2017-11-16 15:31:52 +00:00
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Hello, World! Pt.2 - Contract constraints
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=========================================
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2017-07-17 11:23:14 +00:00
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2017-11-16 15:31:52 +00:00
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.. note:: This tutorial extends the CorDapp built during the :doc:`Hello, World tutorial <hello-world-introduction>`.
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In the Hello, World tutorial, we built a CorDapp allowing us to model IOUs on ledger. Our CorDapp was made up of two
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2017-07-17 11:23:14 +00:00
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elements:
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2018-11-13 11:50:24 +00:00
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* An ``IOUState``, representing IOUs on the blockchain
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2018-12-03 22:30:15 +00:00
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* An ``IOUFlow`` and ``IOUFlowResponder`` flow pair, orchestrating the process of agreeing the creation of an IOU on-ledger
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2017-07-17 11:23:14 +00:00
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2018-11-13 11:50:24 +00:00
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However, our CorDapp did not impose any constraints on the evolution of IOUs on the blockchain over time. Anyone was free
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2017-11-16 15:31:52 +00:00
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to create IOUs of any value, between any party.
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2017-07-17 11:23:14 +00:00
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2017-11-16 15:31:52 +00:00
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In this tutorial, we'll write a contract to imposes rules on how an ``IOUState`` can change over time. In turn, this
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will require some small changes to the flow we defined in the previous tutorial.
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2017-07-17 11:23:14 +00:00
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2018-06-21 15:57:30 +00:00
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We'll start by writing the contract.
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.. toctree::
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:maxdepth: 1
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tut-two-party-contract
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tut-two-party-flow
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