2016-10-04 12:56:31 +00:00
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.. _graphstream: http://graphstream-project.org/
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Client RPC API
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==============
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In this tutorial we will build a simple command line utility that connects to a node and dumps the transaction graph to
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2016-10-05 09:38:26 +00:00
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the standard output. We will then put some simple visualisation on top. For an explanation on how the RPC works see
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:doc:`clientrpc`.
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2016-10-04 12:56:31 +00:00
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We start off by connecting to the node itself. For the purposes of the tutorial we will run the Trader demo on some
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local port and connect to the Buyer side. We will pass in the address as a command line argument. To connect to the node
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we also need to access the certificates of the node, we will access the node's ``certificates`` directory directly.
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2016-11-10 13:14:38 +00:00
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.. literalinclude:: example-code/src/main/kotlin/net.corda.docs/ClientRpcTutorial.kt
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2016-10-04 12:56:31 +00:00
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:language: kotlin
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:start-after: START 1
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:end-before: END 1
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2016-10-20 16:55:16 +00:00
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Now we can connect to the node itself using a valid RPC login. By default the user `user1` is available with password `test`.
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2016-10-04 12:56:31 +00:00
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2016-11-10 13:14:38 +00:00
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.. literalinclude:: example-code/src/main/kotlin/net.corda.docs/ClientRpcTutorial.kt
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2016-10-04 12:56:31 +00:00
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:language: kotlin
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:start-after: START 2
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:end-before: END 2
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``proxy`` now exposes the full RPC interface of the node:
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2016-11-10 13:14:38 +00:00
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.. literalinclude:: ../../node/src/main/kotlin/net.corda.node/services/messaging/CordaRPCOps.kt
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2016-10-04 12:56:31 +00:00
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:language: kotlin
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:start-after: interface CordaRPCOps
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:end-before: }
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The one we need in order to dump the transaction graph is ``verifiedTransactions``. The type signature tells us that the
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RPC will return a list of transactions and an Observable stream. This is a general pattern, we query some data and the
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node will return the current snapshot and future updates done to it.
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2016-11-10 13:14:38 +00:00
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.. literalinclude:: example-code/src/main/kotlin/net.corda.docs/ClientRpcTutorial.kt
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2016-10-04 12:56:31 +00:00
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:language: kotlin
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:start-after: START 3
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:end-before: END 3
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The graph will be defined by nodes and edges between them. Each node represents a transaction and edges represent
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output-input relations. For now let's just print ``NODE <txhash>`` for the former and ``EDGE <txhash> <txhash>`` for the
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latter.
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2016-11-10 13:14:38 +00:00
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.. literalinclude:: example-code/src/main/kotlin/net.corda.docs/ClientRpcTutorial.kt
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2016-10-04 12:56:31 +00:00
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:language: kotlin
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:start-after: START 4
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:end-before: END 4
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Now we can start the trader demo as per described in :doc:`running-the-demos`::
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# Build the demo
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./gradlew installDist
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# Start the buyer
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./build/install/r3prototyping/bin/trader-demo --role=BUYER
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In another terminal we can connect to it with our client::
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# Connect to localhost:31337
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2016-10-10 09:12:35 +00:00
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./docs/source/example-code/build/install/docs/source/example-code/bin/client-rpc-tutorial localhost:31337 Print
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2016-10-04 12:56:31 +00:00
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We should see some ``NODE``-s printed. This is because the buyer self-issues some cash for the demo.
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Unless we ran the seller before we shouldn't see any ``EDGE``-s because the cash hasn't been spent yet.
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In another terminal we can now start the seller::
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# Start sellers in a loop
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for i in {0..9} ; do ./build/install/r3prototyping/bin/trader-demo --role=SELLER ; done
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We should start seeing new ``NODE``-s and ``EDGE``-s appearing.
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Now let's try to visualise the transaction graph. We will use a graph drawing library called graphstream_
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2016-11-10 13:14:38 +00:00
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.. literalinclude:: example-code/src/main/kotlin/net.corda.docs/ClientRpcTutorial.kt
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2016-10-04 12:56:31 +00:00
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:language: kotlin
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:start-after: START 5
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:end-before: END 5
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If we run the client with ``Visualise`` we should see a simple graph being drawn as new transactions are being created
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by the seller runs.
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That's it! We saw how to connect to the node and stream data from it.
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