Comment by morshu9001 2 days ago
In what ASN1 application is protobuf spec too limited? I've used protobuf for tons of different things, it's always felt right. Though I understand certain encodings of ASN1 can have better performance for specific things.
Numbers bigger than 64-bits, character sets other than Unicode (and ASCII), OIDs, etc.
These are only scalars that you'd encode into bytes. I guess it's slightly annoying that both ends have to agree on how to serialize rather than protobuf itself doing it, but it's not a big enough problem.
Also I don't see special ASN1 support for non-Unicode string encodings, only subsets of Unicode like ascii or printable ascii. It's a big can of worms once you bring in things like Latin-1.
ASN.1 has support for ISO 2022 as well as ASCII and Unicode (ASCII is a subset of Unicode as well as a subset of ISO 2022). (My own nonstandard extensions add a few more (such as TRON character code and packed BCD), and the standard unrestricted character string type can be used if you really need arbitrary character sets.) (Unicode is not a very good character set, anyways.)
Also, DER allows to indicate the type of data within the file (unless you are using implicit types). Protobuf has only a limited case of this (you cannot always identify the types), and it requires different framing for different types. However, DER uses the same framing for all types, and strings are not inherently limited to 2GB by the file format.
Furthermore, there are other non-scalar types as well.
In any of these cases, you do not have to use all of the types (nor do you need to implement all of the types); you only need to use the types that are applicable for your use.
I will continue to use ASN.1; Protobuf is not good enough in my opinion.
To be fair, if you don't need to support anything other than Unicode, then this is not an advantage, and over time we're all going to need non-Unicode less and less. That said I'm a big fan of ASN.1 (see my comment history).
Open types, constrained types, parameterized types, not needing tags, etc.