Getting Started
Orbs Contracts
Gamma in Depth
Deploying your first contract
This tutorial will take you through the entire process of writing a contract and deploying it on a local instance of ORBS in just a few minutes.
1. Write a simple contract
Let's write a simple example that implements a counter. Create a file named
counter.go and type in the following contentcounter.go
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package main
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​
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import (
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"github.com/orbs-network/orbs-contract-sdk/go/sdk/v1"
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"github.com/orbs-network/orbs-contract-sdk/go/sdk/v1/state"
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)
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​
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var PUBLIC = sdk.Export(add, get)
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var SYSTEM = sdk.Export(_init)
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​
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var COUNTER_KEY = []byte("count")
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​
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func _init() {
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state.WriteUint64(COUNTER_KEY, 0)
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}
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​
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func add(amount uint64) {
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count := state.ReadUint64(COUNTER_KEY)
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count += amount
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state.WriteUint64(COUNTER_KEY, count)
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}
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​
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func get() uint64 {
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return state.ReadUint64(COUNTER_KEY)
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}
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Don't worry if you don't fully understand the code at this point.
2. Start Gamma server
We'll test our contract on Gamma server. Start it from terminal
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gamma-cli start-local
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You can keep an eye on Prism (http://localhost:3000/) to see new blocks and transactions apear as you continue with the deployment in the next steps.
3. Deploy the contract
To deploy the counter contract, run in terminal
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gamma-cli deploy counter.go -name MyCounter
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If the deploy is successful, you'll see a response similar to this
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{
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"RequestStatus": "COMPLETED",
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"TxId": "7Y4urVmKvunYsxh7kKhUoQ72XjSJcdkBxxzBcauC9icC9gzMy8mPDcg",
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"ExecutionResult": "SUCCESS",
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"OutputArguments": [],
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"TransactionStatus": "COMMITTED",
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"BlockHeight": "1869",
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"BlockTimestamp": "2018-12-05T13:05:51.347Z"
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}
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4. Send a transaction to increment the counter
Write the transaction details in a JSON file named
add-25.jsonadd-25.json
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{
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"ContractName": "MyCounter",
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"MethodName": "add",
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"Arguments": [
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{
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"Type": "uint64",
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"Value": "25"
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}
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]
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}
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More Information about sending transactions and the Gamma-cli json files structures can be found at the gamma in depth chapter of this documentation
To increment the counter by 75, let's send this transaction 3 times from terminal
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gamma-cli send-tx add-25.json -signer user1
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gamma-cli send-tx add-25.json -signer user1
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gamma-cli send-tx add-25.json -signer user1
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Note that the transaction will be signed by
user1, an example account found in orbs-test-keys.json5. Read the counter value
Write the query details in a JSON file named
get.jsonget.json
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{
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"ContractName": "MyCounter",
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"MethodName": "get",
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"Arguments": []
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}
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This query will read the counter value from the contract's state. Send it from terminal
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gamma-cli run-query get.json
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Note that transactions that change state require consensus by several nodes. Reading state with queries is a simpler action that doesn't require consensus.
6. Stop Gamma server
Since we're done testing, the server is no longer needed. Let's stop it from terminal
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gamma-cli stop-local
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