Dear Christian,

my problem is fixed. My xquery sent not a json-string, but a string and within a json-string:
>>>"{\"query\":\"Mensch\",\"top_k\":\"20\",\"autor\":\"hvk\",\"genre\":\"\"}"<<<

With data = json.loads(json.loads(data_string)) inside the python-code all is going well.
So far with BaseX 9.1 I didn´t had any problems with the code, but BaseX 12.0 made the difference.

That´s the xquery code

let $search-results :=
    if ($query) then
        let $url := "http://localhost:5003/search"
        let $request :=
        <http:request
            href="{$url}"
            method="post">
            <http:body
                media-type="application/json">
                {
                    serialize(
                    map {
                        "query": $query,
                        "top_k": $top_k,
                        "autor": $autor,
                        "genre": $genre
                    },
                    map {"method": "json"}
                    )
                }
            </http:body>
        </http:request>
        
        let $response := http:send-request($request)
        let $response-body := $response
        
        return
            (
            if ($response-body) then
                <div>{$response-body}</div>
            else
                <p>Fehler bei der Suche: Keine Antwort erhalten.</p>
            )
    
    
    else
        ()

Best,
Günter



Am 05.08.2025 um 18:49 schrieb Christian Grün <cg@basex.org>:

Dear Günter,

Difficult to tell again. What does the Flask server logs say about the rejected response?

Best,
Christian

Von: Günter Dunz-Wolff <guenter.dunzwolff@gmail.com>
Gesendet: Dienstag, 5. August 2025 18:15
An: Christian Grün <cg@basex.org>
Cc: basex-talk@mailman.uni-konstanz.de <basex-talk@mailman.uni-konstanz.de>
Betreff: Re: [basex-talk] Migration einer alten RESTXQ-Anwendung nach BaseX 12.0 - ClassNotFoundException für Servlets
 
Dear Christian,

thanks for asking. The problem has now been reduced to a persistent error that blocks communication between a basex xquery and a local Flask server. Error 500 is constantly displayed in the browser, while no error is displayed in the basex log. A curl query also works smoothly. The BaseX version 9.1 I've been using so far has never had any problems with it. I've reduced the basex environment to an absolute minimum, just one file that makes an http:send request. Here's the small xquery code:

xquery version "3.0";

module namespace test = "http://example.com/test";

import module namespace http = "http://expath.org/ns/http-client";

declare
%rest:path("test-flask")
%rest:GET
%output:method("xml")
function test:call-flask() {
let $url := "http://127.0.0.1:5003/search"

(: Create the JSON payload as a string :)
let $payload := serialize(
map {
"query": "Krieg",
"autor": "hvk",
"genre": "",
"top_k": "5"
},
map {"method": "json"}
)

(: Create the request element. It does NOT contain a body. :)
let $request :=
<http:request href="{$url}" method="post">
<http:body media-type="application/json"/>
</http:request>

(: Execute the request.
Argument 1: the request element.
Argument 2: is empty in this case, since the URL is in the request element.
Argument 3: the body/payload.
:)
let $response := http:send-request($request, (), $payload)

return
<result>
<status>{$response[2]/@status}</status>
<body>{try { fn:parse-xml($response[1]) } catch * { $response[1] }}</body>
</result>
};



As mentioned, BaseX v9.1 didn't cause any problems here. Here's an excerpt from the old code that produces the same problems in BaseX v12.0.

let $search-results := 
if ($query) then 
let $url := "http://localhost:5003/search" 
let $request := 
<http:request 
href="{$url}" 
method="post"> 
<http:body 
media-type="application/json"> 
{ 
serialize( 
map { 
"query": $query, 
"top_k": $top_k, 
"author": $author, 
"genre": $genre 
}, 
map {"method": "json"} 
) 
} 
</http:body> 
</http:request> 

let $response := http:send-request($request) 
let $response-body := $response 

return 
( 
if ($response-body) then 
<div>{$response-body}</div>
else
<p>Search error: No answer found.</p>
)

else
()


Any information is helpful. Thank you in advance.
Günter

Am 04.08.2025 um 17:13 schrieb Christian Grün <cg@basex.org>:

Dear Günter,

You may need to supply us with some more information to make this better reproducible:

• Which distribution of BaseX do you use (ZIP, Windows installer, …)?
• Did you write the systemd service on your own? What does it do?
• Where did the instructions come from (Fügen Sie den Inhalt Ihrer web.xml bei)?

Thanks in advance,
Christian
Von: Günter Dunz-Wolff <guenter.dunzwolff@gmail.com>
Gesendet: Montag, 4. August 2025 11:44
An: basex-talk@mailman.uni-konstanz.de <basex-talk@mailman.uni-konstanz.de>
Betreff: [basex-talk] Migration einer alten RESTXQ-Anwendung nach BaseX 12.0 - ClassNotFoundException für Servlets
 

  • "Ich migriere eine bestehende Anwendung von einer alten BaseX-Version auf BaseX 12.0."

  • "Mein 

    systemd
    -Dienst startet den Server, aber die Anwendung schlägt mit einem 
    503
    -Fehler fehl."

  • "Das Log zeigt 

    java.lang.ClassNotFoundException
     für 
    org.basex.http.rest.RestServlet
     und 
    org.basex.http.restxq.RestXqServlet
    ."

  • Fügen Sie den Inhalt Ihrer 

    web.xml
     bei.

  • Frage: "Wie lauten die korrekten Klassennamen und die korrekte 

    web.xml
    -Konfiguration, um REST und RESTXQ in BaseX 12.0 zu aktivieren?"