/// <summary>
/// Query the store using a SPARQL query
/// </summary>
/// <param name="storeName">Store to query</param>
/// <param name="queryExpression">SPARQL query string</param>
/// <param name="defaultGraphUris"></param>
/// <param name="ifNotModifiedSince">OPTIONAL : If this parameter is provided and the store has not been changed since the time specified,
/// a BrightstarClientException will be raised with the message "Store not modified".</param>
/// <param name="resultsFormat">OPTIONAL: The serialization format for the SPARQL results set. Defaults to <see cref="SparqlResultsFormat.Xml"/>.</param>
/// <returns>A stream containing XML SPARQL result XML</returns>
/// <remarks>If the <paramref name="ifNotModifiedSince"/> parameter is used by an application, then the default caching provided
/// by this class will be bypassed</remarks>
public Stream ExecuteQuery(string storeName, string queryExpression, IEnumerable<string> defaultGraphUris, DateTime? ifNotModifiedSince = null, SparqlResultsFormat resultsFormat = null)
{
ValidateStoreName(storeName);
if (queryExpression == null)
throw new ArgumentNullException("queryExpression", Strings.BrightstarServiceClient_QueryMustNotBeNull);
if (String.Empty.Equals(queryExpression))
throw new ArgumentException(Strings.BrightstarServiceClient_QueryMustNotBeEmptyString, "queryExpression");
var g = defaultGraphUris == null ? null : defaultGraphUris.ToArray();
string cacheKey = null;
CachedQueryResult cachedResult = null;
if (ifNotModifiedSince == null && _queryCache != null)
{
cacheKey = storeName + "_" + queryExpression.GetHashCode();
if (defaultGraphUris != null)
{
cacheKey = cacheKey + "_" + String.Join(",", g).GetHashCode();
}
cachedResult = _queryCache.Lookup<CachedQueryResult>(cacheKey);
if (cachedResult != null)
{
ifNotModifiedSince = cachedResult.Timestamp;
}
}
try
{
var mediaType = resultsFormat == null
? SparqlResultsFormat.Xml.MediaTypes.First() + "; charset=utf-8"
: resultsFormat.ToString();
var resultStream = _service.ExecuteQuery(storeName, queryExpression, defaultGraphUris == null ? null : g.ToArray(), ifNotModifiedSince, mediaType);
if (_queryCache != null && cacheKey != null && LastResponseTimestamp.HasValue)
{
using (var streamReader = new StreamReader(resultStream))
{
var resultString = streamReader.ReadToEnd();
cachedResult = new CachedQueryResult(LastResponseTimestamp.Value, resultString);
_queryCache.Insert(cacheKey, cachedResult, CachePriority.Normal);
return new MemoryStream(streamReader.CurrentEncoding.GetBytes(cachedResult.Result));
}
}
else
{
return resultStream;
}
}
catch (FaultException<ExceptionDetail> fault)
{
if (cachedResult != null)
{
if (fault.Detail.Type.Equals("BrightstarDB.Client.BrightstarClientException") &&
fault.Detail.InnerException != null &&
fault.Detail.InnerException.Type.Equals("BrightstarDB.BrightstarStoreNotModifiedException"))
{
// Cached result is still fine
return new MemoryStream(
resultsFormat == null
? Encoding.UTF8.GetBytes(cachedResult.Result)
: resultsFormat.Encoding.GetBytes(cachedResult.Result));
}
}
throw new BrightstarClientException(fault);
}
}
/// <summary>
/// Query the store using a SPARQL query
/// </summary>
/// <param name="storeName">Store to query</param>
/// <param name="queryExpression">SPARQL query string</param>
/// <param name="ifNotModifiedSince">OPTIONAL : If this parameter is provided and the store has not been changed since the time specified,
/// a BrightstarClientException will be raised with the message "Store not modified".</param>
/// <param name="resultsFormat">OPTIONAL: The serialization format for the SPARQL results set. Defaults to <see cref="SparqlResultsFormat.Xml"/>.</param>
/// <returns>A stream containing XML SPARQL result XML</returns>
/// <remarks>If the <paramref name="ifNotModifiedSince"/> parameter is used by an application, then the default caching provided
/// by this class will be bypassed</remarks>
public Stream ExecuteQuery(string storeName, string queryExpression, DateTime?ifNotModifiedSince = null, SparqlResultsFormat resultsFormat = null)
{
ValidateStoreName(storeName);
if (queryExpression == null)
{
throw new ArgumentNullException("queryExpression", Strings.BrightstarServiceClient_QueryMustNotBeNull);
}
if (String.Empty.Equals(queryExpression))
{
throw new ArgumentException(Strings.BrightstarServiceClient_QueryMustNotBeEmptyString, "queryExpression");
}
string cacheKey = null;
CachedQueryResult cachedResult = null;
if (ifNotModifiedSince == null && _queryCache != null)
{
cacheKey = storeName + "_" + queryExpression.GetHashCode();
cachedResult = _queryCache.Lookup <CachedQueryResult>(cacheKey);
if (cachedResult != null)
{
ifNotModifiedSince = cachedResult.Timestamp;
}
}
try
{
var mediaType = resultsFormat == null
? SparqlResultsFormat.Xml.MediaTypes.First() + "; charset=utf-8"
: resultsFormat.ToString();
var resultStream = _service.ExecuteQuery(storeName, queryExpression, ifNotModifiedSince, mediaType);
if (_queryCache != null && cacheKey != null && LastResponseTimestamp.HasValue)
{
using (var streamReader = new StreamReader(resultStream))
{
var resultString = streamReader.ReadToEnd();
cachedResult = new CachedQueryResult(LastResponseTimestamp.Value, resultString);
_queryCache.Insert(cacheKey, cachedResult, CachePriority.Normal);
return(new MemoryStream(streamReader.CurrentEncoding.GetBytes(cachedResult.Result)));
}
}
else
{
return(resultStream);
}
}
catch (FaultException <ExceptionDetail> fault)
{
if (cachedResult != null)
{
if (fault.Detail.Type.Equals("BrightstarDB.Client.BrightstarClientException") &&
fault.Detail.InnerException != null &&
fault.Detail.InnerException.Type.Equals("BrightstarDB.BrightstarStoreNotModifiedException"))
{
// Cached result is still fine
return(new MemoryStream(
resultsFormat == null
? Encoding.UTF8.GetBytes(cachedResult.Result)
: resultsFormat.Encoding.GetBytes(cachedResult.Result)));
}
}
throw new BrightstarClientException(fault);
}
}
