How to get the listitems async from a SharePoint 2010 webservice

Question

I am developing a Web api in C#. In the Webapi I make a call to a SharePoint webservice.

In the method i use the method listservice.GetListItems. The problem is that it isn't async and i would like to have it async. Is there a possiblity to make it async?

 //create listservice instance
            var listService = GetListService();
            //Get the listName and rowlimit
            string rowLimit = MaxItemsList;

            //Create elements for the faq list
            XmlElement query = xmlDoc.CreateElement("Query");
            XmlElement viewFields = xmlDoc.CreateElement("ViewFields");
            XmlElement queryOptions = xmlDoc.CreateElement("QueryOptions");
            var sPList = listService.GetList(listName);
            if (sPList != null)
            {
                //get the faq items
                return listService.GetListItems(listName, string.Empty,   query, viewFields, rowLimit,
                    queryOptions, null);
            }

I hope you guys can help me me

Answer 1

Sure, SharePoint Web Services methods could be invoked asynchronously , the following example demonstrates how to convert your example:

using (var listService = GetListService(webUri,userName,password))
{
     listService.GetListAsync(listName, listName);
     listService.GetListCompleted += ProcessListResult;
}

where

    static void ProcessListResult(object sender, GetListCompletedEventArgs e)
    {
        var proxy = sender as Contoso.Lists;
        var listName = e.UserState as string;

        var xmlDoc = new System.Xml.XmlDocument();
        var ndQuery = xmlDoc.CreateElement("Query");
        var ndViewFields = xmlDoc.CreateElement("ViewFields");
        var ndQueryOptions = xmlDoc.CreateElement("QueryOptions");
        proxy.GetListItemsAsync(listName, null, ndQuery, ndViewFields, null, ndQueryOptions, null);
        proxy.GetListItemsCompleted += ProcessListItemsResult;
    }

    static void ProcessListItemsResult(object sender, GetListItemsCompletedEventArgs e)
    {
        //omitted for clarity...
    }