Messages, Connected devices, and Disconnected devices

The Questra Enterprise Server communicates with an intelligent device by way of messages. For example, it may issue a message to a device requesting it to perform a particular operation or to run a particular diagnostic test. Once the device performs the requested operation, it returns the results of the operation to the Enterprise Server in another message.

How messages are exchanged between the Enterprise server and a device depends on whether the device is connected or disconnected.

A connected device is one that is network-accessible, and it may or may not be directly contactable on its network:

• Contactable device – Contactable connected devices are those whose network configuration allows the Enterprise Server to communicate directly with the Service Agents installed on them. A simple example, albeit an uncommon one due to typical Internet network topology (firewalls, proxy servers, etc.), is a device accessible via a virtual private network (VPN).

• Non-contactable device – In most cases, the Enterprise Server cannot directly communicate with a connected device, but the device (actually, its Service Agent) can initiate communication with the Enterprise Server. For example, consider a network-accessible copier on a company’s local area network sitting behind a corporate firewall. The Enterprise Server cannot penetrate the firewall into the local network, but the device can send messages through the firewall out to the Internet. In this situation, the Enterprise Server queues its request messages, waiting for the copier to initiate contact. Later, the copier collects the request messages, performs the requested operations, and sends back the results. In this manner, communication between server and the device is asynchronous.

In many circumstances, devices may not be network-accessible at all, despite being capable of connection. A disconnected device may be a standalone device or be connected only to a local area network that is not Internet-accessible. Examples include devices that are located outdoors (such as building ventilation equipment) and those that are frequently moved (such as medical carts or patient beds).

Because messages cannot be exchanged between the Enterprise Server and disconnected devices, messages are handled through site visits. A user with the appropriate permission can use SoftwareCourier feature of the Questra IDM Application Suite to create and assign one or more "site visits" to a field service technician. The technician, using the Questra Courier application, delivers those messages on site to the disconnected devices and retrieves Enterprise-bound messages from them. For more information on the SoftwareCourier feature of the Questra IDM Application Suite, see Site Visits.