- ---
- order: 1
- ---
-
- # Getting Started
-
- ## First Tendermint App
-
- As a general purpose blockchain engine, Tendermint is agnostic to the
- application you want to run. So, to run a complete blockchain that does
- something useful, you must start two programs: one is Tendermint Core,
- the other is your application, which can be written in any programming
- language. Recall from [the intro to
- ABCI](../introduction/what-is-tendermint.md#abci-overview) that Tendermint Core handles all the p2p and consensus stuff, and just forwards transactions to the
- application when they need to be validated, or when they're ready to be
- committed to a block.
-
- In this guide, we show you some examples of how to run an application
- using Tendermint.
-
- ### Install
-
- The first apps we will work with are written in Go. To install them, you
- need to [install Go](https://golang.org/doc/install), put
- `$GOPATH/bin` in your `$PATH` and enable go modules with these instructions:
-
- ```bash
- echo export GOPATH=\"\$HOME/go\" >> ~/.bash_profile
- echo export PATH=\"\$PATH:\$GOPATH/bin\" >> ~/.bash_profile
- ```
-
- Then run
-
- ```sh
- go get github.com/tendermint/tendermint
- cd $GOPATH/src/github.com/tendermint/tendermint
- make install_abci
- ```
-
- Now you should have the `abci-cli` installed; you'll notice the `kvstore`
- command, an example application written
- in Go. See below for an application written in JavaScript.
-
- Now, let's run some apps!
-
- ## KVStore - A First Example
-
- The kvstore app is a [Merkle
- tree](https://en.wikipedia.org/wiki/Merkle_tree) that just stores all
- transactions. If the transaction contains an `=`, e.g. `key=value`, then
- the `value` is stored under the `key` in the Merkle tree. Otherwise, the
- full transaction bytes are stored as the key and the value.
-
- Let's start a kvstore application.
-
- ```sh
- abci-cli kvstore
- ```
-
- In another terminal, we can start Tendermint. You should already have the
- Tendermint binary installed. If not, follow the steps from
- [here](../introduction/install.md). If you have never run Tendermint
- before, use:
-
- ```sh
- tendermint init validator
- tendermint start
- ```
-
- If you have used Tendermint, you may want to reset the data for a new
- blockchain by running `tendermint unsafe_reset_all`. Then you can run
- `tendermint start` to start Tendermint, and connect to the app. For more
- details, see [the guide on using Tendermint](../tendermint-core/using-tendermint.md).
-
- You should see Tendermint making blocks! We can get the status of our
- Tendermint node as follows:
-
- ```sh
- curl -s localhost:26657/status
- ```
-
- The `-s` just silences `curl`. For nicer output, pipe the result into a
- tool like [jq](https://stedolan.github.io/jq/) or `json_pp`.
-
- Now let's send some transactions to the kvstore.
-
- ```sh
- curl -s 'localhost:26657/broadcast_tx_commit?tx="abcd"'
- ```
-
- Note the single quote (`'`) around the url, which ensures that the
- double quotes (`"`) are not escaped by bash. This command sent a
- transaction with bytes `abcd`, so `abcd` will be stored as both the key
- and the value in the Merkle tree. The response should look something
- like:
-
- ```json
- {
- "check_tx": { ... },
- "deliver_tx": {
- "tags": [
- {
- "key": "YXBwLmNyZWF0b3I=",
- "value": "amFl"
- },
- {
- "key": "YXBwLmtleQ==",
- "value": "YWJjZA=="
- }
- ]
- },
- "hash": "9DF66553F98DE3C26E3C3317A3E4CED54F714E39",
- "height": 14
- }
- ```
-
- We can confirm that our transaction worked and the value got stored by
- querying the app:
-
- ```sh
- curl -s 'localhost:26657/abci_query?data="abcd"'
- ```
-
- The result should look like:
-
- ```json
- {
- "response": {
- "log": "exists",
- "index": "-1",
- "key": "YWJjZA==",
- "value": "YWJjZA=="
- }
- }
- ```
-
- Note the `value` in the result (`YWJjZA==`); this is the base64-encoding
- of the ASCII of `abcd`. You can verify this in a python 2 shell by
- running `"YWJjZA==".decode('base64')` or in python 3 shell by running
- `import codecs; codecs.decode(b"YWJjZA==", 'base64').decode('ascii')`.
- Stay tuned for a future release that [makes this output more
- human-readable](https://github.com/tendermint/tendermint/issues/1794).
-
- Now let's try setting a different key and value:
-
- ```sh
- curl -s 'localhost:26657/broadcast_tx_commit?tx="name=satoshi"'
- ```
-
- Now if we query for `name`, we should get `satoshi`, or `c2F0b3NoaQ==`
- in base64:
-
- ```sh
- curl -s 'localhost:26657/abci_query?data="name"'
- ```
-
- Try some other transactions and queries to make sure everything is
- working!
-
-
- ## CounterJS - Example in Another Language
-
- We also want to run applications in another language - in this case,
- we'll run a Javascript version of the `counter`. To run it, you'll need
- to [install node](https://nodejs.org/en/download/).
-
- You'll also need to fetch the relevant repository, from
- [here](https://github.com/tendermint/js-abci), then install it:
-
- ```sh
- git clone https://github.com/tendermint/js-abci.git
- cd js-abci
- npm install abci
- ```
-
- Kill the previous `counter` and `tendermint` processes. Now run the app:
-
- ```sh
- node example/counter.js
- ```
-
- In another window, reset and start `tendermint`:
-
- ```sh
- tendermint unsafe_reset_all
- tendermint start
- ```
-
- Once again, you should see blocks streaming by - but now, our
- application is written in Javascript! Try sending some transactions, and
- like before - the results should be the same:
-
- ```sh
- # ok
- curl localhost:26657/broadcast_tx_commit?tx=0x00
- # invalid nonce
- curl localhost:26657/broadcast_tx_commit?tx=0x05
- # ok
- curl localhost:26657/broadcast_tx_commit?tx=0x01
- ```
-
- Neat, eh?
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