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Comment by memling | Hacker News Reader

> Why would you need a support SLA for ASN.1 and not for PB/FB? That makes no sense. And there's plenty of open source ASN.1 tooling now -- just look around this thread!

If your business depends on five nines plus of reliability in your 5g communications stack, you might be willing to fork over the price for it. Or if you need a bug fix made in a timely fashion to the compiker or runtime, likewise. As I've noted above, a client of mine moved to a commercial suite of tools for this reason.

Protobuf and flatbuffers have different use cases in my experience, although that's somewhat limited. Protobuf at least also introduced breaking changes between versions 2 and 3. ASN.1 isn't perfect in this regard, but these days incompatibikities have to go through ISO or ITU, etc.

Your experience may be different of course. I'm just pointing out that there are reasons people will opt for a commercial product.

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> Protobuf and flatbuffers have different use cases in my experience, although that's somewhat limited.

This is true for the ASN.1 encoding rules as well.

> Protobuf at least also introduced breaking changes between versions 2 and 3. ASN.1 isn't perfect in this regard,

When has ASN.1 ever broken backwards compatibility? I've never heard of an ASN.1 backwards incompatibility. Maybe, if you stretch an interpretation of ASN.1 in 1984 to allow new fields to be added to `SEQUENCE { }` then the later addition of extensibility markers could count as a very weak backwards-incompatible change -- weak in that existing specs that use ASN.1 had to add those markers to `SEQUENCE { }`s that were actually intended to be extensible, but no running code was actually broken. I would be shocked if the ITU-T broke backwards compat for running code.

> When has ASN.1 ever broken backwards compatibility? I've never heard of an ASN.1 backwards incompatibility. Maybe, if you stretch an interpretation of ASN.1 in 1984 to allow new fields to be added to `SEQUENCE { }` then the later addition of extensibility markers could count as a very weak backwards-incompatible change -- weak in that existing specs that use ASN.1 had to add those markers to `SEQUENCE { }`s that were actually intended to be extensible, but no running code was actually broken. I would be shocked if the ITU-T broke backwards compat for running code.

Good question. I was thinking of the transitions in the '80s, although my experience with standards written during that time is very limited.

But yes, one of the reasons people use ASN.1 is because of its hard and fast commitments to backwards compatibility.

> But yes, one of the reasons people use ASN.1 is because of its hard and fast commitments to backwards compatibility.

To be fair I think that's generally expected of things like it. XDR? Stable. DCE/RPC? Obsolete, yes, but stable. MSRPC? A derivative of DCE/RPC, and yes, stable. XML? Stable. JSON? Stable. And so on. All of them stable. If PB broke backwards-compat once then to me that's a very serious problem -- details?

> If PB broke backwards-compat once then to me that's a very serious problem -- details?

Proto2 and Proto3 differ in how they handle default and required elements. Regarding these differences, I found a few references online:

    https://softwareengineering.stackexchange.com/questions/350443/why-protobuf-3-made-all-fields-on-the-messages-optional    

    https://groups.google.com/g/protobuf/c/Pezwn5UYZss

    https://www.hackingnote.com/en/versus/proto2-vs-proto3/

I don't use protobuf regularly, and they claim that the wire formats are bidirectionally compatible. When I last evaluated them with another developer years ago, I don't recall this being the case. (It was not merely a difference between their syntaxes.) I'm not sure the semantics are preserved between the two versions, either (e.g., did I provide a default value? was this element optional and missing? etc.).

They have lately (this is news to me) moved to protobuf editions: https://protobuf.dev/editions/overview/. This provides some flexibility in the code generation and may require some maintenance on the part of the user to ensure that codec behavior remains consistent. Google, for their part, are trying to minimize these disruptions:

> When the subsequent editions are released, default behaviors for features may change. You can have Prototiller do a no-op transformation of your .proto file or you can choose to accept some or all of the new behaviors. Editions are planned to be released roughly once a year.

> five nines

Does one pay for an SLA for every piece of hardware, firmware, and software? The codecs are the least likely cause of downtime.

> Does one pay for an SLA for every piece of hardware, firmware, and software? The codecs are the least likely cause of downtime.

I don't recall saying that—just that I have had clients for whom the support was sufficiently important (because of their own reliability concerns) that they went commercial instead of open source. (They required, among other things, 24x7 support and dedicated resources to fix bugs when found; they also sought guarantees on turn-around time.)

Fair enough.

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