/// <summary>
/// worker method for the query case
/// </summary>
/// <param name="data"></param>
/// <param name="asyncOp"></param>
/// <param name="completionMethodDelegate"></param>
/// <returns></returns>
private void AsyncQueryWorker(AsyncQueryData data, AsyncOperation asyncOp, SendOrPostCallback completionMethodDelegate)
{
try
{
long contentLength;
using (var responseStream = Query(data.UriToUse, data.Modified, null, out contentLength))
{
HandleResponseStream(data, responseStream, contentLength);
}
}
catch (Exception e)
{
data.Exception = e;
}
completionMethodDelegate(data);
}
/// <summary>
/// the basic interface as an async version. This call will return directly
/// and you need to rely on the events fired to figure out what happened.
/// </summary>
/// <param name="queryUri">the Uri to Query</param>
/// <param name="ifModifiedSince">The ifmodifiedsince date, use DateTime.MinValue if you want everything</param>
/// <param name="doParse">if true, returns a feed, else a stream</param>
/// <param name="userData">The userData token. this must be unique if you make several async requests at once</param>
/// <returns>nothing</returns>
private void QueryAsync(Uri queryUri, DateTime ifModifiedSince, bool doParse, Object userData)
{
AsyncOperation asyncOp = AsyncOperationManager.CreateOperation(userData);
AsyncQueryData data = new AsyncQueryData(queryUri, ifModifiedSince, doParse, asyncOp, userData, this.ProgressReportDelegate);
AddUserDataToDictionary(userData, asyncOp);
// Start the asynchronous operation.
WorkerQueryEventHandler workerDelegate = new WorkerQueryEventHandler(AsyncQueryWorker);
workerDelegate.BeginInvoke(
data,
asyncOp,
this.CompletionMethodDelegate,
null,
null);
}
/// <summary>
/// Queries the database for information, composing the query with information provided in the
/// specified query structure. This method is a convenience wrapper around the async-query routes
/// to handle pagination, and it also executes a callback function for each row of data.
/// </summary>
/// <param name="databaseId">
/// The unique identifier of the EMS database to query.
/// </param>
/// <param name="query">
/// The information used to construct a query for which results are returned.
/// </param>
/// <param name="callback">
/// A callback to execute for each row of data received.
/// </param>
/// <param name="rowsPerCall">
/// The number of rows to read for each API call.
/// </param>
/// <param name="emsSystem">
/// The unique identifier of the system containing the EMS data.
/// </param>
public virtual async Task QueryAsync(string databaseId, DatabaseQuery query, RowCallback callback, int rowsPerCall = 20000, int emsSystem = NoEmsServerSpecified)
{
AsyncQueryInfo info = await StartQueryAsync(databaseId, query, emsSystem);
var result = new DatabaseQueryResult(info.Header);
int startingRow = 0;
bool moreToRead = true;
while (moreToRead)
{
AsyncQueryData data = await ReadQueryAsync(databaseId, info.Id, startingRow, startingRow + rowsPerCall - 1, emsSystem);
result.CallbackRows(query, data.Rows, callback);
startingRow = startingRow + rowsPerCall;
moreToRead = data.HasMoreRows;
}
await StopQueryAsync(databaseId, info.Id, emsSystem);
}
