Replace websocket with RestAPI

[01Parzival10]

Replaced the websocket with a simple RestAPI
Also refactored the backend in the process

DONT MERGE YET
I need to adjust the backend Server nginx first

[01Parzival10]

Test Version (with Mitigation) is already up and running on https://webeditor.t-hueller.de

[Copilot]

Pull request overview

This PR replaces the frontend↔backend WebSocket protocol with a simple HTTP REST API and refactors the backend server code accordingly (Jetty + servlets + service classes).

Changes:

• Removed the WebSocket client/server implementation and wiring on both frontend and backend.
• Added a REST-based DfdApiClient on the frontend and new /api/* servlets/services on the backend.
• Refactored the loading indicator delay behavior from JS timeout-based logic to CSS-based delay.

Reviewed changes

Copilot reviewed 32 out of 32 changed files in this pull request and generated 14 comments.

Show a summary per file

File	Description
frontend/webEditor/src/webSocket/webSocket.ts	Removes the old WebSocket client implementation.
frontend/webEditor/src/webSocket/di.config.ts	Removes DI bindings for the WebSocket client.
frontend/webEditor/src/startUpAgent/webSocketConnect.ts	Removes startup logic that forced WebSocket initialization.
frontend/webEditor/src/startUpAgent/di.config.ts	Stops registering the WebSocket startup agent.
frontend/webEditor/src/serialize/saveFile.ts	Updates loading indicator API usage (hideIndicator).
frontend/webEditor/src/serialize/saveDfdAndDdFile.ts	Switches “save DD” backend call from WebSocket to REST client.
frontend/webEditor/src/serialize/loadPalladioFile.ts	Switches PCM loading call to REST client.
frontend/webEditor/src/serialize/loadJson.ts	Updates loading indicator usage and adds alert on error; makes postLoadActions public.
frontend/webEditor/src/serialize/loadDfdAndDdFile.ts	Switches DFD+DD loading call to REST client.
frontend/webEditor/src/serialize/analyze.ts	Switches analyze call to REST client.
frontend/webEditor/src/loadingIndicator/loadingIndicator.ts	Refactors indicator show/hide logic to class-based CSS toggling.
frontend/webEditor/src/loadingIndicator/loadingIndicator.css	Implements CSS-based delayed visibility for the loading overlay.
frontend/webEditor/src/index.ts	Loads the new REST client DI module instead of the WebSocket module.
frontend/webEditor/src/dfdApiClient/di.config.ts	Adds DI module for the new REST client.
frontend/webEditor/src/dfdApiClient/dfdApiClient.ts	Adds REST client that POSTs to /api/{action} and parses responses.
frontend/webEditor/.gitignore	Adds .vs/ and fixes formatting.
backend/.../websocket/WebSocketServerUtils.java	Removes WebSocket server bootstrap.
backend/.../websocket/WebSocketServerHandler.java	Removes WebSocket message handler implementation.
backend/.../services/Util.java	Adds shared JSON/constraint/temp-file helpers for the REST services.
backend/.../services/SaveDDService.java	Adds service for converting WebEditor JSON to DFD+DD file content.
backend/.../services/LoadPCMService.java	Adds service for parsing PCM uploads and converting to WebEditor JSON.
backend/.../services/LoadDDService.java	Adds service for parsing DFD+DD uploads and converting to WebEditor JSON.
backend/.../services/AnalyzeService.java	Adds service for analyzing/annotating WebEditor JSON.
backend/.../server/ApiServer.java	Adds Jetty server that exposes REST endpoints via servlets.
backend/.../Main.java	Switches the CLI entrypoint to start the REST API server.
backend/.../Application.java	Switches the Equinox application entrypoint to start the REST API server.
backend/.../api/Servlet.java	Adds common servlet base class for reading request bodies and writing text responses.
backend/.../api/SaveDDServlet.java	Adds /api/saveDD endpoint.
backend/.../api/LoadPCMServlet.java	Adds /api/loadPCM endpoint.
backend/.../api/LoadDDServlet.java	Adds /api/loadDD endpoint.
backend/.../api/AnalyzeServlet.java	Adds /api/analyze endpoint.
backend/.../analysis/Converter.java	Removes the old “Converter” utility that mixed multiple responsibilities.

Comments suppressed due to low confidence (1)

backend/analysisBackendServer/bundles/org.dataflowanalysis.standalone/src/org/dataflowanalysis/standalone/server/ApiServer.java:27

• ApiServer.start() calls server.join(), so it blocks the calling thread. In Application.start(), this means the code below (Scanner loop / exit handling) is never reached. Consider starting Jetty on a separate thread, or returning the Server instance and letting the caller decide whether to join().

    public static void start() throws Exception {
        Server server = new Server(new InetSocketAddress("localhost", 3000));

        ServletContextHandler context = new ServletContextHandler(ServletContextHandler.NO_SESSIONS);
        context.setContextPath("/");

        context.addServlet(AnalyzeServlet.class, "/api/analyze");
        context.addServlet(LoadDDServlet.class, "/api/loadDD");
        context.addServlet(LoadPCMServlet.class, "/api/loadPCM");
        context.addServlet(SaveDDServlet.class, "/api/saveDD");        

        server.setHandler(context);
        server.start();
        server.join();
    }

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[BenjaminArp]

use speaking name here

[BenjaminArp]

Could this cause problems if multiple people tried to call the default.diagram at the same time?

[BenjaminArp]

is this dead code?