Add SDK_By_Examples to doc (#1795)

* Add simple gov example and sdk-by-example folder

* Add simple gov example

* Add simple gov example and sdk-by-example folder

* Add simple gov example

* fix sectino title

* Jb feedback + Offload some of the content in other docs

* Add what is cosmos back

* platform to framewoork

* Reemove testnet

docs/introduction/tendermint-cosmos.md

@@ -0,0 +1,27 @@
+## Tendermint and Cosmos
+
+Blockchains can be divided into three conceptual layers:
+
+- **Networking:** Responsible for propagating transactions.
+- **Consensus:** Enables validator nodes to agree on the next set of transactions to process (i.e. add blocks of transactions to the blockchain).
+- **Application:** Responsible for updating the state given a set of transactions, i.e. processing transactions.
+
+The *networking* layer makes sure that each node receives transactions. The *consensus* layer makes sure that each node agrees on the same transactions to modify their local state. As for the *application* layer, it processes transactions. Given a transaction and a state, the application will return a new state. In Bitcoin for example, the application state is a ledger or list of balances for each account (in reality, it's a list of UTXO, short for Unspent Transaction Output, but let's call them balances for the sake of simplicity), and the transactions modify the application's state by changing these list of balances. In the case of Ethereum, the application is a virtual machine. Each transaction goes through this virtual machine and modifies the application state according to the the smart contract that is called within it. 
+
+Before Tendermint, building a blockchain required building all three layers from the ground up. It was such a tedious task that most developers preferred to fork or replicate the Bitcoin codebase, but were constrainted by the limitations of Bitcoin's protocol. The Ethereum Virtual Machine (EVM) was designed to solve this problem and simplify decentralized application development by allowing customizable logic to be executed through smart contracts. But it did not resolve the limitations (interoperability, scalability and customization) of blockchains themselves. Go-Ethereum remains a very monolithic tech stack that is difficult to hard-fork much like Bitcoin's codebase. 
+
+Tendermint was designed to address these issues and provide developers with an laternative. The goal of Tendermint is to provide the *networking* and *consensus* layers of a blockchain as a generic engine to power any application developers want to build. With Tendermint, developers only have to focus on the *application* layer, thereby saving hundreds of hours of work and costly development set-ups. For reference, Tendermint also designates the name of the byzantine fault tolerant consensus algorithm used within the Tendermint Core engine.
+
+Tendermint connects the blockchain engine, Tendermint Core (*networking* and *consensus* layers), to the *application* layer via a socket protocol called the  [ABCI](https://github.com/tendermint/abci), short for Application-BlockChain Interface. Developers only have to implement a few messages to build an ABCI-enabled application that runs on top of the Tendermint Core engine. ABCI is language agnostic, meaning that developers can build the *application* part of their blockchain in any programming language. Building on top of the Tendermint Core engine also provides the following benefits:
+
+- **Public or private blockchain capable.** Developers can deploy any blockchain application, permissioned (private) and permissionless (public), on top of Tendermint Core. 
+- **Performance.** Tendermint Core is a state-of-the-art blockchain consensus engine able to handle large number of transactions in short timespan. A block time on Tendermint Core can be as low as one second and can process thousands of transactions in that time period.
+- **Instant finality.** A property of the Tendermint consensus algorithm is instant finality, meaning that forks are never created, as long as less than a third of the validators are malicious (byzantine). Users can be sure their transactions are finalized as soon as a block is created.
+- **Security.** Tendermint Core's consensus is not only fault tolerant, it’s optimally Byzantine fault-tolerant (BFT), with accountability. If the blockchain forks, there is a way to determine liability.
+- **Light-client support**. Tendermint provides built-in light-clients.
+
+But most importantly, Tendermint is natively compatible with the [Inter-Blockchain Communication Protocol](https://github.com/cosmos/cosmos-sdk/tree/develop/docs/spec/ibc) (IBC). This means that any Tendermint-based blockchain, whether public or private, can be natively connected to the Cosmos ecosystem and securely exchange tokens with other blockchains in the ecosystem. Note that benefiting from interoperability via IBC and Cosmos preserves the sovereignty of your Tendermint chain. Non-Tendermint chains can also be connected to Cosmos via IBC adapters or Peg-Zones, but this is out of scope for this document.
+
+For a more detailed overview of the Cosmos ecosystem, you can read [this article](https://blog.cosmos.network/understanding-the-value-proposition-of-cosmos-ecaef63350d).
+
+For more on Tendermint, go [here](tendermint.md)

docs/introduction/tendermint.md

@@ -5,9 +5,43 @@ Tendermint is software for securely and consistently replicating an application
 Tendermint is designed to be easy-to-use, simple-to-understand, highly performant, and useful for a wide variety of distributed applications.
 
 ## Byzantine Fault Tolerance
+
 The ability to tolerate machines failing in arbitrary ways, including becoming malicious, is known as Byzantine fault tolerance (BFT). The theory of BFT is decades old, but software implementations have only became popular recently, due largely to the success of “blockchain technology” like Bitcoin and Ethereum. Blockchain technology is just a re-formalization of BFT in a more modern setting, with emphasis on peer-to-peer networking and cryptographic authentication. The name derives from the way transactions are batched in blocks, where each block contains a cryptographic hash of the previous one, forming a chain. In practice, the blockchain data structure actually optimizes BFT design.
 
 ## Application Blockchain Interface
+
 Tendermint consists of two chief technical components: a blockchain consensus engine and a generic application interface. The consensus engine, called Tendermint Core, ensures that the same transactions are recorded on every machine in the same order. The application interface, called the Application Blockchain Interface (ABCI), enables the transactions to be processed in any programming language. Unlike other blockchain and consensus solutions developers can use Tendermint for BFT state machine replication in any programming language or development environment. Visit the [Tendermint docs](https://tendermint.readthedocs.io/projects/tools/en/master/introduction.html#abci-overview) for a deep dive into the ABCI.
 
-The [Cosmos SDK](/sdk/overview.md) is an ABCI framework written in Go. [Lotion JS](/lotion/overview.md) is an ABCI framework written in JavaScript.
+## Understanding the roles of the different layers
+
+It is important to have a good understanding of the respective responsibilities of both the *Application* and the *Consensus Engine*.
+
+Responsibilities of the *Consensus Engine*:
+- Propagate transactions
+- Agree on the order of valid transactions
+
+Reponsibilities of the *Application*:
+- Generate Transactions
+- Check if transactions are valid
+- Process Transactions (includes state changes)
+
+It is worth underlining that the *Consensus Engine* has knowledge of a given validator set for each block, but that it is the responsiblity of the *Application* to trigger validator set changes. This is the reason why it is possible to build both **public and private chains** with the Cosmos-SDK and Tendermint. A chain will be public or private depending on the rules, defined at application level, that governs a validator's set changes.
+
+The ABCI establishes the connection between the *Consensus Engine* and the *Application*. Essentially, it boils down to two messages:
+
+- `CheckTx`: Ask the application if the transaction is valid. When a validator's node receives a transaction, it will run `CheckTx` on it. If the transaction is valid, it is added to the mempool.
+- `DeliverTx`: Ask the application to process the transaction and update the state.
+
+Let us give a high-level overview of  how the *Consensus Engine* and the *Application* interract with each other.
+
+- At all times, when the consensus engine (Tendermint Core) of a validator node receives a transaction, it passes it to the application via `CheckTx` to check its validity. If it is valid, the transaction is added to the mempool.
+- Let us say we are at block N. There is a validator set V. A proposer of the next block is selected from V by the *Consensus Engine*. The proposer gathers valid transaction from its mempool to form a new block. Then, the block is gossiped to other validators to be signed/commited. The block becomes block N+1 once 2/3+ of V have signed a *precommit* on it (For a more detailed explanation of the consensus algorithm, click [here](https://github.com/tendermint/tendermint/wiki/Byzantine-Consensus-Algorithm)).
+- When block N+1 is signed by 2/3+ of V, it is gossipped to full-nodes. When full-nodes receive the block, they confirm its validity. A block is valid if it it holds valid signatures from more than 2/3 of V and if all the transactions in the block are valid. To check the validity of transactions, the *Consensus Engine* transfers them to the application via `DeliverTx`. After each transaction, `DeliverTx` returns a new state if the transaction was valid. At the end of the block, a final state is committed. Of course, this means that the order of transaction within a block matters.
+
+## Application frameworks
+
+Even if Tendermint makes it easy for developers to build their own blockchain by enabling them to focus on the *Application* layer of their blockchain, building an *Application* can be a challenging task in itself. This is why *Application Frameworks* exist. They provide developers with a secure and features-heavy environment to develop Tendermint-based applications. Here are some examples of *Application Frameworks* :
+
+- The [Cosmos SDK](/sdk/overview.md) is an ABCI framework written in Go. 
+- [Lotion JS](/lotion/overview.md) is an ABCI framework written in JavaScript.
+

docs/introduction/what-is-cosmos.md

@@ -4,4 +4,4 @@ Cosmos is a decentralized network of independent parallel blockchains, each powe
 
 The first blockchain in the Cosmos Network is the [Cosmos Hub](), whose native token is the Atom. Cosmos is a permission-less network, meaning that anybody can build a blockchain on it.
 
-Cosmos can interoperate with multiple other applications and cryptocurrencies. By creating a new zone, you can plug any blockchain system into the Cosmos hub and pass tokens back and forth between those zones, without the need for an intermediary.
+Cosmos can interoperate with multiple other applications and cryptocurrencies. By creating a new zone, you can plug any blockchain system into the Cosmos hub and pass tokens back and forth between those zones, without the need for an intermediary.

docs/sdk/overview.md

@@ -1,14 +1,16 @@
 # Cosmos SDK Overview
 
-The Cosmos-SDK is a framework for building Tendermint ABCI applications in
+The [Cosmos-SDK](https://github.com/cosmos/cosmos-sdk) is a framework for building multi-asset Proof-of-Stake (PoS) blockchains, like the Cosmos Hub, as well as Proof-Of-Authority (PoA) blockchains.
-Golang. It is designed to allow developers to easily create custom interoperable
-blockchain applications within the Cosmos Network.
 
-To achieve its goals of flexibility and security, the SDK makes extensive use of
+The goal of the Cosmos-SDK is to allow developers to easily create custom interoperable blockchain applications within the Cosmos Network without having to recreate common blockchain functionality, thus removing the complexity of building a Tendermint ABCI application. We envision the SDK as the npm-like framework to build secure blockchain applications on top of Tendermint.
-the [object-capability
+
-model](https://en.wikipedia.org/wiki/Object-capability_model)
+In terms of its design, the SDK optimizes flexibility and security. The framework is designed around a modular execution stack which allows applications to mix and match elements as desired. In addition, all modules are sandboxed for greater application security.
-and the [principle of least
+
-privilege](https://en.wikipedia.org/wiki/Principle_of_least_privilege).
+It is based on two major principles:
+
+- **Composability:** Anyone can create a module for the Cosmos-SDK and integrating the already-built modules is as simple as importing them into your blockchain application.
+
+- **Capabilities:** The SDK is inspired by capabilities-based security, and informed by years of wrestling with blockchain state-machines. Most developers will need to access other 3rd party modules when building their own modules. Given that the Cosmos-SDK is an open framework and that we assume that some of those modules may be malicious, we designed the SDK using object-capabilities (ocaps) based principles. In practice, this means that instead of having each module keep an access control list for other modules, each module implements special objects called keepers that can be passed to other modules to grant a pre-defined set of capabilities. For example, if an instance of module A's keepers is passed to module B, the latter will be able to call a restricted set of module A's functions. The capabilities of each keeper are defined by the module's developer, and it's the developer's job to understand and audit the safety of foreign code from 3rd party modules based on the capabilities they are passing into each 3rd party module. For a deeper look at capabilities, you can read this [article](http://habitatchronicles.com/2017/05/what-are-capabilities/).
 
 For an introduction to object-capabilities, see this [article](http://habitatchronicles.com/2017/05/what-are-capabilities/).
 

docs/sdk/sdk-by-examples/intro.md

@@ -0,0 +1,7 @@
+**SDK by Examples** offers an alternative and complementary way to learn about the Cosmos-SDK. It contains several examples that showcase how to build a decentralised application on top of the Cosmos-SDK from start to finish.  
+
+Without further ado, let us get into it!
+
+- [Simple governance example](./simple-governance/intro.md)
+
+If you have an example you would like to add to the list, feel free to open a PR [here](https://github.com/cosmos/cosmos-sdk/pulls).

docs/sdk/sdk-by-examples/simple-governance/app-cli.md

@@ -0,0 +1,23 @@
+## Application CLI 
+
+**File: [`cmd/simplegovcli/maing.go`](https://github.com/cosmos/cosmos-sdk/blob/fedekunze/module_tutorial/examples/simpleGov/cmd/simplegovcli/main.go)**
+
+To interact with our application, let us add the commands from the `simple_governance` module to our `simpleGov` application, as well as the pre-built SDK commands:
+
+```go
+//  cmd/simplegovcli/main.go
+...
+	rootCmd.AddCommand(
+		client.GetCommands(
+			simplegovcmd.GetCmdQueryProposal("proposals", cdc),
+			simplegovcmd.GetCmdQueryProposals("proposals", cdc),
+			simplegovcmd.GetCmdQueryProposalVotes("proposals", cdc),
+			simplegovcmd.GetCmdQueryProposalVote("proposals", cdc),
+		)...)
+	rootCmd.AddCommand(
+		client.PostCommands(
+			simplegovcmd.PostCmdPropose(cdc),
+			simplegovcmd.PostCmdVote(cdc),
+		)...)
+...
+```

docs/sdk/sdk-by-examples/simple-governance/app-codec.md

@@ -0,0 +1,21 @@
+## Application codec
+
+**File: [`app/app.go`](https://github.com/cosmos/cosmos-sdk/blob/fedekunze/module_tutorial/examples/simpleGov/app/app.go)**
+
+Finally, we need to define the `MakeCodec()` function and register the concrete types and interface from the various modules.
+
+```go
+func MakeCodec() *wire.Codec {
+    var cdc = wire.NewCodec()
+    wire.RegisterCrypto(cdc) // Register crypto.
+    sdk.RegisterWire(cdc)    // Register Msgs
+    bank.RegisterWire(cdc)
+    simplestake.RegisterWire(cdc)
+    simpleGov.RegisterWire(cdc)
+
+    // Register AppAccount
+    cdc.RegisterInterface((*auth.Account)(nil), nil)
+    cdc.RegisterConcrete(&types.AppAccount{}, "simpleGov/Account", nil)
+    return cdc
+}
+```

docs/sdk/sdk-by-examples/simple-governance/app-commands.md

@@ -0,0 +1,9 @@
+## App commands
+
+We will need to add the newly created commands to our application. To do so, go to the `cmd` folder inside your root  directory:
+
+```bash
+// At root level of directory
+cd cmd
+```
+`simplegovd` is the folder that stores the command for running the server daemon, whereas `simplegovcli` defines the commands of your application.

docs/sdk/sdk-by-examples/simple-governance/app-constructor.md

@@ -0,0 +1,61 @@
+## Application constructor
+
+**File: [`app/app.go`](https://github.com/cosmos/cosmos-sdk/blob/fedekunze/module_tutorial/examples/simpleGov/app/app.go)**
+
+Now, we need to define the constructor for our application.
+
+```go
+func NewSimpleGovApp(logger log.Logger, db dbm.DB) *SimpleGovApp
+```
+
+In this function, we will:
+
+- Create the codec
+
+```go
+var cdc = MakeCodec()
+```
+
+- Instantiate our application. This includes creating the keys to access each of the substores.
+
+```go
+// Create your application object.
+    var app = &SimpleGovApp{
+        BaseApp:              bam.NewBaseApp(appName, cdc, logger, db),
+        cdc:                  cdc,
+        capKeyMainStore:      sdk.NewKVStoreKey("main"),
+        capKeyAccountStore:   sdk.NewKVStoreKey("acc"),
+        capKeyStakingStore:   sdk.NewKVStoreKey("stake"),
+        capKeySimpleGovStore: sdk.NewKVStoreKey("simpleGov"),
+    }
+```
+
+- Instantiate the keepers. Note that keepers generally need access to other module's keepers. In this case, make sure you only pass an instance of the keeper for the functionality that is needed. If a keeper only needs to read in another module's store, a read-only keeper should be passed to it.
+
+```go
+app.coinKeeper = bank.NewKeeper(app.accountMapper)
+app.stakeKeeper = simplestake.NewKeeper(app.capKeyStakingStore, app.coinKeeper,app.RegisterCodespace(simplestake.DefaultCodespace))
+app.simpleGovKeeper = simpleGov.NewKeeper(app.capKeySimpleGovStore, app.coinKeeper, app.stakeKeeper, app.RegisterCodespace(simpleGov.DefaultCodespace))
+```
+
+- Declare the handlers.
+
+```go
+app.Router().
+        AddRoute("bank", bank.NewHandler(app.coinKeeper)).
+        AddRoute("simplestake", simplestake.NewHandler(app.stakeKeeper)).
+        AddRoute("simpleGov", simpleGov.NewHandler(app.simpleGovKeeper))
+```
+
+- Initialize the application.
+
+```go
+// Initialize BaseApp.
+    app.MountStoresIAVL(app.capKeyMainStore, app.capKeyAccountStore, app.capKeySimpleGovStore, app.capKeyStakingStore)
+    app.SetAnteHandler(auth.NewAnteHandler(app.accountMapper, app.feeCollectionKeeper))
+    err := app.LoadLatestVersion(app.capKeyMainStore)
+    if err != nil {
+        cmn.Exit(err.Error())
+    }
+    return app
+```

docs/sdk/sdk-by-examples/simple-governance/app-design.md

@@ -0,0 +1,78 @@
+## Application design
+
+### Application description
+
+For this tutorial, we will code a **simple governance application**, accompagnied by a **simple governance module**. It will allow us to explain most of the basic notions required to build a functioning application on the Cosmos-SDK. Note that this is not the governance module used for the Cosmos Hub. A much more [advanced governance module](https://github.com/cosmos/cosmos-sdk/tree/develop/x/gov) will be used instead.
+
+All the code for the `simple_governance` application can be found [here](https://github.com/gamarin2/cosmos-sdk/tree/module_tutorial/examples/simpleGov/x/simple_governance). You'll notice that the module and app aren't located at the root level of the repo but in the examples directory. This is just for convenience, you can code your module and application directly in the root directory.
+
+Without further talk, let's get into it!
+
+### Requirements
+
+We will start by writting down your module's requirements. We are designing a simple governance module, in which we want:
+
+- Simple text proposals, that any coin holder can submit.
+- Proposals must be submitted with a deposit in Atoms. If the deposit is larger than a  `MinDeposit`, the associated proposal enters the voting period. Otherwise it is rejected. 
+- Bonded Atom holders can vote on proposal on a 1 bonded Atom 1 vote basis
+- Bonded Atom holders can choose between 3 options when casting a vote: `Yes`, `No` and `Abstain`.
+- If, at the end of the voting period, there are more `Yes` votes than `No` votes, the proposal is accepted. Otherwise, it is rejected.
+- Voting period is 2 weeks
+
+When designing a module, it is good to adopt a certain methodology. Remember that a blockchain application is just a replicated state-machine. The state is the representation of the application at a given time. It is up to the application developer to define what the state represents, depending on the goal of the application. For example, the state of a simple cryptocurrency application will be a mapping of addresses to balances.
+
+The state can be updated according to predefined rules. Given a state and a transaction, the state-machine (i.e. the application) will return a new state. In a blockchain application, transactions are bundled in blocks, but the logic is the same. Given a state and a set of transactions (a block), the application returns a new state. A SDK-module is just a subset of the application, but it is based on the same principles. As a result, module developers only have to define a subset of the state and a subset of the transaction types, which trigger state transitions.
+
+In summary, we have to define:
+
+- A `State`, which represents a subset of the current state of the application.
+- `Transactions`, which contain messages that trigger state transitions.
+
+### State
+
+Here, we will define the types we need (excluding transaction types), as well as the stores in the multistore.
+
+Our voting module is very simple, we only need a single type: `Proposal`. `Proposals` are item to be voted upon. They can be submitted by any user. A deposit has to be provided.
+
+```go
+type Proposal struct {
+    Title           string          // Title of the proposal
+    Description     string          // Description of the proposal
+    Submitter       sdk.Address     // Address of the submitter. Needed to refund deposit if proposal is accepted.
+    SubmitBlock     int64           // Block at which proposal is submitted. Also the block at which voting period begins.
+    State           string          // State can be either "Open", "Accepted" or "Rejected"
+
+    YesVotes        int64           // Total number of Yes votes
+    NoVotes         int64           // Total number of No votes
+    AbstainVotes    int64           // Total number of Abstain votes
+}
+```
+
+In terms of store, we will just create one [KVStore](#kvstore) in the multistore to store `Proposals`. We will also store the `Vote` (`Yes`, `No` or `Abstain`) chosen by each voter on each proposal.
+
+
+### Messages
+
+As a module developer, what you have to define are not `Transactions`, but `Messages`. Both transactions and messages exist in the Cosmos-SDK, but a transaction differs from a message in that a message is contained in a transaction. Transactions wrap around messages and add standard information like signatures and fees. As a module developer, you do not have to worry about transactions, only messages.
+
+Let us define the messages we need in order to modify the state. Based on the requirements above, we need to define two types of messages: 
+
+- `SubmitProposalMsg`: to submit proposals
+- `VoteMsg`: to vote on proposals
+
+```go
+type SubmitProposalMsg struct {
+    Title           string      // Title of the proposal
+    Description     string      // Description of the proposal
+    Deposit         sdk.Coins   // Deposit paid by submitter. Must be > MinDeposit to enter voting period
+    Submitter       sdk.Address // Address of the submitter
+}
+```
+
+```go
+type VoteMsg struct {
+    ProposalID  int64           // ID of the proposal
+    Option      string          // Option chosen by voter
+    Voter       sdk.Address     // Address of the voter
+}
+```

docs/sdk/sdk-by-examples/simple-governance/app-init.md

@@ -0,0 +1,11 @@
+## Application initialization 
+
+In the root of your fork of the SDK, create an `app` and `cmd` folder. In this folder, we will create the main file for our application, `app.go` and the repository to handle REST and CLI commands for our app. 
+
+```bash
+mkdir app cmd 
+mkdir -p cmd/simplegovcli cmd/simplegovd
+touch app/app.go cmd/simplegovcli/main.go cmd/simplegovd/main.go
+```
+
+We will take care of these files later in the tutorial. The first step is to take care of our simple governance module.

docs/sdk/sdk-by-examples/simple-governance/app-makefile.md

@@ -0,0 +1,22 @@
+## Makefile
+
+The [Makefile](https://en.wikipedia.org/wiki/Makefile) compiles the Go program by defining a set of rules with targets and recipes. We'll need to add our application commands to it:
+
+```
+// Makefile
+build_examples:
+ifeq ($(OS),Windows_NT)
+	...
+	go build $(BUILD_FLAGS) -o build/simplegovd.exe ./examples/simpleGov/cmd/simplegovd
+	go build $(BUILD_FLAGS) -o build/simplegovcli.exe ./examples/simpleGov/cmd/simplegovcli
+else
+	...
+	go build $(BUILD_FLAGS) -o build/simplegovd ./examples/simpleGov/cmd/simplegovd
+	go build $(BUILD_FLAGS) -o build/simplegovcli ./examples/simpleGov/cmd/simplegovcli
+endif
+...
+install_examples:
+    ...
+	go install $(BUILD_FLAGS) ./examples/simpleGov/cmd/simplegovd
+	go install $(BUILD_FLAGS) ./examples/simpleGov/cmd/simplegovcli
+```

docs/sdk/sdk-by-examples/simple-governance/app-rest.md

@@ -0,0 +1,57 @@
+##### Rest server
+
+**File: [`cmd/simplegovd/main.go`](https://github.com/cosmos/cosmos-sdk/blob/fedekunze/module_tutorial/examples/simpleGov/cmd/simplegovd/main.go)**
+
+The `simplegovd` command will run the daemon server as a background process. First, let us create some `utils` functions:
+
+```go
+//  cmd/simplegovd/main.go
+// SimpleGovAppInit initial parameters
+var SimpleGovAppInit = server.AppInit{
+	AppGenState: SimpleGovAppGenState,
+	AppGenTx:    server.SimpleAppGenTx,
+}
+
+// SimpleGovAppGenState sets up the app_state and appends the simpleGov app state
+func SimpleGovAppGenState(cdc *wire.Codec, appGenTxs []json.RawMessage) (appState json.RawMessage, err error) {
+	appState, err = server.SimpleAppGenState(cdc, appGenTxs)
+	if err != nil {
+		return
+	}
+	return
+}
+
+func newApp(logger log.Logger, db dbm.DB) abci.Application {
+	return app.NewSimpleGovApp(logger, db)
+}
+
+func exportAppState(logger log.Logger, db dbm.DB) (json.RawMessage, error) {
+	dapp := app.NewSimpleGovApp(logger, db)
+	return dapp.ExportAppStateJSON()
+}
+```
+
+Now, let us define the command for the daemon server within the `main()` function:
+
+```go
+//  cmd/simplegovd/main.go
+func main() {
+	cdc := app.MakeCodec()
+	ctx := server.NewDefaultContext()
+
+	rootCmd := &cobra.Command{
+		Use:               "simplegovd",
+		Short:             "Simple Governance Daemon (server)",
+		PersistentPreRunE: server.PersistentPreRunEFn(ctx),
+	}
+
+	server.AddCommands(ctx, cdc, rootCmd, SimpleGovAppInit,
+		server.ConstructAppCreator(newApp, "simplegov"),
+		server.ConstructAppExporter(exportAppState, "simplegov"))
+
+	// prepare and add flags
+	rootDir := os.ExpandEnv("$HOME/.simplegovd")
+	executor := cli.PrepareBaseCmd(rootCmd, "BC", rootDir)
+	executor.Execute()
+}
+```

docs/sdk/sdk-by-examples/simple-governance/app-structure.md

@@ -0,0 +1,55 @@
+## Application structure
+
+Now, that we have built all the pieces we need, it is time to integrate them into the application. Let us exit the `/x` director go back at the root of the SDK directory.
+
+
+```bash
+// At root level of directory
+cd app
+```
+
+We are ready to create our simple governance application!
+
+*Note: You can check the full file (with comments!) [here](link)*
+
+The `app.go` file is the main file that defines your application. In it, you will declare all the modules you need, their keepers, handlers, stores, etc. Let us take a look at each section of this file to see how the application is constructed.
+
+Secondly, we need to define the name of our application.
+
+```go
+const (
+    appName = "SimpleGovApp"
+)
+```
+
+Then, let us define the structure of our application.
+
+```go
+// Extended ABCI application
+type SimpleGovApp struct {
+    *bam.BaseApp
+    cdc *wire.Codec
+
+    // keys to access the substores
+    capKeyMainStore      *sdk.KVStoreKey
+    capKeyAccountStore   *sdk.KVStoreKey
+    capKeyStakingStore   *sdk.KVStoreKey
+    capKeySimpleGovStore *sdk.KVStoreKey
+
+    // keepers
+    feeCollectionKeeper auth.FeeCollectionKeeper
+    coinKeeper          bank.Keeper
+    stakeKeeper         simplestake.Keeper
+    simpleGovKeeper     simpleGov.Keeper
+
+    // Manage getting and setting accounts
+    accountMapper auth.AccountMapper
+}
+```
+
+- Each application builds on top of the `BaseApp` template, hence the pointer.
+- `cdc` is the codec used in our application.
+- Then come the keys to the stores we need in our application. For our simple governance app, we need 3 stores + the main store.
+- Then come the keepers and mappers.
+
+Let us do a quick reminder so that it is  clear why we need these stores and keepers. Our application is primarily based on the `simple_governance` module. However, we have established in section [Keepers for our app](module-keeper.md) that our module needs access to two other modules: the `bank` module and the `stake` module. We also need the `auth` module for basic account functionalities. Finally, we need access to the main multistore to declare the stores of each of the module we use.

docs/sdk/sdk-by-examples/simple-governance/cast-vote.md

@@ -0,0 +1,19 @@
+## Cast a vote to an existing proposal
+
+Let's cast a vote on the created proposal:
+
+```bash
+simplegovcli vote --proposal-id=1 --option="No"
+```
+
+Get the value of the option from your casted vote :
+
+```bash
+simplegovcli proposal-vote 1 <your_address>
+```
+
+You can also check all the casted votes of a proposal:
+
+```bash
+simplegovcli proposals-votes 1
+```

docs/sdk/sdk-by-examples/simple-governance/intro.md

@@ -0,0 +1,58 @@
+# SDK By Examples - Simple Governance Application 
+
+In this tutorial, you will learn the basics of coding an application with the Cosmos-SDK. Applications built on top of the SDK are called *Application-specific blockchains*. They are decentralised applications running on their own blockchains. The application we will build in this tutorial is a simple governance application.
+
+Before getting in the bulk of the code, we will start by some introductory content on Tendermint, Cosmos and the programming philosophy of the SDK. Let us get started!
+
+## Table of contents:
+
+### Introduction - Prerequsite reading
+
+- [Intro to Tendermint and Cosmos](../../../introduction/tendermint-cosmos.md)
+- [Tendermint Core and ABCI](../../../introduction/tendermint.md)
+- [Intro to Cosmos-SDK](../../overview.md)
+- [Starting your own project](start.md)
+
+### Setup and design phase
+
+- [Setup](setup.md)
+- [Application design](app-design.md)
+
+### Implementation of the application
+
+**Important note: All the code for this application can be found [here](https://github.com/cosmos/cosmos-sdk/tree/fedekunze/module_tutorial/examples/simpleGov). Snippets will be provided throughout the tutorial, but please refer to the provided link for the full implementation details**
+
+- [Application initialization](app-init.md)
+- Simple Governance module
+    + [Module initialization](module-init.md)
+    + [Types](module-types.md)
+    + [Keeper](module-keeper.md)
+    + [Handler](module-handler.md)
+    + [Wire](module-wire.md)
+    + [Errors](module-errors.md)
+    + Command-Line Interface and Rest API
+        * [Command-Line Interface](module-cli.md)
+        * [Rest API](module-rest.md)
+- Bridging it all together
+    + [Application structure](app-structure.md)
+    + [Application CLI and Rest Server](app-commands.md)
+        * [Application CLI](app-cli.md)
+        * [Rest Server](app-rest.md)
+    + [Makefile](app-makefile.md)
+    + [Application constructor](app-constructor.md)
+    + [Application codec](app-codec.md)
+- Running the application
+    + [Installation](run-install.md)
+    + [Submit a proposal](submit-proposal.md)
+    + [Cast a vote](cast-vote.md)
+
+## Useful links
+
+If you have any question regarding this tutorial or about development on the SDK, please reach out us through our official communication channels:
+
+- [Cosmos-SDK Riot Channel](https://riot.im/app/#/room/#cosmos-sdk:matrix.org)
+- [Telegram](https://t.me/cosmosproject)
+
+Or open an issue on the SDK repo:
+
+- [Cosmos-SDK repo](https://github.com/cosmos/cosmos-sdk/)

docs/sdk/sdk-by-examples/simple-governance/module-cli.md

@@ -0,0 +1,33 @@
+## Command-Line Interface (CLI)
+
+**File: [`x/simple_governance/client/cli/simple_governance.go`](https://github.com/cosmos/cosmos-sdk/blob/fedekunze/module_tutorial/examples/simpleGov/x/simple_governance/client/cli/simple_governance.go)**
+
+Go in the `cli` folder and create a `simple_governance.go` file. This is where we will define the commands for our module.
+
+The CLI builds on top of [Cobra](https://github.com/spf13/cobra). Here is the schema to build a command on top of Cobra:
+
+```go
+    // Declare flags
+    const(
+        Flag = "flag"
+        ...
+    )
+
+    // Main command function. One function for each command.
+    func Command(codec *wire.Codec) *cobra.Command {
+        // Create the command to return
+        command := &cobra.Command{
+            Use: "actual command",
+            Short: "Short description",
+            Run: func(cmd *cobra.Command, args []string) error {
+                // Actual function to run when command is used
+            },
+        }
+
+        // Add flags to the command
+        command.Flags().<Type>(FlagNameConstant, <example_value>, "<Description>")
+
+        return command
+    }
+```
+

docs/sdk/sdk-by-examples/simple-governance/module-errors.md

@@ -0,0 +1,7 @@
+## Errors 
+
+**File: [`x/simple_governance/errors.go`](https://github.com/cosmos/cosmos-sdk/blob/fedekunze/module_tutorial/examples/simpleGov/x/simple_governance/errors.go)**
+
+The `error.go` file allows us to define custom error messages for our module.  Declaring errors should be relatively similar in all modules. You can look in the `error.go` file directly for a concrete example. The code is self-explanatory.
+
+Note that the errors of our module inherit from the `sdk.Error` interface and therefore possess the method `Result()`. This method is useful when there is an error in the `handler` and an error has to be returned in place of an actual result.

docs/sdk/sdk-by-examples/simple-governance/module-handler.md

@@ -0,0 +1,73 @@
+## Handler 
+
+**File: [`x/simple_governance/handler.go`](https://github.com/cosmos/cosmos-sdk/blob/fedekunze/module_tutorial/examples/simpleGov/x/simple_governance/handler.go)**
+
+### Constructor and core handlers
+
+Handlers implement the core logic of the state-machine. When a transaction is routed from the app to the module, it is run by the `handler` function.
+
+In practice, one `handler` will be implemented for each message of the module. In our case, we have two message types. We will therefore need two `handler` functions. We will also need a constructor function to route the message to the correct `handler`:
+
+```go
+func NewHandler(k Keeper) sdk.Handler {
+    return func(ctx sdk.Context, msg sdk.Msg) sdk.Result {
+        switch msg := msg.(type) {
+        case SubmitProposalMsg:
+            return handleSubmitProposalMsg(ctx, k, msg)
+        case VoteMsg:
+            return handleVoteMsg(ctx, k, msg)
+        default:
+            errMsg := "Unrecognized gov Msg type: " + reflect.TypeOf(msg).Name()
+            return sdk.ErrUnknownRequest(errMsg).Result()
+        }
+    }
+}
+```
+
+The messages are routed to the appropriate `handler` depending on their type. For our simple governance module, we only have two `handlers`, that correspond to our two message types. They have similar signatures:
+
+```go
+func handleSubmitProposalMsg(ctx sdk.Context, k Keeper, msg SubmitProposalMsg) sdk.Result
+```
+
+Let us take a look at the parameters of this function:
+
+- The context `ctx` to access the stores.
+- The keeper `k` allows the handler to read and write from the different stores, including the module's store (`SimpleGovernance` in our case) and all the stores from other modules that the keeper `k` has been granted an access to (`stake` and `bank` in our case).
+- The message `msg` that holds all the information provided by the sender of the transaction.
+
+The function returns a `Result` that is returned to the application. It contains several useful information such as the amount of `Gas` for this transaction and wether the message was succesfully processed or not. At this point, we exit the boundaries of our simple governance module and go back to root application level. The `Result` will differ from application to application. You can check the `sdk.Result` type directly [here](https://github.com/cosmos/cosmos-sdk/blob/develop/types/result.go) for more info.
+
+### BeginBlocker and EndBlocker
+
+In contrast to most smart-contracts platform, it is possible to perform automatic (i.e. not triggered by a transaction sent by an end-user) execution of logic in Cosmos-SDK applications.
+
+This automatic execution of code takes place in the `BeginBlock` and `EndBlock` functions that are called at the beginning and at the end of every block. They are powerful tools, but it is important for application developers to be careful with them. For example, it is crutial that developers control the amount of computing that happens in these functions, as expensive computation could delay the block time, and never-ending loop freeze the chain altogether.
+
+`BeginBlock` and `EndBlock` are composable functions, meaning that each module can implement its own `BeginBlock` and `EndBlock` logic. When needed, `BeginBlock` and `EndBlock` logic is implemented in the module's `handler`. Here is the standard way to proceed for `EndBlock` (`BeginBlock` follows the exact same pattern):
+
+```go
+func NewEndBlocker(k Keeper) sdk.EndBlocker {
+    return func(ctx sdk.Context, req abci.RequestEndBlock) (res abci.ResponseEndBlock) {
+        err := checkProposal(ctx, k)
+        if err != nil {
+            panic(err)
+        }
+        return
+    }
+}
+```
+
+Do not forget that each module need to declare its `BeginBlock` and `EndBlock` constructors at application level. See the [Application - Bridging it all together](app-structure.md).
+
+For the purpose of our simple governance application, we will use `EndBlock` to automatically tally the results of the vote. Here are the different steps that will be performed:
+
+1. Get the oldest proposal from the `ProposalProcessingQueue`
+2. Check if the `CurrentBlock` is the block at which the voting period for this proposal ends. If Yes, go to 3.. If no, exit.
+3. Check if proposal is accepted or rejected. Update the proposal status.
+4. Pop the proposal from the `ProposalProcessingQueue` and go back to 1.
+
+Let us perform a quick safety analysis on this process.
+- The loop will not run forever because the number of proposals in `ProposalProcessingQueue` is finite
+- The computation should not be too expensive because tallying of individual proposals is not expensive and the number of proposals is expected be relatively low. That is because proposals require a `Deposit` to be accepted. `MinDeposit` should be high enough so that we don't have too many `Proposals` in the queue.
+- In the eventuality that the application becomes so successful that the `ProposalProcessingQueue` ends up containing so many proposals that the blockchain starts slowing down, the module should be modified to mitigate the situation. One clever way of doing it is to cap the number of iteration per individual `EndBlock` at `MaxIteration`. This way, tallying will be spread over many blocks if the number of proposals is too important and block time should remain stable. This would require to modify the current check `if (CurrentBlock == Proposal.SubmitBlock + VotingPeriod)` to `if (CurrentBlock > Proposal.SubmitBlock + VotingPeriod) AND (Proposal.Status == ProposalStatusActive)`.

docs/sdk/sdk-by-examples/simple-governance/module-init.md

@@ -0,0 +1,31 @@
+## Module initialization 
+
+First, let us go into the module's folder and create a folder for our module.
+
+```bash
+cd x/
+mkdir simple_governance
+cd simple_governance
+mkdir -p client/cli client/rest
+touch client/cli/simple_governance.go client/rest/simple_governance.go errors.go handler.go handler_test.go keeper_keys.go keeper_test.go keeper.go test_common.go test_types.go types.go wire.go
+```
+
+Let us start by adding the files we will need. Your module's folder should look something like that:
+
+```
+x
+└─── simple_governance
+      ├─── client
+      │     ├───  cli
+      │     │     └─── simple_governance.go
+      │     └─── rest
+      │           └─── simple_governance.go
+      ├─── errors.go
+      ├─── handler.go
+      ├─── keeper_keys.go
+      ├─── keeper.go
+      ├─── types.go
+      └─── wire.go
+```
+
+Let us go into the detail of each of these files.

docs/sdk/sdk-by-examples/simple-governance/module-keeper.md

@@ -0,0 +1,96 @@
+## Keeper
+
+**File: [`x/simple_governance/keeper.go`](https://github.com/cosmos/cosmos-sdk/blob/fedekunze/module_tutorial/examples/simpleGov/x/simple_governance/keeper.go)**
+
+### Short intro to keepers
+
+`Keepers` are a module abstraction that handle reading/writing to the module store. This is a practical implementation of the **Object Capability Model** for Cosmos. 
+
+
+As module developers, we have to define keepers to interact with our module's store(s) not only from within our module, but also from other modules. When another module wants to access one of our module's store(s), a keeper for this store has to be passed to it at the application level. In practice, it will look like that:
+
+```go
+// in app.go
+
+// instanciate keepers
+keeperA = moduleA.newKeeper(app.moduleAStoreKey)
+keeperB = moduleB.newKeeper(app.moduleBStoreKey)
+
+// pass instance of keeperA to handler of module B
+app.Router().
+        AddRoute("moduleA", moduleA.NewHandler(keeperA)).
+        AddRoute("moduleB", moduleB.NewHandler(keeperB, keeperA))   // Here module B can access one of module A's store via the keeperA instance
+```
+
+`KeeperA` grants a set of capabilities to the handler of module B. When developing a module, it is good practice to think about the sensitivity of the different capabilities that can be granted through keepers. For example, some module may need to read and write to module A's main store, while others only need to read it. If a module has multiple stores, then some keepers could grant access to all of them, while others would only grant access to specific sub-stores. It is the job of the module developer to make sure it is easy for  application developers to instanciate a keeper with the right capabilities. Of course, the handler of a module will most likely get an unrestricted instance of that module's keeper.
+
+### Store for our app
+
+Before we delve into the keeper itself, let us see what objects we need to store in our governance sub-store, and how to index them.
+
+- `Proposals` will be indexed by `'proposals'|<proposalID>`.
+- `Votes` (`Yes`, `No`, `Abstain`) will be indexed by `'proposals'|<proposalID>|'votes'|<voterAddress>`.
+
+Notice the quote mark on `'proposals'` and `'votes'`. They indicate that these are constant keywords. So, for example, the option casted by voter with address `0x01` on proposal `0101` will be stored at index `'proposals'|0101|'votes'|0x01`.
+
+These keywords are used to faciliate range queries. Range queries (TODO: Link to formal spec) allow developer to query a subspace of the store, and return an iterator. They are made possible by the nice properties of the [IAVL+ tree](https://github.com/tendermint/iavl) that is used in the background. In practice, this means that it is possible to store and query a Key-Value pair in O(1), while still being able to iterate over a given subspace of Key-Value pairs. For example, we can query all the addresses that voted on a given proposal, along with their votes, by calling `rangeQuery(SimpleGovStore, <proposalID|'addresses'>)`.
+
+### Keepers for our app
+
+In our case, we only have one store to access, the `SimpleGov` store. We will need to set and get values inside this store via our keeper. However, these two actions do not have the same impact in terms of security. While there should no problem in granting read access to our store to other modules, write access is way more sensitive. So ideally application developers should be able to create either a governance mapper that can only get values from the store, or one that can both get and set values. To this end, we will introduce two keepers: `Keeper` and `KeeperRead`. When application developers create their application, they will be able to decide which of our module's keeper to use.
+
+Now, let us try to think about which keeper from **external** modules our module's keepers need access to.
+Each proposal requires a deposit. This means our module needs to be able to both read and write to the module that handles tokens, which is the `bank` module. We also need to be able to determine the voting power of each voter based on their stake. To this end, we need read access to the store of the `staking` module. However, we don't need write access to this store. We should therefore indicate that in our module, and the application developer should be careful to only pass a read-only keeper of the `staking` module to our module's handler.
+
+With all that in mind, we can define the structure of our `Keeper`:
+
+```go
+    type Keeper struct {
+        SimpleGov    sdk.StoreKey        // Key to our module's store
+        cdc                 *wire.Codec         // Codec to encore/decode structs
+        ck                  bank.Keeper         // Needed to handle deposits. This module onlyl requires read/writes to Atom balance
+        sm                  stake.Keeper        // Needed to compute voting power. This module only needs read access to the staking store.
+        codespace           sdk.CodespaceType   // Reserves space for error codes
+    }
+```
+
+And the structure of our `KeeperRead`:
+
+```go
+type KeeperRead struct {
+    Keeper
+}
+```
+
+`KeeperRead` will inherit all methods from `Keeper`, except those that we override. These will be the methods that perform writes to the store.
+
+### Functions and Methods
+
+The first function we have to create is the constructor.
+
+```go
+func NewKeeper(SimpleGov sdk.StoreKey, ck bank.Keeper, sm stake.Keeper, codespace sdk.CodespaceType) Keeper
+```
+
+This function is called from the main [`app.go`](https://github.com/cosmos/cosmos-sdk/blob/fedekunze/module_tutorial/examples/simpleGov/app/app.go) file to instanciate a new `Keeper`. A similar function exits for `KeeperRead`.
+
+```go
+func NewKeeperRead(SimpleGov sdk.StoreKey, ck bank.Keeper, sm stake.Keeper, codespace sdk.CodespaceType) KeeperRead
+```
+
+Depending on the needs of the application and its modules, either `Keeper`, `KeeperRead`, or both, will be instanciated at application level.
+
+*Note: Both the `Keeper` type name and `NewKeeper()` function's name are standard names used in every module. It is no requirement to follow this standard, but doing so can facilitate the life of application developers*
+
+Now, let us describe the methods we need for our module's `Keeper`. For the full implementation, please refer to `keeper.go`.
+
+- `GetProposal`: Get a `Proposal` given a `proposalID`. Proposals need to be decoded from `byte` before they can be read.
+- `SetProposal`: Set a `Proposal` at index `'proposals'|<proposalID>`. Proposals need to be encoded to `byte` before they can be stored.
+- `NewProposalID`: A function to generate a new unique `proposalID`.
+- `GetVote`: Get a vote `Option` given a `proposalID` and a `voterAddress`.
+- `SetVote`: Set a vote `Option` given a `proposalID` and a `voterAddress`.
+- Proposal Queue methods: These methods implement a standard proposal queue to store `Proposals` on a First-In First-Out basis. It is used to tally the votes at the end of the voting period.
+
+The last thing that needs to be done is to override certain methods for the `KeeperRead` type. `KeeperRead` should not have write access to the stores. Therefore, we will override the methods `SetProposal()`, `SetVote()` and `NewProposalID()`, as well as `setProposalQueue()` from the Proposal Queue's methods. For `KeeperRead`, these methods will just throw an error.
+
+*Note: If you look at the code, you'll notice that the context `ctx` is a parameter of many of the methods. The context `ctx` provides useful information on the current state such as the current block height and allows the keeper `k` to access the `KVStore`. You can check all the methods of `ctx` [here](https://github.com/cosmos/cosmos-sdk/blob/develop/types/context.go#L144-L168)*.

docs/sdk/sdk-by-examples/simple-governance/module-rest.md

@@ -0,0 +1,32 @@
+## Rest API
+
+**File: [`x/simple_governance/client/rest/simple_governance.goo`](https://github.com/cosmos/cosmos-sdk/blob/fedekunze/module_tutorial/examples/simpleGov/x/simple_governance/client/rest/simple_governance.go)**
+
+The Rest Server, also called [Light-Client Daemon (LCD)](https://github.com/cosmos/cosmos-sdk/tree/master/client/lcd), provides support for **HTTP queries**.
+
+________________________________________________________
+
+USER INTERFACE <=======> REST SERVER <=======> FULL-NODE
+
+________________________________________________________
+
+It allows end-users that do not want to run full-nodes themselves to interract with the chain. The LCD can be configured to perform **Light-Client verification** via the flag `--trust-node`, which can be set to `true` or `false`.
+
+- If *light-client verification* is enabled, the Rest Server acts as a light-client and needs to be run on the end-user's machine. It allows them to interract with the chain in a trustless way without having to store the whole chain locally.
+
+- If *light-client verification* is disabled, the Rest Server acts as a simple relayer for HTTP calls. In this setting, the Rest server needs not be run on the end-user's machine. Instead, it will probably be run by the same entity that operates the full-node the server connects to. This mode is useful if end-users trust the full-node operator and do not want to store anything locally.
+
+Now, let us define endpoints that will be available for users to query through HTTP requests. These endpoints will be defined in a `simple_governance.go` file stored in the `rest` folder.
+
+| Method | URL                             | Description                                                 |
+|--------|---------------------------------|-------------------------------------------------------------|
+| GET    | /proposals                      | Range query to get all submitted proposals                  |
+| POST   | /proposals                      | Submit a new proposal                                       |
+| GET    | /proposals/{id}                 | Returns a proposal given its ID                             |
+| GET    | /proposals/{id}/votes           | Range query to get all the votes casted on a given proposal |
+| POST   | /proposals/{id}/votes           | Cast a vote on a given proposal                             |
+| GET    | /proposals/{id}/votes/{address} | Returns the vote of a given address on a given proposal     |
+
+It is the job of module developers to provide sensible endpoints so that front-end developers and service providers can properly interact with it.
+
+Additionaly, here is a [link](https://hackernoon.com/restful-api-designing-guidelines-the-best-practices-60e1d954e7c9) for REST APIs best practices.

docs/sdk/sdk-by-examples/simple-governance/module-types.md

@@ -0,0 +1,23 @@
+## Types 
+
+**File: [`x/simple_governance/types.go`](https://github.com/cosmos/cosmos-sdk/blob/fedekunze/module_tutorial/examples/simpleGov/x/simple_governance/types.go)**
+
+In this file, we define the custom types for our module. This includes the types from the [State](app-design.md#State) section and the custom message types defined in the [Messages](app-design#Messages) section.
+
+For each new type that is not a message, it is possible to add methods that make sense in the context of the application. In our case, we will implement an `updateTally` function to easily update the tally of a given proposal as vote messages come in.
+
+Messages are a bit different. They implement the `Message` interface defined in the SDK's `types` folder. Here are the methods you need to implement when you define a custom message type:
+
+- `Type()`: This function returns the name of our module's route. When messages are processed by the application, they are routed using the string returned by the `Type()` method.
+- `GetSignBytes()`: Returns the byte representation of the message. It is used to sign the message.
+- `GetSigners()`: Returns address(es) of the signer(s).
+- `ValidateBasic()`: This function is used to discard obviously invalid messages. It is called at the beginning of `runTx()` in the baseapp file. If `ValidateBasic()` does not return `nil`, the app stops running the transaction.
+- `Get()`: A basic getter, returns some property of the message.
+- `String()`: Returns a human-readable version of the message
+
+For our simple governance messages, this means:
+
+- `Type()` will return `"simpleGov"`
+- For `SubmitProposalMsg`, we need to make sure that the attributes are not empty and that the deposit is both valid and positive. Note that this is only basic validation, we will therefore not check in this method that the sender has sufficient funds to pay for the deposit
+- For `VoteMsg`, we check that the address and option are valid and that the proposalID is not negative.
+- As for other methods, less customization is required. You can check the code to see a standard way of implementing these.

docs/sdk/sdk-by-examples/simple-governance/module-wire.md

@@ -0,0 +1,13 @@
+## Wire 
+
+**File: [`x/simple_governance/wire.go`](https://github.com/cosmos/cosmos-sdk/blob/fedekunze/module_tutorial/examples/simpleGov/x/simple_governance/wire.go)**
+
+The `wire.go` file allows developers to register the concrete message types of their module into the codec. In our case, we have two messages to declare:
+
+```go
+func RegisterWire(cdc *wire.Codec) {
+    cdc.RegisterConcrete(SubmitProposalMsg{}, "simple_governance/SubmitProposalMsg", nil)
+    cdc.RegisterConcrete(VoteMsg{}, "simple_governance/VoteMsg", nil)
+}
+```
+Don't forget to call this function in `app.go` (see [Application - Bridging it all together](app-structure.md)) for more).

docs/sdk/sdk-by-examples/simple-governance/run-install.md

@@ -0,0 +1,18 @@
+## Installation
+
+Once you have finallized your application, install it using `go get`. The following commands will install the pre-built modules and examples of the SDK as well as your `simpleGov` application:
+
+```bash
+go get github.com/<your_username>/cosmos-sdk
+cd $GOPATH/src/github.com/<your_username>/cosmos-sdk
+make get_vendor_deps
+make install
+make install_examples
+```
+
+Check that the app is correctly installed by typing:
+
+```bash
+simplegovcli -h
+simplegovd -h
+```

docs/sdk/sdk-by-examples/simple-governance/setup.md

@@ -0,0 +1,32 @@
+## Setup
+
+### Prerequisites
+
+- Have [go](https://golang.org/dl/) and [git](https://git-scm.com/downloads) installed
+- Don't forget to set your `PATH` and `GOPATH`
+
+### Setup work environment
+
+Go to the [Cosmos-SDK repo](https://githum.com/cosmos/cosmos-sdk) and fork it. Then open a terminal and:
+
+```bash
+cd $GOPATH/src/github.com/your_username
+git clone github.com/your_username/cosmos-sdk
+cd cosmos-sdk
+```
+
+Now we'll add the origin Cosmos-SDK as upstream in case some cool feature or module gets merged:
+
+```bash
+git remote add upstream github.com/cosmos/cosmos-sdk
+git fetch upstream
+git rebase upstream/master
+```
+
+We will also create a branch dedicated to our module:
+
+```bash
+git checkout -b my_new_application
+```
+
+We are all set!

docs/sdk/sdk-by-examples/simple-governance/start.md

@@ -0,0 +1,10 @@
+## Starting your own project 
+
+To get started, you just have to follow these simple steps:
+
+1. Clone the [Cosmos-SDK](https://github.com/cosmos/cosmos-sdk/tree/develop)repo
+2. Code the modules needed by your application that do not already exist.
+3. Create your app directory. In the app main file, import the module you need and instantiate the different stores.
+4. Launch your blockchain.
+
+Easy as pie! With the introduction over, let us delve into practice and learn how to code a SDK application with an example.

docs/sdk/sdk-by-examples/simple-governance/submit-proposal.md

@@ -0,0 +1,19 @@
+## Submit a proposal
+
+Uuse the CLI to create a new proposal:
+
+```bash
+simplegovcli propose --title="Voting Period update" --description="Should we change the proposal voting period to 3 weeks?" --deposit=300Atoms
+```
+
+Get the details of your newly created proposal:
+
+```bash
+simplegovcli proposal 1
+```
+
+You can also check all the existing open proposals:
+
+```bash
+simplegovcli proposals --active=true
+```