Brev

Current Peppol, as one modular JDK 26 library.

Brev is a dependency-free JVM library for constructing, writing, reading, and later transporting current Peppol business documents. It lives in one repository. Applications take only the module they need.

The name is Norwegian for “letter.”

Warning

0.1.1 replaces ReAI's Digipost billing writer. ReAI still uses ph-ubl for inbound documents, while brev-smp and brev-ap publish types only. Keep official PHIVE validation on the send path until generated-rule parity exists.

Why one repo, not ten

The Helger stack is the interoperability reference. It is also split across many repositories because it preserves every UBL version, every Peppol profile, and years of API compatibility.

Brev occupies the opposite corner:

• one repo, independently published modules;
• current Peppol only;
• JDK 26 baseline, no older-Java tax;
• typed documents instead of the full UBL schema;
• zero third-party runtime dependencies in every published module.

Module	Take it when you need	Status
brev-core	identifiers, codes, release metadata	shipping
brev-documents	Billing invoice/credit note model, writer, reader	shipping
brev-smp	typed SMP lookup results	types only
brev-ap	typed send/receive messages	types only

See docs/modules.md, DESIGN.md, and ROADMAP.md.

Current document target

Component	Target
Peppol BIS Billing	3.0.21
EN 16931 validation artefacts	1.3.16
Mandatory from	2026-08-17
UBL syntax	Invoice and CreditNote 2.1
Process	Billing profile 01

Historical rule sets are not bundled. When Billing 4 is mandatory, Brev will replace this writer rather than keep a compatibility flag.

Example

var invoice = BillingDocument.invoice()
        .id("INV-1")
        .issueDate(LocalDate.of(2026, 8, 17))
        .dueDate(LocalDate.of(2026, 9, 1))
        .currency(new CurrencyCode("NOK"))
        .buyerReference("buyer-reference")
        .seller(seller)
        .buyer(buyer)
        .payment(new PaymentInstruction("NO9386011117947", "payment-reference"))
        .line(new BillingLine(
                "1",
                "Consulting",
                new Quantity(new BigDecimal("10"), UnitCode.HOUR),
                new UnitPrice(new CurrencyCode("NOK"), new BigDecimal("1250")),
                VatCategory.standard(new BigDecimal("25"))))
        .build();

Documents.write(invoice, outputStream);
BillingDocument parsed = Documents.read(Documents.toByteArray(invoice));

The writer emits compact XML straight to the supplied stream and does not close it. Attachments are Base64-encoded incrementally.

What ReAI can generate today

• invoices and credit notes
• VAT categories S, Z, E, G, AE, O
• Norwegian supplier identity (0192, VAT, Foretaksregisteret)
• order reference, billing reference, IBAN/BIC
• embedded PDF and other attachments
• price-level allowances
• optional payment, due date, and address parts

Unsupported Peppol Billing features fail through the absence of an API.

Building

Brev requires JDK 26.

./gradlew clean build
./gradlew :benchmark:jmh

The build fails if a published module acquires a third-party runtime dependency. Conformance runs official PHIVE/Saxon Billing 3.0.21 artefacts as a test-only oracle.

License

Apache License 2.0. Imported standards and validation artefacts retain their own licenses and provenance.