What follows is a summary of the architecture and the components that are involved in running a Cartesi Compute Application, meaning some DApp that makes use of our SDK. It is convenient to start with the description of the typical ingredients involved in a decentralized application. Namely, the blockchain node and the client software.
- create and initialize project for the Calculator Cartesi Compute DApp
Cartesi Compute SDK Environment
- describe easy-to-use environment available for developing Cartesi Compute DApps
Creating basic DApp
- create and initialize a basic project for a Cartesi Compute DApp
Dogecoin Hash project
- create and initialize project for the Dogecoin Hash Cartesi Compute DApp
This section describes in detail the Drive _inputDrives parameter of the instantiate call.
At this point, an overview has been given of what constitutes a Cartesi computation, who are the parties involved, and what the software components of Cartesi Compute are. It is important to understand better what events happen during the execution of a Cartesi Machine.
- ensure all dependencies necessary for running the tutorials are installed
Generic Script project
- create and initialize project for the Generic Script Cartesi Compute DApp
GPG Verify project
- understand use case of using GPG for document signature verification
How it works
Cartesi Compute SDK allows Cartesi DApps to specify and request verifiable computations to Cartesi Machines. Additionally, the SDK provides tools to facilitate and reduce the cost of inputting data into Cartesi Machines.
This section describes the main ingredient of the on-chain Cartesi Compute infrastructure.
- give step by step instructions about how to build a DApp using the Cartesi Compute SDK
A relevant limitation of the Cartesi Machines as they have been described until now is the size of their input drives.
Although an extensive documentation of Cartesi Machines can be found here, one may choose to skip this reading and jump right away to their usage inside the blockchain through Cartesi Compute. For that, it is enough to regard a Cartesi Machine as a black box that executes computations.
Having discussed the concept of Cartesi Machines off-chain, capable of booting a Linux operating system and loading heavy-weight libraries, one naturally wonders how this will ever be stored or executed on the limited environment of a blockchain. The simple answer is that it won’t be.
Having informally discussed how Cartesi Compute represents Cartesi Machines on-chain, one can now describe in more details the API for requesting and retrieving computations in Cartesi Compute.
Cartesi Compute allows you to implement a function in which you receive a set of inputs and it provides an output. So you can think of a Compute DApp as a computational oracle that tells you the result of a computation.
Platform Services is a new product developed and maintained by the Cartesi team that hosts Cartesi Node infrastructure for DApps. The service is elastic, making resources available to DApps upon demand. Developers deploy their Cartesi DApps on Platform Services and it automatically allocates resources according to user activity.
After going through the last section, the reader is already able to specify drives if the data was available to the caller at the time of instantiation.
Putting Things Together
To better understand how Cartesi Compute can be used, imagine the following simple Cartesi DApp with one claimer and one challenger. The DApp can be a skill-based game where players place their bets and challenge each other for the highest score over the blockchain. The winner takes the pot.
Broadly speaking, the Cartesi layer-2 platform architecture should be perceived as blockchain-agnostic, given that in principle any network could use Cartesi Machines to move complex computations off-chain without compromising on decentralization.
The off-chain API
After the call for instantiate, the blockchain may already have all information that is necessary to execute the machine. But in many cases it also needs to get input from other users. In a game for example, the user may need to insert their decisions on input drives for later processing.
When users interact with their blockchain DApps, they are free to manage and run their own blockchain nodes if so they wish. In a common scenario of the usage of the Ethereum network, DApps are accessed via browser and blockchain transaction requests are carried out by Metamask. The user signs the transaction which is typically sent to a remotely hosted node, such as Infura.
Cartesi is a second layer solution.