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IBackgroundCopyJob3::AddFileWithRanges method

  • Article

Adds a file to a download job and specifies the ranges of the file you want to download.

Syntax

HRESULT AddFileWithRanges(
  [in] LPCWSTR       RemoteUrl,
  [in] LPCWSTR       LocalName,
  [in] DWORD         RangeCount,
  [in] BG_FILE_RANGE Ranges[]
);

Parameters

  • RemoteUrl [in]
    Null-terminated string that contains the name of the file on the server. For information on specifying the remote name, see the RemoteName member and Remarks section of the BG_FILE_INFO structure. The SMB protocol is not supported for ranges.

  • LocalName [in]
    Null-terminated string that contains the name of the file on the client. For information on specifying the local name, see the LocalName member and Remarks section of the BG_FILE_INFO structure.

  • RangeCount [in]
    Number of elements in Ranges.

  • Ranges [in]
    Array of one or more BG_FILE_RANGE structures that specify the ranges to download. Do not specify duplicate or overlapping ranges.

Return value

This method returns the following return values, as well as others.

Return code Description
S_OK

Success
E_INVALIDARG

You can receive this error for one of the following reasons:

  • The RangeCount parameter is zero; you must specify one or more ranges.
  • The local or remote file name is not valid.
  • The remote file name uses an unsupported protocol.
  • The local file name was specified using a relative path.
E_NOTIMPL

You cannot call this method for upload or upload-reply jobs; only call this method for download jobs.
E_ACCESSDENIED

User does not have permission to write to the specified directory on the client.
BG_E_INVALID_RANGE

One of the ranges is invalid. For example, InitialOffset is set to BG_LENGTH_TO_EOF.
BG_E_OVERLAPPING_RANGES

You cannot specify duplicate or overlapping ranges.

Note  The ranges are sorted by the offset of the value, not the length. If ranges are entered that have the same offset, but are in reverse order, then this error will be returned. For example, if 100.5 and 100.0 are entered in that order, then you will not be able to add the file to the job.
 
BG_E_TOO_MANY_RANGES_IN_FILE

The MaxRangesPerFile Group Policy setting determines how many ranges you can specify for a file. Adding these ranges exceeds the MaxRangesPerFile limit.
BG_E_INVALID_STATE

The state of the job cannot be BG_JOB_STATE_CANCELLED or BG_JOB_STATE_ACKNOWLEDGED.

 

Remarks

The ranges are written to the LocalName file in the order given. For example, if Ranges identifies bytes 100-199, 900-999, and 400-499 of the remote file, the local file will be 300 bytes long. Bytes 0-99 of the local file will contain bytes 100-199 of the remote file, bytes 100-199 of the local file will contain bytes 900-999 of the remote file, and bytes 200-299 of the local file will contain bytes 400-499 of the remote file.

The following table identifies possible error codes that can occur after you resume the job. These errors place the job in the BG_JOB_STATE_ERROR state.

Error code Description
BG_E_INVALID_SERVER_RESPONSE DO does not support servers that consolidate duplicate or overlapping ranges.
BG_E_INVALID_RANGE One of the ranges is outside the boundaries of the remote file.
BG_E_INSUFFICIENT_RANGE_SUPPORT The server does not support ranges.

 

DO guarantees that the version of a file (based on file size and date, not content) that it transfers will be consistent; however, it does not guarantee that a set of files will be consistent. For example, if DO is in the middle of downloading the second of two files in the job at the time that the files are updated on the server, DO restarts the download of the second file; however, the first file is not downloaded again.

By default, a user can add up to 500 ranges for a file. This limit does not apply to administrators or service accounts. To change the default, set the MaxRangesPerFile group policy.

For better performance on Windows BranchCache-enabled file transfers, it is recommended that you set the range length to at least 400 bytes.

Requirements

Minimum supported client

Windows 10, version 1709 [desktop apps only]

Minimum supported server

Windows Server 2016 [desktop apps only]

Header

 Deliveryoptimization.h

IDL

 DeliveryOptimization.idl

Library

 Dosvc.lib

DLL

 Dosvc.dll

IID

IID_IBackgroundCopyJob3 is defined as 443C8934-90FF-48ED-BCDE-26F5C7450042

See also

BG_FILE_RANGE

IBackgroundCopyFile2::GetFileRanges

IBackgroundCopyJob::AddFile

IBackgroundCopyJob3