Trusted multistep realtime transaction

Question

I'm not sure if this is possible using multichain but I'm trying to build a multi-step app where for e.g. to accomplish  Transaction A, we want the processing to go through Step1,Step2 and Step3. Similarly to accomplish Transaction B - Step1,Step2 and Step4. Say each of the steps is executed in a distributed way by different computer/container. As each step is executed by respective computer, we want to make sure previous step was executed, and the call is coming from computer running the previous step. When I look at transaction A after completion, I should be able to prove that all steps were completed by respective authentic players. How can I accomplish this for a real-time application using multichain?

Answer 1

You would use a combination of MultiChain features for this:

1. You can use a stream which enables each party to publish the proof that they did a certain thing, and this can be viewable by other parties. Although publishing into a stream already includes a signature by the source, consider using signmessage to add an extra layer of explicit signing within the stream data payload, for the convenience of the subsequent steps.
2. You can attach these proofs as multiple pieces of metadata in the final transaction (for example see the data parameter in APIs like createrawsendfrom) for anyone to see.
3. If you want to enforce a rule, on the blockchain level, to ensure that transactions are only accepted if they contain the necessary pieces of metadata, you can use a transaction filter for that.