HTTP Trigger

Start Process by receiving web request.

Ossi Galkin avatar
Written by Ossi Galkin
Updated over a week ago

HTTP Triggers allow you to trigger the Processes by HTTP, HTTPS, or both requests. The HTTP endpoint is hosted by the Frends Agent, using the operating system's HttpListener interfaces. The Agent can be configured to listen for requests on multiple ports. Each hosted HTTP Trigger will have its own path for triggering just the specific process.


HTTP Method

The HTTP Method determines which methods the Trigger URL can be called with. Allowed values are GET, POST, PUT, DELETE, HEAD, OPTIONS, PATCH and ANY. ANY allows any method to go trough, while the others allows only the defined method.


All paths configured for an Agent Group need to be unique in combination with the method, overlapping paths will cause errors. The paths may contain variables as route parameters (inside the path: runmyprocess/{variable}) or as query parameters (in the end of the path: runmyprocess?id=1)

For example, if you have

  • Agent running on host

  • Agent configured to use port 9998.

  • HTTP Trigger configured as runmyProcess/{myvariable}.

This will register a Trigger that listens on the address{myvariable}

If you call the Trigger with the following URL: 

the following references and their values will be available in the Process: = anyValyeForMyVariable = 1 = "foo"

Allowed Protocols

HTTP Triggers can be configured to accept requests with HTTP, HTTPS, or both. If a request is made with a protocol that is not allowed, the reply will be Forbidden (403).


HTTP Triggers can use four different kinds of authentication:

  • None - No authentication at all.

  • Basic - Authenticate with HTTP basic authentication.

  • Certificate - Use a client certificate to authenticate.

  • API key - Authenticate with an API key.

We strongly recommend using authentication only over HTTPS. 

Basic authentication authenticates the user either against the Active Directory or the local users. Which one is used depends on the Frends Agent service user. If the Agent uses a local user account, users are authenticated against the local machine users. If the Agent uses an AD user account, users are authenticated against the AD users. Username and password need to be encoded with UTF-8 before being converted to Base64 for the basic authentication header. Basic authentication is not supported on cloud Agents by the platform, but it is possible to check authentication headers in Process. 

Certificate authentication requires that the client certificate is valid for the Frends Agent user on the Agent machine. Also, the issuer for the certificate needs to be found in the Agent user's Client Authentication Issuers certificate store.

API key authentication uses an API key together with Rulesets to determine if the client has access to a URL. For more information, see API keys.

Allow requests from these origins (CORS) 

If there is a need to allow a certain page to Trigger a Process, it is possible to do so with Cross-Origin Resource Sharing (CORS). Check the "Allow requests from these origins" setting, and define the allowed origins in the textbox. The * character allows calls from all origins. Multiple origins can be provided separated with a colon , or semicolon ;.

Note: if the call does not come from the default port, it must be included in the origin. The origin making the call must also support CORS.

Public / private HTTP Triggers

You can choose to mark the HTTP Trigger public by checking the "Public - will be accessible on API Gateways" setting. As the option says, this means the Trigger endpoint will be published on API gateways. Private Triggers can only be accessed from the actual execution Agents. This way, you can e.g., limit some APIs to be used only from your internal network. 

Pass content to process as unparsed, Base64 encoded byte array

You can process the HTTP request as raw bytes if you turn on the "Pass content to process as unparsed, Base64 encoded byte array" option. In this case, the HTTP message body will be left unparsed. Instead, the request will be passed as is, as a byte array (serialized as a Base64 string), accessible via the reference.

Note: if the setting is turned on, the reference will not be available.

Trigger Reference List

  •  Dictionary<string, string> of parameters passed in the URL, both route and query parameters. (e.g., anotherVariable).
    DEPRECATED - Use pathParameters or queryParameters to access the path and query parameters.

  •  Dictionary<string, string> of passed HTTP query parameters.

  •  Dictionary<string, string> of passed path parameters.

  •  Dictionary<string, string> of passed HTTP request headers (e.g., Host, Accept).

  •  HTTP request body as a string.

  •  HTTP method type (e.g., GET, POST).

  •  Request URI (e.g.,

  •  IP of the client as a string.

  •   Cookies associated with the request as a Dictionary<string,string>.

  •  The username associated with the caller, only set if authentication is used. The following values are passed for the different types of authentication:

    • API Key: The name of the API key

    • Basic authentication: The provided username

    • Certificate: The certificate's SubjectName.Name field

  • You can try to access an optional reference from any of the references (e.g. ) and if it is found, the value will be returned; and if not the value will be set to null.

Intermediate Response

A Process can return a response for the user before the Process is finished. This functionality is enabled by adding an Intermediate Result element to the Process. When this element is executed, the caller will receive an HTTP response from the Process. This can, for example, be used when calling a long-running Process, and the caller should be notified that the long-running Task has started.

HTTP Response Formatting

The HTTP Trigger returns the result of the executed Process as the HTTP response. The response varies according to the following conditions: When the result of the Process is a string, the string is set as the body of the response. If it was an object, it will be returned either as JSON or XML, depending on the request's ACCEPT header, or JSON by default. For example, ACCEPT: application/XML would produce an XML response, while ACCEPT: application/json would produce a JSON response.

If the result is an object with the properties HttpStatusCode and Content, the result will be mapped to a response as follows:

  • HttpStatusCode  Response status code (int)

  • Content  The body of the response (string)  

  • ContentEncoding  The encoding for the body, e.g. utf-8 (string)

  • ContentType   ContentType header value, e.g. application/xml or application/json (string)

  • HttpHeaders   Response headers (KeyValuePair[])

Http response

The Process elements Return, Intermediate Return and Throw all have the option to generate a pre-defined HTTP response. See HTTP Response results in Parameter Editor.




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