Definition: An API (application programming interface) is a clearly defined interface through which a software system makes data or functions available to other systems. The API defines which requests are permitted, in which format data is transferred and how a calling system authenticates itself. On the web, these are usually HTTP interfaces with JSON as the data format.

In B2B mechanical engineering, APIs connect 3D content with the systems in which product knowledge is created: ERP (items, prices, availability), PIM (product data, texts, variants), CAD/PLM (geometry, bills of materials) and CRM (customers, quotes, leads). This way, 3D models, configurators and AR applications automatically stay up to date with the master data.

Advantage: You maintain data once and use it in all channels, instead of copying it manually.

English: API (Application Programming Interface)
German: Programmierschnittstelle, Schnittstelle

How It Works

Request and response

With a web API, each call follows the same pattern:

  1. The client sends a request: for example "Give me all variants of machine X" to a defined address (endpoint).
  2. The server checks the authorization: API keys or tokens show who sends the request and what they are permitted to do.
  3. The server processes the request: it reads data from the database or starts an action.
  4. The server responds: with a status code (for example 200 for success, 404 for "not found") and data, usually in JSON format.

A contract instead of an agreement

An API is a contract between systems. As long as both sides follow the description, they can be developed independently of each other. Formal descriptions such as the OpenAPI Specification make this contract machine-readable: you can generate documentation, test tools and client code from it.

API Architectures Compared

REST

REST (Representational State Transfer) is the most common style for web APIs. Data is represented as resources with their own URL, for example /maschinen/123/varianten. HTTP methods describe the action: GET reads, POST creates, PUT or PATCH changes, DELETE deletes.

Strength: Simple, easy to cache, supported by almost every system.

GraphQL

With GraphQL, the client requests exactly the fields that it needs, also across several linked objects, in one single request. For a 3D configurator, this can mean: machine, options, prices and model URLs in one call.

Strength: Fewer requests, no unnecessary data. Effort: Caching and access control are more complex than with REST.

Webhooks

Webhooks reverse the direction: instead of asking regularly ("Did something change?"), the source system actively reports an event with an HTTP call to a stored address. Example: someone changes a product description in the PIM, and the webhook starts the update in the 3D viewer.

Important: Webhook receivers should check the signature of the message (usually with HMAC), so that they process only real events.

Approach Direction Typical use
REST Client sends a request Read and write master data
GraphQL Client sends a targeted request Front ends with a lot of linked data
Webhooks Server reports an event Synchronization when data changes

Integration Patterns for 3D Content

Point-to-point

Each application communicates directly with each source system. This is fast to implement, but becomes confusing with many systems: when the ERP interface changes, all connected applications must change too.

Central integration layer

A middleware or integration platform collects data from ERP, PIM, CAD and CRM, standardizes it and makes it available through its own API. The web viewer, the kiosk application and the AR app access only this layer. You adapt changes in a source system in one location.

Event-driven

Systems publish changes as events (through webhooks or message brokers), and the applications that need them react to them. This decouples the systems in time and is especially suitable for the synchronization of large product portfolios.

In practice: Many companies combine the patterns, for example a central layer for master data and events for changes to CAD versions.

B2B Applications

Sales: configurator with live data

A 3D product configurator shows a packaging machine in the browser. Prices and delivery times come through the ERP API, option texts through the PIM API. When the configuration is complete, a CRM API automatically creates a quote or a lead. In the CRM, sales sees which variant the customer selected.

Trade show: control content centrally

Kiosk terminals, tablets and screens on the booth get their 3D content through an API from a central system. You maintain new exhibits or changed texts once, and they appear on all devices. Visitor contacts from the kiosk application go directly into the CRM through an API.

Service: spare parts in the 3D model

A technician selects a component in the 3D model of a CNC milling machine. With the component ID, the application gets the item number, stock level and price from the ERP and creates an order when necessary. This works on the web, on the tablet and in an augmented reality view with the same interface.

Training: report training data back

VR or web training sessions report results (completed modules, errors, duration) through an API to the learning management system or the HR department. This way, you can prove who received training on which machine.

Design review: take over the CAD version automatically

When a new design version is released in the PLM system, a webhook starts the conversion in the 3D pipeline. The review team always sees the current version in the browser or in virtual reality, without sending files by email.

Security and Operation

  • Authentication: API keys for simple server-to-server connections, OAuth 2.0 with short-lived tokens for access on behalf of users.
  • Minimum rights: A configurator needs read access to prices, but no write access to the ERP.
  • Encryption: Transfer only through HTTPS (TLS).
  • Rate limiting: Servers limit the requests per time period and respond with status code 429 when the limit is exceeded.
  • Versioning: New API versions run in parallel with the old version, so that existing integrations do not break.
  • Data security and data privacy: Share original CAD data and customer data only as far as the use case requires.

Frequently Asked Questions (FAQ)

What is the difference between an API and an interface?

In German, the two terms are often used as synonyms. Strictly speaking, "interface" is the general term, also for hardware or file exchange. An API is an interface between programs with defined calls and data formats.

REST or GraphQL: which is better for 3D applications?

REST is sufficient for most integrations and ERP and PIM systems support it widely. GraphQL is worth it when a front end needs a lot of linked data from several sources, for example a configurator with options, dependencies and prices. You can combine both.

Are the 3D models themselves transferred through the API?

Usually not directly. The API supplies metadata and an address from which the application gets the model file (for example glTF or USDZ), often through a content delivery network. This way, API responses stay small and the models are cached efficiently.

When do I need webhooks instead of regular queries?

When changes must arrive quickly and occur rarely. Regular queries (polling) cause a high load, although usually nothing has changed. Webhooks report only real events. For reliability, the receiver should still be able to compare missed events later.

What should good API documentation contain?

A machine-readable description (for example OpenAPI), examples of typical calls, an explanation of the authentication, error codes, rate limits and an overview of the versions with their changes. A test environment (sandbox) makes the integration much easier for IT teams.

Industry Standards and Technologies

Integration: - ERP – Enterprise resource planning and master data - PIM – Product information management - PLM / CAD – Design data - CRM – Customer relationships - Middleware – Layer between systems

API technologies: - REST – Resource-based web APIs - GraphQL – Query language for APIs - Webhooks – Event notification - JSON – Data format - OAuth 2.0 – Authorization - API gateway – Central control of access

3D content: - 3D model – Geometric basis - 3D pipeline – From CAD to real-time 3D - 3D product configurators – Configuration in the browser - WebGL – 3D in the browser - USDZ – 3D format for Apple platforms - OBJ – Simple exchange format

Connected systems: - IoT – Connected machines - Digital twin – Digital copy of a machine - OPC UA – Industrial data exchange

Security: - Data security – Protection of data and systems - Data privacy – Handling of personal data