Architecture

Zentto Digital Print is implemented as the zentto-imprenta-seniat microservice (Node/Express + TypeScript + PostgreSQL), acting as a fiscal issuance gateway. The client system (ERP, POS or an integrator) builds a canonical document and sends it to the gateway; Zentto generates the NCF-D control number from its own series, chains the record with a SHA-256 hash and persists the result.

Components

Component	Description
Client system (ERP / POS / Integrator)	Builds the canonical document and consumes the gateway. Persists the control number and lookup data.
Gateway /v1/fiscal/gateway	Fiscal operations layer: ping, emit, status, download, annul, numbering/assign, numbering/query. Authenticated by X-API-Key (internal channel).
Domain /v1/imprenta	Web vertical API: dashboard, branches, billing points, numberings, assignments, documents, reports, users, audit, configuration. JWT from zentto-auth.
Backoffice /v1/imprenta/backoffice	Administers own series, metering (billable consumption), tariffs, integrators, distributors and commissions.
Integrator API /api/*	Public API for third parties: tokenUsuario+secret → short JWT; issuance against own series.
In-house generation (provider propio)	Assigns the NCF-D locally from imprenta."ControlSerie", chains with SHA-256 and records the billable event in imprenta."ConsumoControl".
SENIAT endpoints /seniat/*	Read-only lookup (by NCF-D, listing, sales book) protected with X-Seniat-Key.
Transmission queue	fiscal."SeniatDispatch" — exponential backoff retry (fn_backoff_next) to SENIAT.

Design principles

• In-house control-number generation. Zentto assigns the NCF-D from internal series, with an atomic counter (SELECT ... FOR UPDATE), gap-free and collision-free under concurrency.
• Chained integrity. Each document stores the hash of the previous record of the same issuer RIF (SHA-256 hash-chain), forming an end-to-end verifiable chain.
• Isolation. The microservice has its own database (schemas fiscal, imprenta, audit, ops) and own domain (imprenta.zentto.net). If it is down, the ERP keeps operating.
• Multi-tenant. Series are assigned per client company (CompanyId); the backoffice manages series and consumption for all companies.
• Non-blocking. Unavailability never blocks the sale: the document is queued and a worker retries with backoff.

Issuance layer

Issuance implements the FiscalProvider interface with ping, emit, getStatus, download, annul, assignNumbering and queryNumbering. The client sends a canonical document (CanonicalDocument) and Zentto translates it to its internal model.

In in-house mode (provider propio):

1. emit invokes imprenta.fn_assign_control_serie(companyId, documentType, serie), which takes the next number of the active series with a row lock (FOR UPDATE).
2. The SHA-256 hash is computed, chained to the previous hash of the issuer RIF.
3. A billable event is inserted into imprenta."ConsumoControl" (metering).
4. controlNumber is returned and documentos.service persists the document.

Business model

Zentto charges the client company by the number of control numbers issued (metering), with per-number or per-block tariffs. Consumption is measured in imprenta."ConsumoControl" and billed from the backoffice.

Database schemas

Schema	Main tables	Use
fiscal	NcfdSequence, DigitalInvoice, SeniatDispatch	NCF-D sequence, document store with hash-chain, transmission queue.
imprenta	ControlSerie, ConsumoControl, TarifaPlan, Integrador, IntegradorCredential, Distribuidor, DistribuidorCartera, ComisionPlan, ComisionLiquidacion, Documento, Sucursal, PuntoFacturacion	Print business domain.
audit	AuditLog	Operations audit trail.
ops	Config, Tenant	Runtime config and company registry.