NetCode Component

Properties   Methods   Events   Config Settings   Errors  

The NetCode component can be used to encode or decode files or strings using a variety of popular encoding formats, such as Base64, UUencode, and URL. UUEncode , MIME's Base64 Quoted-Printable , and URL encoding formats, as well as secure hash functions such as MD5 and SHA1, are currently supported.

Syntax

TipwNetCode

Remarks

The encoding format is specified by the Format property. The binary data, or the name of the file containing binary data, is specified by the DecodedData property and the encoded data or filename is specified by the EncodedData property. The FileName property may be used to override the default file names or to specify a directory during uuencoding. After uudecoding, the FileName property contains the fully specified file name of the decoded file.

Understanding Encoding/Decoding

Most mail systems use only 7 bits to transmit messages. A binary file, such as an archive or a non-plaintext-formatted file produced from a text processor should be first encoded in 7-bit code before email transfer.

Decoding is the inverse process (i.e., creation of the original file from the encoded data). Encoded data are often split over several files because of the size limit placed on the email message. Each message is preceded by information about this splitting, as well as the mail header. NetCode supports this case in both directions:

- During encoding, setting the MaxFileSize configuration setting to the maximum size of a message body instructs NetCode to split the encoded data over several files. Multiple filenames can be specified by using question marks '?' (see the EncodedData property for more information).

- During decoding, the body messages can be saved in separate files named namexxx.ext, where xxx is a numeral starting at 000 and ext is '.uue', '.b16', or '.q_p' according to Format. These multiple filenames should be given to EncodedData.

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.

DecodedData Property (NetCode Component)

This property includes the decoded data.

Syntax

property DecodedData: String read get_DecodedData write set_DecodedData;
property DecodedDataB: TBytes read get_DecodedDataB write set_DecodedDataB;

Default Value

''

Remarks

This property contains the decoded data. When uuencoding, the value of FileName is the filename that will be written in EncodedData. If FileName is empty, an error will be returned.

This property is not available at design time.

DecodedFile Property (NetCode Component)

This property includes the filename of the decoded data.

Syntax

property DecodedFile: String read get_DecodedFile write set_DecodedFile;

Default Value

''

Remarks

This property contains the filename of the decoded data. When uuencoding, the value of FileName is the filename that will be written in EncodedData. If FileName is empty, the value of the DecodedFile property is taken, if a valid file has been specified. It is recommended that EncodedData contains the full path and that FileName contains only the filename so that no problems occur while uudecoding in a foreign system.

When decoding, the component tries to generate the name for the created file in the following order: DecodedFile, FileName, or when the format is UUEncode, the specified filename in the uuencoded data. If DecodedFile or FileName end with a backslash '\' they are interpreted as directories, and the component will try to create the given filename in this directory. If this is the case, FileName shows the name of the file that was created.

EncodedData Property (NetCode Component)

This property includes the encoded data.

Syntax

property EncodedData: String read get_EncodedData write set_EncodedData;
property EncodedDataB: TBytes read get_EncodedDataB write set_EncodedDataB;

Default Value

''

Remarks

This property contains the data that either have been encoded or are set to be decoded.

This property is not available at design time.

EncodedFile Property (NetCode Component)

This property includes the filename of the encoded data.

Syntax

property EncodedFile: String read get_EncodedFile write set_EncodedFile;

Default Value

''

Remarks

This property contains the filename of the encoded data. If the encoded data are spread over several files, the filenames are passed to EncodedFile in the form name?. Question marks '?' are expanded to numerals starting with 0. The filenames should exist as path\file000.ext and are passed to EncodedFile in the form name???. Question marks '?' are expanded to numerals starting with 000 (the number of zeros '0' equals that of question marks '?').

The component appends the extension '.uue', '.b16', or '.q_p' depending on Format immediately after the generated numbers. FileCnt contains the number of encoded files.

See also the Format property, and the MaxFileSize configuration setting when working with multiple files.

FileCnt Property (NetCode Component)

This property shows the number of encoded files the component has read from or written into.

Syntax

property FileCnt: Integer read get_FileCnt;

Default Value

0

Remarks

This property shows the number of encoded files the component has read from or written into. If the user specifies one or more questions marks '?' in EncodedFile, they will be expanded from 000 to FileCnt - 1 (the number of question marks '?' specifies the number of figures).

Please refer to EncodedFile for filename conventions.

This property is read-only.

FileName Property (NetCode Component)

This property includes the destination filename for the encoded data.

Syntax

property FileName: String read get_FileName write set_FileName;

Default Value

''

Remarks

This property contains the destination filename for the encoded data. When uuencoding, this property contains the filename that is specified in the uuencoded data.

When decoding, if the value of the property is not empty, it shows the component where to write the decoded data. It can be either the filename or the directory where the file should be written. If is should be written to a directory, it should end with a backslash '\'.

After a decode operation, this property contains the filename for the created file. If the file couldn't be created because of an illegal filename, examining this property might provide a hint about the reason of the failure.

This property must be set to '' (empty string) after each decode operation because it contains the full specification of the file.

An error occurs if a uuencoding operation is initiated with an empty FileName.

If you want to first check the uuencoded filename before creating it on disk, you may assign an illegal directory name to this property (always use a closing backslash '\' to denote it as a directory), then trap the error and check the filename appended to this property.

Format Property (NetCode Component)

This property includes the type of encoding to be used.

Syntax

property Format: TipwTFmts read get_Format write set_Format;

TipwTFmts = (
  fmtUUEncode,
  fmtBase64,
  fmtQP,
  fmtURL,
  fmtJIS,
  fmtYEncode,
  fmtMD5Hash,
  fmtSHA1Hash,
  fmtHex,
  fmtHTML,
  fmtHMAC,
  fmtUTF8,
  fmtUTF7,
  fmtBase32,
  fmtBase64URL,
  fmtSHA256Hash,
  fmtPunycode
);

Default Value

fmtUUEncode

Remarks

This property contains the type of encoding to be used. The following are the possible values for this property, and the corresponding descriptions:

Mode Property (NetCode Component)

This property includes the UNIX-style filemode when uuencoding and uudecoding.

Syntax

property Mode: String read get_Mode write set_Mode;

Default Value

'0755'

Remarks

This property contains the UNIX-style filemode when uuencoding and uudecoding. The filemode is usually an octal number, such as 755 or 600, which gives the protections of that file. If the file to uudecode is correctly read, then this property contains the protection string given in the uuencoded data.

This is given for compatibility with other systems and is used only when Format is fmtUUE.

Overwrite Property (NetCode Component)

This property controls whether created file(s) should overwrite already existing file(s).

Syntax

property Overwrite: Boolean read get_Overwrite write set_Overwrite;

Default Value

false

Remarks

This property controls whether created file(s) should overwrite already existing file(s).

Note: More than one file may be created during uuencoding.

ProgressStep Property (NetCode Component)

This property controls the granularity at which the Progress event is fired. Values are 0-100.

Syntax

property ProgressStep: Integer read get_ProgressStep write set_ProgressStep;

Default Value

1

Remarks

This property controls the granularity at which the Progress event is fired. Values are 0-100. If this property is not 0, the Progress event will be fired when 0%, n* ProgressStep and 100% of input data are read.

If this property is 0, the Progress event is disabled.

Config Method (NetCode 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.

Decode Method (NetCode Component)

This method decodes a string.

Syntax

procedure Decode();

Remarks

This method decodes according to the Format type. The component will decode the data in the input stream if SetInputStream has been set to a valid stream. If this stream is null, the component will then try to read the data from the file set by the EncodedFile property. If no valid file has been specified, the component will use the EncodedData property.

The resulting decoded data are written to the output stream if one has been set. If not, the component will attempt to write the decoded data to the DecodedFile. If no file was specified, the decoded data may be retrieved through the DecodedData property.

When UUDecoding the created filename will by default be the one specified in the uuencoded data. The FileName property will contain this value. DecodedFile or, if DecodedFile is empty, FileName can be used to override this value.

When YDecoding, the source path and filename is specified in EncodedFile and the destination path and filename in DecodedFile. If the encoded data indicate the name of the original file before decoding, this value will be stored in the FileName property. To decode a multipart message, all parts must be concatenated in order in the source file.

Encode Method (NetCode Component)

This method encodes the data.

Syntax

procedure Encode();

Remarks

This method encodes the data according to the Format type. The component will encode the data in the input stream if SetInputStream has been set to a valid stream. If this stream is null, the component will then try to read the data from the file set by the DecodedFile property. If no valid file has been specified, the component will use the DecodedData property.

The resulting encoded data are written to the output stream if one has been set. If not, the component will attempt to write the encoded data to the EncodedFile. If no file was specified, the encoded data may be retrieved through the EncodedData property.

The data are considered binary while uuencoding and Base64 Formats, and text during QuotedPrintable ones.

When uuencoding or yencoding, the filename encoded into the data is taken from the FileName property.

The current version of NetCode does not create message headers. If a MIME standard encoding is used, such as Base64 Encoding or Quoted Printable Encoding, the user should fill the header values appropriately.

If EncodedFile and MaxFileSize is set and the encoded data take more space than MaxFileSize, the data are split over several files. In this case, the user can specify more than one filename by passing them to EncodedFile in the form name?. The filenames should exist as path\file0.ext, path\file1.ext ... Question marks '?' are expanded to numerals starting with 0. Alternatively the filenames can be given at each line of EncodedData. NetCode appends the extension ".uue", ".b16", or ".q_p" (depending on the value of Format) to the filename.

Reset Method (NetCode Component)

Reset the component.

Syntax

procedure Reset();

Remarks

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

ResetData Method (NetCode Component)

This method resets the values of all data and stream properties.

Syntax

procedure ResetData();

Remarks

This method resets the values of all data and stream properties. It is an easy way to reset the component's properties before another call to Encode or Decode. The input and output streams and the data and file properties will all be reset.

SetInputStream Method (NetCode Component)

This method sets the input stream of data.

Syntax

procedure SetInputStream(InputStream: TStream);

Remarks

Use this method to set the input stream of data for the component to read from. If Encode or Decode is called, and this is not null, the data will be read from this stream when the specified action occurs. You may reset this by calling ResetData.

SetOutputStream Method (NetCode Component)

This method sets the output stream of data.

Syntax

procedure SetOutputStream(OutputStream: TStream);

Remarks

Use this method to set the output stream of data for the component to write. If Encode or Decode is called, and this is not null, the data will be written to this stream when the specified action occurs. You may reset this by calling ResetData.

Error Event (NetCode 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.

Progress Event (NetCode Component)

This event occurs when PercentDone of the input is read.

Syntax

type TProgressEvent = procedure (
  Sender: TObject;
  PercentDone: Integer
) of Object;

property OnProgress: TProgressEvent read FOnProgress write FOnProgress;

Remarks

The ProgressStep property determines how often the event is fired.

Config Settings (NetCode 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.

NetCode Config Settings

Base Config Settings

Trappable Errors (NetCode Component)

NetCode Errors

	1   Short uuencoded file.
	2   The closing 'end' was not found (uudecoded file may be too short).
	3   Cannot create the file for write (illegal name or disk is write-protected).
	4   Cannot open the file for read (does not exist?).
	5   Cannot read from file.
	6   Cannot write to file (disk full?).
	7   Please supply a filename for uuencoded data.
	8   File exists and Overwrite was set to False.
	9   Space is not sufficient in the output string.
	10   The given filenames are insufficient to split all the encoded data.
	11   Please supply a filename for the encoded data.
	12   Encoded data cannot be written in more than 100 files.
	13   Could not write to file. Permission denied.
	14   Could not write to file. Disk full.
	15   Too many open files. No more file handles are available, so no more files can be opened.
	16   The given filename does not exist.
	17   There are no more files to read from or write to.
	18   The starting 'begin' was not found. Is it uuencoded data?
	19   The current format is not supported.
	20   The specified stream does not support Available().
	21   Format error when YDecoding.
	22   No '=yend' found when YDecoding.
	23   Escape character found at end of line when YDecoding.
	24   CRC check failed when YDecoding (Corrupt data).
	25   Output buffer length was not calculated.
	26   Invalid character in Base64 data.