1## Redfish OEM Resources 2 3The Redfish specification allows for OEM resources and properties to be 4implemented by OEMs. As a general rule, OpenBMC discourages the use of OEM 5namespaces in APIs. In line with this, bmcweb does not expose an API for adding 6OEM properties in a backward API compatible way for resources that have not been 7merged to master. 8 9### Why? 10OEM properties in an open source project pose many problems when compared to 11their closed source brethren in terms of reliability, code reuse, compatibility, 12and maintenance. 13 141. As a general rule, OpenBMCs external Redfish API aims to be as compatible 15 between systems as possible. Adding machine-specific resources, properties, 16 and types largely defeats some of that goal, as clients must implement 17 machine-specific APIs, some of which are likely to overlap, which increases 18 the amount of code overall. OpenBMC also has very little visibility into 19 clients that might interface with Redfish, and therefore needs to take care 20 when adding new, non-standard APIs. 21 222. In practice, OEM resources trend toward a lower level of quality and testing 23 than their spec-driven alternatives, given the lack of available systems to 24 test on, and the limited audience of both producers and consumers. This poses 25 a problem for maintenance in the long run, as it is very difficult to make a 26 breaking change to an external API, given that clients are likely to be 27 implemented in projects that OpenBMC isn't aware of. 28 293. If a given workflow eventually becomes standardized, OpenBMC OEM endpoints 30 now have to break an API boundary to be able to move to the standard 31 implementation. Given the amount of effort it takes to break an API, it is 32 much simpler to wait for the standard to be completed before merging the OEM 33 code to master. 34 354. DMTF has many more Redfish experts than OpenBMC. While the bmcweb 36 maintainers do their best to stay current on the evolving Redfish ecosystem, 37 we have significantly limited scope, knowledge, and influence over the 38 standard when compared to the experts within DMTF. Getting a DMTF opinion 39 almost always leads to positive API design changes up front, which increases 40 the usefulness of the code we write within the industry. 41 42### How? 43 44If you've read the above, and still think an OEM property is warranted, please 45take the following steps. 46 471. Present the new feature and use case to DMTF either through the [Redfish 48 forum](https://www.redfishforum.com), or at a DMTF meeting. If possible, 49 message the new feature through the normal openbmc communications channels to 50 ensure OpenBMC is properly represented in the meeting/forum. 512. If DMTF is interested in the proposal, proceed using their documented process 52 for change requests, and get your schema changes standardized; While OpenBMC 53 does not merge new schemas that have not been ratified by DMTF, feel free to 54 push them to gerrit. If the features are major enough to warrant it, feel 55 free to discuss with maintainers about hosting a branch within gerrit while 56 your DMTF proposal is in progress. If the DMTF feedback is documented as 57 something to the effect of "this use case is unique to OpenBMC", proceed to 58 write an OpenBMC design document about the new feature you intend to 59 implement as OEM, under the OpenBMC (generic to all platforms) OEM namespace. 603. If OpenBMC feedback is that this feature is specific to a single OEM or ODM, 61 and is unlikely to be used across platforms, then maintainers will provide 62 you the option of adding your feature under an OEM/ODM specific namespace. 63 64Regardless of the OEM namespace being used, implementations should plan to 65implement all appropriate CSDL and OpenAPI schemas for their given OEM 66resources, should pass the redfish service validator, and should follow redfish 67API design practices. We require this same level of quality as non OEM to 68ensure that OEM is truly required by the contributor to satisfy their use case. 69If OEM were held to a lesser level of quality requirements, bwcweb would consist 70entirely of OEM code. 71 72bmcweb maintainers retain the final approval on OEM schemas. 73