RPC Protocol

JTL-Connector uses a protocol similar to JSON-RPC, along with some vendor-specific modifications. To fully understand how an endpoint works, at least a basic understanding of its function is required.

As stated earlier, JTL-Connector follows the MVC (Model-View-Controller) pattern. The Core library provides both models and view logic. JTL-Connector’s view logic is represented by the layer that provides the RPC protocol implementation we are using.

The models are PHP versions of the domain objects inside JTL-Wawi. They must stay compatible for JTL-Connector to work properly with JTL-Wawi.

Protocol versioning

Data structure changes inside Core are likely to happen in future. These modifications become necessary when new functionality is being introduced or existing functionality changes its behaviour in a way that breaks backwards compatibility (BC). To detect incompatibilities between the version of JTL-Wawi and the models used by the running endpoint, a supported protocol version is set by the Core. The protocol version sent by the endpoint is verified from JTL-Wawi. An error message appears in JTL-Wawi and the synchronization process is aborted in case the versions do not match.


The Core is updated regularly. You can (and should) follow its development, to be informed about updates that break BC.

Data models

All models used by JTL-Connector stay inside the Jtl\Connector\Core\Model namespace. Refer to their source code to learn about the data they supply. Each RPC call transports a hierarchy of data objects that belong together.

Some of these data objects have a special position throughout communication. Those objects (called main objects) are not only data objects, they are also used as RPC objects, i.e. they are being used in RPC calls. The main objects are:

  • Category
  • Customer
  • CustomerOrder
  • CrossSelling
  • DeliveryNote
  • GlobalData
  • Image
  • Manufacturer
  • Payment
  • Product
  • Specific

The following additional RPC objects cover special functionality, although they are not considered as main objects:

  • Connector
  • ProductPrice
  • ProductStockLevel
  • StatusChange