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255 lines
7.1 KiB
255 lines
7.1 KiB
Using ABCI-CLI
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==============
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To facilitate testing and debugging of ABCI servers and simple apps, we
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built a CLI, the ``abci-cli``, for sending ABCI messages from the
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command line.
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Install
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-------
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Make sure you `have Go installed <https://golang.org/doc/install>`__.
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Next, install the ``abci-cli`` tool and example applications:
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::
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go get -u github.com/tendermint/abci/cmd/...
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If this fails, you may need to use ``glide`` to get vendored
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dependencies:
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::
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go get github.com/Masterminds/glide
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cd $GOPATH/src/github.com/tendermint/abci
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glide install
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go install ./cmd/...
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Now run ``abci-cli --help`` to see the list of commands:
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::
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COMMANDS:
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batch Run a batch of ABCI commands against an application
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console Start an interactive console for multiple commands
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echo Have the application echo a message
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info Get some info about the application
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set_option Set an option on the application
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deliver_tx Append a new tx to application
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check_tx Validate a tx
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commit Get application Merkle root hash
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help, h Shows a list of commands or help for one command
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GLOBAL OPTIONS:
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--address "tcp://127.0.0.1:46658" address of application socket
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--help, -h show help
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--version, -v print the version
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Dummy - First Example
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---------------------
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The ``abci-cli`` tool lets us send ABCI messages to our application, to
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help build and debug them.
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The most important messages are ``deliver_tx``, ``check_tx``, and
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``commit``, but there are others for convenience, configuration, and
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information purposes.
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Let's start a dummy application, which was installed at the same time as
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``abci-cli`` above. The dummy just stores transactions in a merkle tree:
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::
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dummy
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In another terminal, run
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::
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abci-cli echo hello
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abci-cli info
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The application should echo ``hello`` and give you some information
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about itself.
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An ABCI application must provide two things:
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- a socket server
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- a handler for ABCI messages
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When we run the ``abci-cli`` tool we open a new connection to the
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application's socket server, send the given ABCI message, and wait for a
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response.
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The server may be generic for a particular language, and we provide a
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`reference implementation in
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Golang <https://github.com/tendermint/abci/tree/master/server>`__. See
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the `list of other ABCI
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implementations <https://tendermint.com/ecosystem>`__ for servers in
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other languages.
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The handler is specific to the application, and may be arbitrary, so
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long as it is deterministic and conforms to the ABCI interface
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specification.
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So when we run ``abci-cli info``, we open a new connection to the ABCI
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server, which calls the ``Info()`` method on the application, which
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tells us the number of transactions in our Merkle tree.
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Now, since every command opens a new connection, we provide the
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``abci-cli console`` and ``abci-cli batch`` commands, to allow multiple
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ABCI messages to be sent over a single connection.
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Running ``abci-cli console`` should drop you in an interactive console
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for speaking ABCI messages to your application.
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Try running these commands:
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::
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> echo hello
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-> data: hello
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> info
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-> data: {"size":0}
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> commit
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-> data: 0x
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> deliver_tx "abc"
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-> code: OK
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> info
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-> data: {"size":1}
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> commit
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-> data: 0x750502FC7E84BBD788ED589624F06CFA871845D1
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> query "abc"
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-> code: OK
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-> data: {"index":0,"value":"abc","exists":true}
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> deliver_tx "def=xyz"
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-> code: OK
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> commit
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-> data: 0x76393B8A182E450286B0694C629ECB51B286EFD5
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> query "def"
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-> code: OK
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-> data: {"index":1,"value":"xyz","exists":true}
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Note that if we do ``deliver_tx "abc"`` it will store ``(abc, abc)``,
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but if we do ``deliver_tx "abc=efg"`` it will store ``(abc, efg)``.
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Similarly, you could put the commands in a file and run
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``abci-cli --verbose batch < myfile``.
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Counter - Another Example
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-------------------------
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Now that we've got the hang of it, let's try another application, the
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"counter" app.
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The counter app doesn't use a Merkle tree, it just counts how many times
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we've sent a transaction, asked for a hash, or committed the state. The
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result of ``commit`` is just the number of transactions sent.
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This application has two modes: ``serial=off`` and ``serial=on``.
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When ``serial=on``, transactions must be a big-endian encoded
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incrementing integer, starting at 0.
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If ``serial=off``, there are no restrictions on transactions.
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We can toggle the value of ``serial`` using the ``set_option`` ABCI
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message.
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When ``serial=on``, some transactions are invalid. In a live blockchain,
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transactions collect in memory before they are committed into blocks. To
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avoid wasting resources on invalid transactions, ABCI provides the
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``check_tx`` message, which application developers can use to accept or
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reject transactions, before they are stored in memory or gossipped to
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other peers.
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In this instance of the counter app, ``check_tx`` only allows
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transactions whose integer is greater than the last committed one.
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Let's kill the console and the dummy application, and start the counter
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app:
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::
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counter
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In another window, start the ``abci-cli console``:
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::
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> set_option serial on
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-> data: serial=on
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> check_tx 0x00
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-> code: OK
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> check_tx 0xff
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-> code: OK
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> deliver_tx 0x00
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-> code: OK
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> check_tx 0x00
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-> code: BadNonce
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-> log: Invalid nonce. Expected >= 1, got 0
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> deliver_tx 0x01
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-> code: OK
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> deliver_tx 0x04
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-> code: BadNonce
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-> log: Invalid nonce. Expected 2, got 4
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> info
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-> data: {"hashes":0,"txs":2}
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This is a very simple application, but between ``counter`` and
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``dummy``, its easy to see how you can build out arbitrary application
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states on top of the ABCI. `Hyperledger's
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Burrow <https://github.com/hyperledger/burrow>`__ also runs atop ABCI,
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bringing with it Ethereum-like accounts, the Ethereum virtual-machine,
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Monax's permissioning scheme, and native contracts extensions.
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But the ultimate flexibility comes from being able to write the
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application easily in any language.
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We have implemented the counter in a number of languages (see the
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example directory).
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To run the Node JS version, ``cd`` to ``example/js`` and run
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::
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node app.js
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(you'll have to kill the other counter application process). In another
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window, run the console and those previous ABCI commands. You should get
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the same results as for the Go version.
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Bounties
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--------
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Want to write the counter app in your favorite language?! We'd be happy
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to add you to our `ecosystem <https://tendermint.com/ecosystem>`__!
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We're also offering `bounties <https://tendermint.com/bounties>`__ for
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implementations in new languages!
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The ``abci-cli`` is designed strictly for testing and debugging. In a
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real deployment, the role of sending messages is taken by Tendermint,
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which connects to the app using three separate connections, each with
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its own pattern of messages.
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For more information, see the `application developers
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guide <./app-development.html>`__. For examples of running an ABCI
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app with Tendermint, see the `getting started
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guide <./getting-started.html>`__.
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