Introduction
This section presents how to build a DApp (Decentralized Application) with Archetype and Completium CLI.
We also recommend the TZombies tutorial for a complete step-by-step overview of how to build a DApp.
Definition
Compared to a standard application, a DApp uses decentralized (peer to peer) backends (that is not owned by any private or public entity):
- a blockchain for its business logic (provided by a smart contract running on it)
- IPFS (Interplanetary File System) for storage
- ...
The user is authenticated on the blockchain with a wallet, whose main role is to sign transactions to the smart contract. The signature principle is the one of asymmetric cryptography: the wallet uses the user's private key to sign, while the public key (or its hash in Tezos case) is used as public address (identity) on the blockchain.
Limits
Many elements of a DApp are centralized.
User interface
The user interface is usually a web page (or a native app) served by a centralized server (owned by an ISP, Github, Gitlab, ...).
The UI code source should be publically available, so that every one can run it locally (the same applies to the wallet).
Endpoints
Accessing to a peer to peer network (blockchain, IPFS, ...) is done by connecting to one machine, called the endpoint, owned by one entity. The integrity of the DApp then depends on that entity.
The DApp should provide the possiblity to set endpoints' URL/IP addresses.
The user could potentially use its own endpoints.
Indexers
Indexers provide key informations to the ecosystem; however, as a centralised point of information access, it is recommended to use them only when necessary, that is when the required information is not available in any contract's storage or in any current block.
For example, when the DApp is required to react to contracts' events, it is recommended to use an embedded block explorer, such as @completium/event-listener