HCL Domino · E-Invoicing · EN 16931 · API-Engine

E-Invoice Processing in HCL Domino – ZUGFeRD, Factur-X & XRechnung

Electronic invoices are increasingly exchanged as structured data rather than documents intended only for human reading. The SL Net-Solutions Domino API-Engine can extract invoice data from hybrid PDF/XML documents and process XML invoices within existing HCL Domino workflows.

A new example in the API-Engine V12.12 Evaluation Package demonstrates the process using a ZUGFeRD/Factur-X invoice. The PDF is read into a BINBUFFER, the embedded invoice XML is extracted in memory, and XML and XPath functions select the relevant invoice fields. The resulting values can then be stored in a Domino document.

Processing pipeline

From an invoice PDF to Domino items

The processing pipeline runs within a server-side API-Engine script. The PDF BINBUFFER may originate from a Domino attachment, a file or another supported source; the extraction logic does not depend on a separate standalone invoice application.

For a pure XML invoice, the PDF extraction stage is skipped. Once the XML has been parsed, the subsequent processing is conceptually similar.

CII XML example

What the structured invoice data looks like

The invoice information is read from structured XML elements, not extracted by recognizing text on the visible PDF page. The following abbreviated CII fragment contains the elements used in our example:

<rsm:CrossIndustryInvoice
  xmlns:rsm="urn:un:unece:uncefact:data:standard:CrossIndustryInvoice:100"
  xmlns:ram="urn:un:unece:uncefact:data:standard:ReusableAggregateBusinessInformationEntity:100"
  xmlns:udt="urn:un:unece:uncefact:data:standard:UnqualifiedDataType:100">

  <rsm:ExchangedDocument>
    <ram:ID>471102</ram:ID>
    <ram:IssueDateTime>
      <udt:DateTimeString format="102">20241115</udt:DateTimeString>
    </ram:IssueDateTime>
  </rsm:ExchangedDocument>

  <rsm:SupplyChainTradeTransaction>
    <ram:ApplicableHeaderTradeAgreement>
      <ram:SellerTradeParty>
        <ram:Name>Example GmbH</ram:Name>
      </ram:SellerTradeParty>
      <ram:BuyerTradeParty>
        <ram:Name>Sample Customer Ltd.</ram:Name>
      </ram:BuyerTradeParty>
    </ram:ApplicableHeaderTradeAgreement>

    <ram:ApplicableHeaderTradeSettlement>
      <ram:InvoiceCurrencyCode>EUR</ram:InvoiceCurrencyCode>
      <ram:SpecifiedTradeSettlementHeaderMonetarySummation>
        <ram:GrandTotalAmount>529.87</ram:GrandTotalAmount>
        <ram:DuePayableAmount>529.87</ram:DuePayableAmount>
      </ram:SpecifiedTradeSettlementHeaderMonetarySummation>
    </ram:ApplicableHeaderTradeSettlement>
  </rsm:SupplyChainTradeTransaction>
</rsm:CrossIndustryInvoice>

Abbreviated, illustrative CII XML with sample values. This is not a complete or validatable ZUGFeRD, Factur-X or XRechnung invoice.

API-Engine XML functions

From an XML handle to an invoice field

After extraction, the API-Engine treats the invoice as an ordinary XML document. The following function sequence illustrates the main steps needed to read an invoice number:

PDF BINBUFFER
  |
  +-- @PDFExtractInvoiceXML(PDFBuffer)
          |
          v
      Invoice XML (BINBUFFER)
          |
          +-- @XMLParse(InvoiceXML; 1)
                  |
                  +-- @XMLGetRoot(Doc)
                  |
                  +-- @XMLSelectSingleNode(
                        Root; XPath; Prefixes; Namespaces)
                  |
                  +-- @XMLGetContent(Node)
                  |
                  +-- Write Domino item

Cleanup: @XMLRelease(Doc), @DestroyBuffer(...)

Schematic sequence, not an executable API-Engine script. The complete example, including database access, function parameters and error handling, is supplied in the Evaluation Package.

For example, the invoice number can be found using this CII XPath:

/rsm:CrossIndustryInvoice
 /rsm:ExchangedDocument
 /ram:ID

Line breaks are added for readability; the actual XPath is written on one line.

Monetary values are located elsewhere in the document, under ram:ApplicableHeaderTradeSettlement and ram:SpecifiedTradeSettlementHeaderMonetarySummation. Prefixes such as rsm, ram and udt must be associated with their namespace URIs when querying the XML.

Important distinction

Extracting invoice data is not the same as validating an invoice

This example focuses on accessing and interpreting structured invoice data. Establishing whether an invoice complies with its declared profile, EN 16931 and applicable business rules is a separate task.

Production workflows may additionally require support for multiple invoice profiles, CII and UBL mapping, error handling, date and amount checks, duplicate detection, audit logging and integration with accounting or ERP applications.

Technical perspective

LotusScript, Java or the API-Engine?

Processing structured invoice XML is not exclusive to the API-Engine. Domino developers already have established XML processing options in both LotusScript and Java. The practical differences concern how PDF attachments, XML parsing and subsequent Domino processing are brought together and maintained.

Conclusion

E-invoice XML as another data source for Domino

Whether the invoice arrives as a hybrid Factur-X/ZUGFeRD PDF or as an XML-only XRechnung document, its structured information can be made available to existing business applications.

The API-Engine connects document input, namespace-aware XML parsing and Domino data processing: from a PDF BINBUFFER through XPath selection to the items stored in an NSF database.