Use Dubhe to develop a contract

Learn how to develop a simple distributed messaging contract with Dubhe

Use Dubhe to develop a contract

Let’s develop one of the simplest examples, called Distributed Messaging, or dms for short. The contract will have a schema called message, which will have a field called content, which will store the message content. The contract will have a method called send, which will take a string as a parameter and store it in the content field of the mailbox schema. The contract will also have an event called MessageSent, which will be triggered when a message is sent.

Dubhe generates some code based on the dubhe.config.ts configuration, so we just need to focus on this file.

import { DubheConfig } from "@0xobelisk/sui-common";
export const dubheConfig = {
  name: "template",
  description: "template",
  schemas: {},
} as DubheConfig;

Let’s go over what’s in dubheConfig

• name: The name of the contract project.
• description: The description of the contract project.
• schemas: The schema of the contract project. Refer to the Schemas section for details of schema.

To complete dms contract I need a Schema to store the numbers, now let’s complete the Schema.

dubhe.config.ts

import { DubheConfig, storage } from "@0xobelisk/sui-common";
export const dubheConfig = {
  name: "dms",
  description: "Distributed Messaging",
  schemas: {
    message: storage('String'),
  },
} as DubheConfig;

The name of this Schema is message, and he has only one number field with storage type StorageValue, which is used to store String.

Now we need to generate the contract frame content using Dubhe’s most powerful feature.

➜  pnpm dubhe schemagen

🚀 Starting Schema Generation Process...
📋 Project Configuration:
     └─ Name: dms
     └─ Description: Distributed Messaging
     └─ Network: testnet

🔨 Starting Schema Structure Generation...
     └─ message: StorageValue<String>

✅  Schema Generation Process Complete!

Take a look at the file structure of dms, we don’t need to concern ourselves with anything else but our business code systems folder.

├── Move.toml
└── sources
    ├── codegen
    │         ├── dapp
    │         │    ├── metadata.move
    │         │    ├── schema.move
    │         │    └── system.move
    │         ├── genesis.move
    │         └── schema.move
    ├── scripts
    │         ├── deploy_hook.move
    │         └── migrate.move
    ├── systems
    └── tests
        └── init.move

7 directories, 9 files

A Message Schema has been generated for you, now you need to write your own business code! We create a new move file called message in the Systems folder.

touch contracts/counter/sources/systems/message.move

This can be easily achieved with the help of Dubhe’s code generation. The contents of the file:

message.move

module dms::message_system {
    use std::ascii::String;
    use dms::dms_schema::Schema;

    public entry fun send(schema: &mut Schema, content: String) {
        schema.message().set(content);
    }
}

Let’s add an error handler so that the length of the content doesn’t exceed 12, how to do error handling?

dubhe.config.ts

import { DubheConfig, storage } from "@0xobelisk/sui-common";
export const dubheConfig = {
  name: "dms",
  description: "Distributed Messaging",
  schemas: {
    message: storage('String'),
  },
  errors: {
    invalid_content_length: "Content length must be less than 12",
  },
} as DubheConfig;

The error handling code has been added, now we also want to add events to the contract to tell us who sent what message.

dubhe.config.ts

import { DubheConfig } from "@0xobelisk/sui-common";
export const dubheConfig = {
  name: "dms",
  description: "Distributed Messaging",
  schemas: {
    message: "StorageValue<String>",
  },
  errors: {
    invalid_content_length: "Content length must be less than 12",
  },
  events: {
    message_sent: {
      sender: "address",
      content: "String",
    },
  },
} as DubheConfig;

Execute the schemagen command here.

➜  dubhe-template-project pnpm dubhe schemagen

🚀 Starting Schema Generation Process...
📋 Project Configuration:
     └─ Name: dms
     └─ Description: Distributed Messaging
     └─ Network: testnet

📦 Starting Schema Event Generation...
     └─ message_sent event: {"sender":"address","content":"String"}

🔨 Starting Schema Structure Generation...
     └─ message: StorageValue<String>

📦 Starting Schema Error Generation...
     └─ invalid_content_length: Content length must be less than 12

✅  Schema Generation Process Complete!

Errors and events are already generated.

First we do an error check, the input content must be greater than 0.

message.move

module dms::message_system {
    use std::ascii::String;
    use dms::dms_schema::Schema;
    use dms::dms_errors::invalid_content_length_error;

    public entry fun send(schema: &mut Schema, content: String) {
        invalid_content_length_error(content.length() < 12);
        schema.message().set(content);
    }
}

Finally we add events to the contract.

message.move

module dms::message_system {
    use std::ascii::String;
    use dms::dms_schema::Schema;
    use dms::dms_errors::invalid_content_length_error;
    use dms::dms_events::message_sent_event;

    public entry fun send(schema: &mut Schema, content: String, ctx: &mut TxContext) {
        invalid_content_length_error(content.length() < 12);
        schema.message().set(content);
        message_sent_event(ctx.sender(), content);
    }
}

By this point we need to write the contents of the deploy_hook, which will be automatically executed for you when the contract is deployed, now we initialise the content in the store to Hello World!.

dubhe-template-project/contracts/counter/sources/scripts/deploy_hook.move

deploy_hook.move

// Copyright (c) Obelisk Labs, Inc.
// SPDX-License-Identifier: Apache-2.0
#[allow(unused_use)]

/* Autogenerated file. Do not edit manually. */

module dms::deploy_hook {
use std::ascii::string;
use dms::dms_schema::Schema;

public(package) fun run(_schema: &mut Schema, _ctx: &mut TxContext) {
      _schema.message().set(string(b"Hello World!"));
}
}

Let’s run the Build command to check for syntax errors.

➜  pnpm dubhe build --network localnet
🚀 Running move build

INCLUDING DEPENDENCY Dubhe
INCLUDING DEPENDENCY Sui
INCLUDING DEPENDENCY MoveStdlib
BUILDING dms
Total number of linter warnings suppressed: 1 (unique lints: 1)