Connectivity Framework
3: Connectivity Reference Architecture
To keep the connectivity architecture manageable, a connectivity technology standard is chosen as the baseline within a functional domain, and referred to as the“ connectivity core standard”( see Figure 3-2). Gateways are used to bridge other connectivity technologies within the domain and to the connectivity core standards used in other functional domains. Connectivity between functional domains, often implemented in a tiered manner, can be intermittent. Connectivity gateways can help mitigate this intermittent connectivity. Applications are simpler and easier to maintain if logic is not needed to react to failed data exchanges.
As shown in Figure 3-2, some endpoints can connect directly to a core standard. Other endpoints and subsystems connect through gateways. A core standard then connects them all together, allowing multiple connectivity technologies to be integrated without having to bridge between all possible pairs, so avoiding the dreaded N-squared bridging problem( see Figure 3-1). Each domain-specific connectivity technology needs only a gateway to just one connectivity core standard.
Connectivity gateways enable incorporation of new connectivity technologies. They provide a stable foundation anchored in the“ best-of-breed” technologies available today, yet can pivot in the future to a new baseline core standard that better satisfies the requirements.
There are several kinds of connectivity gateways:
• Framework gateways expand the logical span of communications across connectivity framework technologies. They preserve the syntactic structure of data, but may change the technical representation.
• Transport gateways expand the logical span of communications across transport technologies. They do not make any logical changes to the byte sequence( payload) and are transparent to it.
• Physical / link / network gateways convert the communications between different physical, link, and networking technologies.
In practice, connectivity gateways may span multiple layers of the connectivity stack( see Figure 2-1).
3.3 CORE GATEWAYS
Using a gateway to a core connectivity standard, a domain-specific endpoint can communicate with endpoints on other domain-specific technologies also connected via gateways to the core connectivity standard( see Figure 3-2). Core connectivity endpoints can directly communicate with each other, and via gateways with domain-specific connectivity endpoints.
Different functional domains may have different choices of core connectivity standards, due to different priorities on technical requirements, tradeoffs and ecosystems. To enable communication between different connectivity core standards, standardized gateways are needed. A standardized gateway between core connectivity standards is referred to as a core gateway. It allows domain-specific endpoints connected to one core standard to communicate with domain-specific endpoints integrated over another core standard, as shown in Figure 3-3. Also, it allows endpoints on the two core connectivity standards to interoperate.
IIC: PUB: G5: V1.0: PB: 20170228- 23-