TFTPClient Component

Properties   Methods   Events   Config Settings   Errors  

The TFTPClient component is used to exchange files with TFTP servers via the TFTP protocol defined in RFC 783.

Syntax

TipwTFTPClient

Remarks

To use the component, first specify the TFTPServer, then a LocalFile and a RemoteFile, and then call GetFile or PutFile. The Transfer event shows the progress of the transfer.

Potential transmission errors and packet loss are managed by the Timeout property, which controls the maximum time to wait for a response from the server, and the MaxRetransmits property, which specifies how many times to resend a failed packet before giving up.

Property List

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

Method List

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

Event List

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

Config Settings

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

Idle Property (TFTPClient Component)

The current status of the component.

Syntax

property Idle: Boolean read get_Idle;

Default Value

true

Remarks

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

This property is read-only.

LocalFile Property (TFTPClient Component)

This property includes a file on the local host to transfer the data to or from.

Syntax

property LocalFile: String read get_LocalFile write set_LocalFile;

Default Value

''

Remarks

If GetFile is called, and LocalFile already exists, it is overwritten. If PutFile is called, LocalFile must point to a valid file or an error will be returned.

LocalHost Property (TFTPClient Component)

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

Syntax

property LocalHost: String read get_LocalHost write set_LocalHost;

Default Value

''

Remarks

This 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 multihomed hosts (machines with more than one IP interface) setting LocalHost to the IP address of an interface will make the component initiate connections (or accept in the case of server components) only through that interface. It is recommended to provide an IP address rather than a hostname when setting this property to ensure the desired interface is used.

If the component 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 multihomed 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.

MaxRetransmits Property (TFTPClient Component)

This property specifies the number of times to retry sending a failed packet before disconnecting.

Syntax

property MaxRetransmits: Integer read get_MaxRetransmits write set_MaxRetransmits;

Default Value

3

Remarks

This property allows you to specify the number of times that you would like to try resending the last data packet if the original packet fails.

The RetransmitTimeout determines the wait time (in seconds) between successive retransmissions.

The default value for the MaxRetransmits property is 3.

RemoteFile Property (TFTPClient Component)

This property includes the file on the remote host.

Syntax

property RemoteFile: String read get_RemoteFile write set_RemoteFile;

Default Value

''

Remarks

When the GetFile is called, this must be a valid file on the TFTPServer.

RetransmitTimeout Property (TFTPClient Component)

This property includes the maximum time in seconds to wait for a reply packet from the server before retransmitting the last packet.

Syntax

property RetransmitTimeout: Integer read get_RetransmitTimeout write set_RetransmitTimeout;

Default Value

5

Remarks

Please refer to the MaxRetransmits property for the number of retransmit efforts before an error is returned.

The default value for the RetransmitTimeout is 5 seconds.

TFTPPort Property (TFTPClient Component)

This property specifies the User Datagram Protocol (UDP) port where the remote TFTP server is listening.

Syntax

property TFTPPort: Integer read get_TFTPPort write set_TFTPPort;

Default Value

69

Remarks

The TFTPPort is the UDP port on the TFTPServer to send TFTP requests to.

This property is not available at design time.

TFTPServer Property (TFTPClient Component)

This property includes the address of the TFTP server to exchange files with.

Syntax

property TFTPServer: String read get_TFTPServer write set_TFTPServer;

Default Value

''

Remarks

To be able to transfer file via TFTP, the remote host must be running TFTP services on port TFTPPort (default 69).

Example. Get a File:

TFTPControl.TFTPServer = "MyServer" TFTPControl.LocalFile = "C:\filename.txt" TFTPControl.RemoteFile = "/remotefile.txt" TFTPControl.GetFile()

Timeout Property (TFTPClient Component)

The timeout for the component.

Syntax

property Timeout: Integer read get_Timeout write set_Timeout;

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 component will wait for the operation to complete before returning control.

The component 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 component raises an exception.

Note: By default, all timeouts are inactivity timeouts, that is, 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.

Config Method (TFTPClient Component)

Sets or retrieves a configuration setting.

Syntax

function Config(ConfigurationString: String): String;

Remarks

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

These settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the component, 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.

DoEvents Method (TFTPClient Component)

This method processes events from the internal message queue.

Syntax

procedure DoEvents();

Remarks

When DoEvents is called, the component processes any available events. If no events are available, it waits for a preset period of time, and then returns.

GetFile Method (TFTPClient Component)

This method downloads a RemoteFile from the TFTP server.

Syntax

procedure GetFile();

Remarks

The remote file specified by RemoteFile is downloaded to the local file specified by LocalFile, or it is retrieved through the Transfer event, if the LocalFile property is '' (empty string).

Example. Get a File:

TFTPControl.TFTPServer = "MyServer" TFTPControl.LocalFile = "C:\filename.txt" TFTPControl.RemoteFile = "/remotefile.txt" TFTPControl.GetFile()

Interrupt Method (TFTPClient Component)

This method interrupts the current method.

Syntax

procedure Interrupt();

Remarks

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

PutFile Method (TFTPClient Component)

This method uploads a file specified by LocalFile to the TFTP server.

Syntax

procedure PutFile();

Remarks

The local file specified by LocalFile is uploaded to the remote file specified by RemoteFile.

Example. Put a File:

TFTPControl.TFTPServer = "MyServer" TFTPControl.LocalFile = "C:\filename.txt" TFTPControl.RemoteFile = "/remotefile.txt" TFTPControl.PutFile()

Reset Method (TFTPClient Component)

This method resets the component.

Syntax

procedure Reset();

Remarks

This method will reset the component's properties to their default values.

EndTransfer Event (TFTPClient Component)

This event is fired when a file finishes downloading or uploading.

Syntax

type TEndTransferEvent = procedure (
  Sender: TObject;
  Direction: Integer
) of Object;

property OnEndTransfer: TEndTransferEvent read FOnEndTransfer write FOnEndTransfer;

Remarks

The EndTransfer event fires when a Data Interface connection is closed. This occurs when the file finishes transferring or a directory listing is finished.

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

Error Event (TFTPClient Component)

Fired when information is available about errors during data delivery.

Syntax

type TErrorEvent = procedure (
  Sender: TObject;
  ErrorCode: Integer;
  const Description: String
) of Object;

property OnError: TErrorEvent read FOnError write FOnError;

Remarks

The Error event is fired in case of exceptional conditions during message processing. Normally the component raises an exception.

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.

StartTransfer Event (TFTPClient Component)

This event fires when a file starts downloading or uploading.

Syntax

type TStartTransferEvent = procedure (
  Sender: TObject;
  Direction: Integer
) of Object;

property OnStartTransfer: TStartTransferEvent read FOnStartTransfer write FOnStartTransfer;

Remarks

The StartTransfer event fires when a Data Interface connection is created. This is when the file starts transferring or a directory listing is started.

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

Transfer Event (TFTPClient Component)

This event is fired during the file download or upload.

Syntax

type TTransferEvent = procedure (
  Sender: TObject;
  Direction: Integer;
  BytesTransferred: Int64;
  PercentDone: Integer;
  const Text: String;
  const TextB: TBytes
) of Object;

property OnTransfer: TTransferEvent read FOnTransfer write FOnTransfer;

Remarks

One or more Transfer events are fired during file transfer. The BytesTransferred parameter shows the number of bytes transferred since the beginning of the transfer.

Text contains the portion of the file data being delivered.

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 (TFTPClient Component)

The component accepts one or more of the following configuration settings. Configuration settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the component, access to these internal properties is provided through the Config method.

TFTPClient Config Settings

UDP Config Settings

Socket Config Settings

Base Config Settings

Trappable Errors (TFTPClient Component)

TFTPClient Errors

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

UDP Errors

SSL Errors

TCP/IP Errors