$.ajax(): what is the difference between calling a transaction and Xacute query?

Question

I can call either:
$.ajax({
     type: "GET",
     url: "/XMII/Illuminator?QueryTemplate=somePathToXacute/someXacute&Content-Type=text/xml&Params...",
     dataType: "xml",
     success: function (result) {...}
$.ajax({
     type: "GET",
     url: "/XMII/Runner?Transaction=somePathToTransaction/someTran&Content-Type=text/xml&Params...&OutputParameter=outXML",
     dataType: "xml",
     success: function (result) {...}
When I call an Xacute query, the first execution works, but the second doesn't. I figured out that I have to add "cache:false" and then it is okay. If I use a transaction instead of Xacute query, it works with or without cache. Why is that? Transactions are not cached? Only Xacute queries?
What is the cost difference in time if I call directly a transaction, instead of an Xacute query? What is the advantage to call an Xacute at all?
Thx

Answer 1

Hi Tibor,
These points should clarify your doubts:
1. Transactions are not cached but queries are.
2. Advantage of using Xacute query is that the Illuminator service used to call Xacute query supports JSON from MII 14.0. Use content-type as text/json in the URL. But the restriction is that the transaction should return the XML in MII Rowsets-Rowset format.
3. Though both the calls would take almost time(I think) but you should call transaction directly( no need to wrap it with Xacute query if not required).
Regards,
Rohit Negi.