SAP-DocuSign Integration Framework

The Problem

Enterprise approval workflows are slow. Purchase orders sit in inboxes waiting for signatures. Approvers are traveling or in meetings. Paper gets lost. Audit trails are incomplete.

Companies using SAP for procurement face a specific challenge: how do you connect a mature (often decades-old) ERP system to modern eSignature platforms like DocuSign?

The typical pain points:

• Manual approval processes that take days instead of hours
• No mobile capability—approvers must be at their desk
• Incomplete audit trails for compliance
• No visibility into where documents are stuck
• Goods receipts processed before approval (compliance risk)

The Solution

A complete integration framework that connects SAP ECC to DocuSign eSignature, enabling automated approval workflows with full audit compliance.

Core Capabilities

• OAuth 2.0 Authentication — Both Authorization Code Grant and JWT Bearer Grant supported, with automatic token refresh
• Envelope Management — Create, send, and track signature envelopes directly from SAP
• Real-time Webhooks — Instant notification when documents are viewed, signed, or declined via DocuSign Connect
• Sequential Approval — Support for multi-level approval chains (Release Strategy integration)
• GR Blocking — Automatically block goods receipt until all approvals complete
• Full Audit Trail — Every action logged with timestamps, users, and status changes

Architecture

The solution follows a clean separation of concerns: a reusable core API package (Z_DS_API) that handles all DocuSign communication, and business-specific implementations (Z_MM_DS_INT) that define the workflows.

Package Structure

Z_DS_API/                    # Core DocuSign API package
├── ZCL_DS_API              # Main API class (OAuth, envelopes, documents)
├── ZCL_DS_WEBHOOK          # Webhook processor (XML parsing, HMAC)
├── ZIF_DS_CALLBACK         # Interface for business callbacks
└── Database Tables         # Configuration, envelope tracking, audit logs

Z_MM_DS_INT/                 # Business integration package
├── ZCL_PO_PDF_GENERATOR    # SmartForm-based PDF generation
├── ZCL_PO_REL_DS_CALLBACK  # PO release callback implementation
├── ZCL_IM_ME_PO_DS_REL     # BADI for ME21N integration
└── ZCL_IM_MB_DOC_DS_CHECK  # BADI for GR blocking

Technical Highlights

OAuth 2.0 Implementation

Full OAuth 2.0 support with automatic token lifecycle management. The system handles initial authorization, token storage, and automatic refresh before expiration—no manual intervention required.

• Authorization Code Grant (recommended for user-context operations)
• JWT Bearer Grant (for server-to-server automation)
• Secure token storage in SAP database
• Automatic refresh 5 minutes before expiration

Webhook Processing

Real-time event processing via DocuSign Connect with full security validation:

• HMAC-SHA256 signature validation on every request
• Idempotent processing (handles duplicate deliveries)
• Event routing based on registered application callbacks
• Complete audit logging of all webhook events

Callback Architecture

The ZIF_DS_CALLBACK interface enables clean separation between the API layer and business logic. New integrations simply implement the interface and register with the framework:

• on_sent() — Envelope sent to signer
• on_delivered() — Signer received the document
• on_completed() — All signatures collected
• on_declined() — Signer declined to sign
• on_voided() — Envelope voided by sender

Business Application: PO Approval

The framework was applied to Purchase Order approval workflows with the following flow:

1. User creates PO in ME21N
2. BADI triggers envelope creation based on release strategy
3. PDF generated via SmartForm with signature anchor text
4. Envelope sent to first approver via DocuSign
5. Sequential routing to additional approvers
6. Webhook receives completion notification
7. Callback triggers BAPI_PO_RELEASE
8. GR block removed, PO fully released

Results

• Approval time reduced from days to hours — Mobile-enabled signing means approvers respond faster
• Complete audit trail — Every signature, timestamp, and status change logged
• Compliance enforcement — GR blocking ensures no receipt before approval
• Reusable framework — Same architecture can support contracts, invoices, any document workflow

Technologies