EdgeWorkers event model

Understand when EdgeWorker scripts are executed. The EdgeWorkers code is invoked based on specific HTTP events. To create a function for any of these events, implement the callbacks as explained in the JavaScript API reference.

event handlers

The responseProvider event handler acts as a surrogate origin to execute EdgeWorkers code. To learn more, go to the Response Orchestration section.

responseProvider event handler

onClientRequest

The onClientRequest event happens for every request as the request is received, before checking if a response is available in cache. Use this event for request modifications before going to cache or to origin. Here's an example of a function that modifies the response based on user location:

// redirect based on originating country of request
 
export function onClientRequest(request) {
   var country = request.userLocation.country;
    if (country === 'FR') {
       request.respondWith(302, {'Location': ['https://www.example.com/fr/']}, '');
    }
}

Review the table for information about the available parameters.

ParameterTypeDescription
requestRequest An object representing the current request. Modifications to this request object are visible in all other event handlers.

onOriginRequest

The onOriginRequest event happens just before sending the request to the origin. This event only happens if the response is not served from cache and not constructed on the edge. Use this event if you want to affect the response coming back from the origin. Changes to the Request Object made during onOriginRequest update the outgoing request to the origin. The changes are not visible in later event handlers.

This function adds a device type header to the origin request:

// send header to origin
 
export function onOriginRequest(request) {
   if (request.device.isMobile) { 
      request.setHeader('X-MyHeader-DeviceType','Mobile'); 
   } 
   else if (request.device.isTablet) { 
      request.setHeader('X-MyHeader-DeviceType', 'Tablet'); 
   } 
   else { 
      request.setHeader('X-MyHeader-DeviceType', 'Desktop'); 
   }
}

Review the table for information about the available parameters.

ParameterTypeDescription
requestRequestAn object representing the outgoing current request. Modifications to this request object are visible to the origin but not visible to any of the other event handlers.

onOriginResponse

The onOriginResponse event happens as the origin response is created. The event only happens if the response is not served from cache and not constructed on the edge. Use this event if you want to modify the response before it is cached.

// remove header returned from origin
 
export function onOriginResponse(request, response) {
response.removeHeader('InternalDebugHeader');
}

Review the table for information about the available parameters.

ParameterTypeDescription
requestRequestAn object representing the current request after modifications by the onClientRequest event hander.
responseResponseAn object representing the current response. Modifications to the Response object are only visible in the onClientRequest event hander.

onClientResponse

The onClientResponse happens before the response is sent to the client.

This example shows how to set a header before the response is sent to the client:

// add response header
 
export function onClientResponse(request, response) {
response.addHeader('Powered-By','Akamai EdgeWorkers');
}

Review the table for information about the available parameters.

ParameterTypeDescription
requestRequestAn object representing the current request, after modifications by the onClientRequest event handler.
responseResponseAn object representing the current response.

responseProvider

The responseProvider event happens if the response is not already found in cache. This example shows how to return a response body:

//add content to the response

export function responseProvider(request) {
return Promise.resolve(createResponse(200, {}, "<html><head></head><body><p>Hello World</p></body></html>"));
}

📘

To find more information about how EdgeWorker scripts are executed during the responseProvider event see Response Orchestration.

Review the table for information about the available parameters.

ParameterTypeDescription
requestRequestAn object representing the incoming request. Modifications to this request object are visible in the onClientResponse event handler.

Event handler methods

View the supported HTTP methods for the EdgeWorkers event handlers.

Event handlerSupported methodsUnsupported methods
onOriginRequest
onOriginResponse
onClientResponse
onClientRequest
responseProvider
GET
HEAD
POST
PUT
PATCH
DELETE
CONNECT
TRACE
OPTIONS

📘

Sub-requests support the GET, HEAD, POST, PUT, and DELETE methods.

Bypass event handlers

To prevent specific event handlers from executing you can create a Property Manager variable.

Refer to this table for the PMUSER_BYPASS variable name to use for each event handler and to see the metadata stage when it's evaluated.

Event handlerVariable nameMetadata stage evaluation
onClientRequestBYPASS_EW_CLTREQ_EVENTclient-request
onOriginRequestBYPASS_EW_ORGNREQ_EVENTforward-request
onOriginResponseBYPASS_EW_ORGNRESP_EVENTforward-response
onClientResponseBYPASS_EW_CLTRESP_EVENTclient-response
responseProviderBYPASS_EW_RP_EVENTclient-request

To bypass an event, set the initial value of the corresponding variable to "true".

👍

The PMUSER_ prefix for the variable is automatically included.

EdgeWorkers event handlers are always bypassed if their respective PMUSER variables are set, no matter which metadata stage they are restricted to. You can use use BYPASS variables in a programmatic manner to:

  • Make decisions in later metadata stages when access to more information is available. For example, you can only execute onClientResponse if a specific response header is present.
  • Set the variables from within an EdgeWorkers event, to bypass later events.