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Variables
The variables described here include Configuration variables, flow variables, and cache variables.
Configuration variables
A configuration variable defines an alias that resolves at run time to a value that is specific to a deployment environment. A deployment environment is represented by a server group. By associating the values of a configuration variable with different server groups, you can run the same map or flow in different environments, servers, and platforms without changing the map or flow.
Defining configuration variable values with environment variables
You can avoid customizing a configuration variable for specific deployments by defining configuration variable values as operating system environment variables. At run time, the $GETENV() function resolves aliases that are defined as environment variables. The $GETENV() function can be used with or without encryption.

Variables
The variables described here include Configuration variables, flow variables, and cache variables.
- Configuration variables
  A configuration variable defines an alias that resolves at run time to a value that is specific to a deployment environment. A deployment environment is represented by a server group. By associating the values of a configuration variable with different server groups, you can run the same map or flow in different environments, servers, and platforms without changing the map or flow.
  - Configuration variable alias resolution
    When a map that includes an alias deploys to a server, the server where the map runs and the server groups defined in the configuration variable determine how the alias resolves.
  - Maximum resource lengths after alias resolution
    Aliases resolve when a map initializes. The type of resource determines the limit on the length of resource after alias resolution.
  - Alias expansion in external interface functions
    During map execution, alias resolution in an external interface function can expand the string by up to 256 bytes longer than its original length.
  - Defining configuration variable values with environment variables
    You can avoid customizing a configuration variable for specific deployments by defining configuration variable values as operating system environment variables. At run time, the $GETENV() function resolves aliases that are defined as environment variables. The $GETENV() function can be used with or without encryption.
  - Master key creation to generate a new cipher key for encryption
    As configuration-variable values contain sensitive data, they are encrypted with a default cipher key. Sensitive data may include user credentials or database passwords among others. An administrator can choose to not use the default cipher key, and create a new master key file to generate a new cipher key to ensure strict confidentiality of the key. Integration Platform uses the Advanced Encryption Standard (AES) algorithm to encrypt and decrypt configuration-variable values by using a secure encryption key. A single key encrypts all configuration variables during installation of the Integration Platform.
  - Encrypting configuration variables and creating a new master key file
    The Link comes with a default master key file (MKF) that contains a cipher key. However, the administrator can create a new MKF to generate a fresh cipher key to ensure that the key is known to none other than only the authorized people.
  - References to Resource Registry in messages and log files
    Some messages and log files refer to the Resource Registry, which resolves configuration variables at run time.
- Flow variables
  Flow variables provide a means of passing information throughout a flow instance without requiring that the information to be passed through data links. flow variables are name-value pairs that persist, unless deleted.
- Cache variables
  Cache variables provide a means of processing information throughout a flow instance without requiring that the information to be passed through data links.

Defining configuration variable values with environment variables

You can avoid customizing a configuration variable for specific deployments by defining configuration variable values as operating system environment variables. At run time, the $GETENV() function resolves aliases that are defined as environment variables. The $GETENV() function can be used with or without encryption.

Procedure

Use an operating system environment variable to define the value. For example, on a Microsoft Windows system, use Control Panel > System > Advanced system settings > Advanced > Environment Variables. The environment variable might be case-sensitive, depending on the operating system.
In the configuration variable, specify the value as $GETENV(env_var) where env_var is the environment variable name. The string must not contain any spaces. The $GETENV() function is not case sensitive.

If the specified environment variable is not defined, the $GETENV() function resolves to an empty (zero-byte) string.

Results

An informational log file message like the following indicates environment variable usage. For example:

DTXLN2154I - Fri Feb 10 07:32:21 2017 - tid: 12068 inst: -1 - Resource Registry Info : Alias [username] uses environment variable [USERNAME] (mresname.c:1243)