Http listener

Embedded web server: listens on a port and path, emits every incoming request as a WebHttpRequest and sends the response it receives back on its Input pin (or from an Http response component). Use it to expose a flow as an HTTP endpoint.

Pins

Pin	Kind	Types	Description
Start	start		Starts the server. Called by the system at flow start when unconnected.
Output	output	Viaducta.Plugins.Http.Types.WebHttpRequest	Called for every request (after authentication). Connect Rest handler, SOAP handler or your own logic.
Input	input	Viaducta.Plugins.Http.Types.WebHttpResponse, Viaducta.Plugins.TextPlugin.Types.TextRecord	Response to send to the caller of the current request.
Authentificate	continue	Viaducta.Plugins.Http.Types.WebHttpRequest	Called first for every request. An error here rejects the request.

Configuration

Field	Type	Default	Description
ListenUrl	listener URL		Required. Format http://<host>:<port>/<path>, see below.
MaxParallelRequests	integer (1-4096)	1024	Max requests processed in parallel. Further requests wait for a free slot until the caller gives up; open (keep-alive) connections are not limited.
MaxRequestBodySize	integer	0	Max body size in bytes, 0 = unlimited (2 GB).
Timeout	integer	60000	Ignored, see Notes.
KeepAliveTimeout	integer	130	Keep-alive timeout in seconds.
MaxRequestHeaderCount	integer	100	Max number of request headers.
KeepRawBody	boolean	false	true: also put the exact request bytes in ByteBody for text and form requests (Body/Form are still filled, IsByteBody stays false). Turn on when a signature over the body is checked, for example by the Webhook receiver.
UseSsl	boolean	false	true: HTTPS.
SslProtocol	dropdown: 0 None, 12 Ssl2, 48 Ssl3, 192 Tls, 240 Default, 768 Tls11, 3072 Tls12, 12288 Tls13	0	Allowed protocol(s) when UseSsl. 0 = OS default.
ServerCertificate	certificate		Name of a certificate object in the repository, used when UseSsl.

ListenUrl format

The editor writes http://localhost:<port>/<path> for a private listener (local machine only) or http://0.0.0.0:<port>/<path> for a public one (all interfaces), e.g. http://0.0.0.0:9000/api. * or + as host also means all interfaces; any other host must be an IP address. Only one URL is supported. A public listener is also reachable through the designer server at <server>/env/<tenantId>-<environment>/<port>/<path> (shown in the editor as the absolute URL).

Behaviour

• Several listeners (and web socket listeners) in a flow can share a port if they use different paths under the same first segment (/api/orders and /api/users, not /api and /api2) and identical SSL, certificate and visibility settings; otherwise the flow fails to start.
• For each request: method, full URL, headers, query string, cookies and remote IP are copied into a WebHttpRequest. Form posts fill Form, text content types fill Body, anything else fills ByteBody (IsByteBody = true). A missing content type is treated as text/json. Request headers ViaSessionId and ViaCorrelationId are copied into the flow metadata session and correlation id.
• Authentificate is called first. Any error returns a JSON error (message, code, type, flowName, componentName, traceId); the status is 401 for errors raised by Http authentification, otherwise 500.
• Then Output is called. No Output connection: empty 404. If the flow finishes without sending a response: 500 "The response ... was never sent". Errors in the flow: JSON error, 500 (or the error's code if it requests that).
• The response: StatusCode (0 = 200), headers, cookies, ContentType, Body or ByteBody, ContentFileName (adds Content-disposition: attachment). A TextRecord becomes a 200 with Value as body. Only the first response per request is sent.
• The plugin keeps the flow running.

Notes

• Timeout is not used: a request waits until the flow finishes.
• With only one listener on a port, it receives every path on that port, not only its own.
• With UseSsl and no ServerCertificate, the default development certificate is used and SslProtocol is not applied.
• Without an Authentificate connection all requests are served (warning shown in the designer).

Example

{ "ListenUrl": "http://0.0.0.0:9000/api", "MaxParallelRequests": 1024 }

Http listener → Rest handler → ... → Http response