AttributeCompressor

Compresses and (optionally) encrypts the values of the specified attributes. The compressed and encrypted attribute values can be decompressed and decrypted using the AttributeDecompressor.

This transformer is particularly useful for compressing large blocks of XML, or geometry-storing attributes.

Jump to Configuration

Typical Uses

Password-encrypt a value for storage in a database, for decryption with the AttributeDecompressor
Compress large blocks of XML to optimize storage
Compress large geometry for storage as blob fields to optimize storage

How does it work?

The AttributeCompressor lets you pick one, some, or all attributes to be compressed, and select the level of compression to apply. You can choose to encrypt the compressed attributes with a user-provided password, or leave them unencrypted.

Features passing through the transformer are output with their attribute names unchanged, but the selected values compressed. The AttributeDecompressor can be used to read them, either elsewhere within the workspace or in a different workspace.

Examples

Usage Notes

The AttributeCompressor uses the zlib library to provide basic compression, and the OpenSSL library to provide encryption.
Different datasets have varying degrees of compressibility, and so results will vary.
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

Transformer parameters can be set by directly entering values, using expressions, or referencing other elements in the workspace such as attribute values or user parameters. Various editors and context menus are available to assist. To see what is available, click beside the applicable parameter.

How to Set Parameter Values

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.

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

Table Tools

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

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.

For more information, see Transformer Parameter Menu Options.

Reference

Processing Behavior	Feature-Based
Feature Holding	No
Dependencies	None
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 AttributeCompressor on the FME Community.

Examples may contain information licensed under the Open Government Licence – Vancouver, Open Government Licence - British Columbia, and/or Open Government Licence – Canada.

Attributes to Compress	After connecting the transformer, click the browse button to select the attributes to be compressed and/or encrypted.
Compression Level	The value of this parameter controls the compression level which will be applied to the attributes. A value of 0 indicates that no compression should be used, while a value of 9 indicates that maximum compression should be used. The default value is 6.

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. The same value may then be used to decrypt the attribute values in the AttributeDecompressor transformer.