stock in a given location that is available for the use in production or deliveries. The allocated days of supply are not available for other customers. |
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 identification information and metadata 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 Days of Supply Exchange Standard
Additional terminology used in this standard can be looked up in the glossary on the association homepage.
2 RELEVANT PARTS OF THE STANDARD FOR SPECIFIC USE CASES
This section is normative
2.1 "DAYS OF SUPPLY"
2.1.1 LIST OF STANDALONE STANDARDS
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-0120] | Short-term Material Demand Exchange | 2.0.0 |
[CX-0121] | Planned Production Output Exchange | 2.0.0 |
[CX-0122] | Item Stock Exchange | 2.0.0 |
[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 Days of Supply data to customers.
- The customer, who orders or uses the part, has a Digital Twin representation to offer Days of Supply 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 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 Days of Supply specific submodels are bound to the specific Part Type's context e.g., meaning that the Days of Supply 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 "DAYS OF SUPPLY" ASPECT MODEL
3.1.1 INTRODUCTION
This section describes the Days Of Supply semantic model used in the Catena-X network. 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].