DataServiceRequest.cs source code in C# .NET

                        Code:
                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / DataWeb / Client / System / Data / Services / Client / DataServiceRequest.cs / 1305376 / DataServiceRequest.cs
                        
                        
                            //---------------------------------------------------------------------- 
// 
//      Copyright (c) Microsoft Corporation.  All rights reserved.
// 
//  
// query request object
//  
//--------------------------------------------------------------------- 

namespace System.Data.Services.Client 
{
    using System;
    using System.Collections;
    using System.Collections.Generic; 
    using System.Diagnostics;
    using System.IO; 
    using System.Linq; 
    using System.Text;
#if !ASTORIA_LIGHT // Data.Services http stack 
    using System.Net;
#else
    using System.Data.Services.Http;
#endif 
    using System.Xml;
 
    /// non-generic placeholder for generic implementation 
    public abstract class DataServiceRequest
    { 
        /// internal constructor so that only our assembly can provide an implementation
        internal DataServiceRequest()
        {
        } 

        /// Element Type 
        public abstract Type ElementType 
        {
            get; 
        }

        /// Gets the URI for a the query
        public abstract Uri RequestUri 
        {
            get; 
        } 

        /// The ProjectionPlan for the request, if precompiled in a previous page; null otherwise. 
        internal abstract ProjectionPlan Plan
        {
            get;
        } 

        /// The TranslateResult associated with this request 
        internal abstract QueryComponents QueryComponents 
        {
            get; 
        }

        /// Gets the URI for a the query
        /// a string with the URI 
        public override string ToString()
        { 
            return this.QueryComponents.Uri.ToString(); 
        }
 
        /// 
        /// get an enumerable materializes the objects the response
        /// 
        /// context 
        /// query components
        /// Projection plan (if compiled in an earlier query). 
        /// contentType 
        /// method to get http response stream
        /// atom materializer 
        [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Reliability", "CA2000:Dispose objects before losing scope", Justification = "Returning MaterializeAtom, caller will dispose")]
        internal static MaterializeAtom Materialize(DataServiceContext context, QueryComponents queryComponents, ProjectionPlan plan, string contentType, Stream response)
        {
            Debug.Assert(null != queryComponents, "querycomponents"); 

            string mime = null; 
            Encoding encoding = null; 
            if (!String.IsNullOrEmpty(contentType))
            { 
                HttpProcessUtility.ReadContentType(contentType, out mime, out encoding);
            }

            if (String.Equals(mime, XmlConstants.MimeApplicationAtom, StringComparison.OrdinalIgnoreCase) || 
                String.Equals(mime, XmlConstants.MimeApplicationXml, StringComparison.OrdinalIgnoreCase))
            { 
                if (null != response) 
                {
                    XmlReader reader = XmlUtil.CreateXmlReader(response, encoding); 
                    return new MaterializeAtom(context, reader, queryComponents, plan, context.MergeOption);
                }
            }
 
            return MaterializeAtom.EmptyResults;
        } 
 
        /// 
        /// Creates a instance of strongly typed DataServiceRequest with the given element type. 
        /// 
        /// element type for the DataServiceRequest.
        /// constructor parameter.
        /// returns the strongly typed DataServiceRequest instance. 
        internal static DataServiceRequest GetInstance(Type elementType, Uri requestUri)
        { 
            Type genericType = typeof(DataServiceRequest<>).MakeGenericType(elementType); 
            return (DataServiceRequest)Activator.CreateInstance(genericType, new object[] { requestUri });
        } 

        /// 
        /// Ends an asynchronous request to an Internet resource.
        ///  
        /// Element type of the result.
        /// Source object of async request. 
        /// The data service context. 
        /// The asyncResult being ended.
        /// The response - result of the request. 
        internal static IEnumerable EndExecute(object source, DataServiceContext context, IAsyncResult asyncResult)
        {
            QueryResult result = null;
            try 
            {
                result = QueryResult.EndExecute(source, asyncResult); 
                return result.ProcessResult(context, result.ServiceRequest.Plan); 
            }
            catch (DataServiceQueryException ex) 
            {
                Exception inEx = ex;
                while (inEx.InnerException != null)
                { 
                    inEx = inEx.InnerException;
                } 
 
                DataServiceClientException serviceEx = inEx as DataServiceClientException;
                if (context.IgnoreResourceNotFoundException && serviceEx != null && serviceEx.StatusCode == (int)HttpStatusCode.NotFound) 
                {
                    QueryOperationResponse qor = new QueryOperationResponse(new Dictionary(ex.Response.Headers), ex.Response.Query, MaterializeAtom.EmptyResults);
                    qor.StatusCode = (int)HttpStatusCode.NotFound;
                    return (IEnumerable)qor; 
                }
 
                throw; 
            }
        } 

#if !ASTORIA_LIGHT // Synchronous methods not available
        /// 
        /// execute uri and materialize result 
        /// 
        /// element type 
        /// context 
        /// query components for request to execute
        /// enumerable of results 
        internal QueryOperationResponse Execute(DataServiceContext context, QueryComponents queryComponents)
        {
            QueryResult result = null;
            try 
            {
                DataServiceRequest serviceRequest = new DataServiceRequest(queryComponents, this.Plan); 
                result = serviceRequest.CreateResult(this, context, null, null); 
                result.Execute();
                return result.ProcessResult(context, this.Plan); 
            }
            catch (InvalidOperationException ex)
            {
                QueryOperationResponse operationResponse = result.GetResponse(MaterializeAtom.EmptyResults); 

                if (null != operationResponse) 
                { 
                    if (context.IgnoreResourceNotFoundException)
                    { 
                        DataServiceClientException cex = ex as DataServiceClientException;
                        if (cex != null && cex.StatusCode == (int)HttpStatusCode.NotFound)
                        {
                            // don't throw 
                            return (QueryOperationResponse)operationResponse;
                        } 
                    } 

                    operationResponse.Error = ex; 
                    throw new DataServiceQueryException(Strings.DataServiceException_GeneralError, ex, operationResponse);
                }

                throw; 
            }
        } 
 
        /// 
        /// Synchronizely get the query set count from the server by executing the $count=value query 
        /// 
        /// The context
        /// The server side count of the query set
        internal long GetQuerySetCount(DataServiceContext context) 
        {
            Debug.Assert(null != context, "context is null"); 
            this.QueryComponents.Version = Util.DataServiceVersion2; 

            QueryResult response = null; 
            DataServiceRequest serviceRequest = new DataServiceRequest(this.QueryComponents, null);
            HttpWebRequest request = context.CreateRequest(this.QueryComponents.Uri, XmlConstants.HttpMethodGet, false, null, this.QueryComponents.Version, false);

            request.Accept = "text/plain"; 
            response = new QueryResult(this, "Execute", serviceRequest, request, null, null);
 
            try 
            {
                response.Execute(); 

                if (HttpStatusCode.NoContent != response.StatusCode)
                {
                    StreamReader sr = new StreamReader(response.GetResponseStream()); 
                    long r = -1;
                    try 
                    { 
                        r = XmlConvert.ToInt64(sr.ReadToEnd());
                    } 
                    finally
                    {
                        sr.Close();
                    } 

                    return r; 
                } 
                else
                { 
                    throw new DataServiceQueryException(Strings.DataServiceRequest_FailGetCount, response.Failure);
                }
            }
            catch (InvalidOperationException ex) 
            {
                QueryOperationResponse operationResponse = null; 
                operationResponse = response.GetResponse(MaterializeAtom.EmptyResults); 
                if (null != operationResponse)
                { 
                    operationResponse.Error = ex;
                    throw new DataServiceQueryException(Strings.DataServiceException_GeneralError, ex, operationResponse);
                }
 
                throw;
            } 
        } 
#endif
 
        /// 
        /// Begins an asynchronous request to an Internet resource.
        /// 
        /// source of execute (DataServiceQuery or DataServiceContext 
        /// context
        /// The AsyncCallback delegate. 
        /// The state object for this request. 
        /// An IAsyncResult that references the asynchronous request for a response.
        internal IAsyncResult BeginExecute(object source, DataServiceContext context, AsyncCallback callback, object state) 
        {
            QueryResult result = this.CreateResult(source, context, callback, state);
            result.BeginExecute();
            return result; 
        }
 
        ///  
        /// Creates the result object for the specified query parameters.
        ///  
        /// The source object for the request.
        /// The data service context.
        /// The AsyncCallback delegate.
        /// The state object for the callback. 
        /// Result representing the create request. The request has not been initiated yet.
        private QueryResult CreateResult(object source, DataServiceContext context, AsyncCallback callback, object state) 
        { 
            Debug.Assert(null != context, "context is null");
            HttpWebRequest request = context.CreateRequest(this.QueryComponents.Uri, XmlConstants.HttpMethodGet, false, null, this.QueryComponents.Version, false); 
            return new QueryResult(source, "Execute", this, request, callback, state);
        }
    }
} 

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
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