BlockchainSimulator

A blockchain simulator for SE 575

Open two terminal windows. In one, run the Simulator build, and in the other run the Frontend installation process, both of which are explained below. Once both are operational, navigate in a web browser to http://localhost:8100.

Simulator

Build

cd Simulator
./gradlew run

(If both JRE and JDK are installed, gradle may use java from the JRE. Ensure JAVA_HOME is set to path of JDK.)

Frontend

Installation

1. Install node.js if it is not already installed. https://nodejs.org/en/download/
2. npm install -g ionic
3. cd Frontend/ionic-app
4. npm install
5. ionic serve
6. Website will be hosted on localhost:8100

Smart Contract Language

(NOTE: NOT INTEGRATED. TRANSACTION DATA IS LIMITED TO INTEGER VALUES FOR CURRENCY TRANSFER)

In order to carry out general computing and value-moving requirements, including the proof-of-stake algorithm, the blockchain simulator will include a simple smart contract system. The smart contracts will provide functions for simple, proof-of-concept programming structures, and will allow for transferring tokens between accounts.

Syntax

The smart contract language for this blockchain will be a fairly easily-assembled low-level language that will carry instructions for calculations in the following grammar:

.<label>
<instr>
<instr> <arg>
<instr> <arg> <arg>
<instr> <arg> <arg> <arg>

Language Reference

Code	Instruction	Argument	Description
0	nop	None	No operation.
1	mov	'to' memory address, 'from' memory address	Move memory values.
2	trn	token volume, 'to' account, 'from' account	Transfer tokens from one account to another.
3	sav	memory address, storage address	Save a value to permanent storage.
4	lod	memory address, storage address	Load a value from permanent storage.
5	add	address, value	Add a value to a given memory location.
6	sub	address, value	Subtract from a given memory location.
7	mul	address, value	Multiply a given memory location by a value.
8	jlt	x, y, label	Jump to label if x is less than y.
9	jgt	x, y, label	Jump to a label if x is greater than y.
10	jeq	x, y, label	Jump to a label if x is equal to y.
11	jmp	label	Jump unconditionally to a label.
12	ret	x	Returns the value in memory address x.
13	act	None	Creates a new account on the chain.
14	bal	acct	Retrieve a balance given an account name.

Examples

Basic Math

add 0 1
add 0 1
ret 0

Returns 2.

add 0 10
loop:
add 1 1
jlt 1 0 loop
ret 1

Sets memory index 0 to 10, then adds 1 to memory index 1 repeatedly until it contains 10. Returns the value of memory index 1.