FYI: This is copy from: https://polkadot.polkassembly.io/post/102, and Europa is the third project that we planned in our roadmap https://polkadot.polkassembly.io/post/100.

Github: [https://github.com/patractlabs/europa](https://github.com/patractlabs/europa)

Europa is inspired by [Ganache](https://www.trufflesuite.com/ganache), [Ethereumjs-VM](https://github.com/ethereumjs/ethereumjs-vm) and [Buidler EVM](https://buidler.dev/buidler-evm/) from the Ethereum ecosystem. Europa is a sandbox of Substrate runtime environment, which would be used to simplify the developing, debugging, and integration test when developers develop Substrate runtime applications and test pallet-contracts. The sandbox will remove P2P and consensus functions, just remaining the execution environment and RPC interface. We will wrap the core modules, then provide a local database, a detailed log print function, a concept of workspaces which isolates different developing environments, and interact with different front-end UIs. The sandbox has no time interval between producing blocks, so debugging can be optimised to be very quickly.


### Summary of Europa's future plan:

**1. v0.1: Have an independent runtime environment to facilitate more subsequent expansion directions.**

 The independent runtime environment of excluded nodes can be expanded more without the constraints of the node environment and WASM compilation, and can be easily integrated with other components. In this version, it is more like simulating the Ganache project in Ethereum ecosystem, enabling contract developers to develop without having to build a contract blockchain. Developers can quickly fire up a personal Substrate chain, which can be used to run tests, execute commands, and inspect state while controlling how the chain operates.

**2. v0.2: Modify at contract module level to provide more information **

In this version, we will fork the pallet-contracts module for secondary development. We will strengthen the part of the error notification for contract developers, such as providing:

* WASM stack traces, the function call stack during WASM contract execution;
* Contracts stack traces, the call stack of a contract calling another contract;
* Console.log, provides libraries and methods to print command lines during contract development;
* Strengthen the error type and error display of the contract module;
* Simple integration with Redspot;

** 3. v0.3: Improve the developement experience, strengthen collaboration with other tools, and extend the sandbox to be compatible with other runtime modules**

* Strengthen the integration with Redspot
* Strengthen the integration with polkadot.js.org/apps to achieve complete RPC support
* Support status data query


### Detailed design of v0.1 (6 weeks, 21 Sept ~ 2 Nov):

**Milestone 1 : (3 developers * 1 weeks)**

* Implement an independent runtime executive environment
* Implement `Externalities` trait for a `Externalities` -like object
* Implement needed `Extension` trait interface.

**Milestone 2 : (3 developers * 1 weeks)**

* Implement a local database for this runtime executive environment to store all trie data, block and extrinsic
* Implement a local database  to store a bypath k/v state data, for exporting and querying from those data.

**Milestone 3 :  (3 developers * 1 weeks)**

* Implement a block packing function to pack blocks directly rather than through consensus process, allowing to pack one or multiple extrinsics at once. 
* Providing a workspace concept to isolate different environment.

**Milestone 4 :  (3 developers * 1 weeks)**

* Implement RPC functions of "forward to height" and "backward to height"
* Providing a way to pack blocks directly to assigned height
* Revert current state to a reverted height

**Milestone 5 : (3 developers * 2 weeks)**

* Integration and testing


### Cost of v0.1 (18 developers * weeks)

* Operating activities: $3600 ( Rent and Devices: $200 per developer * week )
* Employee payments: $36000 ($1900 per developer * week)
* —————————— +
* Total Cost: $37800
* Exchange Rate: $4/ New DOT
* Treasury Proposal: 9450 New DOT


### How to verify v0.1: Youtube demo video & Github source

* Build and run in an independent executable file
* Can start from different workspaces, and a new workspace is an empty chain
* Can receive extrinsics to set_code, deploy and call contracts directly
* Can interact with Redspot
* Can use RPC to jump over some blocks and revert to a specified height to revert states

 Approve a proposal. At a later time, the proposal will be allocated to the beneficiary
 and the original deposit will be returned.

 May only be called from `T::ApproveOrigin`.

 # <weight>
 - Complexity: O(1).
 - DbReads: `Proposals`, `Approvals`
 - DbWrite: `Approvals`
 # </weight>

- Europa is a sandbox for developers to simplify the development and testing of Substrate runtime applications.
- It removes P2P and consensus functions and focuses on the execution environment and RPC interface.
- Europa has future plans to expand its runtime environment, provide more information for contract developers, and improve the development experience.
- The detailed design for v0.1 includes implementing an independent runtime environment, a local database, block packing function, and RPC functions.
- The cost for v0.1 is $37,800 and it can be verified through a demo video and the Github source.

#28 Patract Labs' treasury proposal for Europa v0.1