mbestavros / supplychain

Final project for CS651: Distributed Systems. Blockchain mixed with distributed systems.

SupplyChain

Final project for CS651: Distributed Systems. Blockchain for supply-chain verification.

Setup:

• Set your GOPATH variable to be the root folder of this repo, and go to that folder. You can do this by navigating to the main directory and running:
  GOPATH=\$(pwd)

• Run the following to get required packages:
  go get github.com/rs/xid
go get github.com/sirupsen/logrus

Build, Run, and Test:

• Whole project
  go build cli
./cli
• Individual packages
  cd <package-name> To run:
  go build <package-name>
./<package-name>
  To test:
  go test

Debugging

We're using the logrus library. To set the log level to Debug, for example, write log.SetLevel(log.DebugLevel). To then log something to Debug, use log.Debug("Debug statement!").

supplychain's Issues

[Task #1] Restructure Transaction structs

• Rewrite Transaction structs so that they use struct embedding (Go's version of class inheritance)
• Resources
  • https://golang.org/doc/effective_go.html#embedding
  • https://medium.com/@simplyianm/why-gos-structs-are-superior-to-class-based-inheritance-b661ba897c67
  • https://stackoverflow.com/questions/21527489/go-inheritance-using-anonymous-type-in-a-struct-as-a-method-parameter

CLI improvements and finalizations

• Complete ability to create all types of transactions w/ authentic details
• Good logging for all sorts of events (user X make Y transaction, user X tried to forge a transaction, your transaction isn't valid for reason Z...)
• make the CLI presentation ready

[Task #6]: Implement filtering and visualizations of JSON data in visualization server

• Server provides JSON raw, and needs some sort of filtering logic
• Need to define exactly which properties we want to expose to visitors, what they can look up, etc

[Task #5]: Function to view what items a user currently owns

Function that takes user id, and returns items they currently own.

We can identify this by every transaction where the user id is the DestinationUser, and this is the most recent transaction for the item id.

Only for the purposes of UI.

[Task #3] History of an Item

• Add a function that takes in an input:
  • Item ID
• Output: ....?
  • A list of users who owned the Item?
  • A list of Transaction structs that contained the Item?

Goes hand in hand with issue #3

[Task #4] Verification of ownership

• Write a verify function that takes in:
  • Item ID
  • User ID
• Outputs a True/False of whether the owner was the last user ID in a transaction with that Item ID

Can probably make a call to the history function in issue #4 and output True/False based on the output

add "view all" option in cli

Add functionality to allow users to view all transactions on the blockchain in cli

[Task #2] Add Item ID to Block Structs

• Add Item ID to each Struct
• Add logic for generating a unique item ID after a create transation has taken place

[Task #7]: Make visualization server publicly accessible

• Visualization server needs to be visible to classmates for demo

add rule check on sending blocks

Currently there is logic for having a rule check for verifying a block when it is received. However, this check should also be in a sendBlock, or else the following scenario happens:

• user1 exchanges diamonds with user2
• user2 rejects validity because it sees that user1 doesn't actually own diamonds
• user1 still appends the invalid block to its own log
• user1 now makes a valid transaction (i.e. create diamonds)
• user2 rejects because of index mismatch (user2 has blockchain of size 0, user1 has blockchain of size 1)

This scenario basically means that any future transaction provided by user1 will never be accepted, even if it attempts to make valid transactions in the future