Scripting

Throughout Membrane, certain plugins like:

setHeader
template
groovy

support expressions written in Javascript, Groovy or SpEL.

Examples

...

Context Attributes

When using Membranes scripting capabilities, a set of pre-defined attributes and APIs are available to provide access to useful information about the current context:

Outcomes

Outcomes are enums that depict the current state of the request/response flow.
Next to the enum class itself Outcome, the individual enum states are available as well.

Outcome	Description
RETURN	Changes the direction of flow. The request handling mechanisms of the active plugins get activated.
CONTINUE	Continues the flow.
ABORT	Aborts the current flow, the direction is changed and the abort handling mechanisms of the active plugins get activated.

Exchange

The exc keyword grants access to the current Exchange object, housing request and response information.

Message

The message keyword is a shortcut to exc.getRequest()/exc.getResponse().
Depending on direction of flow, message can stand for a request or response object.

Params

The params keyword can be used to access request query parameters.

JSON

If the body of a message is of type application/json, json is a parsed JSON object representation of the body's JSON document.

Flow

The flow keyword houses the Flow enum. Values are REQUEST and RESPONSE.
These stand for the direction of flow.

Properties

The properties keyword is a shortcut to exc.getProperties().

Spring

The spring keyword grants access to Membrane's Spring ApplicationContext.

SpEL Reference

Context Variables

The following variables are available in SpEL expressions:

Variable	Type	Description
`exchange`	`Exchange`	Current exchange.
`message`	`Message`	Current message depending on `flow` (request/response).
`body`	`Body`	Message body
`headers` / `header`	`Map<String, Object>`	Header map
`cookies` / `cookie`	`Map<String, Object>`	Cookie map
`properties` / `property`	`Map<String, Object>`	Exchange properties.
`params` / `param`	`Map<String, Object>`	Query parameters.
`pathParam`	`Map<String, Object>`	Path parameters from URI templates.
`path`	`String`	Request path
`method`	`String`	HTTP method
`statusCode`	`int`	Response status code (if response exists).
`request`	`Request`	Request wrapper.
`response`	`Response`	Response wrapper.
`json`	`Map<String,Object>`	Parsed JSON body as map.
`scopes`	`String`	List of authentication scopes (may be `null`).
`flow`	`Flow`	`REQUEST` or `RESPONSE`.

Aliases: header=headers, cookie=cookies, property=properties, param=params.

Built-in Functions

Signature	Description
`jsonPath(String jsonPath)` → `Object`	Runs JSONPath on decoded body; returns `null` on errors. Example: `jsonPath('$.user.id')`
`weight(double percent)` → `boolean`	Random boolean with given `true` probability (0–100%). Example: `weight(10)`
`isLoggedIn(String beanName)` → `boolean`	Verified session present for given interceptor bean? Example: `isLoggedIn('loginInterceptor')`
`getDefaultSessionLifetime(String beanName)` → `long`	Default session lifetime in seconds; `-1` if unavailable. Example: `getDefaultSessionLifetime('loginInterceptor')`
`isBearerAuthorization()` → `boolean`	`Authorization` header starts with `Bearer`? Example: `isBearerAuthorization()`
`scopes()` → `List<String>`	All scopes from available security schemes. Example: `scopes()`
`scopes(String scheme)` → `List<String>`	Scopes for a scheme (`http`, `apiKey`, `oauth2`). Example: `scopes('oauth2')`
`hasScope(String scope)` → `boolean`	Scope present? Example: `hasScope('admin')`
`hasScope()` → `boolean`	At least one scope present. Example: `hasScope()`
`hasScope(List<String> scopes)` → `boolean`	Contains all given scopes. Example: `hasScope({'read','write'})`
`isJSON()` → `boolean`	Message body is JSON. Example: `isJSON()`
`isXML()` → `boolean`	Message body is XML. Example: `isXML()`
`base64Encode(String s)` → `String`	Base64 encodes the input string. Example: `base64Encode('string')`