.. highlight:: kotlin
.. raw:: html

   <script type="text/javascript" src="_static/jquery.js"></script>
   <script type="text/javascript" src="_static/codesets.js"></script>

Running our CorDapp
===================

Now that we've written a CorDapp, it's time to test it by running it on some real Corda nodes.

Deploying our CorDapp
---------------------
Let's take a look at the nodes we're going to deploy. Open the project's ``build.gradle`` file and scroll down to the
``task deployNodes`` section. This section defines three nodes. There are two standard nodes (``PartyA`` and
``PartyB``), plus a special Controller node that is running the network map service and advertises a validating notary
service.

.. code:: bash

    task deployNodes(type: net.corda.plugins.Cordform, dependsOn: ['jar']) {
        directory "./build/nodes"
        node {
            name "O=Controller,L=London,C=GB"
            advertisedServices = ["corda.notary.validating"]
            p2pPort 10002
            rpcPort 10003
            cordapps = ["net.corda:corda-finance:$corda_release_version"]
        }
        node {
            name "O=PartyA,L=London,C=GB"
            p2pPort 10005
            rpcPort 10006
            webPort 10007
            cordapps = ["net.corda:corda-finance:$corda_release_version"]
            rpcUsers = [[ user: "user1", "password": "test", "permissions": []]]
        }
        node {
            name "O=PartyB,L=New York,C=US"
            p2pPort 10008
            rpcPort 10009
            webPort 10010
            cordapps = ["net.corda:corda-finance:$corda_release_version"]
            rpcUsers = [[ user: "user1", "password": "test", "permissions": []]]
        }
    }

We can run this ``deployNodes`` task using Gradle. For each node definition, Gradle will:

* Package the project's source files into a CorDapp jar
* Create a new node in ``build/nodes`` with our CorDapp already installed

We can do that now by running the following commands from the root of the project:

.. code:: bash

    // On Windows
    gradlew clean deployNodes

    // On Mac
    ./gradlew clean deployNodes

Running the nodes
-----------------
Running ``deployNodes`` will build the nodes under ``build/nodes``. If we navigate to one of these folders, we'll see
the three node folders. Each node folder has the following structure:

    .. code:: bash

        .
        |____corda.jar                     // The runnable node
        |____corda-webserver.jar           // The node's webserver
        |____node.conf                     // The node's configuration file
        |____cordapps
        |____java/kotlin-source-0.1.jar  // Our IOU CorDapp

Let's start the nodes by running the following commands from the root of the project:

.. code:: bash

    // On Windows
    build/nodes/runnodes.bat

    // On Mac
    build/nodes/runnodes

This will start a terminal window for each node, and an additional terminal window for each node's webserver - eight
terminal windows in all. Give each node a moment to start - you'll know it's ready when its terminal windows displays
the message, "Welcome to the Corda interactive shell.".

  .. image:: resources/running_node.png
     :scale: 25%
     :align: center

Interacting with the nodes
--------------------------
Now that our nodes are running, let's order one of them to create an IOU by kicking off our ``IOUFlow``. In a larger
app, we'd generally provide a web API sitting on top of our node. Here, for simplicity, we'll be interacting with the
node via its built-in CRaSH shell.

Go to the terminal window displaying the CRaSH shell of PartyA. Typing ``help`` will display a list of the available
commands.

We want to create an IOU of 100 with PartyB. We start the ``IOUFlow`` by typing:

.. code:: bash

    start IOUFlow iouValue: 99, otherParty: "O=PartyB,L=New York,C=US"

This single command will cause PartyA and PartyB to automatically agree an IOU. This is one of the great advantages of
the flow framework - it allows you to reduce complex negotiation and update processes into a single function call.

If the flow worked, it should have recorded a new IOU in the vaults of both PartyA and PartyB. Let's check.

We can check the contents of each node's vault by running:

.. container:: codeset

    .. code-block:: java

        run vaultQuery contractStateType: com.template.state.IOUState

    .. code-block:: kotlin

        run vaultQuery contractStateType: com.template.IOUState

The vaults of PartyA and PartyB should both display the following output:

.. code:: bash

    states:
    - state:
        data:
          value: 99
          lender: "C=GB,L=London,O=PartyA"
          borrower: "C=US,L=New York,O=PartyB"
          participants:
          - "C=GB,L=London,O=PartyA"
          - "C=US,L=New York,O=PartyB"
        contract: "com.template.contract.IOUContract"
        notary: "C=GB,L=London,O=Controller,CN=corda.notary.validating"
        encumbrance: null
        constraint:
          attachmentId: "F578320232CAB87BB1E919F3E5DB9D81B7346F9D7EA6D9155DC0F7BA8E472552"
      ref:
        txhash: "5CED068E790A347B0DD1C6BB5B2B463406807F95E080037208627565E6A2103B"
        index: 0
    statesMetadata:
    - ref:
        txhash: "5CED068E790A347B0DD1C6BB5B2B463406807F95E080037208627565E6A2103B"
        index: 0
      contractStateClassName: "com.template.state.IOUState"
      recordedTime: 1506415268.875000000
      consumedTime: null
      status: "UNCONSUMED"
      notary: "C=GB,L=London,O=Controller,CN=corda.notary.validating"
      lockId: null
      lockUpdateTime: 1506415269.548000000
    totalStatesAvailable: -1
    stateTypes: "UNCONSUMED"
    otherResults: []

This is the transaction issuing our ``IOUState`` onto a ledger.

Conclusion
----------
We have written a simple CorDapp that allows IOUs to be issued onto the ledger. Our CorDapp is made up of two key
parts:

* The ``IOUState``, representing IOUs on the ledger
* The ``IOUFlow``, orchestrating the process of agreeing the creation of an IOU on-ledger

Next steps
----------
There are a number of improvements we could make to this CorDapp:

* We chould add unit tests, using the contract-test and flow-test frameworks
* We chould change ``IOUState.value`` from an integer to a proper amount of a given currency
* We could add an API, to make it easier to interact with the CorDapp

But for now, the biggest priority is to add an ``IOUContract`` imposing constraints on the evolution of each
``IOUState`` over time. This will be the focus of our next tutorial.