NATS.IO

The evoVIU camera supports native integration with NATS.io, enabling the direct transmission of image data, metadata, or inspection results via lightweight, high-performance messaging channels. This allows the camera to be seamlessly integrated into distributed systems, cloud infrastructures, or edge computing architectures.

Communication is handled via an integrated NATS client component, which publishes messages to predefined topics. At the same time, the camera can subscribe to receive incoming messages, enabling it to process commands or configuration changes from the system. This allows for bidirectional communication between the camera and its environment.

The connection to an NATS server (e.g., nats://nats01:4222) and the desired subjects can be easily configured via the web interface. Messages can be sent in JSON or binary format; JSON offers easy readability, while the binary format is preferable for efficient transmission of large image data.

The NATS connection is designed for low latency and high reliability. Features such as automatic reconnection, heartbeat monitoring, and optional TLS-secured connections ensure stable and secure communication. If needed, messages can be tagged with reply subjects to enable direct response mechanisms (request/reply).

Thanks to this integration, the evoVIU camera can be flexibly integrated into event-driven architectures and scalable IIoT or Industry 4.0 scenarios.

When using NATS.io within evoVIU VISIONWEB, unlike other connection types, the subscription is always created in conjunction with a client. The client first establishes the connection to the desired endpoint. The subscription can then be linked to the client and its endpoint using the "Client Name" parameter.

Connection parameters

Therefore, the client must have the following information to establish a successful and secure connection:

• Client certificate (e.g. .crt, .pem, etc.)

• Root CA certificate (e.g. .crt, .pem, etc.)

• Key file (optional) (.key)

• Key file password (optional, if the key file is encrypted)

The table below shows the data you will need, which you should request from your IT department, for each specific situation.

Notes on the settings

Depending on the NATS server configuration, authentication can be performed using either credentials and/or certificates. The configuration options for this are "Use Credentials Authentication" and "Use Certificate Authentication" (as toggle switches).

When authenticating using certificates, the required files (CA file, certificate file, and key file) can be loaded from the file system. These files must be stored in the file system beforehand.

If the key file is encrypted, the required password can be entered using the "Is Encrypted Key File" toggle and the "Key File Password" input field.

Workflow Setup

Difference between NATS Client and NATS Subscription

The NATS client is used to establish a connection to an NATS server and to send messages to a specific subject (publish). On the other hand, a NATS subscription allows you to receive messages as soon as new data is published to that particular subject.

The VISIONWEB platform allows you to configure any number of clients and subscriptions. For example, image capture, including associated metadata, can be triggered via a subscription and then sent to a desired destination endpoint via a connected client. Simultaneously, status data can be provided via a different client.

Creating the NATS Client - step by step

1. In Workflows, under Components, click the ➕.

2. Search for "NATS Client" and click on the entry to add the component.

3. A new component called "MQTT Client" has been added.

4. Please enter the connection parameters.

The minimum requirements are the client name (for linking with any future subscriptions) and the URL. All other fields are optional and can be used depending on the authentication method.

5. Select the Event Graph tab and open the context menu by right-clicking.

6. Find the "Publish Value" node under Connections and NATS.io, and add it to your workflow to send data.

7. Next, select the component labeled "Get NATS Client" and connect it to the Publish component. Then, enter the desired "Subject" – which is the location where the data will be stored – as provided by the server.

8. Select the variable or data structure you want to send and paste it into the Value wildcard field.

9. If desired, you can have the result of the transfer displayed as a Boolean value to check whether the transfer was successful.

Congratulations! You can now send your data to the desired NATS server.

Creating the NATS Subscription - step by step

Before proceeding with this step, you must first create an NATS client, and a client name (in our example, "nats-evoviu-1") must be defined for linking within the client component. This name can be chosen freely.

1. In Workflows, under Components, click the ➕.

2. Search for "NATS Subscription" and select the entry to add the component.

3. A new component named "NATS Subscription" will appear. You can change this name at any time.

4. Please enter the connection parameters.

The minimum requirements are the client name (for linking with any future subscriptions) and the URL. All other fields are optional and can be used depending on the authentication method.

5. Select the Event Graph tab and open the context menu by right-clicking.

6. Under Events, search for the "NATS Subscription" node and add it to trigger a flow when the subject is updated.

7. Retrieve the data set using the wildcard value and store it directly in the desired variable.

8. Optionally: If you need to send a confirmation of receipt directly to the NATS server, you can use the "Reply Message" node to send the desired information back. This node also allows you to bypass the "Publish Value" node. However, in this case, the reply will be sent to the original sending subject, rather than to a freely selectable subject as with the "Publish Value" node.

9. Optionally: If you want to reply directly to the incoming message using the "Publish Value" node, you can connect the "Reply To" output of the Subscription node directly to the "Subject" input of the "Publish Value" node.

Congratulations! You can now receive data about a subject when changes occur, and use this to trigger a flow.

Using the „Publish“ node

With the "Publish" node, you can flexibly and dynamically send data to any subject in NATS. You can either enter the desired subject directly in the node's parameter field, or have it automatically generated and included in the workflow.

Please ensure that the subject lines are correctly formatted. If you have any doubts, please contact your IT department.

Generally, the following conventions apply to subject lines:

• Simple subjects (direct names) usually consist of a single term:
  mySubject

• Hierarchical subjects consist of tokens separated by periods:
  mySubject.mySub.myData

• Slashes (/) are not used, as in MQTT—only periods (.) are allowed.

• Do not include a trailing period at the end of the subject.

If data is not being sent or received as expected, please check that the subject line is spelled correctly. Incorrect syntax is a common cause of transmission problems.

The value can contain any data as a wildcard. This allows not only metadata and results to be transmitted, but also complete datasets, including images, if needed.

Using the „Value“ node as a Wildcard

With the "Value" node, you can dynamically insert variables or data structures into the message, which are populated during workflow execution. Simply select the desired variable and connect it to the "Value" input of the Publish node. Unlike with MQTT, no conversion to a byte array is required—data structures can be connected directly (after conversion to JSON). The wildcard sockets are marked in gray and accept any data type. This allows you to flexibly generate content at runtime and send it to the configured topic, without being limited to fixed data types.