Agent Core Concepts

The most important concepts implemented in the Agent application and its corresponding Iotellect Server driver:

  • The Agent application maps data provided by hardware into variables, functions, and events of a single context (Agent's context).
  • Iotellect Server creates a Device context that mimics variables, functions and events of context provided by Agent application.
  • All variables (settings) provided by Agent are read and cached on the server side (see synchronization).
  • All control requests (function calls) to Iotellect Server's Device context are directly forwarded to Agent for execution. Replies are sent back to Iotellect Server.
  • Iotellect Server receives and persistently stores all events received from Agent.

Agent Startup

  • When a programmable controller running Iotellect powers up or PC-based Agent application is started, it tries to establish a connection with Iotellect Server.
  • If a connection is established, it completes the login sequence by sending some commands to the server and checking the replies. This involves checking the validity of Iotellect password stored in server-side Device account.
  • After that, the Iotellect Server starts a full synchronization. It reads information about context provided by Agent along with the definitions of its variables, functions and events, synchronizes Agent's real-time clock with the server time and then switches to "normal operation".

    • During normal operation Iotellect Server:

    • Periodically synchronizes variable values between the server and agent contexts;
    • Forward operation requests to Agent and receives execution results;
    • Receives device events from Agent and processes/stores them.

    Normal Iotellect Server Communication Mode

    In this mode, Agent receives commands from Iotellect and processes them. It may also generate some events asynchronously and send them to the server.

    Supported elements of Iotellect Communications Protocol:

    Incoming Messages (from server):

    • Start Message. Processed automatically by Iotellect Server intercommunication module.
    • Operation Message. Parsed and processed by Iotellect Server intercommunication module.

    Outgoing Messages (to server):

    • Event Message. Send to the server asynchronously by Iotellect Server intercommunication module when device-specific code decides to generate and event.

    Replies:

    • Success
    • Denied
    • Error

    All replies are automatically generated by the Iotellect Server intercommunication module. The Denied reply may be returned only if version of Agent is not compatible with Iotellect Server. In such a case Agent will not be able to communicate with the server.

    Operations:

    • Get Variable.
    • Set Variable.
    • Call Function.

    These are automatically handled by the Iotellect Server intercommunication module. If an operation is related to a variable or function defined by the Iotellect Server intercommunication module itself (e.g. synchronization of real-time clock between server and Agent), the corresponding command is automatically processed by this module. Otherwise, command processing is delegated to the device-specific module, which may:

    • Fetch data from a connected device, EEPROM, flash disk, memory or other source and send it to the server (as described below) for a Get Variable operation.
    • Send data to equipment or store it internally in the for a Set Variable operation.
    • Perform data processing or send commands to the connected equipment in for a Call Function operation.

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