Architecture of PEPPOL platform

 The PEPPOL (Pan-European Public Procurement Online) platform is designed to facilitate cross-border e-procurement and e-invoicing across Europe. The architecture of the PEPPOL platform is modular and decentralized, ensuring interoperability and seamless integration between different stakeholders. Here is an overview of its key components:

1. PEPPOL Network

Access Points (APs)

• Access Points act as gateways, enabling organizations to exchange electronic documents within the PEPPOL network.
• Each participant needs to be connected to an AP to send and receive documents.
• APs use the AS4 protocol (Applicability Statement 4) for secure and reliable messaging.

Service Metadata Publisher (SMP)

• The SMP is a registry service that stores metadata about PEPPOL participants.
• It provides information about the capabilities and locations of participants.
• When an AP needs to send a document, it queries the SMP to find the recipient's AP and the document formats they support.

Service Metadata Locator (SML)

• The SML acts as a DNS-like service that points to the appropriate SMP.
• It enables the resolution of participant identifiers to the SMP that contains their metadata.

2. Document Standards

PEPPOL BIS (Business Interoperability Specifications)

• PEPPOL BIS defines the specifications for various document types, such as invoices, orders, and catalogues.
• These specifications are based on existing standards like UBL (Universal Business Language) and CEN (European Committee for Standardization).

Transport Infrastructure

• The PEPPOL transport infrastructure ensures secure and reliable exchange of documents.
• It includes protocols like AS2 (Applicability Statement 2) and AS4 for message transport.

3. Governance and Compliance

PEPPOL Authority

• PEPPOL Authorities oversee the implementation and compliance of the PEPPOL network within their jurisdictions.
• They are responsible for certifying Access Points and ensuring adherence to PEPPOL policies.

Participant Identification

• Each participant in the PEPPOL network is assigned a unique identifier, often based on their country’s business registration number.
• This identifier is used to route documents correctly.

4. Security and Trust

PKI (Public Key Infrastructure)

• PEPPOL relies on a robust PKI to ensure the authenticity and integrity of the exchanged documents.
• Digital certificates are used for signing and encrypting documents.

Compliance and Interoperability Testing

• Access Points and other participants must undergo rigorous testing to ensure they comply with PEPPOL standards.
• Interoperability testing ensures that documents can be exchanged seamlessly across different systems and platforms.

5. Use Cases and Implementation

E-Invoicing

• One of the primary use cases for PEPPOL is e-invoicing, enabling businesses to send and receive electronic invoices across borders.
• PEPPOL e-invoicing is mandatory in several European countries for public procurement.

E-Procurement

• Beyond invoicing, PEPPOL supports a wide range of e-procurement processes, including ordering, cataloguing, and tendering.
  

Here’s a detailed breakdown of how PEPPOL works with the internal architecture of an organization:

1. Internal Systems

ERP Systems

• Enterprise Resource Planning (ERP) systems manage core business processes, such as finance, HR, manufacturing, and supply chain.
• ERP systems generate and process business documents like invoices, orders, and delivery notes.

Middleware/Integration Layer

• This layer connects internal systems to the PEPPOL network.
• Middleware handles data transformation, mapping internal data formats to PEPPOL-compliant formats (e.g., UBL).

2. Document Preparation

Data Mapping and Transformation

• Internal business documents are mapped to the PEPPOL Business Interoperability Specifications (BIS).
• Tools like XML converters or custom scripts can be used for this transformation.

Validation

• Documents are validated against PEPPOL standards to ensure compliance.
• Validation tools check for correct structure, mandatory fields, and business rules.

3. Connectivity and Secure Messaging

Access Point (AP)

• The organization connects to the PEPPOL network through a certified Access Point.
• The AP ensures secure, reliable document transmission using protocols like AS2 or AS4.

Security and Encryption

• Documents are encrypted and signed using digital certificates.
• PKI (Public Key Infrastructure) ensures data integrity and authenticity.

4. Document Exchange Process

Outbound Documents

1. Document Creation: An invoice is created in the ERP system.
2. Data Mapping: The invoice data is mapped to the PEPPOL BIS format.
3. Validation: The formatted invoice is validated for compliance.
4. Transmission: The validated invoice is sent to the Access Point.
5. Routing: The Access Point queries the SMP to find the recipient's Access Point.
6. Delivery: The invoice is securely transmitted to the recipient’s Access Point and then to their internal system.

Inbound Documents

1. Receipt: An inbound document, such as a purchase order, is received by the organization's Access Point.
2. Validation: The document is validated for compliance with PEPPOL standards.
3. Data Mapping: The validated document is mapped from PEPPOL BIS format to the internal format.
4. Processing: The document is integrated into the ERP system for processing.