echo-plus DApp

Cartesi Rollups version: 1.0.x

echo-plus is a customized DApp written in Python, which originally resembles the one provided by the sample Echo Python DApp. Contrary to that example, this DApp uses sunodo to build and run, and as such the commands for building, and running are different.

Requirements

This project works with sunodo, so run it you should first install sunodo.

npm install -g @sunodo/cli
alias sunodo="npx @sunodo/cli"

Building

To build the application, run the following command:

sunodo build

Running

To start the application, execute the following command:

sunodo run

The application can afterwards be shut down with ctrl+c

Interacting with the application

You can send using sunodo send command. Optionally, you can use the frontend web frontend-web application to interact with the DApp.

The DApp works as an echo dapp, but it answers some special commands such as:

deposits (it sends vouchers to depositor with the same assets)
json You can check if lat long lies within a fence - e.g.:

{"latitude":34.639,"longitude":-118.051,"fence":"{\"type\":\"Polygon\",\"coordinates\":[[[-118.053,34.6403],[-118.050492679131423,34.637611825591407],[-118.04191282470596,34.642500320185789],[-118.044382904834507,34.645229032100403],[-118.053002827442867,34.640396678176792]]]}"}

You can send sql statements - e.g.:

{"sql":"create table developers (name string, company string, age integer);"}

{"sql":"insert into developers (name, company, age) values('John', 'abc company', 50);"}

{"sql":"select * from developers;"}

You can send arrays to be ordered with numpy - e.g.:

{"array":[3,5,1,4,2]}

You can send mint nfts - e.g.:

{"erc721_to_mint":"0xd8b9...3fa8","selector":"0x755edd17"}

{"erc721_to_mint":"0xd914...9138","selector":"0xd0def521","string":"nftTest"}

You can send images (converted to base64) to be processed with opencv (and mint nft with file multihash) - e.g.:

{"image":"iVBORw0...uQmCC"}

{"image":"iVBORw0...uQmCC","erc721_to_mint":"0xd914...9138","selector":"0xd0def521"}

Using standard linux tools you can convert an image to base64 with base64 img.png and convert back to with base64 -d <<< $(cat img_processed.png.b64) > img_processed.png
strings (it performs some operations depending on the string: report, reject, exception, ...)

Running the back-end in host mode

When developing an application, it is often important to easily test and debug it. For that matter, it is possible to run the Cartesi Rollups environment with the backend running in the host machine, allowing it to be debugged using regular development tools such as an IDE.

To start the rollups node, execute the following command:

sunodo run --no-backend

This DApp's back-end is written in Python, so to run it in your machine you need to have python3 installed. The backend uses shapely library, so you should install libgeos-c on your host (refer to geos).

In order to start the back-end, run the following commands in a dedicated terminal: