Device Servers, Device Server Accounts and External Device Servers Accounts

Below we will cover the difference between hardware Device Servers, Device Server Accounts and External Device Servers. These terms are widely used throughout the manual, and it's important to form a clear distinction between them at this point.

The first term refers to a piece of hardware. The latter two terms refer to logical parts of LinkServer software.

It's important to understand that a single hardware Device Server may be treated by AggreGate as a normal Device Server (i.e, one with a Device Server Account) and also as external (i.e. one with an External Device Server Account) at the same time. A hardware Device Server may be configured to work with LinkServer as a normal Device Server, and log in to the server on power-up, but if LinkServer detects it while broadcasting for External Device Servers, an External Device Server Account is automatically created for it.

A Hardware Device Server is referred as a "Device Server" in most parts of this manual. It is a hardware device that is used to connect Data Terminals to the LinkServer. A hardware Device Server may be physically implemented as a separate device, or embedded into the design of a Data Terminal and placed on its printed circuit board (PCB). When the Device Server is a dedicated hardware device, it is usually connected to a Data Terminal using an RS-232, ZigBee or WiFi link. When the Device Server is embedded, communication between Device Server IC and main IC of the Data Terminal is performed by a serial interface.

In an AggreGate Agent, the Device Server and Data Terminal are unified, both physically and logically. In this case, Device Server the logic is implemented by a custom application that runs in the programmable IC. Another part of the same application implements logic of the Data Terminal itself.

When a hardware Device Server connects to LinkServer and tries to log in, the server checks if a corresponding Device Server Account exists and is not blocked.

A Device Server Account is a special LinkServer context that contains information about a single hardware Device Server that may connect to LinkServer. This account defines the password that should be used the by the hardware Device Server to log in, the Data Transfer/Device Plugin that will process data received from the hardware Device Server and some other options.

It is technically possible to create a Device Server Account that does not match any hardware Device Server. Such accounts may be used for testing, debugging, etc.

In contrast to External Device Server Accounts, normal Device Server Accounts are used to "accept" connections of hardware Device Servers. Every hardware Device Server that is supposed to connect to the LinkServer and exchange data with it should have a corresponding Device Server Account.

The primary purpose of External Device Server Accounts is to allow LinkServer to access hardware Device Servers that are not configured to connect to the LinkServer themselves. In most cases, this is necessary during initial configuration of new hardware Device Servers that were just plugged in to the network and powered up.

The difference between account types is that External Device Server Accounts are used by LinkServer to initiate outgoing connections to any local hardware Device Servers, while normal accounts allow LinkServer to accept incoming connections from "known" hardware Device Servers.

Every External Device Server Account contains information about the IP or MAC address of a corresponding Device Server, the communication method used to access it and some other connection-related information.

During day-to-day use of LinkServer, External Device Server Accounts are used to perform initial configuration of hardware Device Server so they'd work with LinkServer (i.e, connect to it on startup). When a hardware Device Server is properly configured and connected to the LinkServer, a normal Device Server account should be used to manage it.

To simplify things, External Device Server Accounts are referred simply as "External Device Servers" in this manual.