Prolog Web Server for AST Generation

Prolog web server which returns a JSON AST representation for a given Prolog source code snippet.

Using the server.pl it is possible to create an HTTP server listening for POST requests with Prolog source code snippets as text/plain and returning the appropriate AST as JSON.

The HTTP server can be started using the following command, which creates a local HTTP server on port 8081:

swipl server/server.pl --port=8081

The project's Makefile also provides a `make server` command.

Message Protocol

The server has a single endpoint: /. It can be used only for POST requests. The Prolog source code is expected as the message body with text/plain as Content-Type. It will return the AST as application/json as response.

For example, the AST for the program and(1,X,X) can be generated using the following curl command from command line:

curl -H "Accept: text/x-prolog" -H "Content-Type: plain/text" -X POST -d 'and(1,X,X).' http://localhost:8081/

By providing the HTTP header Accept: application/json, the JSON representation needed for ASTExplorer is created:

curl -H "Accept: application/json" -H "Content-Type: plain/text" -X POST -d 'and(1,X,X).' http://localhost:8081/

If the given Prolog source code is not syntactically correct at all, the following JSON gets replied:

{
  "type": "error",
  "message": "Program could not be parsed."
}

We provide a fork of astexplorer that uses this message protocol for a web-based editor to inspect a Prolog program's parstree (i.e., using prolog_parsetree/3):