Synnefo » Pithos MS Client

// **CloudFilesClient** provides a simple client interface to CloudFiles and Pithos

//

// The class provides methods to upload/download files, delete files, manage containers

using System;

using System.Collections.Generic;

using System.ComponentModel.Composition;

using System.Diagnostics.Contracts;

using System.IO;

using System.Linq;

using System.Net;

using System.Security.Cryptography;

using System.Text;

using System.Threading.Tasks;

using Newtonsoft.Json;

using Pithos.Interfaces;

using log4net;

namespace Pithos.Network

{

    [Export(typeof(ICloudClient))]

    public class CloudFilesClient:ICloudClient

    {

        //CloudFilesClient uses *_baseClient* internally to communicate with the server

        //RestClient provides a REST-friendly interface over the standard WebClient.

        private RestClient _baseClient;

        //During authentication the client provides a UserName 

        public string UserName { get; set; }

        //and and ApiKey to the server

        public string ApiKey { get; set; }

        //And receives an authentication Token. This token must be provided in ALL other operations,

        //in the X-Auth-Token header

        private string _token;

        public string Token

        {

            get { return _token; }

            set

            {

                _token = value;

                _baseClient.Headers["X-Auth-Token"] = value;

            }

        }

        //The client also receives a StorageUrl after authentication. All subsequent operations must

        //use this url

        public Uri StorageUrl { get; set; }

        protected Uri RootAddressUri { get; set; }

        private Uri _proxy;

        public Uri Proxy

        {

            get { return _proxy; }

            set

            {

                _proxy = value;

                if (_baseClient != null)

                    _baseClient.Proxy = new WebProxy(value);                

            }

        }

        public double DownloadPercentLimit { get; set; }

        public double UploadPercentLimit { get; set; }

        public string AuthenticationUrl { get; set; }

        public string VersionPath

        {

            get { return UsePithos ? "v1" : "v1.0"; }

        }

        public bool UsePithos { get; set; }

        private static readonly ILog Log = LogManager.GetLogger("CloudFilesClient");

        public CloudFilesClient(string userName, string apiKey)

        {

            UserName = userName;

            ApiKey = apiKey;

        }

        public CloudFilesClient(AccountInfo accountInfo)

        {

            if (accountInfo==null)

                throw new ArgumentNullException("accountInfo");

            Contract.Ensures(!String.IsNullOrWhiteSpace(Token));

            Contract.Ensures(StorageUrl != null);

            Contract.Ensures(_baseClient != null);

            Contract.Ensures(RootAddressUri != null);

            Contract.EndContractBlock();

            _baseClient = new RestClient

            {

                BaseAddress = accountInfo.StorageUri.ToString(),

                Timeout = 10000,

                Retries = 3

            };

            StorageUrl = accountInfo.StorageUri;

            Token = accountInfo.Token;

            UserName = accountInfo.UserName;

            //Get the root address (StorageUrl without the account)

            var storageUrl = StorageUrl.AbsoluteUri;

            var usernameIndex = storageUrl.LastIndexOf(UserName);

            var rootUrl = storageUrl.Substring(0, usernameIndex);

            RootAddressUri = new Uri(rootUrl);

        }

        public AccountInfo Authenticate()

        {

            if (String.IsNullOrWhiteSpace(UserName))

                throw new InvalidOperationException("UserName is empty");

            if (String.IsNullOrWhiteSpace(ApiKey))

                throw new InvalidOperationException("ApiKey is empty");

            if (String.IsNullOrWhiteSpace(AuthenticationUrl))

                throw new InvalidOperationException("AuthenticationUrl is empty");

            Contract.Ensures(!String.IsNullOrWhiteSpace(Token));

            Contract.Ensures(StorageUrl != null);

            Contract.Ensures(_baseClient != null);

            Contract.Ensures(RootAddressUri != null);

            Contract.EndContractBlock();

            Log.InfoFormat("[AUTHENTICATE] Start for {0}", UserName);

            using (var authClient = new RestClient{BaseAddress=AuthenticationUrl})

            {

                if (Proxy != null)

                    authClient.Proxy = new WebProxy(Proxy);

                Contract.Assume(authClient.Headers!=null);

                authClient.Headers.Add("X-Auth-User", UserName);

                authClient.Headers.Add("X-Auth-Key", ApiKey);

                authClient.DownloadStringWithRetry(VersionPath, 3);

                authClient.AssertStatusOK("Authentication failed");

                var storageUrl = authClient.GetHeaderValue("X-Storage-Url");

                if (String.IsNullOrWhiteSpace(storageUrl))

                    throw new InvalidOperationException("Failed to obtain storage url");

                _baseClient = new RestClient

                {

                    BaseAddress = storageUrl,

                    Timeout = 10000,

                    Retries = 3

                };

                StorageUrl = new Uri(storageUrl);

                //Get the root address (StorageUrl without the account)

                var usernameIndex=storageUrl.LastIndexOf(UserName);

                var rootUrl = storageUrl.Substring(0, usernameIndex);

                RootAddressUri = new Uri(rootUrl);

                var token = authClient.GetHeaderValue("X-Auth-Token");

                if (String.IsNullOrWhiteSpace(token))

                    throw new InvalidOperationException("Failed to obtain token url");

                Token = token;

            }

            Log.InfoFormat("[AUTHENTICATE] End for {0}", UserName);

            return new AccountInfo {StorageUri = StorageUrl, Token = Token, UserName = UserName};            

        }

        public IList<ContainerInfo> ListContainers(string account)

        {

            using (var client = new RestClient(_baseClient))

            {

                if (!String.IsNullOrWhiteSpace(account))

                    client.BaseAddress = GetAccountUrl(account);

                client.Parameters.Clear();

                client.Parameters.Add("format", "json");

                var content = client.DownloadStringWithRetry("", 3);

                client.AssertStatusOK("List Containers failed");

                if (client.StatusCode == HttpStatusCode.NoContent)

                    return new List<ContainerInfo>();

                var infos = JsonConvert.DeserializeObject<IList<ContainerInfo>>(content);

                foreach (var info in infos)

                {

                    info.Account = account;

                }

                return infos;

            }

        }

        private string GetAccountUrl(string account)

        {

            return new Uri(this.RootAddressUri, new Uri(account,UriKind.Relative)).AbsoluteUri;

        }

        public IList<ShareAccountInfo> ListSharingAccounts(DateTime? since=null)

        {

            using (log4net.ThreadContext.Stacks["Share"].Push("List Accounts"))

            {

                if (Log.IsDebugEnabled) Log.DebugFormat("START");

                using (var client = new RestClient(_baseClient))

                {

                    client.Parameters.Clear();

                    client.Parameters.Add("format", "json");

                    client.IfModifiedSince = since;

                    //Extract the username from the base address

                    client.BaseAddress = RootAddressUri.AbsoluteUri;

                    var content = client.DownloadStringWithRetry(@"", 3);

                    client.AssertStatusOK("ListSharingAccounts failed");

                    //If the result is empty, return an empty list,

                    var infos = String.IsNullOrWhiteSpace(content)

                                    ? new List<ShareAccountInfo>()

                                //Otherwise deserialize the account list into a list of ShareAccountInfos

                                    : JsonConvert.DeserializeObject<IList<ShareAccountInfo>>(content);

                    Log.DebugFormat("END");

                    return infos;

                }

            }

        }

        //Request listing of all objects in a container modified since a specific time.

        //If the *since* value is missing, return all objects

        public IList<ObjectInfo> ListSharedObjects(DateTime? since = null)

        {

            using (log4net.ThreadContext.Stacks["Share"].Push("List Objects"))

            {

                if (Log.IsDebugEnabled) Log.DebugFormat("START");

                var objects = new List<ObjectInfo>();

                var accounts = ListSharingAccounts(since);

                foreach (var account in accounts)

                {

                    var containers = ListContainers(account.name);

                    foreach (var container in containers)

                    {

                        var containerObjects = ListObjects(account.name, container.Name, null);

                        objects.AddRange(containerObjects);

                    }

                }

                if (Log.IsDebugEnabled) Log.DebugFormat("END");

                return objects;

            }

        }

        public void ShareObject(string account, string container, string objectName, string shareTo, bool read, bool write)

        {

            if (String.IsNullOrWhiteSpace(Token))

                throw new InvalidOperationException("The Token is not set");

            if (StorageUrl==null)

                throw new InvalidOperationException("The StorageUrl is not set");

            if (String.IsNullOrWhiteSpace(container))

                throw new ArgumentNullException("container");

            if (String.IsNullOrWhiteSpace(objectName))

                throw new ArgumentNullException("objectName");

            if (String.IsNullOrWhiteSpace(account))

                throw new ArgumentNullException("account");

            if (String.IsNullOrWhiteSpace(shareTo))

                throw new ArgumentNullException("shareTo");

            Contract.EndContractBlock();

            using (log4net.ThreadContext.Stacks["Share"].Push("Share Object"))

            {

                if (Log.IsDebugEnabled) Log.DebugFormat("START");

                using (var client = new RestClient(_baseClient))

                {

                    client.BaseAddress = GetAccountUrl(account);

                    client.Parameters.Clear();

                    client.Parameters.Add("format", "json");

                    string permission = "";

                    if (write)

                        permission = String.Format("write={0}", shareTo);

                    else if (read)

                        permission = String.Format("read={0}", shareTo);

                    client.Headers.Add("X-Object-Sharing", permission);

                    var content = client.DownloadStringWithRetry(container, 3);

                    client.AssertStatusOK("ShareObject failed");

                    //If the result is empty, return an empty list,

                    var infos = String.IsNullOrWhiteSpace(content)

                                    ? new List<ObjectInfo>()

                                //Otherwise deserialize the object list into a list of ObjectInfos

                                    : JsonConvert.DeserializeObject<IList<ObjectInfo>>(content);

                    if (Log.IsDebugEnabled) Log.DebugFormat("END");

                }

            }

        }

        public AccountInfo GetAccountPolicies(AccountInfo accountInfo)

        {

            if (accountInfo==null)

                throw new ArgumentNullException("accountInfo");

            Contract.EndContractBlock();

            using (log4net.ThreadContext.Stacks["Account"].Push("GetPolicies"))

            {

                if (Log.IsDebugEnabled) Log.DebugFormat("START");

                using (var client = new RestClient(_baseClient))

                {

                    if (!String.IsNullOrWhiteSpace(accountInfo.UserName))

                        client.BaseAddress = GetAccountUrl(accountInfo.UserName);

                    client.Parameters.Clear();

                    client.Parameters.Add("format", "json");                    

                    client.Head(String.Empty, 3);

                    var quotaValue=client.ResponseHeaders["X-Account-Policy-Quota"];

                    var bytesValue= client.ResponseHeaders["X-Account-Bytes-Used"];

                    long quota, bytes;

                    if (long.TryParse(quotaValue, out quota))

                        accountInfo.Quota = quota;

                    if (long.TryParse(bytesValue, out bytes))

                        accountInfo.BytesUsed = bytes;

                    return accountInfo;

                }

            }

        }

        public IList<ObjectInfo> ListObjects(string account, string container, DateTime? since = null)

        {

            if (String.IsNullOrWhiteSpace(container))

                throw new ArgumentNullException("container");

            Contract.EndContractBlock();

            using (log4net.ThreadContext.Stacks["Objects"].Push("List"))

            {

                if (Log.IsDebugEnabled) Log.DebugFormat("START");

                using (var client = new RestClient(_baseClient))

                {

                    if (!String.IsNullOrWhiteSpace(account))

                        client.BaseAddress = GetAccountUrl(account);

                    client.Parameters.Clear();

                    client.Parameters.Add("format", "json");

                    client.IfModifiedSince = since;

                    var content = client.DownloadStringWithRetry(container, 3);

                    client.AssertStatusOK("ListObjects failed");

                    //If the result is empty, return an empty list,

                    var infos = String.IsNullOrWhiteSpace(content)

                                    ? new List<ObjectInfo>()

                                //Otherwise deserialize the object list into a list of ObjectInfos

                                    : JsonConvert.DeserializeObject<IList<ObjectInfo>>(content);

                    foreach (var info in infos)

                    {

                        info.Container = container;

                        info.Account = account;

                    }

                    if (Log.IsDebugEnabled) Log.DebugFormat("START");

                    return infos;

                }

            }

        }

        public IList<ObjectInfo> ListObjects(string account, string container, string folder, DateTime? since = null)

        {

            if (String.IsNullOrWhiteSpace(container))

                throw new ArgumentNullException("container");

            if (String.IsNullOrWhiteSpace(folder))

                throw new ArgumentNullException("folder");

            Contract.EndContractBlock();

            using (log4net.ThreadContext.Stacks["Objects"].Push("List"))

            {

                if (Log.IsDebugEnabled) Log.DebugFormat("START");

                using (var client = new RestClient(_baseClient))

                {

                    if (!String.IsNullOrWhiteSpace(account))

                        client.BaseAddress = GetAccountUrl(account);

                    client.Parameters.Clear();

                    client.Parameters.Add("format", "json");

                    client.Parameters.Add("path", folder);

                    client.IfModifiedSince = since;

                    var content = client.DownloadStringWithRetry(container, 3);

                    client.AssertStatusOK("ListObjects failed");

                    var infos = JsonConvert.DeserializeObject<IList<ObjectInfo>>(content);

                    if (Log.IsDebugEnabled) Log.DebugFormat("END");

                    return infos;

                }

            }

        }

        public bool ContainerExists(string account, string container)

        {

            if (String.IsNullOrWhiteSpace(container))

                throw new ArgumentNullException("container", "The container property can't be empty");

            Contract.EndContractBlock();

            using (log4net.ThreadContext.Stacks["Containters"].Push("Exists"))

            {

                if (Log.IsDebugEnabled) Log.DebugFormat("START");

                using (var client = new RestClient(_baseClient))

                {

                    if (!String.IsNullOrWhiteSpace(account))

                        client.BaseAddress = GetAccountUrl(account);

                    client.Parameters.Clear();

                    client.Head(container, 3);

                    bool result;

                    switch (client.StatusCode)

                    {

                        case HttpStatusCode.OK:

                        case HttpStatusCode.NoContent:

                            result=true;

                            break;

                        case HttpStatusCode.NotFound:

                            result=false;

                            break;

                        default:

                            throw CreateWebException("ContainerExists", client.StatusCode);

                    }

                    if (Log.IsDebugEnabled) Log.DebugFormat("END");

                    return result;

                }

            }

        }

        public bool ObjectExists(string account, string container, string objectName)

        {

            if (String.IsNullOrWhiteSpace(container))

                throw new ArgumentNullException("container", "The container property can't be empty");

            if (String.IsNullOrWhiteSpace(objectName))

                throw new ArgumentNullException("objectName", "The objectName property can't be empty");

            Contract.EndContractBlock();

            using (var client = new RestClient(_baseClient))

            {

                if (!String.IsNullOrWhiteSpace(account))

                    client.BaseAddress = GetAccountUrl(account);

                client.Parameters.Clear();

                client.Head(container + "/" + objectName, 3);

                switch (client.StatusCode)

                {

                    case HttpStatusCode.OK:

                    case HttpStatusCode.NoContent:

                        return true;

                    case HttpStatusCode.NotFound:

                        return false;

                    default:

                        throw CreateWebException("ObjectExists", client.StatusCode);

                }

            }

        }

        public ObjectInfo GetObjectInfo(string account, string container, string objectName)

        {

            if (String.IsNullOrWhiteSpace(container))

                throw new ArgumentNullException("container", "The container property can't be empty");

            if (String.IsNullOrWhiteSpace(objectName))

                throw new ArgumentNullException("objectName", "The objectName property can't be empty");

            Contract.EndContractBlock();

            using (log4net.ThreadContext.Stacks["Objects"].Push("GetObjectInfo"))

            {                

                using (var client = new RestClient(_baseClient))

                {

                    if (!String.IsNullOrWhiteSpace(account))

                        client.BaseAddress = GetAccountUrl(account);

                    try

                    {

                        client.Parameters.Clear();

                        client.Head(container + "/" + objectName, 3);

                        if (client.TimedOut)

                            return ObjectInfo.Empty;

                        switch (client.StatusCode)

                        {

                            case HttpStatusCode.OK:

                            case HttpStatusCode.NoContent:

                                var keys = client.ResponseHeaders.AllKeys.AsQueryable();

                                var tags = (from key in keys

                                            where key.StartsWith("X-Object-Meta-")

                                            let name = key.Substring(14)

                                            select new {Name = name, Value = client.ResponseHeaders[name]})

                                    .ToDictionary(t => t.Name, t => t.Value);

                                var extensions = (from key in keys

                                                  where key.StartsWith("X-Object-") && !key.StartsWith("X-Object-Meta-")

                                                  select new {Name = key, Value = client.ResponseHeaders[key]})

                                    .ToDictionary(t => t.Name, t => t.Value);

                                var info = new ObjectInfo

                                               {

                                                   Account = account,

                                                   Container = container,

                                                   Name = objectName,

                                                   Hash = client.GetHeaderValue("ETag"),

                                                   Content_Type = client.GetHeaderValue("Content-Type"),

                                                   Bytes = Convert.ToInt64(client.GetHeaderValue("Content-Length")),

                                                   Tags = tags,

                                                   Last_Modified = client.LastModified,

                                                   Extensions = extensions

                                               };

                                return info;

                            case HttpStatusCode.NotFound:

                                return ObjectInfo.Empty;

                            default:

                                throw new WebException(

                                    String.Format("[FAIL] GetObjectInfo for {0} failed with unexpected status code {1}",

                                                  objectName, client.StatusCode));

                        }

                    }

                    catch (RetryException)

                    {

                        Log.WarnFormat("[RETRY FAIL] GetObjectInfo for {0} failed.");

                        return ObjectInfo.Empty;

                    }

                    catch (WebException e)

                    {

                        Log.Error(

                            String.Format("[FAIL] GetObjectInfo for {0} failed with unexpected status code {1}",

                                          objectName, client.StatusCode), e);

                        throw;

                    }

                }                

            }

        }

        public void CreateFolder(string account, string container, string folder)

        {

            if (String.IsNullOrWhiteSpace(container))

                throw new ArgumentNullException("container", "The container property can't be empty");

            if (String.IsNullOrWhiteSpace(folder))

                throw new ArgumentNullException("folder", "The folder property can't be empty");

            Contract.EndContractBlock();

            var folderUrl=String.Format("{0}/{1}",container,folder);

            using (var client = new RestClient(_baseClient))

            {

                if (!String.IsNullOrWhiteSpace(account))

                    client.BaseAddress = GetAccountUrl(account);

                client.Parameters.Clear();

                client.Headers.Add("Content-Type", @"application/directory");

                client.Headers.Add("Content-Length", "0");

                client.PutWithRetry(folderUrl, 3);

                if (client.StatusCode != HttpStatusCode.Created && client.StatusCode != HttpStatusCode.Accepted)

                    throw CreateWebException("CreateFolder", client.StatusCode);

            }

        }

        public ContainerInfo GetContainerInfo(string account, string container)

        {

            if (String.IsNullOrWhiteSpace(container))

                throw new ArgumentNullException("container", "The container property can't be empty");

            Contract.EndContractBlock();

            using (var client = new RestClient(_baseClient))

            {

                if (!String.IsNullOrWhiteSpace(account))

                    client.BaseAddress = GetAccountUrl(account);                

                client.Head(container);

                switch (client.StatusCode)

                {

                    case HttpStatusCode.OK:

                    case HttpStatusCode.NoContent:

                        var containerInfo = new ContainerInfo

                                                {

                                                    Account=account,

                                                    Name = container,

                                                    Count =

                                                        long.Parse(client.GetHeaderValue("X-Container-Object-Count")),

                                                    Bytes = long.Parse(client.GetHeaderValue("X-Container-Bytes-Used")),

                                                    BlockHash = client.GetHeaderValue("X-Container-Block-Hash"),

                                                    BlockSize=int.Parse(client.GetHeaderValue("X-Container-Block-Size")),

                                                    Last_Modified=client.LastModified

                                                };

                        return containerInfo;

                    case HttpStatusCode.NotFound:

                        return ContainerInfo.Empty;

                    default:

                        throw CreateWebException("GetContainerInfo", client.StatusCode);

                }

            }

        }

        public void CreateContainer(string account, string container)

        {            

            if (String.IsNullOrWhiteSpace(container))

                throw new ArgumentNullException("container", "The container property can't be empty");

            Contract.EndContractBlock();

            using (var client = new RestClient(_baseClient))

            {

                if (!String.IsNullOrWhiteSpace(account))

                    client.BaseAddress = GetAccountUrl(account);

                client.PutWithRetry(container, 3);

                var expectedCodes = new[] {HttpStatusCode.Created, HttpStatusCode.Accepted, HttpStatusCode.OK};

                if (!expectedCodes.Contains(client.StatusCode))

                    throw CreateWebException("CreateContainer", client.StatusCode);

            }

        }

        public void DeleteContainer(string account, string container)

        {

            if (String.IsNullOrWhiteSpace(container))

                throw new ArgumentNullException("container", "The container property can't be empty");

            Contract.EndContractBlock();

            using (var client = new RestClient(_baseClient))

            {

                if (!String.IsNullOrWhiteSpace(account))

                    client.BaseAddress = GetAccountUrl(account);

                client.DeleteWithRetry(container, 3);

                var expectedCodes = new[] {HttpStatusCode.NotFound, HttpStatusCode.NoContent};

                if (!expectedCodes.Contains(client.StatusCode))

                    throw CreateWebException("DeleteContainer", client.StatusCode);

            }

        }

        /// <summary>

        /// 

        /// </summary>

        /// <param name="account"></param>

        /// <param name="container"></param>

        /// <param name="objectName"></param>

        /// <param name="fileName"></param>

        /// <returns></returns>

        /// <remarks>This method should have no timeout or a very long one</remarks>

        //Asynchronously download the object specified by *objectName* in a specific *container* to 

        // a local file

        public Task GetObject(string account, string container, string objectName, string fileName)

        {

            if (String.IsNullOrWhiteSpace(container))

                throw new ArgumentNullException("container", "The container property can't be empty");

            if (String.IsNullOrWhiteSpace(objectName))

                throw new ArgumentNullException("objectName", "The objectName property can't be empty");            

            Contract.EndContractBlock();

            try

            {

                //WebClient, and by extension RestClient, are not thread-safe. Create a new RestClient

                //object to avoid concurrency errors.

                //

                //Download operations take a long time therefore they have no timeout.

                var client = new RestClient(_baseClient) { Timeout = 0 };

                if (!String.IsNullOrWhiteSpace(account))

                    client.BaseAddress = GetAccountUrl(account);

                //The container and objectName are relative names. They are joined with the client's

                //BaseAddress to create the object's absolute address

                var builder = client.GetAddressBuilder(container, objectName);

                var uri = builder.Uri;

                //Download progress is reported to the Trace log

                Log.InfoFormat("[GET] START {0}", objectName);

                client.DownloadProgressChanged += (sender, args) => 

                    Log.InfoFormat("[GET PROGRESS] {0} {1}% {2} of {3}",

                                    fileName, args.ProgressPercentage,

                                    args.BytesReceived,

                                    args.TotalBytesToReceive);                                

                //Start downloading the object asynchronously

                var downloadTask = client.DownloadFileTask(uri, fileName);

                //Once the download completes

                return downloadTask.ContinueWith(download =>

                                      {

                                          //Delete the local client object

                                          client.Dispose();

                                          //And report failure or completion

                                          if (download.IsFaulted)

                                          {

                                              Log.ErrorFormat("[GET] FAIL for {0} with \r{1}", objectName,

                                                               download.Exception);

                                          }

                                          else

                                          {

                                              Log.InfoFormat("[GET] END {0}", objectName);                                             

                                          }

                                      });

            }

            catch (Exception exc)

            {

                Log.ErrorFormat("[GET] END {0} with {1}", objectName, exc);

                throw;

            }

        }

        public Task<IList<string>> PutHashMap(string account, string container, string objectName, TreeHash hash)

        {

            if (String.IsNullOrWhiteSpace(container))

                throw new ArgumentNullException("container");

            if (String.IsNullOrWhiteSpace(objectName))

                throw new ArgumentNullException("objectName");

            if (hash==null)

                throw new ArgumentNullException("hash");

            if (String.IsNullOrWhiteSpace(Token))

                throw new InvalidOperationException("Invalid Token");

            if (StorageUrl == null)

                throw new InvalidOperationException("Invalid Storage Url");

            Contract.EndContractBlock();

            //Don't use a timeout because putting the hashmap may be a long process

            var client = new RestClient(_baseClient) { Timeout = 0 };

            if (!String.IsNullOrWhiteSpace(account))

                client.BaseAddress = GetAccountUrl(account);

            //The container and objectName are relative names. They are joined with the client's

            //BaseAddress to create the object's absolute address

            var builder = client.GetAddressBuilder(container, objectName);

            builder.Query = "format=json&hashmap";

            var uri = builder.Uri;

            //Send the tree hash as Json to the server            

            client.Headers[HttpRequestHeader.ContentType] = "application/octet-stream";

            var uploadTask=client.UploadStringTask(uri, "PUT", hash.ToJson());

            return uploadTask.ContinueWith(t =>

            {

                var empty = (IList<string>)new List<string>();

                //The server will respond either with 201-created if all blocks were already on the server

                if (client.StatusCode == HttpStatusCode.Created)                    

                {

                    //in which case we return an empty hash list

                    return empty;

                }

                //or with a 409-conflict and return the list of missing parts

                //A 409 will cause an exception so we need to check t.IsFaulted to avoid propagating the exception                

                if (t.IsFaulted)

                {

                    var ex = t.Exception.InnerException;

                    var we = ex as WebException;

                    var response = we.Response as HttpWebResponse;

                    if (response!=null && response.StatusCode==HttpStatusCode.Conflict)

                    {

                        //In case of 409 the missing parts will be in the response content                        

                        using (var stream = response.GetResponseStream())

                        using(var reader=new StreamReader(stream))

                        {

                            //We need to cleanup the content before returning it because it contains

                            //error content after the list of hashes

                            var hashes = new List<string>();

                            string line=null;

                            //All lines up to the first empty line are hashes

                            while(!String.IsNullOrWhiteSpace(line=reader.ReadLine()))

                            {

                                hashes.Add(line);

                            }

                            return hashes;

                        }                        

                    }

                    else

                        //Any other status code is unexpected and the exception should be rethrown

                        throw ex;

                }

                //Any other status code is unexpected but there was no exception. We can probably continue processing

                else

                {

                    Log.WarnFormat("Unexcpected status code when putting map: {0} - {1}",client.StatusCode,client.StatusDescription);                    

                }

                return empty;

            });

        }

        public Task<byte[]> GetBlock(string account, string container, Uri relativeUrl, long start, long? end)

        {

            if (String.IsNullOrWhiteSpace(Token))

                throw new InvalidOperationException("Invalid Token");

            if (StorageUrl == null)

                throw new InvalidOperationException("Invalid Storage Url");

            if (String.IsNullOrWhiteSpace(container))

                throw new ArgumentNullException("container");

            if (relativeUrl== null)

                throw new ArgumentNullException("relativeUrl");

            if (end.HasValue && end<0)

                throw new ArgumentOutOfRangeException("end");

            if (start<0)

                throw new ArgumentOutOfRangeException("start");

            Contract.EndContractBlock();

            //Don't use a timeout because putting the hashmap may be a long process

            var client = new RestClient(_baseClient) {Timeout = 0, RangeFrom = start, RangeTo = end};

            if (!String.IsNullOrWhiteSpace(account))

                client.BaseAddress = GetAccountUrl(account);

            var builder = client.GetAddressBuilder(container, relativeUrl.ToString());

            var uri = builder.Uri;

            return client.DownloadDataTask(uri)

                .ContinueWith(t=>

                                  {

                                      client.Dispose();

                                      return t.Result;

                                  });

        }

        public Task PostBlock(string account, string container, byte[] block, int offset, int count)

        {

            if (String.IsNullOrWhiteSpace(container))

                throw new ArgumentNullException("container");

            if (block == null)

                throw new ArgumentNullException("block");

            if (offset < 0 || offset >= block.Length)

                throw new ArgumentOutOfRangeException("offset");

            if (count < 0 || count > block.Length)

                throw new ArgumentOutOfRangeException("count");

            if (String.IsNullOrWhiteSpace(Token))

                throw new InvalidOperationException("Invalid Token");

            if (StorageUrl == null)

                throw new InvalidOperationException("Invalid Storage Url");                        

            Contract.EndContractBlock();

            //Don't use a timeout because putting the hashmap may be a long process

            var client = new RestClient(_baseClient) { Timeout = 0 };

            if (!String.IsNullOrWhiteSpace(account))

                client.BaseAddress = GetAccountUrl(account);

            var builder = client.GetAddressBuilder(container, "");

            //We are doing an update

            builder.Query = "update";

            var uri = builder.Uri;

            client.Headers[HttpRequestHeader.ContentType] = "application/octet-stream";

            Log.InfoFormat("[BLOCK POST] START");

            client.UploadProgressChanged += (sender, args) => 

                Log.InfoFormat("[BLOCK POST PROGRESS] {0}% {1} of {2}",

                                    args.ProgressPercentage, args.BytesSent,

                                    args.TotalBytesToSend);

            client.UploadFileCompleted += (sender, args) => 

                Log.InfoFormat("[BLOCK POST PROGRESS] Completed ");

            //Send the block

            var uploadTask = client.UploadDataTask(uri, "POST", block)

            .ContinueWith(upload =>

            {

                client.Dispose();

                if (upload.IsFaulted)

                {

                    var exception = upload.Exception.InnerException;

                    Log.ErrorFormat("[BLOCK POST] FAIL with \r{0}", exception);                        

                    throw exception;

                }

                Log.InfoFormat("[BLOCK POST] END");

            });

            return uploadTask;            

        }

        public Task<TreeHash> GetHashMap(string account, string container, string objectName)

        {

            if (String.IsNullOrWhiteSpace(container))

                throw new ArgumentNullException("container");

            if (String.IsNullOrWhiteSpace(objectName))

                throw new ArgumentNullException("objectName");

            if (String.IsNullOrWhiteSpace(Token))

                throw new InvalidOperationException("Invalid Token");

            if (StorageUrl == null)

                throw new InvalidOperationException("Invalid Storage Url");

            Contract.EndContractBlock();

            try

            {

                //WebClient, and by extension RestClient, are not thread-safe. Create a new RestClient

                //object to avoid concurrency errors.

                //

                //Download operations take a long time therefore they have no timeout.

                //TODO: Do we really? this is a hashmap operation, not a download

                var client = new RestClient(_baseClient) { Timeout = 0 };

                if (!String.IsNullOrWhiteSpace(account))

                    client.BaseAddress = GetAccountUrl(account);

                //The container and objectName are relative names. They are joined with the client's

                //BaseAddress to create the object's absolute address

                var builder = client.GetAddressBuilder(container, objectName);

                builder.Query = "format=json&hashmap";

                var uri = builder.Uri;

                //Start downloading the object asynchronously

                var downloadTask = client.DownloadStringTask(uri);

                //Once the download completes

                return downloadTask.ContinueWith(download =>

                {

                    //Delete the local client object

                    client.Dispose();

                    //And report failure or completion

                    if (download.IsFaulted)

                    {

                        Log.ErrorFormat("[GET HASH] FAIL for {0} with \r{1}", objectName,

                                        download.Exception);

                        throw download.Exception;

                    }

                    //The server will return an empty string if the file is empty

                    var json = download.Result;

                    var treeHash = TreeHash.Parse(json);

                    Log.InfoFormat("[GET HASH] END {0}", objectName);                                             

                    return treeHash;

                });

            }

            catch (Exception exc)

            {

                Log.ErrorFormat("[GET HASH] END {0} with {1}", objectName, exc);

                throw;

            }

        }

        /// <summary>

        /// 

        /// </summary>