217 lines
8.3 KiB
HTML
217 lines
8.3 KiB
HTML
<!--
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Test/Development/Documentation page; install as plugin to test
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-->
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<div class="panel panel-primary">
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<div class="panel-heading">Asynchronous Command Streaming</div>
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<div class="panel-body">
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<h3>Synopsis</h3>
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<p class="lead"><code>[jqxhr=] loadcmd(command [,target] [,filter] [,timeout])</code></p>
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<p>The <code>loadcmd()</code> function executes a shell command or evaluates javascript
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code with asynchronous streaming of the output into a target element or onto a function.</p>
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<h3>Basic Usage</h3>
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<p>As this is the underlying function for command buttons, basic usage
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is very similar, but fully scriptable:</p>
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<p>
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<button type="button" class="btn btn-default" onclick="loadcmd('boot status', '#out1')">
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Show boot status
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</button>
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</p>
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<pre id="out1" />
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<p>As with command buttons, you can append the output by prefixing the target
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selector with "+". You can omit the output by passing null as the target. If target
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is a DOM element, loadcmd automatically sets the <code>loading</code> class on the
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target while the command is processed.</p>
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<p>The target element's min-height is automatically fixed to the current height
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of the target before the output is set. This avoids page layout jumps when
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reusing a target for commands.</p>
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<p>If the target is scrollable and the content exceeds the visible area, the
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element is automatically scrolled to show the new content, unless the user has
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done a manual scrolling on the element.</p>
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<p>If the command output stops for <code>timeout</code> seconds, the request is
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aborted and a timeout error is shown. Default timeout is 20 seconds for standard
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commands, 300 seconds for known long running commands.</p>
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<h3>Evaluate Javascript Code</h3>
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<p>To execute Javascript, either pass an object instead of the <code>command</code> string,
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containing the command as property "command" and a second property "type" with
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value "js", or simply use the wrapper call <code>loadjs()</code>. Example:</p>
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<p>
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<button type="button" class="btn btn-default"
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onclick="loadjs('print(OvmsVehicle.Type())', '#out1js')">
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Show vehicle type
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</button>
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</p>
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<pre id="out1js" />
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<p>Javascript evaluation is not limited to a single command or line. Hint: to avoid
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encoding complex JS code in the onclick attribute, store the code in some hidden
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DOM element and read it via <code>$(…).text()</code>.</p>
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<h3>Output Encoding & Binary Streams</h3>
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<p>To allow binary data to be sent by a command and to enable processing of the
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result by Javascript on the browser without character encoding issues, the command
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API supports output "binary" mode.</p>
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<p>Primary application for this is exchanging CBOR encoded objects between the
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module and the web frontend. To fully support this, the OVMS web frontent includes
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the CBOR library by Patrick Gansterer. Example use:</p>
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<pre>
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loadjs({ command: "auxbatmon.dump('CBOR')", output: "binary" }).done((data) => {
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history = CBOR.decode(data);
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});
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</pre>
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<p>See the AuxBatMon and PwrMon OVMS plugins for full examples.</p>
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<p><code>output</code> modes supported by the command API are:</p>
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<ul>
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<li><code>text</code> → Content-Type: text/plain; charset=utf-8</li>
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<li><code>json</code> → Content-Type: application/json; charset=utf-8</li>
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<li><code>binary</code> → Content-Type: application/octet-stream; charset=x-user-defined</li>
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<li>default/other → Content-Type: application/octet-stream; charset=utf-8</li>
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</ul>
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<h3>jqXHR Object</h3>
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<p><code>loadcmd()</code> returns the jqXHR (XMLHttpRequest) object in charge for
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the asynchronous execution of the request. This can be used to track the results
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of the execution, check for errors or to abort the command.</p>
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<p>
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<button type="button" class="btn btn-default" id="startcg">Start chargen</button>
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<button type="button" class="btn btn-default" id="abortcg" disabled>Abort chargen</button>
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</p>
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<pre id="out2" style="max-height:200px; overflow:auto;" />
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<p>The jQuery XHR object is also a "thenable", so actions to be performed after
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the command execution can simply be chained to the object. Example:</p>
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<p><button type="button" class="btn btn-default" id="showstat">Show stat</button></p>
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<p>See <a target="_blank" href="http://api.jquery.com/jQuery.ajax/#jqXHR">jQuery
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documentation</a> for full details and options.</p>
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<h3>Filter / Process Output</h3>
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<p>Supply a filter function to hook into the asynchronous output stream. Use filters
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to filter (ahem…) / preprocess / reformat the command output, scan the stream for some
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info you'd like to know as soon as possible, or completely take over the output
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processing.</p>
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<p>The filter function is called when a new chunk of output has arrived or when
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a stream error has occurred. The function gets a message object containing
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the <code>request</code> object and either a <code>text</code> for normal outputs
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or an <code>error</code>, which is a preformatted error output you can use or
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ignore.</p>
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<p>If the filter function returns a string, that will be added to the output target.
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If it returns <code>null</code>, the target will remain untouched.</p>
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<p>Hint: if you just want to scan the text for some info, you can pass on the message
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after your scan to the default <code>standardTextFilter()</code>.</p>
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<p>Example: let's reformat a <code>can status</code> dump into a nice Bootstrap table:</p>
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<p><button type="button" class="btn btn-default" id="canstatus">CAN1 status</button></p>
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<table class="table table-condensed table-border table-striped table-hover" id="canout">
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<thead>
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<tr><th class="col-xs-6">Key</th><th class="col-xs-6">Value</th></tr>
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</thead>
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<tbody/>
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</table>
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</div>
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</div>
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<script>
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(function(){
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/* Show page source: */
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var pagesrc = $('#main').html();
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$('.panel-heading').prepend('<button type="button" class="btn btn-sm btn-info action-showsrc"' +
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' style="float:right; position:relative; top:-5px;">Show page source</button>');
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$('.action-showsrc').on('click', function() {
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$('<div/>').dialog({
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title: 'Source Code',
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body: '<pre style="font-size:85%; height:calc(100vh - 230px);">'
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+ encode_html(pagesrc) + '</pre>',
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size: 'lg',
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});
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});
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/* Example: jqXHR.abort() */
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var xhr;
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$('#startcg').on('click', function() {
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xhr = loadcmd('test chargen 20 600', '#out2');
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$('#abortcg').prop('disabled', false);
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});
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$('#abortcg').on('click', function() {
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xhr.abort();
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});
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/* Example: jqXHR.then() */
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$('#showstat').on('click', function() {
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loadcmd('stat').then(function(output) {
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confirmdialog('STAT result', '<samp>' + output + '</samp>', ['Close']);
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});
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});
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/* Example: filter / output processor */
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$('#canstatus').on('click', function() {
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var $table = $('#canout > tbody');
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var buf = '';
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$table.empty();
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loadcmd('can can1 status', function(msg) {
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if (msg.error) {
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// Render error into table row:
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$('<tr class="danger"><td colspan="2">' + msg.error + '</td></tr>').appendTo($table);
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}
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else if (msg.text) {
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// As this is a stream, the text chunks received need not be single or complete lines.
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// We're interested in lines here, so we buffer the chunks and split the buffer at '\n':
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buf += msg.text;
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var lines = buf.split('\n');
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if (lines.length > 1) {
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buf = lines[lines.length-1];
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for (var i = 0; i < lines.length-1; i++) {
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// Skip empty lines:
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if (lines[i] == "") continue;
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// Split line into columns:
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var col = lines[i].split(/: +/);
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// Create table row & append to table, add some color on error counters:
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if (col[0].match("[Ee]rr"))
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$('<tr class="warning"><th>' + col[0] + '</th><td>' + col[1] + '</td></tr>').appendTo($table);
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else
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$('<tr><th>' + col[0] + '</th><td>' + col[1] + '</td></tr>').appendTo($table);
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}
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}
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}
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// Filter has handled everything:
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return null;
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});
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});
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})();
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</script>
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