HadoopDFS Control

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The HadoopDFS control provides easy access to files stored in HDFS clusters.

Syntax

HadoopDFS

Remarks

The HadoopDFS control offers an easy-to-use API compatible with any Hadoop distributed file system (HDFS) cluster that exposes Hadoop's standard WebHDFS REST API. Capabilities include uploading and downloading files, strong encryption support, creating folders, file manipulation and organization, and more.

Authentication

First, set the URL property to the base WebHDFS URL of the server (see URL for more details).

Depending on how the server is configured, there are a few different authentication mechanisms that might be used; or, the server might not require authentication at all). Refer to the AuthMechanism property for more information about configuring the control to authenticate correctly.

Addressing Resources

HDFS addresses resources (files, directories, and symlinks) using Linux-style absolute paths. Unless otherwise specified, the control always works in terms of absolute paths, and will always prepend a forward slash (/) to any path passed to it that does not already start with one.

Listing Directory Contents

ListResources lists resources (files, directories, and symlinks) within the specified directory. Calling this method will fire the ResourceList event once for each resource, and will also populate the Resource* properties. // ResourceList event handler. hdfs.OnResourceList += (s, e) => { Console.WriteLine(e.Name); }; hdfs.ListResources("/work_files/serious_business/cats"); for (int i = 0; i < hdfs.Resources.Count; i++) { // Process resources here. }

Downloading Files

The DownloadFile method downloads files.

If LocalFile is set, the file will be saved to the specified location; otherwise, the file data will be held by ResourceData.

To download and decrypt an encrypted file, set EncryptionAlgorithm and EncryptionPassword before calling this method.

Download Notes

In the simplest use-case, downloading a file looks like this: hdfs.LocalFile = "../MyFile.zip"; hdfs.DownloadFile(hdfs.Resources[0].Path);

Resuming Downloads

The control also supports resuming failed downloads by using the StartByte property. If a download is interrupted, set StartByte to the appropriate offset before calling this method to resume the download. string downloadFile = "../MyFile.zip"; hdfs.LocalFile = downloadFile; hdfs.DownloadFile(hdfs.Resources[0].Path); //The transfer is interrupted and DownloadFile() above fails. Later, resume the download: //Get the size of the partially downloaded file hdfs.StartByte = new FileInfo(downloadFile).Length; hdfs.DownloadFile(hdfs.Resources[0].Path);

Resuming Encrypted File Downloads

Resuming encrypted file downloads is only supported when LocalFile was set in the initial download attempt.

If LocalFile is set when beginning an encrypted download, the control creates a temporary file in TempPath to hold the encrypted data until the download is complete. If the download is interrupted, DownloadTempFile will be populated with the path of the temporary file that holds the partial data.

To resume, DownloadTempFile must be populated, along with StartByte, to allow the remainder of the encrypted data to be downloaded. Once the encrypted data is downloaded it will be decrypted and written to LocalFile. hdfs.LocalFile = "../MyFile.zip"; hdfs.EncryptionPassword = "password"; hdfs.DownloadFile(hdfs.Resources[0].Path); //The transfer is interrupted and DownloadFile() above fails. Later, resume the download: //Get the size of the partially download temp file hdfs.StartByte = new FileInfo(hdfs.Config("DownloadTempFile")).Length; hdfs.DownloadFile(hdfs.Resources[0].Path);

Uploading Files

The UploadFile method uploads new files.

If LocalFile is set the file will be uploaded from the specified path. If LocalFile is not set the data in ResourceData will be used.

To encrypt the file before uploading it, set EncryptionAlgorithm and EncryptionPassword. hdfs.LocalFile = "../MyFile.zip"; hdfs.UploadFile("/MyFile.zip");

Additional Functionality

The HadoopDFS control offers advanced functionality beyond simple uploads and downloads. For instance:

• Encrypt and decrypt files using the EncryptionAlgorithm and EncryptionPassword properties.
• Basic file and folder manipulation and organization using methods such as AppendFile, DeleteResource, MakeDirectory, MoveResource, and TruncateFile.
• Advanced file and directory manipulation with SetFileReplication, SetOwner, SetPermission, and SetTimes.
• Retrieval of both general file/directory information, as well as directory quota information, using GetResourceInfo and GetDirSummary.
• Execute any arbitrary WebHDFS operation with ease using the DoCustomOp method.
• And more!

Property List

The following is the full list of the properties of the control with short descriptions. Click on the links for further details.

Method List

The following is the full list of the methods of the control with short descriptions. Click on the links for further details.

Event List

The following is the full list of the events fired by the control with short descriptions. Click on the links for further details.

Config Settings

The following is a list of config settings for the control with short descriptions. Click on the links for further details.

AuthMechanism Property (HadoopDFS Control)

The authentication mechanism to use when connecting to the server.

Syntax

hadoopdfscontrol.AuthMechanism[=integer]

Possible Values

amNone(0), 
amSimple(1), 
amBasic(2), 
amNTLM(3), 
amNegotiate(4), 
amOAuth(5)

Default Value

0

Remarks

This property controls what authentication mechanism the control should use when connecting to the server.

Possible values are:

When set to 1 (amSimple), the value of the User property is automatically sent in every request using the user.name query parameter.

When set to 2 (amBasic), 3 (amNTLM), or 4 (amNegotiate), the values held by the User and Password properties will be used to perform Basic, NTLM, or Negotiate (e.g., Kerberos SPNEGO) authentication.

When set to 5 (amOAuth), the value of the Authorization property is automatically sent in every request using the Authorization HTTP header.

Data Type

Integer

Authorization Property (HadoopDFS Control)

OAuth 2.0 Authorization Token.

Syntax

hadoopdfscontrol.Authorization[=string]

Default Value

""

Remarks

This control supports authentication via OAuth 2.0. First, perform OAuth authentication using the OAuth* properties, using the OAuth control or a separate process. If using the OAuth* properties, then the Authorization property will not be used.

Bearer ACCESS_TOKEN

Refer to AuthMechanism for more information.

Data Type

String

DirSummaryDirCount Property (HadoopDFS Control)

The number of subdirectories within the directory.

Syntax

hadoopdfscontrol.DirSummaryDirCount

Default Value

0

Remarks

The number of subdirectories within the directory.

This property reflects the number of subdirectories contained within the directory, calculated recursively. Note that this count will always include the directory itself; i.e., this property would return 1 for a directory with no subfolders.

This property is read-only and not available at design time.

Data Type

Long64

DirSummaryFileCount Property (HadoopDFS Control)

The number of files within the directory.

Syntax

hadoopdfscontrol.DirSummaryFileCount

Default Value

0

Remarks

The number of files within the directory.

This property reflects the number of files contained within the directory, calculated recursively.

This property is read-only and not available at design time.

Data Type

Long64

DirSummaryNameQuota Property (HadoopDFS Control)

The name quota imposed on the directory.

Syntax

hadoopdfscontrol.DirSummaryNameQuota

Default Value

-1

Remarks

The name quota imposed on the directory.

This property reflects the name quota imposed on the directory, or -1 if the directory doesn't have a name quota set.

A name quota limits the number of files and directories that can be created within a directory (calculated recursively). Note that a directory's own name is counted against its own quota, so the minimum name quota that may be applied to a directory is 1 (which will force the directory to stay empty).

This property is read-only and not available at design time.

Data Type

Long64

DirSummarySize Property (HadoopDFS Control)

The total size of the directory contents, excluding file replicas.

Syntax

hadoopdfscontrol.DirSummarySize

Default Value

0

Remarks

The total size of the directory contents, excluding file replicas.

This property reflects the total size (in bytes) of the directory's contents, calculated recursively.

Unlike DirSummarySpaceUsed, this property's value does not take file replicas into account, and thus should not be interpreted as the actual number of bytes the directory's contents use on disk.

This property is read-only and not available at design time.

Data Type

Long64

DirSummarySpaceQuota Property (HadoopDFS Control)

The space quota imposed on the directory.

Syntax

hadoopdfscontrol.DirSummarySpaceQuota

Default Value

-1

Remarks

The space quota imposed on the directory.

This property reflects the overall space quota (in bytes) imposed on the directory, or -1 if the directory doesn't have a space quota set.

A space quota limits the total number of bytes the files within a directory (or any of its subdirectories) may consume across all storage mediums. Space quotas are tracked separately from each directory's various DirSummaryStorageQuotas, and only one space quota may be applied to any given directory.

This property is read-only and not available at design time.

Data Type

Long64

DirSummarySpaceUsed Property (HadoopDFS Control)

The total amount of space the directory consumes on disk.

Syntax

hadoopdfscontrol.DirSummarySpaceUsed

Default Value

0

Remarks

The total amount of space the directory consumes on disk.

This property reflects the total amount of space (in bytes) that the directory's contents, calculated recursively, consume on disk.

Unlike DirSummarySize, this property's value includes space consumed by file replicas.

This property is read-only and not available at design time.

Data Type

Long64

DirSummaryStorageQuota Property (HadoopDFS Control)

The storage type quota imposed on the directory.

Syntax

hadoopdfscontrol.DirSummaryStorageQuota

Default Value

-1

Remarks

The storage type quota imposed on the directory.

This property reflects the storage type quota (in bytes) imposed on the directory for the DirSummaryStorageQuotaType currently selected by DirSummaryStorageQuotaIndex.

Storage type quotas limit the number of bytes that files within a directory (or any of its subdirectories) may consume on specific types of storage mediums. Multiple storage type quotas, each associated with a different type of storage medium, may be imposed on a directory simultaneously. Storage type quotas are tracked separately from a directory's overall DirSummarySpaceQuota.

Use DirSummaryStorageQuotaCount to determine how many storage type quotas are imposed on a directory, and DirSummaryStorageQuotaIndex to select which storage type quota's information to reflect in the DirSummaryStorageQuota, DirSummaryStorageQuotaType, and DirSummaryStorageQuotaUsed properties.

Note that it is possible for a storage type quota to be imposed on a directory without actually restricting any space usage, in which case this property's value will be -1.

This property is read-only and not available at design time.

Data Type

Long64

DirSummaryStorageQuotaCount Property (HadoopDFS Control)

The number of storage type quotas associated with the directory.

Syntax

hadoopdfscontrol.DirSummaryStorageQuotaCount

Default Value

0

Remarks

The number of storage type quotas associated with the directory.

This property reflects the number of storage type quotas associated with the directory. Use the DirSummaryStorageQuotaIndex property to select which storage type quota's information to reflect in the DirSummaryStorageQuota, DirSummaryStorageQuotaType, and DirSummaryStorageQuotaUsed properties.

This property is read-only and not available at design time.

Data Type

Integer

DirSummaryStorageQuotaIndex Property (HadoopDFS Control)

Selects the storage type quota to show information for.

Syntax

hadoopdfscontrol.DirSummaryStorageQuotaIndex

Default Value

-1

Remarks

Selects the storage type quota to show information for.

This property selects which storage type quota's information to reflect in the DirSummaryStorageQuota, DirSummaryStorageQuotaType, and DirSummaryStorageQuotaUsed properties; those properties are re-populated when this property's value is changed.

Valid values for this property are -1 to (DirSummaryStorageQuotaCount - 1); invalid indices are ignored. The default value is 0 if DirSummaryStorageQuotaCount is greater than 0, and -1 otherwise.

This property is read-only and not available at design time.

Data Type

Integer

DirSummaryStorageQuotaType Property (HadoopDFS Control)

The storage type associated with the storage type quota.

Syntax

hadoopdfscontrol.DirSummaryStorageQuotaType

Default Value

""

Remarks

The storage type associated with the storage type quota.

This property reflects the storage type associated with the storage type quota currently selected by DirSummaryStorageQuotaIndex

This property is read-only and not available at design time.

Data Type

String

DirSummaryStorageQuotaUsed Property (HadoopDFS Control)

The number of bytes consumed for the storage type quota.

Syntax

hadoopdfscontrol.DirSummaryStorageQuotaUsed

Default Value

0

Remarks

The number of bytes consumed for the storage type quota.

This property reflects the number of bytes that have been consumed for the storage type quota currently selected by DirSummaryStorageQuotaIndex

This property is read-only and not available at design time.

Data Type

Long64

EncryptionAlgorithm Property (HadoopDFS Control)

The encryption algorithm.

Syntax

hadoopdfscontrol.EncryptionAlgorithm[=integer]

Possible Values

eaAES(0), 
eaBlowfish(1), 
eaCAST(2), 
eaDES(3), 
eaIDEA(4), 
eaRC2(5), 
eaRC4(6), 
eaTEA(7), 
eaTripleDES(8), 
eaTwofish(9), 
eaRijndael(10), 
eaChaCha(11), 
eaXSalsa20(12)

Default Value

0

Remarks

This property specifies the encryption algorithm to be used. The maximum allowable key size is automatically used for the selected algorithm. Possible values are:

Data Type

Integer

EncryptionPassword Property (HadoopDFS Control)

The encryption password.

Syntax

hadoopdfscontrol.EncryptionPassword[=string]

Default Value

""

Remarks

If this property is populated when UploadFile or DownloadFile is called, the control will attempt to encrypt or decrypt the data before uploading or after downloading it.

The control uses the value specified here to generate the necessary encryption Key and IV values using the PKCS5 password digest algorithm. This provides a simpler alternative to creating and managing Key and IV values directly.

However, it is also possible to explicitly specify the Key and IV values to use by setting the EncryptionKey and EncryptionIV configuration settings. This may be necessary if, e.g., the data needs to be encrypted/decrypted by another utility which generates Key and IV values differently.

This property is not available at design time.

Data Type

String

FirewallAutoDetect Property (HadoopDFS Control)

This property tells the control whether or not to automatically detect and use firewall system settings, if available.

Syntax

hadoopdfscontrol.FirewallAutoDetect[=boolean]

Default Value

False

Remarks

This property tells the control whether or not to automatically detect and use firewall system settings, if available.

Data Type

Boolean

FirewallType Property (HadoopDFS Control)

This property determines the type of firewall to connect through.

Syntax

hadoopdfscontrol.FirewallType[=integer]

Possible Values

fwNone(0), 
fwTunnel(1), 
fwSOCKS4(2), 
fwSOCKS5(3), 
fwSOCKS4A(10)

Default Value

0

Remarks

This property determines the type of firewall to connect through. The applicable values are as follows:

Data Type

Integer

FirewallHost Property (HadoopDFS Control)

This property contains the name or IP address of firewall (optional).

Syntax

hadoopdfscontrol.FirewallHost[=string]

Default Value

""

Remarks

This property contains the name or IP address of firewall (optional). If a FirewallHost is given, the requested connections will be authenticated through the specified firewall when connecting.

If this property is set to a Domain Name, a DNS request is initiated. Upon successful termination of the request, this property is set to the corresponding address. If the search is not successful, the control fails with an error.

Data Type

String

FirewallPassword Property (HadoopDFS Control)

This property contains a password if authentication is to be used when connecting through the firewall.

Syntax

hadoopdfscontrol.FirewallPassword[=string]

Default Value

""

Remarks

This property contains a password if authentication is to be used when connecting through the firewall. If FirewallHost is specified, the FirewallUser and FirewallPassword properties are used to connect and authenticate to the given firewall. If the authentication fails, the control fails with an error.

Data Type

String

FirewallPort Property (HadoopDFS Control)

This property contains the transmission control protocol (TCP) port for the firewall Host .

Syntax

hadoopdfscontrol.FirewallPort[=integer]

Default Value

0

Remarks

This property contains the transmission control protocol (TCP) port for the firewall FirewallHost. See the description of the FirewallHost property for details.

Note: This property is set automatically when FirewallType is set to a valid value. See the description of the FirewallType property for details.

Data Type

Integer

FirewallUser Property (HadoopDFS Control)

This property contains a user name if authentication is to be used connecting through a firewall.

Syntax

hadoopdfscontrol.FirewallUser[=string]

Default Value

""

Remarks

This property contains a user name if authentication is to be used connecting through a firewall. If the FirewallHost is specified, this property and FirewallPassword properties are used to connect and authenticate to the given Firewall. If the authentication fails, the control fails with an error.

Data Type

String

Idle Property (HadoopDFS Control)

The current status of the control.

Syntax

hadoopdfscontrol.Idle

Default Value

True

Remarks

Idle will be False if the component is currently busy (communicating and/or waiting for an answer), and True at all other times.

This property is read-only.

Data Type

Boolean

LocalFile Property (HadoopDFS Control)

The location of the local file.

Syntax

hadoopdfscontrol.LocalFile[=string]

Default Value

""

Remarks

This property specifies the location of a file on disk. This is used as the source file when calling UploadFile or AppendFile, and as the destination file when calling DownloadFile or DoCustomOp.

Data Type

String

LocalHost Property (HadoopDFS Control)

The name of the local host or user-assigned IP interface through which connections are initiated or accepted.

Syntax

hadoopdfscontrol.LocalHost[=string]

Default Value

""

Remarks

The LocalHost property contains the name of the local host as obtained by the gethostname() system call, or if the user has assigned an IP address, the value of that address.

In multi-homed hosts (machines with more than one IP interface) setting LocalHost to the value of an interface will make the control initiate connections (or accept in the case of server controls) only through that interface.

If the control is connected, the LocalHost property shows the IP address of the interface through which the connection is made in internet dotted format (aaa.bbb.ccc.ddd). In most cases, this is the address of the local host, except for multi-homed hosts (machines with more than one IP interface).

NOTE: LocalHost is not persistent. You must always set it in code, and never in the property window.

Data Type

String

OtherHeaders Property (HadoopDFS Control)

This property includes other headers as determined by the user (optional).

Syntax

hadoopdfscontrol.OtherHeaders[=string]

Default Value

""

Remarks

This property can be set to a string of headers to be appended to the HTTP request headers created from other properties like ContentType and From.

The headers must follow the format Header: Value as described in the HTTP specifications. Header lines should be separated by CRLF (Chr$(13) & Chr$(10)) .

Use this property with caution. If this property contains invalid headers, HTTP requests may fail.

This property is useful for extending the functionality of the control beyond what is provided.

This property is not available at design time.

Data Type

String

Overwrite Property (HadoopDFS Control)

Whether to overwrite the local or remote file.

Syntax

hadoopdfscontrol.Overwrite[=boolean]

Default Value

False

Remarks

When calling DownloadFile, this property determines if LocalFile should be overwritten if it already exists.

When calling UploadFile, this property determines if the remote file should be overwritten if it already exists.

Data Type

Boolean

ParsedHeaderCount Property (HadoopDFS Control)

The number of records in the ParsedHeader arrays.

Syntax

hadoopdfscontrol.ParsedHeaderCount

Default Value

0

Remarks

This property controls the size of the following arrays:

• ParsedHeaderField
• ParsedHeaderValue

The array indices start at 0 and end at ParsedHeaderCount - 1.

This property is read-only and not available at design time.

Data Type

Integer

ParsedHeaderField Property (HadoopDFS Control)

This property contains the name of the HTTP header (this is the same case as it is delivered).

Syntax

hadoopdfscontrol.ParsedHeaderField(ParsedHeaderIndex)

Default Value

""

Remarks

This property contains the name of the HTTP Header (this is the same case as it is delivered).

The ParsedHeaderIndex parameter specifies the index of the item in the array. The size of the array is controlled by the ParsedHeaderCount property.

This property is read-only and not available at design time.

Data Type

String

ParsedHeaderValue Property (HadoopDFS Control)

This property contains the header contents.

Syntax

hadoopdfscontrol.ParsedHeaderValue(ParsedHeaderIndex)

Default Value

""

Remarks

This property contains the Header contents.

The ParsedHeaderIndex parameter specifies the index of the item in the array. The size of the array is controlled by the ParsedHeaderCount property.

This property is read-only and not available at design time.

Data Type

String

Password Property (HadoopDFS Control)

The password to use for authentication.

Syntax

hadoopdfscontrol.Password[=string]

Default Value

""

Remarks

This property specifies the password to user for authentication.

Refer to AuthMechanism for more information.

This property is not available at design time.

Data Type

String

ProxyAuthScheme Property (HadoopDFS Control)

This property is used to tell the control which type of authorization to perform when connecting to the proxy.

Syntax

hadoopdfscontrol.ProxyAuthScheme[=integer]

Possible Values

authBasic(0), 
authDigest(1), 
authProprietary(2), 
authNone(3), 
authNtlm(4), 
authNegotiate(5)

Default Value

0

Remarks

This property is used to tell the control which type of authorization to perform when connecting to the proxy. This is used only when the ProxyUser and ProxyPassword properties are set.

ProxyAuthScheme should be set to authNone (3) when no authentication is expected.

By default, ProxyAuthScheme is authBasic (0), and if the ProxyUser and ProxyPassword properties are set, the component will attempt basic authentication.

If ProxyAuthScheme is set to authDigest (1), digest authentication will be attempted instead.

If ProxyAuthScheme is set to authProprietary (2), then the authorization token will not be generated by the control. Look at the configuration file for the control being used to find more information about manually setting this token.

If ProxyAuthScheme is set to authNtlm (4), NTLM authentication will be used.

For security reasons, setting this property will clear the values of ProxyUser and ProxyPassword.

Data Type

Integer

ProxyAutoDetect Property (HadoopDFS Control)

This property tells the control whether or not to automatically detect and use proxy system settings, if available.

Syntax

hadoopdfscontrol.ProxyAutoDetect[=boolean]

Default Value

False

Remarks

This property tells the control whether or not to automatically detect and use proxy system settings, if available. The default value is .

Data Type

Boolean

ProxyPassword Property (HadoopDFS Control)

This property contains a password if authentication is to be used for the proxy.

Syntax

hadoopdfscontrol.ProxyPassword[=string]

Default Value

""

Remarks

This property contains a password if authentication is to be used for the proxy.

If ProxyAuthScheme is set to Basic Authentication, the ProxyUser and ProxyPassword are Base64 encoded and the proxy authentication token will be generated in the form Basic [encoded-user-password].

If ProxyAuthScheme is set to Digest Authentication, the ProxyUser and ProxyPassword properties are used to respond to the Digest Authentication challenge from the server.

If ProxyAuthScheme is set to NTLM Authentication, the ProxyUser and ProxyPassword properties are used to authenticate through NTLM negotiation.

Data Type

String

ProxyPort Property (HadoopDFS Control)

This property contains the Transmission Control Protocol (TCP) port for the proxy Server (default 80).

Syntax

hadoopdfscontrol.ProxyPort[=integer]

Default Value

80

Remarks

This property contains the Transmission Control Protocol (TCP) port for the proxy ProxyServer (default 80). See the description of the ProxyServer property for details.

Data Type

Integer

ProxyServer Property (HadoopDFS Control)

If a proxy Server is given, then the HTTP request is sent to the proxy instead of the server otherwise specified.

Syntax

hadoopdfscontrol.ProxyServer[=string]

Default Value

""

Remarks

If a proxy ProxyServer is given, then the HTTP request is sent to the proxy instead of the server otherwise specified.

If the ProxyServer property is set to a domain name, a DNS request is initiated. Upon successful termination of the request, the ProxyServer property is set to the corresponding address. If the search is not successful, an error is returned.

Data Type

String

ProxySSL Property (HadoopDFS Control)

This property determines when to use a Secure Sockets Layer (SSL) for the connection to the proxy.

Syntax

hadoopdfscontrol.ProxySSL[=integer]

Possible Values

psAutomatic(0), 
psAlways(1), 
psNever(2), 
psTunnel(3)

Default Value

0

Remarks

This property determines when to use a Secure Sockets Layer (SSL) for the connection to the proxy. The applicable values are as follows:

Data Type

Integer

ProxyUser Property (HadoopDFS Control)

This property contains a username if authentication is to be used for the proxy.

Syntax

hadoopdfscontrol.ProxyUser[=string]

Default Value

""

Remarks

This property contains a username if authentication is to be used for the proxy.

If ProxyAuthScheme is set to Basic Authentication, the ProxyUser and ProxyPassword properties are Base64 encoded and the proxy authentication token will be generated in the form Basic [encoded-user-password].

If ProxyAuthScheme is set to Digest Authentication, the ProxyUser and ProxyPassword properties are used to respond to the Digest Authentication challenge from the server.

If ProxyAuthScheme is set to NTLM Authentication, the ProxyUser and ProxyPassword properties are used to authenticate through NTLM negotiation.

Data Type

String

QueryParamCount Property (HadoopDFS Control)

The number of records in the QueryParam arrays.

Syntax

hadoopdfscontrol.QueryParamCount[=integer]

Default Value

0

Remarks

This property controls the size of the following arrays:

• QueryParamName
• QueryParamValue

The array indices start at 0 and end at QueryParamCount - 1.

This property is not available at design time.

Data Type

Integer

QueryParamName Property (HadoopDFS Control)

The name of the query parameter.

Syntax

hadoopdfscontrol.QueryParamName(QueryParamIndex)[=string]

Default Value

""

Remarks

The name of the query parameter.

This property specifies the name of the query parameter.

The QueryParamIndex parameter specifies the index of the item in the array. The size of the array is controlled by the QueryParamCount property.

This property is not available at design time.

Data Type

String

QueryParamValue Property (HadoopDFS Control)

The value of the query parameter.

Syntax

hadoopdfscontrol.QueryParamValue(QueryParamIndex)[=string]

Default Value

""

Remarks

The value of the query parameter.

This property specifies the value of the query parameter. The control will automatically URL-encode this value when sending the request.

The QueryParamIndex parameter specifies the index of the item in the array. The size of the array is controlled by the QueryParamCount property.

This property is not available at design time.

Data Type

String

ReadBytes Property (HadoopDFS Control)

The number of bytes to read when downloading a file.

Syntax

hadoopdfscontrol.ReadBytes[=long64]

Default Value

-1

Remarks

This property specifies how many bytes should be read when DownloadFile is called. It can be used in tandem with StartByte to specify a specific range of the file to download.

If set to -1 (default), there is no limit on how many bytes will be read.

This property is not available at design time.

Data Type

Long64

ResourceData Property (HadoopDFS Control)

The data that was downloaded, or that should be uploaded.

Syntax

hadoopdfscontrol.ResourceData[=string]

Default Value

""

Remarks

This property is populated with file data after calling DownloadFile if LocalFile is not set.

This property can also be set before calling UploadFile; its data will be uploaded if LocalFile is not set.

To read or write binary data to the property, a Variant (Byte Array) version is provided in .ResourceDataB.

This property is not available at design time.

Data Type

Binary String

ResourceCount Property (HadoopDFS Control)

The number of records in the Resource arrays.

Syntax

hadoopdfscontrol.ResourceCount

Default Value

0

Remarks

This property controls the size of the following arrays:

• ResourceAccessTime
• ResourceBlockSize
• ResourceChildCount
• ResourceGroup
• ResourceModifiedTime
• ResourceName
• ResourceOwner
• ResourcePath
• ResourcePermission
• ResourceReplication
• ResourceSize
• ResourceSymlinkTarget
• ResourceType

The array indices start at 0 and end at ResourceCount - 1.

This property is read-only and not available at design time.

Data Type

Integer

ResourceAccessTime Property (HadoopDFS Control)

The last access time of the resource.

Syntax

hadoopdfscontrol.ResourceAccessTime(ResourceIndex)

Default Value

0

Remarks

The last access time of the resource.

This property reflects the last access time of the resource, in milliseconds relative to the Unix epoch.

The ResourceIndex parameter specifies the index of the item in the array. The size of the array is controlled by the ResourceCount property.

This property is read-only and not available at design time.

Data Type

Long64

ResourceBlockSize Property (HadoopDFS Control)

The block size of the file.

Syntax

hadoopdfscontrol.ResourceBlockSize(ResourceIndex)

Default Value

0

Remarks

The block size of the file.

This property reflects the block size of the file, in bytes.

The ResourceIndex parameter specifies the index of the item in the array. The size of the array is controlled by the ResourceCount property.

This property is read-only and not available at design time.

Data Type

Long64

ResourceChildCount Property (HadoopDFS Control)

The number of children in the directory.

Syntax

hadoopdfscontrol.ResourceChildCount(ResourceIndex)

Default Value

0

Remarks

The number of children in the directory.

This property reflects the number of immediate children in the directory. Always 0 for files.

The ResourceIndex parameter specifies the index of the item in the array. The size of the array is controlled by the ResourceCount property.

This property is read-only and not available at design time.

Data Type

Long64

ResourceGroup Property (HadoopDFS Control)

The name of the resource's group.

Syntax

hadoopdfscontrol.ResourceGroup(ResourceIndex)

Default Value

""

Remarks

The name of the resource's group.

This property reflects the name of the resource's group.

The ResourceIndex parameter specifies the index of the item in the array. The size of the array is controlled by the ResourceCount property.

This property is read-only and not available at design time.

Data Type

String

ResourceModifiedTime Property (HadoopDFS Control)

The last modified time of the resource.

Syntax

hadoopdfscontrol.ResourceModifiedTime(ResourceIndex)

Default Value

0

Remarks

The last modified time of the resource.

This property reflects the last modified time of the resource, in milliseconds relative to the Unix epoch.

The ResourceIndex parameter specifies the index of the item in the array. The size of the array is controlled by the ResourceCount property.

This property is read-only and not available at design time.

Data Type

Long64

ResourceName Property (HadoopDFS Control)

The name of the resource.

Syntax

hadoopdfscontrol.ResourceName(ResourceIndex)

Default Value

""

Remarks

The name of the resource.

This property reflects the name of the resource.

The ResourceIndex parameter specifies the index of the item in the array. The size of the array is controlled by the ResourceCount property.

This property is read-only and not available at design time.

Data Type

String

ResourceOwner Property (HadoopDFS Control)

The name of the resource's owner.

Syntax

hadoopdfscontrol.ResourceOwner(ResourceIndex)

Default Value

""

Remarks

The name of the resource's owner.

This property reflects the name of the resource's owner.

The ResourceIndex parameter specifies the index of the item in the array. The size of the array is controlled by the ResourceCount property.

This property is read-only and not available at design time.

Data Type

String

ResourcePath Property (HadoopDFS Control)

The full path of the resource.

Syntax

hadoopdfscontrol.ResourcePath(ResourceIndex)

Default Value

""

Remarks

The full path of the resource.

This property reflects the full path of the resource. (Note that this property's value is not returned by the server, it is calculated by the control for convenience.)

The ResourceIndex parameter specifies the index of the item in the array. The size of the array is controlled by the ResourceCount property.

This property is read-only and not available at design time.

Data Type

String

ResourcePermission Property (HadoopDFS Control)

The resource's permission bits.

Syntax

hadoopdfscontrol.ResourcePermission(ResourceIndex)

Default Value

""

Remarks

The resource's permission bits.

This property reflects the resource's permission bits, represented as an octal string (e.g., 755).

The ResourceIndex parameter specifies the index of the item in the array. The size of the array is controlled by the ResourceCount property.

This property is read-only and not available at design time.

Data Type

String

ResourceReplication Property (HadoopDFS Control)

The replication factor of the file.

Syntax

hadoopdfscontrol.ResourceReplication(ResourceIndex)

Default Value

0

Remarks

The replication factor of the file.

This property reflects the replication factor of the file. Always 0 for directories.

A file's replication factor determines how many copies of the file's data ("replicas") are maintained by HDFS. For example, a replication factor of 3 means that HDFS will maintain 2 replicas in addition to the original file. Thus, the minimum replication factor a file can have is 1.

The ResourceIndex parameter specifies the index of the item in the array. The size of the array is controlled by the ResourceCount property.

This property is read-only and not available at design time.

Data Type

Integer

ResourceSize Property (HadoopDFS Control)

The size of the file.

Syntax

hadoopdfscontrol.ResourceSize(ResourceIndex)

Default Value

0

Remarks

The size of the file.

This property reflects the size of the file, in bytes. Always 0 for directories.

Note that the actual amount of space the file consumes will be greater than this property's value if ResourceReplication is greater than 1. In that case, multiply the values of this property and ResourceReplication to obtain the total number of bytes consumed by the file and its replicas.

The ResourceIndex parameter specifies the index of the item in the array. The size of the array is controlled by the ResourceCount property.

This property is read-only and not available at design time.

Data Type

Long64

ResourceSymlinkTarget Property (HadoopDFS Control)

The full target path of the symlink.

Syntax

hadoopdfscontrol.ResourceSymlinkTarget(ResourceIndex)

Default Value

""

Remarks

The full target path of the symlink.

This property reflects the full target path of the symlink, if ResourceType is 2 (ftSymLink) and the server returns the target path information, or empty string otherwise.

The ResourceIndex parameter specifies the index of the item in the array. The size of the array is controlled by the ResourceCount property.

This property is read-only and not available at design time.

Data Type

String

ResourceType Property (HadoopDFS Control)

The resource type.

Syntax

hadoopdfscontrol.ResourceType(ResourceIndex)

Possible Values

hrtFile(0), 
hrtDirectory(1), 
hrtSymLink(2)

Default Value

0

Remarks

The resource type.

This property reflects the resource's type. Possible values are:

The ResourceIndex parameter specifies the index of the item in the array. The size of the array is controlled by the ResourceCount property.

This property is read-only and not available at design time.

Data Type

Integer

SSLAcceptServerCertEncoded Property (HadoopDFS Control)

This is the certificate (PEM/Base64 encoded).

Syntax

hadoopdfscontrol.SSLAcceptServerCertEncoded[=string]

Default Value

""

Remarks

This is the certificate (PEM/Base64 encoded). This property is used to assign a specific certificate. The SSLAcceptServerCertStore and SSLAcceptServerCertSubject properties also may be used to specify a certificate.

When SSLAcceptServerCertEncoded is set, a search is initiated in the current SSLAcceptServerCertStore for the private key of the certificate. If the key is found, SSLAcceptServerCertSubject is updated to reflect the full subject of the selected certificate; otherwise, SSLAcceptServerCertSubject is set to an empty string.

To read or write binary data to the property, a Variant (Byte Array) version is provided in .SSLAcceptServerCertEncodedB.

This property is not available at design time.

Data Type

Binary String

SSLCertEncoded Property (HadoopDFS Control)

This is the certificate (PEM/Base64 encoded).

Syntax

hadoopdfscontrol.SSLCertEncoded[=string]

Default Value

""

Remarks

This is the certificate (PEM/Base64 encoded). This property is used to assign a specific certificate. The SSLCertStore and SSLCertSubject properties also may be used to specify a certificate.

When SSLCertEncoded is set, a search is initiated in the current SSLCertStore for the private key of the certificate. If the key is found, SSLCertSubject is updated to reflect the full subject of the selected certificate; otherwise, SSLCertSubject is set to an empty string.

To read or write binary data to the property, a Variant (Byte Array) version is provided in .SSLCertEncodedB.

This property is not available at design time.

Data Type

Binary String

SSLCertStore Property (HadoopDFS Control)

This is the name of the certificate store for the client certificate.

Syntax

hadoopdfscontrol.SSLCertStore[=string]

Default Value

"MY"

Remarks

This is the name of the certificate store for the client certificate.

The SSLCertStoreType property denotes the type of the certificate store specified by SSLCertStore. If the store is password protected, specify the password in SSLCertStorePassword.

SSLCertStore is used in conjunction with the SSLCertSubject property to specify client certificates. If SSLCertStore has a value, and SSLCertSubject or SSLCertEncoded is set, a search for a certificate is initiated. Please see the SSLCertSubject property for details.

Designations of certificate stores are platform dependent.

The following designations are the most common User and Machine certificate stores in Windows:

When the certificate store type is PFXFile, this property must be set to the name of the file. When the type is PFXBlob, the property must be set to the binary contents of a PFX file (i.e., PKCS#12 certificate store).

To read or write binary data to the property, a Variant (Byte Array) version is provided in .SSLCertStoreB.

Data Type

Binary String

SSLCertStorePassword Property (HadoopDFS Control)

If the type of certificate store requires a password, this property is used to specify the password needed to open the certificate store.

Syntax

hadoopdfscontrol.SSLCertStorePassword[=string]

Default Value

""

Remarks

If the type of certificate store requires a password, this property is used to specify the password needed to open the certificate store.

Data Type

String

SSLCertStoreType Property (HadoopDFS Control)

This is the type of certificate store for this certificate.

Syntax

hadoopdfscontrol.SSLCertStoreType[=integer]

Possible Values

cstUser(0), 
cstMachine(1), 
cstPFXFile(2), 
cstPFXBlob(3), 
cstJKSFile(4), 
cstJKSBlob(5), 
cstPEMKeyFile(6), 
cstPEMKeyBlob(7), 
cstPublicKeyFile(8), 
cstPublicKeyBlob(9), 
cstSSHPublicKeyBlob(10), 
cstP7BFile(11), 
cstP7BBlob(12), 
cstSSHPublicKeyFile(13), 
cstPPKFile(14), 
cstPPKBlob(15), 
cstXMLFile(16), 
cstXMLBlob(17), 
cstJWKFile(18), 
cstJWKBlob(19), 
cstSecurityKey(20), 
cstBCFKSFile(21), 
cstBCFKSBlob(22), 
cstPKCS11(23), 
cstAuto(99)

Default Value

0

Remarks

This is the type of certificate store for this certificate.

The control supports both public and private keys in a variety of formats. When the cstAuto value is used, the control will automatically determine the type. This property can take one of the following values:

Data Type

Integer

SSLCertSubject Property (HadoopDFS Control)

This is the subject of the certificate used for client authentication.

Syntax

hadoopdfscontrol.SSLCertSubject[=string]

Default Value

""

Remarks

This is the subject of the certificate used for client authentication.

This property must be set after all other certificate properties are set. When this property is set, a search is performed in the current certificate store to locate a certificate with a matching subject.

If a matching certificate is found, the property is set to the full subject of the matching certificate.

If an exact match is not found, the store is searched for subjects containing the value of the property.

If a match is still not found, the property is set to an empty string, and no certificate is selected.

The special value "*" picks a random certificate in the certificate store.

The certificate subject is a comma-separated list of distinguished name fields and values. For instance, "CN=www.server.com, OU=test, C=US, E=support@nsoftware.com". Common fields and their meanings are as follows:

If a field value contains a comma, it must be quoted.

Data Type

String

SSLProvider Property (HadoopDFS Control)

This specifies the SSL/TLS implementation to use.

Syntax

hadoopdfscontrol.SSLProvider[=integer]

Possible Values

sslpAutomatic(0), 
sslpPlatform(1), 
sslpInternal(2)

Default Value

0

Remarks

This property specifies the SSL/TLS implementation to use. In most cases the default value of 0 (Automatic) is recommended and should not be changed. When set to 0 (Automatic) the control will select whether to use the platform implementation or the internal implementation depending on the operating system as well as the TLS version being used.

Possible values are:

In most cases using the default value (Automatic) is recommended. The control will select a provider depending on the current platform.

When Automatic is selected the platform implementation is used by default. When TLS 1.3 is enabled via SSLEnabledProtocols the internal implementation is used.

Data Type

Integer

SSLServerCertEncoded Property (HadoopDFS Control)

This is the certificate (PEM/Base64 encoded).

Syntax

hadoopdfscontrol.SSLServerCertEncoded

Default Value

""

Remarks

This is the certificate (PEM/Base64 encoded). This property is used to assign a specific certificate. The SSLServerCertStore and SSLServerCertSubject properties also may be used to specify a certificate.

When SSLServerCertEncoded is set, a search is initiated in the current SSLServerCertStore for the private key of the certificate. If the key is found, SSLServerCertSubject is updated to reflect the full subject of the selected certificate; otherwise, SSLServerCertSubject is set to an empty string.

To read or write binary data to the property, a Variant (Byte Array) version is provided in .SSLServerCertEncodedB.

This property is read-only and not available at design time.

Data Type

Binary String

StartByte Property (HadoopDFS Control)

The byte offset from which to start downloading a file.

Syntax

hadoopdfscontrol.StartByte[=long64]

Default Value

0

Remarks

This property specifies an offset (in bytes) from which to start reading a file when DownloadFile is called. It can be used in tandem with ReadBytes to specify a specific range of the file to download.

This property is not available at design time.

Data Type

Long64

Timeout Property (HadoopDFS Control)

A timeout for the control.

Syntax

hadoopdfscontrol.Timeout[=integer]

Default Value

60

Remarks

If the Timeout property is set to 0, all operations will run uninterrupted until successful completion or an error condition is encountered.

If Timeout is set to a positive value, the control will wait for the operation to complete before returning control.

The control will use DoEvents to enter an efficient wait loop during any potential waiting period, making sure that all system events are processed immediately as they arrive. This ensures that the host application does not "freeze" and remains responsive.

If Timeout expires, and the operation is not yet complete, the control fails with an error.

Please note that by default, all timeouts are inactivity timeouts, i.e. the timeout period is extended by Timeout seconds when any amount of data is successfully sent or received.

The default value for the Timeout property is 60 seconds.

Data Type

Integer

URL Property (HadoopDFS Control)

The URL of the Hadoop WebHDFS server.

Syntax

hadoopdfscontrol.URL[=string]

Default Value

""

Remarks

This property specifies the URL of the Hadoop WebHDFS server to make requests against.

A full WebHDFS URL looks like http[s]://<HOST>:<PORT>/webhdfs/v1. Anytime this property is set to a non-empty string, the control will automatically append /webhdfs/v1 to its value (if necessary).

The control automatically detects whether to secure the connection using SSL/TLS based on whether the URL begins with http (not secured) or https (secured).

This property is not available at design time.

Data Type

String

User Property (HadoopDFS Control)

The user name to use for authentication.

Syntax

hadoopdfscontrol.User[=string]

Default Value

""

Remarks

This property specifies the user name to use for authentication.

Refer to AuthMechanism for more information.

This property is not available at design time.

Data Type

String

AddQueryParam Method (HadoopDFS Control)

Adds a query parameter to the QueryParams properties.

Syntax

hadoopdfscontrol.AddQueryParam Name, Value

Remarks

This method is used to add a query parameter to the QueryaParam* properties. Name specifies the name of the parameter, and Value specifies the value of the parameter.

All specified Values will be URL encoded by the control automatically. Consult the service documentation for details on the available parameters.

AppendFile Method (HadoopDFS Control)

Appends data to an existing file.

Syntax

hadoopdfscontrol.AppendFile FilePath

Remarks

This method appends data to the existing file at FilePath.

If LocalFile is set data will be read from the file at the specified path. If LocalFile is not set the data in ResourceData will be used.

CalcAuthorization Method (HadoopDFS Control)

Calculates the Authorization header based on provided credentials.

Syntax

hadoopdfscontrol.CalcAuthorization 

Remarks

This method calculates the Authorization value using the values provided in AuthScheme, User and Password.

In most cases this method does not need to be called. The control will automatically calculate any required authorization values when a method is called such as Get or Post.

This method may be useful in cases where the Authorization value needs to be calculated prior to sending a request.

Config Method (HadoopDFS Control)

Sets or retrieves a configuration setting.

Syntax

hadoopdfscontrol.Config ConfigurationString

Remarks

Config is a generic method available in every control. It is used to set and retrieve configuration settings for the control.

These settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the control, access to these internal properties is provided through the Config method.

To set a configuration setting named PROPERTY, you must call Config("PROPERTY=VALUE"), where VALUE is the value of the setting expressed as a string. For boolean values, use the strings "True", "False", "0", "1", "Yes", or "No" (case does not matter).

To read (query) the value of a configuration setting, you must call Config("PROPERTY"). The value will be returned as a string.

DeleteResource Method (HadoopDFS Control)

Deletes a resource.

Syntax

hadoopdfscontrol.DeleteResource Path

Remarks

This method deletes the resource at Path.

The RecursiveDelete configuration setting can be used to control whether this method will recursively delete non-empty directories (it is enabled by default).

DoCustomOp Method (HadoopDFS Control)

Executes an arbitrary WebHDFS operation.

Syntax

hadoopdfscontrol.DoCustomOp HttpMethod, RequestPath, Op

Remarks

This method can be used to execute any WebHDFS operation the control does not explicitly implement.

Valid values for HttpMethod are:

• GET (default if empty)
• POST
• PUT
• DELETE

RequestPath must either be a valid resource path, or empty string. Op must be a valid WebHDFS operation (refer to the Hadoop WebHDFS documentation for a full list of supported operations).

Usage

When this method is called, the control will do the following:

1. Build a request URL using URL, RequestPath, Op, and the query parameters held by the QueryParam* properties.
2. Send the request using the given HttpMethod, the request URL built in step 1, the headers held by OtherHeaders, and the currently-configured authentication (if any; refer to AuthMechanism for more information). The request is always sent with an empty body.
3. Store the response headers in the ParsedHeader* properties, and the response body in the specified LocalFile, or ResourceData (using the same logic as DownloadFile).

If the response body is JSON data, the XPath, XText, and other X* configuration settings can then be used to navigate and extract information from it.

DownloadFile Method (HadoopDFS Control)

Downloads a file.

Syntax

hadoopdfscontrol.DownloadFile FilePath

Remarks

This method downloads the file at FilePath.

If LocalFile is set, the file will be saved to the specified location; otherwise, the file data will be held by ResourceData.

To download and decrypt an encrypted file, set EncryptionAlgorithm and EncryptionPassword before calling this method.

Download Notes

In the simplest use-case, downloading a file looks like this: hdfs.LocalFile = "../MyFile.zip"; hdfs.DownloadFile(hdfs.Resources[0].Path);

Resuming Downloads

The control also supports resuming failed downloads by using the StartByte property. If a download is interrupted, set StartByte to the appropriate offset before calling this method to resume the download. string downloadFile = "../MyFile.zip"; hdfs.LocalFile = downloadFile; hdfs.DownloadFile(hdfs.Resources[0].Path); //The transfer is interrupted and DownloadFile() above fails. Later, resume the download: //Get the size of the partially downloaded file hdfs.StartByte = new FileInfo(downloadFile).Length; hdfs.DownloadFile(hdfs.Resources[0].Path);

Resuming Encrypted File Downloads

Resuming encrypted file downloads is only supported when LocalFile was set in the initial download attempt.

If LocalFile is set when beginning an encrypted download, the control creates a temporary file in TempPath to hold the encrypted data until the download is complete. If the download is interrupted, DownloadTempFile will be populated with the path of the temporary file that holds the partial data.

To resume, DownloadTempFile must be populated, along with StartByte, to allow the remainder of the encrypted data to be downloaded. Once the encrypted data is downloaded it will be decrypted and written to LocalFile. hdfs.LocalFile = "../MyFile.zip"; hdfs.EncryptionPassword = "password"; hdfs.DownloadFile(hdfs.Resources[0].Path); //The transfer is interrupted and DownloadFile() above fails. Later, resume the download: //Get the size of the partially download temp file hdfs.StartByte = new FileInfo(hdfs.Config("DownloadTempFile")).Length; hdfs.DownloadFile(hdfs.Resources[0].Path);

GetDirSummary Method (HadoopDFS Control)

Gets a content summary for a directory.

Syntax

hadoopdfscontrol.GetDirSummary DirPath

Remarks

This method gets a content summary for the directory at DirPath, populating the DirSummary* properties.

DirPath may be empty to get a content summary for the root directory (/).

GetResourceInfo Method (HadoopDFS Control)

Gets information about a specific resource.

Syntax

hadoopdfscontrol.GetResourceInfo Path

Remarks

This method gets information about the resource at Path. Path may be empty to get information about the root directory (/).

Calling this method will fire the ResourceList event, and will populate the Resource* properties with a single item (clearing any previously-held items in the process).

Interrupt Method (HadoopDFS Control)

Interrupt the current method.

Syntax

hadoopdfscontrol.Interrupt 

Remarks

If there is no method in progress, Interrupt simply returns, doing nothing.

JoinFileBlocks Method (HadoopDFS Control)

Joins multiple files' blocks together into one file.

Syntax

hadoopdfscontrol.JoinFileBlocks TargetFilePath, SourceFilePaths

Remarks

This method joins the blocks from the files at one or more SourceFilePaths onto the end of the file at TargetFilePath. (If this operations is successful, the original source files will no longer be accessible.)

The order of the source files' paths in SourceFilePaths determines the order in which their blocks are joined onto the file at TargetFilePath.

Usage Constraints

The server imposes a number of constraints that must be satisfied in order for the join operation to complete successfully.

TargetFilePath and SourceFilePaths must both be non-empty.

SourceFilePaths must be specified as a comma-separated list of source file paths, with no duplicates or paths that match TargetFilePath.

Additionally, all files referred to by both TargetFilePath and SourceFilePaths must satisfy the following constraints:

• All files must already exist.
• All files must be located in the exact same directory (i.e., all files must be siblings).
• The block size of all source files must be less than or equal to the block size of the target file.

If any of the above constraints are not satisfied, the server will return an error.

The control will take care of verifying that all parameters are non-empty and that all paths begin with a forward slash (/).

ListResources Method (HadoopDFS Control)

Lists resources in a given directory.

Syntax

hadoopdfscontrol.ListResources DirPath

Remarks

This method lists resources within the directory at DirPath.

Calling this method will fire the ResourceList event once for each resource, and will also populate the Resource* properties.

DirPath may be empty to list resources in the root directory (/). // ResourceList event handler. hdfs.OnResourceList += (s, e) => { Console.WriteLine(e.Name); }; hdfs.ListResources("/work_files/serious_business/cats"); for (int i = 0; i < hdfs.Resources.Count; i++) { // Process resources here. }

MakeDirectory Method (HadoopDFS Control)

Makes a directory.

Syntax

hadoopdfscontrol.MakeDirectory NewDirPath

Remarks

This method makes a new directory at NewDirPath and returns the full path of the new directory. Any non-existent parent directories will also be created.

If the CreatePermission configuration setting is non-empty, the directory will be created with the permission it specifies. Otherwise, the server's default (755) will be used.

MoveResource Method (HadoopDFS Control)

Moves a resource.

Syntax

hadoopdfscontrol.MoveResource FromPath, ToPath

Remarks

This method moves the resource at FromPath to ToPath.

Reset Method (HadoopDFS Control)

Resets the control to its initial state.

Syntax

hadoopdfscontrol.Reset 

Remarks

This method resets the control to its initial state.

SetFileReplication Method (HadoopDFS Control)

Sets the replication factor for a file.

Syntax

hadoopdfscontrol.SetFileReplication FilePath, Replication

Remarks

This method sets the replication factor for the file at FilePath to Replication.

Valid values for Replication are 1 through 32767 (inclusive); or 0 to reset the file's replication factor back to the server default.

SetOwner Method (HadoopDFS Control)

Sets a resource's owner and/or group.

Syntax

hadoopdfscontrol.SetOwner Path, Owner, Group

Remarks

This method set the owner and/or group of the resource at Path to the given values.

If non-empty, Owner must be a valid user name, and Group must be a valid group name. If either parameter is empty, the file's current value will remain unchanged. (If both parameters are empty, no request is sent.)

SetPermission Method (HadoopDFS Control)

Assigns the given permission to a resource.

Syntax

hadoopdfscontrol.SetPermission Path, Permission

Remarks

This method assigns the given Permission to the resource at Path.

Permission must be formatted as an octal permission string. If Permission is empty string, the resource's permission will be reset to the server default (755).

SetTimes Method (HadoopDFS Control)

Sets a resource's modification and/or access times.

Syntax

hadoopdfscontrol.SetTimes Path, ModifiedTime, AccessTime

Remarks

This method sets the modification and/or access times of the resource at Path to the given values.

Both ModifiedTime and AccessTime should be specified as a number of milliseconds relative to the Unix epoch. If either parameter is negative, the file's current value will remain unchanged. (If both parameters are negative, no request is sent.)

TruncateFile Method (HadoopDFS Control)

Truncates a file to a given size.

Syntax

hadoopdfscontrol.TruncateFile FilePath, NewSize

Remarks

This method truncates the file at FilePath to the given NewSize (specified in bytes). NewSize must not be less than 0 or greater than the file's current size.

This method returns if the file has been truncated successfully and is immediately ready for further modifications.

This method returns if the server is still in the process of truncating the file (this could happen, e.g., if the server needs to truncate multiple replicas of the file). In this case, the server will reject any further attempts to modify the file until it has finished truncating it. Monitor the file's size using GetResourceInfo to determine when the truncation process has finished.

UploadFile Method (HadoopDFS Control)

Uploads a file.

Syntax

hadoopdfscontrol.UploadFile NewFilePath

Remarks

This method uploads a new file to NewFilePath and returns the full path of the uploaded file. If a file already exists on the server at NewFilePath, the Overwrite property controls whether the server will overwrite the file or return an error.

If the CreatePermission configuration setting is non-empty, the file will be created with the permission it specifies. Otherwise, the server's default (755) will be used.

If LocalFile is set the file will be uploaded from the specified path. If LocalFile is not set the data in ResourceData will be used.

To encrypt the file before uploading it, set EncryptionAlgorithm and EncryptionPassword. hdfs.LocalFile = "../MyFile.zip"; hdfs.UploadFile("/MyFile.zip");

EndTransfer Event (HadoopDFS Control)

This event fires when a document finishes transferring.

Syntax

Sub hadoopdfscontrol_EndTransfer(Direction As Integer)

Remarks

The EndTransfer event is fired when the document text finishes transferring from the server to the local host.

The Direction parameter shows whether the client (0) or the server (1) is sending the data.

Error Event (HadoopDFS Control)

Fired when information is available about errors during data delivery.

Syntax

Sub hadoopdfscontrol_Error(ErrorCode As Integer, Description As String)

Remarks

The Error event is fired in case of exceptional conditions during message processing. Normally the control fails with an error.

The ErrorCode parameter contains an error code, and the Description parameter contains a textual description of the error. For a list of valid error codes and their descriptions, please refer to the Error Codes section.

Header Event (HadoopDFS Control)

This event is fired every time a header line comes in.

Syntax

Sub hadoopdfscontrol_Header(Field As String, Value As String)

Remarks

The Field parameter contains the name of the HTTP header (which is the same as it is delivered). The Value parameter contains the header contents.

If the header line being retrieved is a continuation header line, then the Field parameter contains "" (empty string).

Log Event (HadoopDFS Control)

This event fires once for each log message.

Syntax

Sub hadoopdfscontrol_Log(LogLevel As Integer, Message As String, LogType As String)

Remarks

This event fires once for each log message generated by the control. The verbosity is controlled by the LogLevel setting.

LogLevel indicates the level of message. Possible values are as follows:

The value 1 (Info) logs basic information, including the URL, HTTP version, and status details.

The value 2 (Verbose) logs additional information about the request and response.

The value 3 (Debug) logs the headers and body for both the request and response, as well as additional debug information (if any).

Message is the log entry.

LogType identifies the type of log entry. Possible values are as follows:

• "Info"
• "RequestHeaders"
• "ResponseHeaders"
• "RequestBody"
• "ResponseBody"
• "ProxyRequest"
• "ProxyResponse"
• "FirewallRequest"
• "FirewallResponse"

Progress Event (HadoopDFS Control)

Fires during an upload or download to indicate transfer progress.

Syntax

Sub hadoopdfscontrol_Progress(Direction As Integer, BytesTransferred As Long64, TotalBytes As Long64, PercentDone As Integer)

Remarks

This event fires during an upload or download to indicate the progress of the transfer of the entire request. By default, this event will fire each time PercentDone increases by one percent; the ProgressStep configuration setting can be used to alter this behavior.

Direction indicates whether the transfer is an upload (0) or a download (1).

BytesTransferred reflects the number of bytes that have been transferred so far, or 0 if the transfer is starting (however, see note below).

TotalBytes reflects the total number of bytes that are to be transferred, or -1 if the total is unknown. This amount includes the size of everything in the request like HTTP headers.

PercentDone reflects the overall progress of the transfer, or -1 if the progress cannot be calculated.

Note: By default, the control tracks transfer progress absolutely. If a transfer is interrupted and later resumed, the values reported by this event upon and after resumption will account for the data that was transferred before the interruption.

For example, if 10MB of data was successfully transferred before the interruption, then this event will fire with a BytesTransferred value of 10485760 (10MB) when the transfer is first resumed, and then continue to fire with successively greater values as usual.

This behavior can be changed by disabling the ProgressAbsolute configuration setting, in which case the control will treat resumed transfers as "new" transfers. In this case, the BytesTransferred parameter will always be 0 the first time this event fires, regardless of whether the transfer is new or being resumed.

ResourceList Event (HadoopDFS Control)

Fires once for each resource returned when listing resources.

Syntax

Sub hadoopdfscontrol_ResourceList(Name As String, Path As String, ResourceType As Integer, ModifiedTime As Long64, AccessTime As Long64, Size As Long64, Permission As String, Owner As String, Group As String, Replication As Integer)

Remarks

This event fires once for each resource returned when ListResources or GetResourceInfo is called.

Name is the name of the resource.

Path is the full path of the resource.

ResourceType reflects the resource's type. Possible values are:

ModifiedTime and AccessTime reflect the resource's last modified and last access times, in milliseconds relative to the Unix epoch.

Size reflects the size of the file, in bytes. Always 0 for directories.

Permission reflects the resource's permission bits, represented as an octal string (e.g., 755).

Owner is the name of the resource's owner.

Group is the name of the resource's group.

Replication reflects the file's replication factor. Always 0 for directories.

SSLServerAuthentication Event (HadoopDFS Control)

Fired after the server presents its certificate to the client.

Syntax

Sub hadoopdfscontrol_SSLServerAuthentication(CertEncoded As String, CertSubject As String, CertIssuer As String, Status As String, Accept As Boolean)

Remarks

During this event, the client can decide whether or not to continue with the connection process. The Accept parameter is a recommendation on whether to continue or close the connection. This is just a suggestion: application software must use its own logic to determine whether or not to continue.

When Accept is False, Status shows why the verification failed (otherwise, Status contains the string OK). If it is decided to continue, you can override and accept the certificate by setting the Accept parameter to True.

SSLStatus Event (HadoopDFS Control)

Fired when secure connection progress messages are available.

Syntax

Sub hadoopdfscontrol_SSLStatus(Message As String)

Remarks

The event is fired for informational and logging purposes only. This event tracks the progress of the connection.

StartTransfer Event (HadoopDFS Control)

This event fires when a document starts transferring (after the headers).

Syntax

Sub hadoopdfscontrol_StartTransfer(Direction As Integer)

Remarks

The StartTransfer event is fired when the document text starts transferring from the server to the local host.

The Direction parameter shows whether the client (0) or the server (1) is sending the data.

Transfer Event (HadoopDFS Control)

This event is fired while a document transfers (delivers document).

Syntax

Sub hadoopdfscontrol_Transfer(Direction As Integer, BytesTransferred As Long64, PercentDone As Integer, Text As String)

Remarks

The Text parameter contains the portion of the document text being received. It is empty if data are being posted to the server.

The BytesTransferred parameter contains the number of bytes transferred in this Direction since the beginning of the document text (excluding HTTP response headers).

The Direction parameter shows whether the client (0) or the server (1) is sending the data.

The PercentDone parameter shows the progress of the transfer in the corresponding direction. If PercentDone can not be calculated the value will be -1.

Note: Events are not re-entrant. Performing time-consuming operations within this event will prevent it from firing again in a timely manner and may affect overall performance.

Config Settings (HadoopDFS Control)

HadoopDFS Config Settings

<firstlevel>
  <one>value</one>
  <two>
    <item>first</item>
    <item>second</item>
  </two>
  <three>value three</three>
</firstlevel>

{
  "firstlevel": {
    "one": "value",
    "two": ["first", "second"],
    "three": "value three"
  }
}

HTTP Config Settings

TCPClient Config Settings

SSL Config Settings

-----BEGIN CERTIFICATE-----
MIIEKzCCAxOgAwIBAgIRANTET4LIkxdH6P+CFIiHvTowDQYJKoZIhvcNAQELBQAw
...
eWHV5OW1K53o/atv59sOiW5K3crjFhsBOd5Q+cJJnU+SWinPKtANXMht+EDvYY2w
F0I1XhM+pKj7FjDr+XNj
-----END CERTIFICATE-----
\r \n
-----BEGIN CERTIFICATE-----
MIIEFjCCAv6gAwIBAgIQetu1SMxpnENAnnOz1P+PtTANBgkqhkiG9w0BAQUFADBp
..
d8q23djXZbVYiIfE9ebr4g3152BlVCHZ2GyPdjhIuLeH21VbT/dyEHHA
-----END CERTIFICATE-----

-----BEGIN CERTIFICATE-----
MIIEKzCCAxOgAwIBAgIRANTET4LIkxdH6P+CFIiHvTowDQYJKoZIhvcNAQELBQAw
...
eWHV5OW1K53o/atv59sOiW5K3crjFhsBOd5Q+cJJnU+SWinPKtANXMht+EDvYY2w
F0I1XhM+pKj7FjDr+XNj
-----END CERTIFICATE-----
\r \n
-----BEGIN CERTIFICATE-----
MIIEFjCCAv6gAwIBAgIQetu1SMxpnENAnnOz1P+PtTANBgkqhkiG9w0BAQUFADBp
..
d8q23djXZbVYiIfE9ebr4g3152BlVCHZ2GyPdjhIuLeH21VbT/dyEHHA
-----END CERTIFICATE-----

Socket Config Settings

Base Config Settings

Trappable Errors (HadoopDFS Control)

Common Errors

The control may also return one of the following error codes, which are inherited from other controls.

HTTP Errors

The control may also return one of the following error codes, which are inherited from other controls.

TCPClient Errors

SSL Errors

TCP/IP Errors