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Noah Zinsmeister
Noah Zinsmeister refactor common interfaces
Latest commit 323eb91 Nov 28, 2018

README.md

Meta Transactions

This example MetaTransactionsProvider sketches out a design for sending meta-transactions on behalf of Identities. Though what follows is a subset of the full, robust functionality offered by a 1484 Identity, it accurately represents a fully functioning meta-transaction flow.

  1. When signing up a new user, the MetaTransactionsProvider generates an address for them and requests a 1484 sign-up signature from this address.
  2. The Provider then calls createIdentityDelegated to assign the user an EIN.
  3. Going forward, whenever the Provider passes an appropriate signature to callViaProxyDelegated, the call is forwarded to arbitrary smart contracts.
  4. Users may also call callViaProxy directly if they have access to an address associated with their EIN.
  5. Calls are either forwarded directly from the MetaTransactionsProvider address, if viaExternal is set to false, or through a per-EIN ExternalProxy contract otherwise. See below for an explanation.

Through an ExternalProxy

Forwarding calls through individual ExternalProxy contracts is powerful in that it facilitates meta-transactions with existing dApps. From the point of view of the dApp, this ExternalProxy is the user's unique identity, and they don't know how the user/Provider is actually accessing MetaTransactionsProvider. This provides full backwards compatibility with existing dApps.

However, it can be slightly limiting, in that it does not work with Resolvers that permission functions on 1484 AssociatedAddresses or Providers. In the case of AssociatedAddresses, since each EIN's ExternalProxy contract is not an AssociatedAddress, nor can it be added as one since it cannot sign messages, the user is stuck. We can of course add the ExternalProxy as a Provider, but this feels fairly roundabout.

Directly from MetaTransactionsProvider

Luckily, in cases like the above, calls can instead be made directly from the MetaTransactionsProvider, which is natively a Provider. This is accomplished by setting viaExternal to false. This means that Resolvers receive all transactions from the same address, so:

  • The EIN must be passed through as an argument to all function calls in the data argument (or else dApps have no way of knowing which EIN the Provider is calling on behalf of)
  • Resolvers should be actively encouraged to allow Providers to call functions on behalf of EINs who've added them if they wish their logic to work in thus scenario (which they are in this best practices document).

Which pattern you use depends on the particular Resolver or dApp in question, but in either case all calls are routed through the MetaTransactionsProvider, and can be triggered by any AssociatedAddress of an EIN (either directly or via a signature).

References

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