Sever-side processing can be quite hard on your server, since it makes an Ajax call to the server for every draw request that is made. On sites with a large number of page views, you could potentially end up DDoSing your own server with your own applications!
This example shows one technique to reduce the number of Ajax calls that are made to the server by
caching more data than is needed for each draw. This is done by intercepting the Ajax call and routing
it through a data cache control; using the data from the cache if available, and making the Ajax
request if not. This intercept of the Ajax request is performed by giving the ajax option
as a function. This function then performs the logic of deciding if another Ajax call is needed, or if
data from the cache can be used.
Keep in mind that this caching is for paging only; the pipeline must be cleared for other interactions such as ordering and searching since the full data set, when using server-side processing, is only available at the server.
| Name | Position | Office | Extn. | Start date | Salary |
|---|---|---|---|---|---|
| Name | Position | Office | Extn. | Start date | Salary |
The Javascript shown below is used to initialise the table shown in this example:
//
// Pipelining function for DataTables. To be used to the `ajax` option of DataTables
//
$.fn.dataTable.pipeline = function ( opts ) {
// Configuration options
var conf = $.extend( {
pages: 5, // number of pages to cache
url: '' // script url
}, opts );
// Private variables for storing the cache
var cacheLower = -1;
var cacheUpper = null;
var cacheLastRequest = null;
var cacheLastJson = null;
return function ( request, drawCallback, settings ) {
var ajax = false;
var requestStart = request.start;
var requestLength = request.length;
var requestEnd = requestStart + requestLength;
if ( cacheLower < 0 || requestStart < cacheLower || requestEnd > cacheUpper ) {
// outside cached data - need to make a request
ajax = true;
}
else if ( JSON.stringify( request.order ) !== JSON.stringify( cacheLastRequest.order ) ||
JSON.stringify( request.columns ) !== JSON.stringify( cacheLastRequest.columns ) ||
JSON.stringify( request.search ) !== JSON.stringify( cacheLastRequest.search )
) {
// properties changed (ordering, columns, searching)
ajax = true;
}
// Store the request for checking next time around
cacheLastRequest = $.extend( true, {}, request );
if ( ajax ) {
// Need data from the server
if ( requestStart < cacheLower ) {
requestStart = requestStart - (requestLength*(conf.pages-1));
if ( requestStart < 0 ) {
requestStart = 0;
}
}
cacheLower = requestStart;
cacheUpper = requestStart + (requestLength * conf.pages);
request.start = requestStart;
request.length = requestLength*conf.pages;
settings.jqXHR = $.ajax( {
"url": conf.url,
"data": request,
"dataType": "json",
"cache": false,
"success": function ( json ) {
cacheLastJson = $.extend(true, {}, json);
if ( cacheLower != requestStart ) {
json.data.splice( 0, requestStart-cacheLower );
}
json.data.splice( requestLength, json.data.length );
drawCallback( json );
}
} );
}
else {
json = $.extend( true, {}, cacheLastJson );
json.draw = request.draw; // Update the echo for each response
json.data.splice( 0, requestStart-cacheLower );
json.data.splice( requestLength, json.data.length );
drawCallback(json);
}
}
};
//
// DataTables initialisation
//
$(document).ready(function() {
$('#example').dataTable( {
"processing": true,
"serverSide": true,
"ajax": $.fn.dataTable.pipeline( {
url: 'scripts/server_processing.php',
pages: 5 // number of pages to cache
} )
} );
} );
In addition to the above code, the following Javascript library files are loaded for use in this example:
The HTML shown below is the raw HTML table element, before it has been enhanced by DataTables:
This example uses a little bit of additional CSS beyond what is loaded from the library files (below), in order to correctly display the table. The additional CSS used is shown below:
The following CSS library files are loaded for use in this example to provide the styling of the table:
This table loads data by Ajax. The latest data that has been loaded is shown below. This data will update automatically as any additional data is loaded.