To interact with EVA ICS node, use HMI service, which provides HTTP (JSON RPC) API
Real-time events can be taken either from a HMI service web socket from a pub/sub server and Replication service connected to it.
Data of a web application can have two parts: public and private.
public placed into EVA_DIR/ui, hosted by HMI service, publicly available.
private placed into EVA_DIR/pvt, hosted by HMI service using Serving private data (PVT) feature.
Structured data parts can be transformed or language-translated on-the-flow. See Serving structured data for more details.
Server Templates can be used to transform other data, such as HTML pages, on the server side.
Robot applications can use API keys to call HTTP RPC methods.
HMI web applications should use user accounts and call HTTP RPC methods with a session tokens.
An application gets a session token using login HTTP RPC method.
The token can be used to call HTTP RPC methods and to subscribe to HMI web socket to receive real-time events.
The token can be switched to read-only mode for security purposes at any time.
After the session is over, login HTTP RPC method must be called to end the session and destroy the authentication token.
It is highly recommended to use both pull (HTTP RPC item.state) and push (web sockets) stategies to handle events. Received events can be compared using ieid field, more recent events always have larger IEIDs.
Handling file uploads
See HMI file uploads.