Deprecate Max_fee and Suggested_fee_multiplier in the ConstructionPreprocessRequest endpoint

[jingweicb]

Deprecate two fields in the ConstructionPreprocessRequest endpoint

The ConstructionPreprocessRequest endpoint includes the max_fee and suggested_fee_multiplier fields, which are optional. Coinbase is looking to remove these fields from the ConstructionPreprocessRequest endpoint.

Why we want to remove it

In our current workflow, we configure these two fields ourselves, instead of using values from Rosetta. As a result, these two fields add unnecessary complexity for Asset Issuers (AIs) and Coinbase.

Situation 1: AIs provide a max_fee that is lower than the current network fee. Rosetta may refuse the transactions, or the transactions will take a long time to be confirmed. This issue adds complexity.

Situation 2: In order to pass the check:construction test, AIs may give the suggested_fee_multiplier value a high number. This will make our TXs fee unnecessary higher, which may lead to money loss for both Coinbase and users.

Benefits

By removing these two fields, our metadata's suggested_fee value will be more reliable.
This will help Coinbase and its users pay appropriate fees for their TXs.

Potential risks

Some AIs are using these fields

Solution:

• If there are no objections within the next two weeks (ending on August 12th, 2022), we will remove the max_fee and suggested_fee_multiplier fields from ConstructionPreprocessRequest.
• If some AIs are using the field, we will ask them to update their implementations (they will need to also remove these fields).
• We will work with all potential comments case by case

After updating the spec, the ConstructionPreprocessRequest will look like :

{
    "network_identifier": {
        "blockchain": "bitcoin",
        "network": "mainnet",
        "sub_network_identifier": {
            "network": "shard 1",
            "metadata": {
                "producer": "0x52bc44d5378309ee2abf1539bf71de1b7d7be3b5"
            }
        }
    },
    "operations": [
        {
            "operation_identifier": {
                "index": 5,
                "network_index": 0
            },
            "related_operations": [
                {
                    "index": 1
                },
                {
                    "index": 2
                }
            ],
            "type": "Transfer",
            "status": "Reverted",
            "account": {
                "address": "0x3a065000ab4183c6bf581dc1e55a605455fc6d61",
                "sub_account": {
                    "address": "0x6b175474e89094c44da98b954eedeac495271d0f",
                    "metadata": {}
                },
                "metadata": {}
            },
            "amount": {
                "value": "1238089899992",
                "currency": {
                    "symbol": "BTC",
                    "decimals": 8,
                    "metadata": {
                        "Issuer": "Satoshi"
                    }
                },
                "metadata": {}
            },
            "coin_change": {
                "coin_identifier": {
                    "identifier": "0x2f23fd8cca835af21f3ac375bac601f97ead75f2e79143bdf71fe2c4be043e8f:1"
                },
                "coin_action": "coin_created"
            },
            "metadata": {
                "asm": "304502201fd8abb11443f8b1b9a04e0495e0543d05611473a790c8939f089d073f90509a022100f4677825136605d732e2126d09a2d38c20c75946cd9fc239c0497e84c634e3dd01 03301a8259a12e35694cc22ebc45fee635f4993064190f6ce96e7fb19a03bb6be2",
                "hex": "48304502201fd8abb11443f8b1b9a04e0495e0543d05611473a790c8939f089d073f90509a022100f4677825136605d732e2126d09a2d38c20c75946cd9fc239c0497e84c634e3dd012103301a8259a12e35694cc22ebc45fee635f4993064190f6ce96e7fb19a03bb6be2"
            }
        }
    ],
    "metadata": {}
}

Backward compatible

No

[patrick-ogrady]

If this is removed, it would be great to see a replacement added to the specification that allows for some fee control (instead of just using metadata JSON, as many assets do now).

[jingweicb]

thanks for the reply! we do have workarounds on fee control

[patrick-ogrady]

See comment here on "design principles" of the metadata field: #107 (reply in thread)