|
The EIB protocol's second toolkit consists of broadcast and point-to-point services and procedures.
These allow the management of:
- network resources;
- device- and application-resources.
EIB supports both connectionless and (transport-layer) connection-oriented point-to-point services.
(Note: from an implementation point of view, EIB broadcast services are more closely related to the run-time group communication mechanisms; their semantics and usage clearly put them in the management toolbox.)
network resources
EIB network resources are mainly identifiers such unique domain and network addresses of individual nodes, group addresses for multicast binding etc. Of course they are stored in the devices, but they are subject to uniqueness or other global consistency constraints; as a consequence, they may be considered to be public resources, owned by the network as a whole, rather than by the device itself.
device- and application-resources
These are local, private resources (parameters) which tune the behaviour of an individual device towards the network, or of it's run-time application functionality.
client-server model
In contrast to the purely peer-to-peer group communication, management operations are asymmetrical, and have a clear master initiating a transaction, and a slave responding to it and carrying it out.
The role of some particular device, say as client (master), holds for a particular transaction. The same device may well be the server (slave) in other transaction it takes part in.
In most cases though, the client device will be a (single) PC or "configuration master" (or "controller") device, with the rest of the devices in the installation acting as servers (!).
managing resources - management toolbox summary
So the bottom line of EIB management is remote access (read / write) to resources – say, properties - stored in the device. To accommodate various needs, EIB permits the following alternatives:
- special properties are accessed via dedicated services; a "modal" property may be accessed via broadcast services, targeting only those devices which are in a special receive mode (referred to as "programming" mode); in the standard EIB configuration approach, a device is brought into programming mode by pressing a button, after which the physical address resource may be set; a node's mask type identifier is an example a resource which is read from a device via point-to-point communication;
- properties of interface objects: interface objects are general-purpose data structures which may be referenced via an object identifier in the device; they contain a set of properties, each of which may store an array of values; regarded abstractly, these properties are addressed as <node>.<object>.<property>(.<element>);
- formatted streams are used to download binary "file" data into the device (in its basic form, this corresponds to device-specific direct memory access or DMA.).
standard system resources and profiles
EIB standardises system resources, including al network resources plus binding indirection tables and node capability descriptors needed for discovery and configuration.
The specification fixes the access type of the resource properties (special, interface object, stream, …) as well as their encoding and data type. For composite resources (interface objects and stream objects), the overall container structure is also laid down.
Sometimes the developer is given the choice between different flavours of the same abstract object. System unity is maintained by fixing a limited set of allowed profiles, and defining a corresponding discovery procedure.
node identification
An EIB node is uniquely identified in its local network environment via its individual "physical" address.
Optionally, devices may have a globally unique serial number assigned ex factory, providing an alternative handle to set its physical address.
device capability descriptors & discovery procedures
Via a special device descriptor property, sometimes combined with descriptive interface objects, a device's communication partners on the EIB network may find out or discover its system profile and application capabilities.
security
If necessary, the security of an installation may be increased by using EIB's authentication mechanisms to protect certain properties from unwanted access.
loadable applets
As an interesting option, with EIB you can download the executable "applet" code to a device at configuration time. The same device may thus be equipped with different application functionality, according to the installation needs.
Via the ETS product database, EIB provides a standard, manufacturer-independent repository for such application libraries.
| 
