Preparing a Legacy System for Israel Invoices Without Replacing It

A legacy system does not have to disappear to support a new workflow. It may still manage customers, inventory, or orders well, while the gap sits only at document generation and allocation. The goal is not to attach an API to every old screen. It is to isolate the accounting workflow at a point that can be controlled.

A transition layer instead of a risky rewrite

Export one structured event from the legacy system: transaction ID, customer, amounts, line items, VAT, and other route-required data. The transition layer validates completeness, retains a request copy, and sends it to the invoicing system or approved component. The response returns as a status and identifier on the old transaction.

Operators keep familiar screens, while one control point shows waiting documents, rejections, retries, and order-to-document reconciliation. Also design for transition-layer downtime: queue the event, do not lose it, and do not create it twice when service returns.

Before launch, test ordinary transactions, credit notes, cancellations, new customers, and missing data. The goal is not only to receive a response but to explain every document from the legacy action to the accounting result.

Source

Israel Invoices - Israel Tax Authority