Valves

A VALVE is a highly specialised building block. In general, it operates on data exposed by the PIPE where the VALVE “lives”. By chaining multiple VALVES one can achieve customised authentication/authorization making the system follow current business requirements but also cater for future requirements changes.

Common configuration

These configuration properties applies to all valves:

Properties
Example

Name	Description	Default
`name`	Valve name (alias or fully qualified class name).
`enabled`	Flag to control if valve is enabled (i.e. included in pipe) or not. Use this property to temporary disable a valve.	`true`
`exec_if_expr`	Predicate expression controlling if valve should be executed or not in the current context. For details, see execution control.	`true`
`config`	Valve specific configuration object. This object is passed to the valve during initialisation and is the configuration the valve has access to.	`{}`

{
    "name":"<alias>",
    "enabled": true,
    "exec_if_expr": "request.exec === 'true'",
    "config": {

    }
}

Execution control

You can control valve execution in runtime using the exec-if predicate expression (a boolean expression that returns true or false). If expression evaluated to true, the valve is executed (this is the default behaviour).

The actual filter is an ECMA-script (JavaScript) that MUST evaluate to true, false or to a boolean function returning true or false.

// Disable valve
"exec_if_expr": "false"

// Only execute if session contains a username property
"exec_if_expr": "session.username != null"

During expression evaluation data is made available in scopes. A scope is a map (i.e key-values or hash) where values are accessed using a name and plain dot notation.

// Get value of request parameter "username"
request.username

// Get id of current session
session.id

// Get first value of multivalue "roles" stored in session
session.roles[0]

// Get value "otp" from state set by previous valve
state.otp

The following are scopes available:

Name	Description	Case-insensitive
`request`	The current pipe request
`session`	The current session
`state`	The current state
`items`	The current items
`exports`	Authenticator globals. Only available if pipe is called in an authentication context (i.e. by an authenticator).

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