Cosmos SDK Workshop: How to Build a Blockchain from Scratch
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The document outlines the process of using the cosmos-sdk to create a blockchain-based distributed name service. It details the components and modules involved, including setup instructions, message handling, and state management. The tutorial emphasizes the development of a decentralized naming system that allows users to buy and manage names, leveraging the features of the cosmos-sdk architecture.
![● nameStoreKey
○ map[name]value - like a Zonefile w traditional DNS
● ownerStoreKey
○ map[sdk_address]name - who owns what
● priceStoreKey
○ map[name]price - how much a name costs
Our Keeper has 3 New Keys](https://image.slidesharecdn.com/sdknstalkshop-190406044039/85/Cosmos-SDK-Workshop-How-to-Build-a-Blockchain-from-Scratch-21-320.jpg)
Cosmos SDK Workshop: How to Build a Blockchain from Scratch
- 2. Before we begin... Talkshop: Talk + Workshop (Interactive presentation) Download the tutorial github.com/cosmos/sdk-application-tutorial goes in $GO_PATH/src/github.com/cosmos/ make get_tools && make get_vendor_deps && make install
- 3. Welcome! Let’s use the Cosmos-SDK To make a Blockchain Replicated State Machine Hi, I’m Jack ✌
- 4. Replicated State Machine What is the initial state? What are the possible state transitions? Is it Byzantine Fault Tolerant?
- 5. Cosmos Developer Kit Golang toolset for building Replicated State Machines Ruby-on-Rails for Blockchain Focus on the Application Proof-of-Stake 🍃 is better than Proof-of-Work ☠🔥 Tendermint for Consensus & Networking
- 6. Our Application! Distributed Name Service No one should be able to limit access to a public utility Distribute the access and responsibility ● Ethereum Name Service ● Handshake ● Namecoin/Blockstack
- 7. Our Application! ● github.com/cosmos/sdk-application-tutorial ● Download the tutorial to follow along with code ● At the end I’ll spin up a node and give everyone money ● You can create and buy names from each other
- 8. The SDK is a Modular Framework ● Aggregates a collection of interoperable modules ● Each Module has its own Message/Transaction processor ● The SDK routes each message to the respective module
- 9. Modules in this Tutorial ● Auth ○ Access Control List (ACL) with Asymmetric Encryption ● Bank ○ Money Money Money ● NameService ○ Whois???
- 10. Modules NOT in this Tutorial ● Staking ○ Used for updating the set of validators ○ We use a fixed set from genesis ○ Private => Permissioned => Public ● Governance ○ Let’s Vote!
- 11. Modules are States & Messages
- 12. Modules: State ● All state goes in one store called multistore ● Contains multiple key/value stores called KVStores ● Our State ○ Accounts (auth) ○ Balances (bank) ○ Domain Names (nameservice)
- 13. Domain Names: nameStore ● Name => Value ○ What does the name resolve to (the zonefile)? ● Name => Owner ○ Who owns the name? ● Name => Price ○ How much to buy it?
- 14. Modules: Messages ● Messages Trigger State Transitions ● The Module Routes the Messages to Handlers ● The Handlers Hand them to Keepers ● The Keepers update the State
- 15. Domain Names: Messages ● MsgSetName ○ This message allows an owner to set the value of a name ● MsgBuyName ○ This message allows anyone to buy a name for some price
- 16. General Flow ● A Transaction contains a Message ● Tendermint nodes receive Transactions in Blocks ● They’re passed to the application via ABCI ○ Application Blockchain Interface ○ Socket Protocol between Tendermint and the application ● Decoded as Messages by baseapp & routed to correct Module ● Each Module has Handlers that decides what to do with them ● Each Handler calls Keepers to update the State
- 17. Let’s begin in ./app.go ● Imports ○ Log - for logs ○ Auth - for accounts and signing ○ Dbm - tendermint database ○ Codec - serialization ○ Baseapp - boilerplate ● Makes a new Type called nameservice ○ That’s our app!
- 18. Let’s begin in ./app.go ● Imports ○ Log - for logs ○ Auth - for accounts and signing ○ Dbm - tendermint database ○ Codec - serialization ○ Bam - Baseapp boilerplate ● Makes a new Type called nameservice ○ That’s our app!
- 19. Our nameservice module ● All modules go in the directory called ./x/ ● Our module goes in the directory called ./x/nameservice/ ● Inside ./x/nameservice/ we’ll have: ○ Handler.go ○ Keeper.go ○ Querier.go ○ Msgs.go ○ Codec.go ○ Client/ => for REST & CLI
- 20. ● Keepers manage the state ○ Like reducers/redux or mutations/vuex ● Handlers call the Keepers ○ Like actions in redux/vuex The Keeper
- 21. ● nameStoreKey ○ map[name]value - like a Zonefile w traditional DNS ● ownerStoreKey ○ map[sdk_address]name - who owns what ● priceStoreKey ○ map[name]price - how much a name costs Our Keeper has 3 New Keys
- 22. ● Getters ○ ResolveName ○ HasOwner ○ GetOwner ○ GetPrice ● Setters ○ SetName ○ SetOwner ○ SetPrice Our Keeper has Getters & Setters
- 23. Our Keeper has Getters & Setters
- 24. Msgs & Handlers ● Msgs trigger Handlers ○ Like user initiated events ● Handlers call the Keepers ○ Like actions in redux/vuex ● Keepers manage the state ○ Like reducers/redux or mutations/vuex
- 25. Msgs go in ./x/nameservice/msgs.go
- 26. Two Msg Types Needed For Our App ● MsgSetName ○ Owners can set the name ● MsgBuyName ○ Names can be bought
- 27. MsgSetName ● Set all the Interfaces ● Example: ValidateBasic
- 28. handleMsgSetName ● Goes in ./x/nameservice/handler.go ● Utilizes the Keeper we made earlier
- 29. Queriers ● Queriers : Getters ● Handlers : Setters ● Goes inside ./x/nameservice/querier.go ● Uses the Keeper to access the KVStore
- 30. Our Queriers ● Resolve ○ Accepts name returns value ● Whois ○ Accepts name returns value, price, owner
- 32. Codec ● Register new msg types for serialization (not whois?) ● Amino is an extension of protobuf ● Goes in ./x/nameservice/codec.go
- 33. Building Clients! ● From the Command Line ○ Utilizes the cobra library ○ Goes in ./x/nameservice/client/cli/query.go ○ Goes in ./x/nameservice/client/cli/tx.go ● From a REST server ○ Goes in ./x/nameservice/client/rest/rest.go ● Export both from Module Client ○ Goes in ./x/nameservice/client/module_client.go
- 34. Pull it all back into app.go ● Import and Initialize all our new pieces ● AddRoute for Handlers and Queriers ● Register the Codecs ● InitChainer for initial application state ○ Takes a genesis.json file that can be generated by the CLI ○ This is where I’ll add everyone’s public key and some balance of token for buying names $ )
- 35. Build our Binaries! ● Wrap our app with commands we can use ● Wrap our client with commands we can use ● ./cmd/nsd/main.go ○ Name Service Daemon runs our node ● ./cmd/nscli/main.go ○ Name Service CLI
- 36. One last step ● Makefile ○ Installs and builds ● Gopkg ○ keeps our versions constrained ● Build! ○ dep ensure -update -v ○ make install
- 37. Claim Your Name! Go to talkshop.name/