serve Action

The serve action can be used to deliver local files to clients. The action implements a simple file server. Optionally, processing of the flow can continue if the content provided by the serve action needs to be modified.


dir and fallback-doc are mandatory:

  • dir="…" defines the directory from which the local files are read. That directory must exist within the project path. The dir directory is resolved relative to the calling flow file.

  • fallback-doc: Defines a fallback document. This document will be used if the requested file cannot be found. The fallback-doc file is resolved relative to the calling flow file.

  • terminate="true|false": if true (default) the file loaded by serve is sent to the client and flow processing stops. Otherwise, the flow continues.

  • The action has no input (in).

  • If further processing of the loaded file is required, the output of serve can be redirected via the out attribute.

<serve dir="../htdocs" fallback-doc="/index.html"/>


The $request/path is resolved relative to dir. If the resolved path references a directory instead of a file, index.html within that directory is used instead. If $request/path references a directory but does not end with a slash (/), a 301 Moved Permanently redirection to the same path with a trailing slash (/) is executed.

If the requested file is found, the following HTTP header fields are set:

  • Content-Type

  • Content-Length

  • Last-Modified

The Content-Type is determined by the suffix of the file. The HTTP status code is set to 200 OK.

If the file is not readable, the HTTP status is set to 403 Forbidden.


  • The attribute dir is missing.

  • The attribute fallback-doc is missing.

  • The directory referenced by dir does not exist or cannot be read.

  • The directory referenced by dir is not within the project directory.

  • The file referenced by fallback-doc is to be loaded but does not exist or cannot be read.

See also