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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.
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.

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.

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.


Function	What's Resolved	Size
EXIT	library name function name	256 bytes extra 256 bytes extra
DDEQUERY	application name topic text	256 bytes extra 256 bytes extra 256 bytes extra
RUN	map name	256 bytes extra
DBQUERY	SQL_statement mdq_filename database_name parameters	256 bytes extra 256 bytes extra 256 bytes extra 256 bytes extra
DBLOOKUP	SQL_statement mdq_filename database_name parameters	256 bytes extra 256 bytes extra 256 bytes extra 256 bytes extra
GET	adapter type adapter command	256 bytes extra 256 bytes extra
PUT	adapter type adapter command	256 bytes extra 256 bytes extra
external parser (document verification)	Location property associated with the Document type property of a schema object	256 bytes extra