web service filling gridview awfully slow, as is paging/sorting

Question

Hi

I am making a page which calls a web service to fill a gridview this is returning alot of data, and is horribly slow.

i ran the svcutil.exe on the wsdl page and it generated me the class and config so i have a load of strongly typed objects coming back from each request to the many service functions.

i am then using LINQ to loop around the objects grabbing the necessary information as i go, but for each row in the grid i need to loop around an object, and grab another list of objects (from the same request) and loop around each of them.. 1 to many parent object > child one.. all of this then gets dropped into a custom datatable a row at a time.. hope that makes sense....

im not sure there is any way to speed up the initial load. but surely i should be able to page/sort alot faster than it is doing. as at the moment, it appears to be taking as long to page/sort as it is to load initially.

i thought if when i first loaded i put the datasource of the grid in the session, that i could whip it out of the session to deal with paging/sorting and the like.

basically it is doing the below

    protected void Page_Load(object sender, EventArgs e)
    {
        //init the datatable
        //grab the filter vars (if there are any)

        WebServiceObj WS = WSClient.Method(args);

        //fill the datatable (around and around we go)
        foreach (ParentObject po in WS.ReturnedObj)
        {
            var COs = from ChildObject c in WS.AnotherReturnedObj
                    where c.whatever.equals(...) ...etc

            foreach(ChildObject c in COs){
               myDataTable.Rows.Add(tlo.this,
                                    tlo.that,
                                    c.thisthing,
                                    c.thatthing,
                                    etc......);
            }
        }
        grdListing.DataSource = myDataTable;
        Session["dt"] = myDataTable;
        grdListing.DataBind();

    }
    protected void Listing_PageIndexChanging(object sender, GridViewPageEventArgs e)
    {
        grdListing.PageIndex = e.NewPageIndex;
        grdListing.DataSource = Session["dt"] as DataTable;
        grdListing.DataBind();
    }


    protected void Listing_Sorting(object sender, GridViewSortEventArgs e)
    {
        DataTable dt = Session["dt"] as DataTable;
        DataView dv = new DataView(dt);
        string sortDirection = " ASC";
        if (e.SortDirection == SortDirection.Descending)
            sortDirection = " DESC";

        dv.Sort = e.SortExpression + sortDirection;
        grdListing.DataSource = dv.ToTable();
        grdListing.DataBind();
     }

am i doing this totally wrongly? or is the slowness just coming from the amount of data being bound in/return from the Web Service.. there are maybe 15 columns(ish) and a whole load of rows.. with more being added to the data the webservice is querying from all the time

any suggestions / tips happily received

thanks

Answer 1

You might be better off working with the raw XML you're getting from the web service, rather than creating a large number of objects in memory (which may be what's slowing it down). You can use XSLT to generate an XML representation of your rows (including the parent/child relationship). I'm not primarily a .NET developer, but I'm pretty sure that you can then populate a DataSet from XML and attach a DataTable to it.