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Merge pull request #110 from michielmulders/websocket-api-doc 

Websocket api documentation usage added for javascript
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Jernej Pregelj 2017-10-16 14:09:35 +02:00 committed by GitHub
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docs/source/usage.rst
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@ -357,6 +357,134 @@ Recap: Asset Creation & Transfer
.then(() => conn.searchAssets('Bicycle Inc.'))
.then(assets => console.log('Found assets with serial number Bicycle Inc.:', assets))
Websocket Event Stream API Usage
--------------------------------
The Event Stream API enables new ways to interact with BigchainDB, making it possible for your application to subscribe to all newly–confirmed transactions that are happening in the system.
Below piece of code can be opened in your web browser. It will connect to your websocket (change it at ``var wsUri``). This web page will display all validated transactions.
.. code-block:: html
<!DOCTYPE html>
<meta charset="utf-8" />
<title>WebSocket BigchainDB</title>
<!-- Latest compiled and minified CSS -->
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css">
<!-- jQuery library -->
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
<!-- Latest compiled JavaScript -->
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js"></script>
<!-- Websocket Script -->
<script language="javascript" type="text/javascript">
var wsUri = "ws://localhost:9985/api/v1/streams/valid_transactions";
var output;
var alertbox;
function init()
{
output = document.getElementById("output");
alertbox = document.getElementById("alert-box");
setWebSocket();
}
function setWebSocket()
{
websocket = new WebSocket(wsUri);
websocket.onopen = function(evt) { onOpen(evt) };
websocket.onclose = function(evt) { onClose(evt) };
websocket.onmessage = function(evt) { onMessage(evt) };
websocket.onerror = function(evt) { onError(evt) };
}
function onOpen(evt)
{
writeAlertMessage("CONNECTED");
}
function onClose(evt)
{
writeAlertMessage("DISCONNECTED");
}
function onMessage(evt)
{
writeToScreen('<a href="#" class="list-group-item"><h4 class="list-group-item-heading">Valid Transaction</h4><p class="list-group-item-text">' + evt.data + '</p></a>');
}
function onError(evt)
{
writeToScreen('<span style="color: red;">ERROR:</span> ' + evt.data);
}
function closeConnection(evt)
{
websocket.close()
}
function writeToScreen(message)
{
var pre = document.createElement("p");
pre.style.wordWrap = "break-word";
pre.innerHTML = message;
output.appendChild(pre);
}
function writeAlertMessage(message)
{
var alert = document.createElement("div");
alert.className = "alert alert-success";
alert.setAttribute("role", "alert");
alert.innerHTML = message;
alertbox.appendChild(alert);
}
/* Initialize websocket and attach all events */
window.addEventListener("load", init, false);
/* Event called on closing browser or refreshing page to close connection */
window.addEventListener("beforeunload", closeConnection, false);
</script>
<!-- HTML Template -->
<div class="container">
<h2>WebSocket API Stream Valid Transactions BigchainDB</h2>
<!-- Box for displaying all alerts -->
<div id="alert-box"></div>
<!-- Div for attachting all outputs -->
<div id="output" class="list-group"></div>
</div>
Besides that, a NodeJs version has been created to display the validated transactions.
All transactions are printed to the console. To use this piece of code, you will need the ``ws`` (WebSocket package) through npm: ``npm install --save ws``.
.. code-block:: js
const WebSocket = require('ws')
const ws = new WebSocket('ws://localhost:9985/api/v1/streams/valid_transactions')
ws.on('open', () => {
console.log("CONNECTED")
});
ws.on('message', (data) => {
let json = JSON.parse(data)
console.log("\nTransactionId: ", json.transaction_id)
console.log("AssetId: ", json.asset_id)
console.log("BlockId: ", json.block_id)
});
Difference unspent and spent output
-----------------------------------
An unspent output is simply an output of a transaction which isn't yet an input of another transaction.