Composable protocols represent another alternative approach. The functionality of protocols and complete protocol stacks can be split into single protocol functions, and a pool of these functions may then be used to construct customized protocol stacks during boot time. Various projects have been initiated to explore and implement this principle of composable protocols,
one of them being ‘DaCaPo’.DaCaPo is a public domain framework that implements protocol configuration during
runtime rather than during compilation. The intention of this framework is to create customized protocols that provide the QoS parameters necessary for the current/ intended connection. Only three layers are defined within the
DaCaPo framework:

• layer A – the application layer
• layer C – communication support layer
• layer T – the transport infrastructure layer

While layers A and T, the adaptation layers, are dependent on the applications and underlying transport mechanisms (e.g. ATM, LAN, MAC, etc.), respectively, layer C is the configurable/ composable protocol layer. It is comprised of agglomerated granular protocol building blocks, each defining a single protocol task.The DaCaPo framework uses four cooperating entities to control messaging between these
building blocks and binding them (i.e. binding them into protocol components) within the Clayer.
The four entities include :

• CoRA (a method for configuration and resource allocation) – determining appropriate protocol configurations at runtime;
• Connection management – controlling establishment, error management, and release of connections to peers;
• a runtime environment coordinating execution (linking, initiation, packet forwarding) of the processing within the layer;
• an entity to monitor the other components and control the resource availability within the communication end systems (i.e. message originator and message sink).

Although developed to implement complete protocol stacks, DaCaPo tackles reconfiguration and customization within protocols during implementation/boot time.

see also :

"Design of Generic and Adaptive Protocol Software (DGAPS)"

"Design, Implementation and Validation of a generic and reconfigurable Protocol Stack Framework for mobile Terminals"