220 lines
6.3 KiB
Markdown
220 lines
6.3 KiB
Markdown
Notes about generic-table
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=========================
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@section gtint What is generic-table?
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Generic-table is a JSON schema and client-side JS file that makes it easy to
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display live, table structured HTML over a ws link.
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An example plugin and index.html using it are provided, but lwsgt itself doesn't
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have its own plugin, it's just a JSON schema and client-side JS that other
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plugins can use to simplify displaying live, table-based data without having
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to reinvent the wheel each time.
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The ws protocol sends JSON describing the table, and then JSON updating the table
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contents when it chooses, the brower table is updated automatically, live.
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\image html lwsgt-overview.png
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- Example protocol plugin (displays directory contents): https://github.com/warmcat/libwebsockets/tree/master/plugins/generic-table/protocol_table_dirlisting.c
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- Example HTML: https://github.com/warmcat/libwebsockets/tree/master/plugins/generic-table/assets/index.html
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- lwsgt.js (client-side table rendering / ws link management): https://github.com/warmcat/libwebsockets/tree/master/plugins/generic-table/assets/lwsgt.js
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@section gteb Enabling for build
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Enable the demo plugin at CMake with -DLWS_WITH_PLUGINS=1
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@section gtinth Integrating with your html
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- In your HEAD section, include lwsgt.js
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```
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<script src="lwsgt.js"></script>
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```
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- Also in your HEAD section, style the lwsgt CSS, eg
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```
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<style>
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.lwsgt_title { font-size: 24; text-align:center }
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.lwsgt_breadcrumbs { font-size: 18; text-align:left }
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.lwsgt_table { font-size: 14; padding:12px; margin: 12px; align:center }
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.lwsgt_hdr { font-size: 18; text-align:center;
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background-color: rgba(40, 40, 40, 0.8); color: white }
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.lwsgt_tr { padding: 10px }
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.lwsgt_td { padding: 3px }
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</style>
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```
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You can skip this but the result will be less beautiful until some CSS is
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provided.
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- In your body section, declare a div with an id (can be whatever you want)
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```
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<tr><td><div id="lwsgt1" class="group1"></div></td></tr>
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```
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lwsgt JS will put its content there.
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- Finally in a <script> at the end of your page, instantiate lwsgt and
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provide a custom callback for clickable links
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```
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<script>
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var v1 = new lwsgt_initial("Dir listing demo",
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"protocol-lws-table-dirlisting",
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"lwsgt1", "lwsgt_dir_click", "v1");
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function lwsgt_dir_click(gt, u, col, row)
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{
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if (u[0] == '=') { /* change directory */
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window[gt].lwsgt_ws.send(u.substring(1, u.length));
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return;
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}
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var win = window.open(u, '_blank');
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win.focus();
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}
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</script>
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```
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In the callback, you can recover the ws object by `window[gt].lwsgt_ws`.
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@section gtc Lwsgt constructor
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To instantiate the ws link and lwsgt instance, your HTML must call a lwsgt
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constructor for each region on the page managed by lwsgt.
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`var myvar = new lwsgt_initial(title, ws_protocol, div_id, click_cb, myvar);`
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All of the arguments are strings.
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| Parameter | Description |
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|-----------------|---------------------------------------------------------|
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| title | Title string to go above the table |
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| ws_protocol | Protocol name string to use when making ws connection |
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| div_id | HTML id of div to fill with content |
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| click_cb | Callback function name string to handle clickable links |
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| myvar | Name of var used to hold this instantiation globally |
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Note "myvar" is needed so it can be passed to the click handling callback.
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@section gtclick Lwsgt click handling function
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When a clickable link produced by lwsgt is clicked, the function named in the
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click_cb parameter to lwsgt_initial is called.
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That function is expected to take four parameters, eg
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`function lwsgt_dir_click(gt, u, col, row)`
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| Parameter | Description |
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|------- ---|-----------------------------------------------------------|
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| gt | Name of global var holding this lwsgt context (ie, myvar) |
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| u | Link "url" string |
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| col | Table column number link is from |
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| row | Table row number link is from |
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@section gtgj Generic-table JSON
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### Column layout
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When the ws connection is established, the protocol should send a JSON message
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describing the table columns. For example
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```
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"cols": [
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{ "name": "Date" },
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{ "name": "Size", "align": "right" },
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{ "name": "Icon" },
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{ "name": "Name", "href": "uri"},
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{ "name": "uri", "hide": "1" }
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]
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}
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```
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- This describes 5 columns
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- Only four columns (not "uri") should be visible
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- "Name" should be presented as a clickable link using "uri" as the
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destination, when a "uri" field is presented.
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- "Size" field should be presented aligned to the right
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### Breadcrumbs
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When a view is hierarchical, it's useful to provide a "path" with links back
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in the "path", known as "breadcrumbs".
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Elements before the last one should provide a "url" member as well as the
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displayable name, which is used to create the link destination.
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The last element, being the current displayed page should not have a url
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member and be displayed without link style.
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```
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"breadcrumbs":[{"name":"top", "url": "/" }, {"name":"mydir"}]
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```
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### Table data
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The actual file data consists of an array of rows, containing the columns
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mentioned in the original "cols" section.
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```
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"data":[
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{
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"Icon":" ",
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"Date":"2015-Feb-06 03:08:35 +0000",
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"Size":"1406",
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"uri":"./serve//favicon.ico",
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"Name":"favicon.ico"
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}
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]
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```
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@section gtdirl Setting up protocol-lws-table-dirlisting
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The example protocol needs two mounts, one to provide the index.html, js and
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the protocol itself
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```
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{
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"mountpoint": "/dirtest",
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"origin": "file:///usr/share/libwebsockets-test-server/generic-table",
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"origin": "callback://protocol-lws-table-dirlisting",
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"default": "index.html",
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"pmo": [{
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"dir": "/usr/share/libwebsockets-test-server"
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}]
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},
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```
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The protocol wants a per-mount option (PMO) to tell it the base directory it
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is serving from, named "dir".
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The other mount is there to simply serve items that get clicked on from the
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table in a secure way
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```
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{
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"mountpoint": "/dirtest/serve",
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"origin": "file:///usr/share/libwebsockets-test-server",
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"default": "index.html"
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},
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```
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This last bit is not related to using lwsgt itself.
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