Concept of Message exchange

The main purpose of the agrirouter platform is to exchange messages between endpoints.

The agrirouter provides a mechanism to receive and forward messages according to a combination of app subscriptions, public or direct addressed messaging and routings configured by the end-user.

Messages can be directly addressed to one or more endpoints. They can also be published to send the message to all subscribed endpoints. It is remarked in the message header if the message is directly sent, published, or if both techniques shall be used. agrirouter will take care of not delivering a message twice to the same endpoint.

After onboarding, every endpoint can send commands to the agrirouter inbox. agrirouter forwards and potentially duplicates the included messages to store them in the feed of the relevant target endpoint(s).

The feed is the time limited storage for messages in each endpoint.

All messages in agrirouter connectivity platform have a retention time of maximum 4 weeks in total before they are deleted. The end-user will be informed about a possible data loss after 3 weeks, so that he has time to react. After an application instance received and confirmed the receipt, the message will be deleted from the agrirouter feed storage.

Every registered endpoint can request the list of messages available in his feed and request specific messages. agrirouter forwards those requested messages to the outbox, delivery to the endpoint depends on the protocol.

EXAMPLE

The following example shall describe the terms and the way of a message through agrirouter.

Every message or command sent to or received from agrirouter consists of a Message header and a payload.

The technical message type describes the type (e.g. the format) of the content of an agrirouter message. Every endpoint capable of sending such a message declares that it is able to create a valid message of such type. Every endpoint capable of receiving such a message declares that it can interpret that message.

Information types are an abstraction of the technical message types to simplify the setting up of routings.

One technical message type can be part of multiple Information types.

Each technical message type must be assigned to an information type, which represents its meaning and purpose. The technical message types Bitmap, PNG and JPEG for example are summarized as Information Type "Image". This means that endpoints can send Bitmaps, PNGs and JPEGs if a routing for Images exists.

Technical message types are defined by groups outside the agrirouter project. If message types are missing, DKE will add a useful standardized message type. DKE however will not standardize any formats.

An information type is a group of technical message types.

The agrirouter message payload has a technical message type, which is indicated on the envelope. The list of technical message types can be found here. The definition of a new technical message type is possible.

Each endpoint has to describe, which technical message types it can send and/or receive. The listing of those technical message types is called capabilities. Each endpoint has to provide its capabilities when starting to communicate with the agrirouter. The capabilities, an endpoint generally supports (e.g. with all optional features enabled) is required for the Certification.

As a sender of a message (e.g. an EFDI Telemetry message) does not always know the relevant endpoints, he can send the message as a published message. Every other endpoint can subscribe to any message type that is part of its capabilities.

Before sending the Subscription message, the endpoint has to send the Capabilities message

The steps for this – in general nd with given routings – are: