No Data retrieved with AJAX Call HTMLDB_GET when using Safari Browser

Question

In my apex (4.0) app i have certain page a which uses JS AJAX htmldb_get to pull some data from an on-demand process using xml structure
var get = new htmldb_Get(null, $v('pFlowId'),
'APPLICATION_PROCESS=get_markerdata', $v('pFlowStepId'));
if (!MEBMarkerdataXML) {// Tabelle mit Kunden leer? Dann aus DB abfragen
MEBMarkerdataXML = get.get('XML');
l_Count = MEBMarkerdataXML.getElementsByTagName("Kunde").length;
I ran into a strange behavior when using Safari Browser (Mac and Windows) when opening the page.
As long as the process retrieves less than 50 rows everything works fine. The data is pulled from the OnDemand Process and delivered to the browser; the XML Data can be selected in JS for further processing
<<<<<<<<<<<<<< HTTP Traffic taken from Safari <<<<<<<<<<<<<<<
Anfrage-URL:http://80.149.218.10:8080/apex/wwv_flow.show
Anfragemethode:POST
Status-Code:200 OK
Anfrage
Content-Type:application/x-www-form-urlencoded
Origin:http://80.149.218.10:8080
Referer:http://80.149.218.10:8080/apex/f?p=41107101:43:1599514482232751::
User-Agent:Mozilla/5.0 (Windows NT 5.1) AppleWebKit/534.55.3 (KHTML, like Gecko) Version/5.1.5 Safari/534.55.3
Formulardaten
p_request:APPLICATION_PROCESS=get_markerdata
p_instance:1599514482232751
p_flow_id:41107101
p_flow_step_id:43
Antwort
Cache-Control:no-cache
Content-Type:text/xml;charset=UTF-8
Date:Thu, 03 May 2012 10:19:35 GMT
Pragma:no-cache
Server:Apache-Coyote/1.1
Transfer-Encoding:Identity
X-DB-Content-length:53329
X-ORACLE-IGNORE:IGNORE, IGNORE, IGNORE, IGNORE
<<<<<<<<<<<<<<<<
When calling for more then 50 rows Safaris shows a POST Error -1001 and no Data is delivered.
This occurs only on some Mac's and my Dev WIN-XP PC using SF Browser; never on iPad/iPhone . Never when using FF on Mac or PC.
I googled a lot of different Sources, it seems to be a Timeout Problem when making a long runing AJAX Call. But i did not find any useful hint.
Any Ideas from the APEX & HTTP Gurus?
Regards
Peter

Answer 1

It's just that in my experience htmldb_Get.get() is troublesome for browsers, due to the fact it performs a synchronous request. The browser can do nothing else while it waits for the response. I've seen Firefox really struggle with it in the past couple years. Also, I've seen no good reason to use synchronous XMLHttpRequest calls. As you can see, it's simple to refactor a call to htmldb_Get.get() into a call to htmldb_Get.GetAsync().
For your case in particular, I was just guessing Safari have implemented a timeout to ensure that they don't end up waiting indefinitely for a request that never returns as this would be fatal. You're probably hitting that timeout.
I don't think htmldb_Get is officially documented anywhere, but you can find the source here... http://apex.oracle.com/i/javascript/uncompressed/apex_4_0.js
There is also a pure jQuery way to perform AJAX request, I recommend using this because at least it's documented. Here's a snippet of a typical APEX AJAX request done the jQuery way:
apex.jQuery.ajax({
  dataType: "xml", //supports text, xml, json, jsonp, script, or html
  type: "post",
  url: "wwv_flow.show",
  traditional: true,
  data: {
    p_request: "APPLICATION_PROCESS=get_markerdata",
    p_flow_id: $("#pFlowId").val(),
    p_flow_step_id: $("#pFlowStepId").val(),
    p_instance: $("#pInstance").val()
  success: function (data, textStatus, jqXHR) {
    // Do your thing in here
  error: function (xhr, ajaxOptions, thrownError) {
    // Handle error in here
});Then you can refer to great documentation here... http://api.jquery.com/jQuery.ajax/