AttributeDecompressor

Decompresses and decrypts the values of the specified attributes that were compressed by the AttributeCompressor.

Typical Uses

Decrypt password-encrypted values that were previously encrypted by the AttributeCompressor
Decompress XML or large geometries that were previously compressed by the AttributeCompressor

How does it work?

The AttributeDecompressor lets you pick one, some, or all attributes on incoming features to be decompressed. If the compressed attributes have been encrypted, the password can be provided to decrypt them. Features passing through the transformer are output with their attribute names unchanged, selected values decompressed, and other values intact.

Examples

Usage Notes

The AttributeDecompressor uses the zlib library to provide basic compression, and the OpenSSL library to provide encryption.
When writing encrypted data to a database, it's best to use a Blob data type. That way the data is always stored in a binary data type and can be decrypted by the AttributeDecompressor. If the database field type is a string, then you should use the BinaryEncoder transformer before writing (to convert the binary value to a string) and the BinaryDecoder transformer after reading (to convert the string back to a binary value capable of being decrypted by the AttributeDecompressor).

Configuration

Input Ports

Output Ports

Parameters

Editing Transformer Parameters

Using a set of menu options, transformer parameters can be assigned by referencing other elements in the workspace. More advanced functions, such as an advanced editor and an arithmetic editor, are also available in some transformers. To access a menu of these options, click beside the applicable parameter. For more information, see Transformer Parameter Menu Options.

Defining Values

There are several ways to define a value for use in a Transformer. The simplest is to simply type in a value or string, which can include functions of various types such as attribute references, math and string functions, and workspace parameters. There are a number of tools and shortcuts that can assist in constructing values, generally available from the drop-down context menu adjacent to the value field.

How to Set Parameter Values

Using the Text Editor

The Text Editor provides a convenient way to construct text strings (including regular expressions) from various data sources, such as attributes, parameters, and constants, where the result is used directly inside a parameter.

Text Editor

Using the Arithmetic Editor

The Arithmetic Editor provides a convenient way to construct math expressions from various data sources, such as attributes, parameters, and feature functions, where the result is used directly inside a parameter.

Arithmetic Editor

Conditional Values

Set values depending on one or more test conditions that either pass or fail.

Parameter Condition Definition Dialog

Content

Expressions and strings can include a number of functions, characters, parameters, and more.

When setting values - whether entered directly in a parameter or constructed using one of the editors - strings and expressions containing String, Math, Date/Time or FME Feature Functions will have those functions evaluated. Therefore, the names of these functions (in the form @<function_name>) should not be used as literal string values.

Content Types

String Functions	These functions manipulate and format strings.
Special Characters	A set of control characters is available in the Text Editor.
Math Functions	Math functions are available in both editors.
Date/Time Functions	Date and time functions are available in the Text Editor.
Math Operators	These operators are available in the Arithmetic Editor.
FME Feature Functions	These return primarily feature-specific values.
FME Parameters	FME and workspace-specific parameters may be used.
Creating and Modifying User Parameters	Create your own editable parameters.

Dialog Options - Tables

Transformers with table-style parameters have additional tools for populating and manipulating values.

Table Tools

Row Reordering

Enabled once you have clicked on a row item. Choices include:

Add a row
Remove a row
Move current row up one
Move current row down one
Move current row to top
Move current row to bottom

Cut, Copy, and Paste

Enabled once you have clicked on a row item. Choices include:

Cut a row - delete and copy to clipboard
Copy a row to the clipboard
Paste a row from the clipboard

Cut, copy, and paste may be used within a transformer, or between transformers.

Filter

Start typing a string, and the matrix will only display rows matching those characters. Searches all columns. This only affects the display of attributes within the transformer - it does not alter which attributes are output.

Import

Import populates the table with a set of new attributes read from a dataset. Specific application varies between transformers.

Reset/Refresh

Generally resets the table to its initial state, and may provide additional options to remove invalid entries. Behavior varies between transformers.

Note: Not all tools are available in all transformers.

Reference

Processing Behavior	Feature-Based
Feature Holding	No
Dependencies	None
FME Licensing Level	FME Professional Edition and above
Aliases
History

FME Community

The FME Community is the place for demos, how-tos, articles, FAQs, and more. Get answers to your questions, learn from other users, and suggest, vote, and comment on new features.

Search for all results about the AttributeDecompressor on the FME Community.

Examples may contain information licensed under the Open Government Licence – Vancouver

Attributes to Decompress	After connecting the transformer, click the browse button to select the attributes to be decompressed and/or decrypted.
Character Encoding for Decompressed Attributes	The decompression/decryption algorithms produce a string of bytes. Use this parameter to instruct the transformer how to interpret those bytes. If an encoded attribute was compressed in the AttributeCompressor transformer, this parameter should be set to the same encoding.

Encryption Type	Use this parameter to select an encryption type. Currently, only the AES-256 encryption algorithm is supported.
Password	If encryption is being used, the value of this parameter will be used to generate an encryption key. This must be the same value used to encrypt the attribute values in the AttributeCompressor transformer.