Semi E125.2

SEMI E125.2 defines a Protocol Buffers (protobuf) encoding for Equipment Self Description — the same data-type, units, valid-range, and sampling-frequency information E125 defines and E125.1 delivers over SOAP, re-expressed as a compact binary protobuf message a host can parse without SOAP's XML envelope and parsing overhead. E125.1 gives EqSD a defined web-service binding inside the existing SOAP-based Interface A ecosystem, but SOAP's XML-over-HTTP overhead is a real cost when a host is discovering self-description data from hundreds of tools at fleet scale — E125.2 is the alternative encoding standard that keeps the same EqSD content but swaps the wire format for one built for machine-to-machine efficiency, the same relationship E120.2's protobuf CEM encoding has to E120.1's XML-schema CEM.

Host needs to discover EqSD data from many tools at scale
SOAP envelope parsing cost adds up across a whole fleet
SEMI E125.2 — Protocol Buffers EqSD encodingSame self-description content, binary wire format
Compact binary message defined by a .proto schema
Smaller payload, faster parse than the equivalent SOAP call
Field-for-field equivalence with E125.1's SOAP response
No information lost moving between encodings
Host discovers equipment capabilities faster at fleet scale
Vendor can publish either binding; EqSD content stays identical

The reason EqSD needed a second encoding standard rather than staying SOAP-only is the same reason CEM needed E120.2 alongside E120.1: a web-services binding that's rigorous and tool-friendly for document-style integration isn't automatically the cheapest format to call repeatedly, and a host rediscovering self-description data for dozens or hundreds of tools benefits from a binary format that skips XML envelope parsing, provided the underlying capability description is exactly equivalent to what the SOAP version carries. E125.2 gives equipment vendors and host developers that same choice EqSD's CEM counterpart already has: publish self-description via E125.1's SOAP binding when existing Interface A web-service tooling matters, or via E125.2's protobuf encoding when discovery speed and payload size matter more, with both representing identical EqSD content either way.

SEMI E125.2 — EqSD Gets the Same Choice CEM Already Has a binary alternative to SOAP, not a competing self-description model E125.1 — SOAP binding WSDL-defined, XML envelope Higher parse/transport cost Fits existing Interface A tooling E125.2 — Protobuf encoding Compact binary, .proto-defined Lower discovery cost at scale Good for fleet-wide discovery Both carry identical data-type/units/range/sampling-frequency content Same E120/E120.1/E120.2 pattern, applied to EqSD instead of CEM

E125.2 completes EqSD's encoding options the same way E120.2 completed CEM's: a fab's host software now has a performance-oriented alternative to the SOAP-based E125.1 binding for exactly the situation where fleet-wide equipment-capability discovery needs to happen fast, without changing anything about what EqSD actually describes.

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