The SAI APIs available in the SAI headers are the function pointers which are registered with the silicon vendor-specific APIs. This vendor specific APIs implementation is the SAI adapter for SDK. SAI adapter consists of the actual glue logic between standard network feature and vendor specific feature. The user can provide the attribute-value pairs to configure particular feature.
SAI project is driven by the Open Compute Project (OCP) and rapidly adapted in the networking industry. The Major switch silicon vendors like Cavium, Barefoot, Broadcom, Mellanox, Marvell, Centec etc. are the contributors in SAI community.