Protocols encode the rules of engagement that coordinate the exchange of a service between a global supplier and a global consumer.
Chris Burniske (Placeholder Capital)
One question that comes to my mind given the above definition: are the rules of engagement globally defined or locally defined per service relationship?
In many blockchain based protocols, the rules of engagement are defined at a global level (i.e. all nodes follow the same consensus rules). While this protocol architecture might be ideal in many cases, is it the only viable architecture? Are there alternative ways to define rules of engagement that might be more appropriate for certain classes of protocols?
Service Agreements
Jorge from Aragon presents one such alternative:
In this approach, the rules of engagement are locally defined because liabilities, that essentially represent service agreements for a capability offered by a provider, can be issued on a per service relationship basis. Some implications of this include:
- A single provider can own many liabilities
- A single capability offered on the network can be associated with different liabilities
Instead of the protocol supporting a single capability associated with a single liability, this protocol structure can support multiple capabilities and multiple liabilities. There are examples of service protocols exploring this design path and reasons why this might be desirable include:
- Some consumers might require stricter service agreement terms than others i.e. heavier penalty for a violation of the agreement
- Some consumers might prefer to use different dispute resolution mechanisms in service agreements depending on their trust/security requirements
While a liability might need to be anchored on-chain in order to enforce a dispute resolution mechanism in the event of a violation of the service agreement, a capability can be defined off-chain as long there is a way to determine that a consumer and provider mutually agreed to associate the capability with a particular liability for a transaction. One way to accomplish this would be for both parties to cryptographically sign a data payload that references the off-chain capability, the on-chain liability and any transaction data that might be needed in the event that a dispute is required. The signatures of both parties along with this data payload function as authenticated evidence of an established mutual agreement between parties for a transaction that can be presented to parties external to the transaction if needed. An additional benefit of parties binding a capability with a liability on per service relationship, the duration of which might only be for a single transaction, is increased flexibility to experiment with and upgrade to different agreement structures that could incentivize different types of behavior in providers.
A service protocol that supports off-chain capabilities and on-chain liabilities allows consumers to exchange with providers based on not only the capabilities offered, but also the liabilities owned (and which ones they choose to use to secure their capabilities) the end result being a network with a diverse set of rules of engagement depending on the preferences and requirements of consumers and providers. But, this brings up a follow up question: in a network with a variety of liabilities and capabilities, how do parties determine if service was delivered according to different agreement terms especially if it is not clear if there are objective, algorithmic and deterministic verification method for certain capabilities?
Subjective Dispute Resolution
This follow up discussion to Jorge’s tweet points at one possible answer:
Aragon Court is as a subjective dispute resolution system (Kleros is another) that incentivizes participants to determine whether a human readable agreement was violated or not and then report the decision on-chain. Introducing a subjective dispute resolution system into a service protocol may incite a negative initial reaction. Doesn’t this run counter to the goal of eliminating human judgement, which can be manipulated, misguided, etc., from the types of permissionless, unstoppable digital marketplaces that service protocols seek to enable? We want objective, algorithmic and deterministic methods for securing service protocols! We want to trust code not humans! This sentiment is understandable.
However, it is worth considering whether there are cases where human powered subjective dispute resolution might actually be more practical than or preferable to objective verification methods that are common in blockchain based protocols today. Consider an image/video transformation service. The goal of the service is to apply a set of permissible transformations to an image/video such that the end result still faithfully represents the content of the original image/video. There are cryptographic techniques for verifying that this service is delivered correctly, but they can be quite computationally expensive which may or may not make sense depending on the requirements of a consumer. The next best solution is to use statistical techniques – for example, a machine learning model can be constructed to classify authentic pairs of images/videos. But, statistical techniques have non-negligible error rate meaning that they will never be 100% accurate. Interestingly, while a machine might mistakenly classify a transformed image/video as authentic or inauthentic, it is actually quite easy and fast for a human to evaluate whether a transformed image/video actually contains the same content as another image/video.
In the cryptography field, one of the desired properties of verifiable computation systems is succinctness meaning that verification is substantially faster/cheaper than running the computation itself. In this case, the system could actually achieve succinctness by using a human verifier! Clearly, it would not be practical for a human to be continuously verifying service delivery, but this observation that a human can be a much more accurate/efficient verifier than a machine for certain types of services might be an indication of that there is potential in designs that introduce human verification only when absolutely needed. Perhaps that is where using subjective dispute resolution systems such as Aragon Court to report the outcomes of human verification on-chain could be useful.
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