Variables

Variables are used for information transfer such as getting values from and sending values to headers, parameters, or body of messages. Definitions are made for project-based use. The Apinizer Platform comes with ready-made variables with the initial installation, and when a new project is created, the variables under the Management menu are copied to the relevant project. All variables can be moved to the Admin page with the ‘Globalize’ option to make them available for use in all projects.

Variable Types

5 different types of variables are created in Apinizer:

Header

Used to get values from HTTP headers

Parameter

Used to get values from URL parameters

Body

Used to get values from message body

Context Value

Used to get values from system properties

Custom Variable

Used to transfer data between policies

The Apinizer Platform comes with ready-made variables with the initial installation. When a new project is created, all variables in the variables section under the Management menu are copied to the relevant project.

Since variables created under the Management menu are used by copying them to projects, update or delete operations on these variables do not affect the definitions in the projects where they are used.

All variables can be moved to the Admin page with the “Globalize” option to make them available for use in all projects and management is left to the Admin user.

Creating Header Type Variable

To create this type of variable, Header is selected as the type and the relevant input fields are filled.

Variable name and header name can be defined differently. The name is a unique definition system-wide. Header name is the value expected from the client.

Field	Description
Name	Field where the name of the variable definition is entered.
Description	Description can be written to facilitate management related to the created variable.
Type	Field where which part of the message the variable is expected is entered.
Header Name	Field where the header name expected in the request from the client is entered. If this field contains multiple values, the first value is used.

Header variables are used to extract data from HTTP headers. For example, values can be retrieved from headers such as X-API-Key, Authorization, Content-Type.

Creating Parameter Type Variable

To create this type of variable, Parameter is selected as the type and the relevant input fields are filled.

Variable name and parameter name can be defined differently. The name is a unique definition system-wide. Parameter name is the value expected from the client.

Field	Description
Name	Field where the name of the variable definition is entered.
Description	Description can be written to facilitate management related to the created variable.
Type	Field where which part of the message the variable is expected is entered.
Parameter Type	Field where the request type of the parameter from the client is selected. Default value is QUERY. Values that can be read as form parameter values are x-www-form values and attached text data part values. In x-www-form values, addition, deletion, and editing can be done; the text data part is read-only, addition/editing cannot be done. Reading can be done from anywhere. Adding/deleting/editing values is only valid for the request (request) line.
Parameter Name	Field where the parameter name expected in the request from the client is entered. If the Parameter Type value is Query and it is a multiple value, the first value is used.

Parameter variables are used to extract data from URL query parameters, path parameters, or form parameters. For example, values can be retrieved from query parameters like ?page=1&limit=10 or path parameters like /users/{id}.

Creating Body Type Variable

To create this type of variable, Body is selected as the type and the relevant input fields are filled.

Field	Description
Name	Field where the name of the variable definition is entered.
Description	Description can be written to facilitate management related to the created variable.
Type	Field where which part of the message the variable is expected is entered.
Message Type	Field where the type of message content is selected. Default value is JSON.
JSON/XML Path	Field where JSON/XPath information necessary to get the value from the request from the client is entered.

There are some differences in how XPath works. It is recommended to refer to the relevant documentation page for detailed information on this topic.

Body variables are used to extract data from message body. JSONPath is used for JSON format, XPath is used for XML format. For example, a username can be extracted from JSON content with a JSONPath expression like $.user.name.

Creating Context Values Type Variable

To create this type of variable, Context Values is selected as the type and the relevant input fields are filled.

Field	Description
Name	Field where the name of the variable definition is entered.
Description	Description can be written to facilitate management related to the created variable.
Type	Field where which part of the message the variable is expected is entered.
Value	Field where the predefined value expected in the request from the client is selected. Only Http Info and Backend Endpoint from these values can be edited; other values are read-only.
Zone ID	This field becomes active if any value from the Date/Time group is selected as the value. Example value: “+03:00” or “Europe/Istanbul”. For more information, you can refer to the Java ZoneId documentation.

Request Information

Request information selectable in the form:

• Client IP address
• HTTP method
• Content type
• Path information
• Query string
• Request URI
• Remote user information
• Server information (name, port, etc.)

Date/Time Values

Date/time values require time zone (zoneId):

• Epoch milliseconds
• Formatted date-time
• Formatted date
• Formatted time
• Year, month, day, hour, minute, second information

Environment and API Proxy Information

• Environment ID and name
• API Proxy Group ID and name
• API Proxy ID and name
• API Method information

Message Information

• Message correlation ID
• Content length
• Response status code
• Compression information

Context values are used to extract data from system properties and request context. These values are selected from a dropdown menu in form-based configuration and displayed with user-friendly labels.

Creating Custom Variable Type Variable

To create this type of variable, Custom Variable is selected as the type and only the name field is filled.

Afterwards, it becomes possible to assign values, read values, and change values from Script and Business Rule policies with the entered name of this variable.

It is mostly used for transferring data from one policy to another.

Field	Description
Name	Field where the name of the variable definition is entered.
Description	Description can be written to facilitate management related to the created variable.
Type	Field where which part of the message the variable is expected is entered.
Initialized with Script	Field used to determine the initial value of the Custom Variable. This field only works if the variable has never been created or is null. To give an initial value, the variable name added to the customVariableMap object with the name used here must be exactly the same. For example, if the variable name is “test”, the expression should be written as customVariableMap.put("test",value) in the last line of the script.
Script Language	Field where Script Language is selected.
Script Body	Field where script content is entered.

Custom Variable is especially used for transferring data between pipelines. Data can be added, read, and changed to Custom Variable during flow with Script and Business Rule policies. This enables data transfer from one policy to another. When adding Business Rule action types, variable type selection and new variable creation screens have been improved for a clearer user experience.

The first value is always taken on the variables screen, even if the header (header) and parameter (parameter) values come as multiple (multiple). Only in script policy, if there is a multiple (multiple) value, it can be used separated by #.

When showing in log records, it is shown as key: val1#val2#val3.

Runtime Context Variable Support (#)

In policies that make HTTP calls and in routing addresses, context variable usage is supported. Placeholders in the #{variable_name} format are replaced on each request with values from the request context (custom variable map).

Supported Fields

• HTTP URL – e.g. https://api.example.com/users/#{userId}
• Header name and value – e.g. Authorization: Bearer #{token}
• Query parameters – e.g. ?sessionId=#{sessionId}
• Form parameters (URL-encoded body)
• Request body content
• Routing address – #{...} can be used at runtime in the backend address
• JSON Error Response Template and XML Error Response Template – #{variableName} can be used. For error details: #{error.customizedErrorCode}, #{error.customizedHttpCode}, #{error.customizedMessage}, #{error.defaultErrorCode}, #{error.defaultMessage}, #{error.defaultHttpCode}

Variable Type Comparison

Format	Description	Resolution Time
${key}	Environment variable	At deploy time (current behavior)
#{key}	Context variable	On each request (new)

• Environment variable: Fixed for the environment; resolved at deploy time.
• Context variable: Per request; read from the custom variable map (can be set by Script policy, data manipulation, etc.).

Affected Policies and Fields

• REST API Policy
• JOSE Validation Policy (dynamic key HTTP request)
• JOSE Implementation Policy (dynamic key HTTP request)
• Authentication API Policy
• OIDC Policy (token endpoint, introspection endpoint, resource endpoint, form parameters)
• Routing addresses (backend address)
• JSON Error Response Template and XML Error Response Template
• Identity Providers: Database Provider, LDAP Provider, API Provider

Behavior

• Missing #{key} values are replaced with empty string ""; no exception is thrown, a warning-level log is written to the application log.
• In Script policy, the custom variable map is already accessed directly, so this placeholder mechanism is not used there.
• Existing variable-based substitution and data manipulation logic is unchanged; this works as an additional layer on top.

Example Usage

• REST API URL: https://${baseHost}/api/v1/users/#{userId} — ${baseHost} is resolved at deploy time, #{userId} on each request.
• JOSE dynamic key endpoint: https://auth.example.com/keys/#{keyId}
• Routing address: https://#{tenant}.backend.example.com — tenant can change per request.

This feature currently applies only in the HTTP context.

Variable Management

Project-Based Usage

Variables are defined at the project level and can be used in all API Proxies in the relevant project.

Management Menu

Variables created under the Management menu are automatically copied to the project when a new project is created.

Globalization

All variables can be moved to the Admin page with the “Globalize” option to make them available for use in all projects.

Independent Management

Updating or deleting variables in the Management menu does not affect the definitions in the projects where they are copied.

Variable Usage Scenarios

Variables are used in the following situations:

Policy Configuration

Used for dynamic values in policy settings. Client definition for policies such as Rate Limiting, Throttling, API Key.

Conditional Policy Execution

Used to make policy execution decisions based on variable values.

Routing and Routing

Used to route to different backends based on variable values.

Message Processing

Used for dynamic values in message transformation operations.

Script Policy

Variable usage in Groovy/JavaScript scripts and adding, reading, and changing data to Custom Variables.

Data Transfer Between Pipelines

Data transfer between pipelines with Custom Variable. Data transfer from Request Pipeline to Response Pipeline, from one policy to another.

Next Steps

Environment Variable

Learn about environment variables

What is Policy?

Learn about the Policy concept

Conditional Policy Execution

Learn about conditional policy execution

Script Policy

Variable usage in Script policy

Variable Definition API

Variable definition API reference