Structured Legal Document Templating & Streaming Generation

In enterprise legal and commerce workflows, generating non-disclosure agreements (NDAs), commercial contracts, legal briefs, and statutory notices represents a core high-frequency requirement. These documents require exacting typesetting control:

• Strict Formatting: Font sizing, indentation, headers/footers, and widow/orphan pagination prevention;
• Security Watermarking: Embedding dynamic diagonal watermarks containing operator names, tenant tokens, and timestamps;
• Streaming Throughput: Large multi-megabyte exports must bypass heap buffer allocation, streaming directly to S3 or HTTP responses.

BitzOrcas.Platform.Documents provides an enterprise-grade document templating and streaming generation engine.

1. Document Pipeline Architecture

The document pipeline comprises four decoupled subsystems:

2. Core Templating Contract: IDocumentGenerator

In BitzOrcas.Platform.Documents.Contracts, the service exposes streaming interfaces:

using System.Collections.Generic;
using System.IO;
using System.Threading;
using System.Threading.Tasks;
using BitzOrcas.Domain.Results;

namespace BitzOrcas.Platform.Documents.Contracts;

/// <summary>
/// Output document format options
/// </summary>
public enum DocumentOutputFormat
{
    Docx = 1,
    Pdf = 2
}

/// <summary>
/// Port contract for structured document generation
/// </summary>
public interface IDocumentGenerator
{
    /// <summary>
    /// Renders the document based on a registered template and parameter dictionary directly to a target stream
    /// </summary>
    /// <param name="templateKey">Unique template token, such as NDA_COMMERCIAL_V2</param>
    /// <param name="parameters">Dictionary of strongly typed replacement tokens</param>
    /// <param name="outputFormat">Target format (Docx or Pdf)</param>
    /// <param name="targetOutputStream">Writable output stream (HTTP Response or S3 stream)</param>
    /// <param name="cancellationToken">Cancellation token</param>
    Task<Result> RenderDocumentStreamAsync(
        string templateKey,
        IReadOnlyDictionary<string, object> parameters,
        DocumentOutputFormat outputFormat,
        Stream targetOutputStream,
        CancellationToken cancellationToken = default);
}

3. Watermarking & Anti-XXE Defense

3.1 Diagonal Translucent Watermark Injection (WatermarkInjector)

For sensitive internal dossiers, the engine renders a diagonal vector watermark across every PDF page:

Watermark Composition Rule: Watermark Text = TenantName + " | " + OperatorName + " (" + EmployeeId + ") | " + Timestamp (UTC+8)

Embedded as native vector paths, the watermark remains permanently legible across both display screenshots and physical paper prints.

3.2 Anti-XXE Parsing Security

Because .docx files are ZIP packages of XML streams, parsing custom uploaded templates presents XML External Entity (XXE) injection risks. BitzOrcas explicitly hardens the XML reader:

var settings = new XmlReaderSettings
{
    DtdProcessing = DtdProcessing.Prohibit, // Physically prohibits DTD processing
    XmlResolver = null                     // Disables external entity resolution
};

4. Related Architecture Decisions & Deep Dives

• Object Storage: MinIO & S3 Compatible Object Storage
• Connectors: Legal Connectors & Judicial Integration
• ADR Reference: ADR 0002: Production Readiness & Quality Gates