Can't find Mercure

[hgalt]

I have Frankenphp running and enabled Mercure successful. Now I want to use it, but I'm not able to find the place, where Mercure is stored.
Therefore I'm not able to send the client requests to the Mercure Hub.
I can't find /.well-known/mercure anywhere,

[henderkes]

It's a URL, not a directory in the filesystem.

your.domain.com {
    mercure {
        ...
    }
}

now it's reachable at
https://your.domain.com/.well-known/mercure.

But it doesn't have a GUI listening there. Please refer to the ui documentation if you need it to test.

In case of a Symfony project you'd now only need to set the MERCURE_URL.

[hgalt]

I don't have Synfony installed What you mean with ui documentation?
As I understand, I have to put some code in the JS-File for the client and to start the update.
A example would helpful.

[henderkes]

https://mercure.rocks/docs/getting-started

[hgalt]

Hi @henderkes ,
thank you for the link.
I have something, which I don't understand.
My requirements are to send specific updates to the client for which I use Jquery to update the WEB page.

// The subscriber subscribes to updates for the https://example.com/users/dunglas topic
// and to any topic matching https://example.com/books/{id}
const url = new URL("https://localhost/.well-known/mercure");
url.searchParams.append("topic", "https://example.com/books/{id}");
url.searchParams.append("topic", "https://example.com/users/dunglas");
// The URL class is a convenient way to generate URLs such as https://localhost/.well-known/mercure?topic=https://example.com/books/{id}&topic=https://example.com/users/dunglas

const eventSource = new EventSource(url);

// The callback will be called every time an update is published
eventSource.onmessage = (e) => console.log(e); // do something with the payload

The url.searchParams.append("topic", "https://example.com/books/{id}"); .
Do I have to use topic or can it be anything?
There is a URL included in the appendix. Must be that a real existing URL?
Or is that only for defining different values which have to be updated?
In the example above there is first books followed by the ID of the book.
Would it be also enough, to append only one value, in this example to use only books?

On the beginning of the example it is mentioned, that the JWT_KEY is used !ChangeThisMercureHubJWTSecretKey! is used. I think in this case the key is the same for subscriber and publisher. But in the curl example:

curl -d 'topic=https://example.com/books/1' -d 'data={"foo": "updated value"}' -H 'Authorization: Bearer eyJhbGciOiJIUzI1NiJ9.eyJtZXJjdXJlIjp7InB1Ymxpc2giOlsiKiJdLCJzdWJzY3JpYmUiOlsiaHR0cHM6Ly9leGFtcGxlLmNvbS9teS1wcml2YXRlLXRvcGljIiwie3NjaGVtZX06Ly97K2hvc3R9L2RlbW8vYm9va3Mve2lkfS5qc29ubGQiLCIvLndlbGwta25vd24vbWVyY3VyZS9zdWJzY3JpcHRpb25zey90b3BpY317L3N1YnNjcmliZXJ9Il0sInBheWxvYWQiOnsidXNlciI6Imh0dHBzOi8vZXhhbXBsZS5jb20vdXNlcnMvZHVuZ2xhcyIsInJlbW90ZUFkZHIiOiIxMjcuMC4wLjEifX19.KKPIikwUzRuB3DTpVw6ajzwSChwFw5omBMmMcWKiDcM' -X POST https://localhost/.well-known/mercure

In the -H option a totally different key is used.
Should it not be the publisher_jwt value?

[henderkes]

url.searchParams.append("topic", "https://example.com/books/{id}");

means you subscribe to the topic for changes of the https://example.com/books/{id} page. You can subscribe to multiple topics, either at once or through multiple EventSources. You can use whatever you later publish to, it doesn't necessarily have to be a url. It's "topic" because that's what tells the Mercure hub what you want to subscribe to.

In the -H option a totally different key is used.
Should it not be the publisher_jwt value?

The publisher_jwt and subscriber_jwt are used to generate json web tokens (JWTs). You can deliberately not use them directly because they are server/client secrets that shouldn't be used directly in transit.

https://www.jwt.io/

[hgalt]

I understand. I guess, I should only the transfer the subscriber_jwt should be only transferedJWT. The genation should be therefore created on the server and implemented in the .js file.
I use the example cURL function. Ich suche aber schon seit Stunden an dem Problem und finde keinen Fehler.
Error Message:

Jan 30 17:47:53 HPradio frankenphp[3210]: {"level":"error","ts":1769791673.7852705,"logger":"frankenphp","msg":"PHP Parse error:  syntax error, unexpected single-quoted string \"topic=https://hpradio.country-...\" in /var/www/html/cr/mairlist.php on line 208","syslog_level":"err","stacktrace":"github.com/dunglas/frankenphp.go_log\n\t/__w/packages/packages/source/frankenphp/frankenphp.go:696\n_cgoexp_634fea83287e_go_log\n\t_cgo_gotypes.go:2004\nruntime.cgocallbackg1\n\t/__w/packages/packages/pkgroot/x86_64-linux/go-xcaddy/src/runtime/cgocall.go:446\nruntime.cgocallbackg\n\t/__w/packages/packages/pkgroot/x86_64-linux/go-xcaddy/src/runtime/cgocall.go:350\nruntime.cgocallback\n\t/__w/packages/packages/pkgroot/x86_64-linux/go-xcaddy/src/runtime/asm_amd64.s:1082"}

Und hier tdie Zeile 208:

			curl -d 'topic=https://hpradio.country-radio.eu/songs' -d 'data={"foo": "updated Value"}' -H 'Authorization: Bearer eyJhbGciOiJIUzI1NiJ9.eyJtZXJjdXJlIjp7InB1Ymxpc2giOlsiKiJdLCJzdWJzY3JpYmUiOlsiaHR0cHM6Ly9leGFtcGxlLmNvbS9teS1wcml2YXRlLXRvcGljIiwie3NjaGVtZX06Ly97K2hvc3R9L2RlbW8vYm9va3Mve2lkfS5qc29ubGQiLCIvLndlbGwta25vd24vbWVyY3VyZS9zdWJzY3JpcHRpb25zey90b3BpY317L3N1YnNjcmliZXJ9Il0sInBheWxvYWQiOnsidXNlciI6Imh0dHBzOi8vZXhhbXBsZS5jb20vdXNlcnMvZHVuZ2xhcyIsInJlbW90ZUFkZHIiOiIxMjcuMC4wLjEifX19.KKPIikwUzRuB3DTpVw6ajzwSChwFw5omBMmMcWKiDcM' -X POST https://hpradio.country-radio.eu/.well-known/mercure

[henderkes]

PHP Parse error: syntax error, unexpected single-quoted string

For some reason the call is hitting your php_server, not mercure.

-H 'Authorization: Bearer eyJhbGciOiJIUzI1NiJ9....

You can't use the token from the example for obvious reasons, you need to generate your own according to the Mercure documentation.

[hgalt]

I was thinking to use the same password and the same JWT value as it is in the example, to get it easier for testing. If it would working, I would change it in the next step. Can I not do it?
Here my Caddyfile:

 The Caddyfile is an easy way to configure FrankenPHP and the Caddy web server.
#
# https://frankenphp.dev/docs/config
# https://caddyserver.com/docs/caddyfile
{
	frankenphp {
        php_ini {
	    memory_limit 256M
		}
	}
    email Hans-Georg@Althoff-fam.de
#   acme_ca https://acme-staging-v02.api.letsencrypt.org/directory
}

localhost {
    encode zstd br gzip
	php_server

}


hpradio.country-radio.eu {
	mercure {
		publisher_jwt !ChangeThisMercureHubJWTSecretKey!
		subscriber_jwt !ChangeThisMercureHubJWTSecretKey!
#	 	anonymous
	}
	tls hans-georg@althoff-fam.de {
	    protocols tls1.2 tls1.3
	}
	php_server

#	root /usr/share/frankenphp/
	root /cr/* /var/www/html/
	root /priv/* /var/www/html/
	root /phpmyadmin/* /var/www/html/
	root /fileadmin/* /var/www/html/typo3/public/
	root /typo3/* /var/www/html/typo3/public/typo3/index.php
	root /* /var/www/html/typo3/public/
	encode zstd br gzip

}

# As an alternative to editing the above site block, you can add your own site
# block files in the Caddyfile.d directory, and they will be included as long
# as they use the .caddyfile extension.
import Caddyfile.d/*.caddyfile

To find the problem with php_server and mercure, I think, I have to understand what I have to do, to send it to mercure.
The php program, where the cURL instruction is implemented, is in /var/www/html/cr/, and it should be handled by php_server of frankenphp, because it is a PHP file.
What I have to do, that it goes to mercure?

Thanks for your help Marc.

[henderkes]

I was thinking to use the same password and the same JWT value as it is in the example, to get it easier for testing. If it would working, I would change it in the next step. Can I not do it?

No, that won't work. Even if the example token was valid at the time of writing the documentation, it wouldn't be an hour later anymore. JWT's are not passwords or immutable API keys.

You need to sign a jwt using the subscriber_jwt secret and pass that to the client, typically in the form of a cookie for browsers, or a prior api response for api clients. The signed token contains information like validity period and permissions.

Usually mercure should automatically be handled before php_server, so I'm not sure on that front. @dunglas any idea?

[dunglas]

IIRC, we use token with not expiration date for documentation purposes. So it should work but they definitely must not he used in production.

[henderkes]

Oh, I didn't expect that. But the mystery remains why their curl call is being handled by php. Since they're using my packages they're on the latest Mercure version. I don't see anything wrong with the Caddyfile.

[hgalt]

OK, so the token should work for the first tests. That's good, because I can now concentrate myself on the cURL instruction.
So let's come back to that problem.
The Mairlist.php file is receiving new update information and should send this information to thr mercure hub. It is a normal PHP script and should be therefore handled by the frankenphp php_server, that's is my current understanding.
But I think, that the cURL example is not compatible with normal PHP. At least I could not find a option -d in the PHP cURL description.
But what I have to do inside Mairlist.php is to send an update to the Mercure Hub. So in my opinion, I can't use the cURL example and I need an example which is compatible with the Frankenphp php_server.
But maybe my understanding is not correct?

Thanks,
HGA

[henderkes]

https://www.php.net/manual/en/curl.constants.php#constant.curlopt-postfields

[hgalt]

Please see my comment to your previous message.

[hgalt]

My curl implementation returns a 400 error, so I decided to use Postman for update the mercure hub.
For Postman I use the following values:
Params:
topic: Songs
data: test

Headers:

So how do have to define the value for the Host Header?
Also my understanding is, that for topic I have not use an URL, it can be any value.
Also the data can be any value, it has not to be an array.

[henderkes]

I cannot answer your questions regarding Postman.

Also my understanding is, that for topic I have not use an URL, it can be any value.

As you can see from my example below, correct.

Also the data can be any value, it has not to be an array.

Also correct, it needs to be valid json though I think.

[henderkes]

I just tried your Caddyfile and Mercure settings (adjusted to localhost) and it's working perfectly fine:

❯❯ symfony-demo git:(main) 18:32 cat Caddyfile 
localhost {
    root ./public
    log
    encode zstd br gzip

    route {
        mercure {
            publisher_jwt {$MERCURE_PUBLISHER_JWT_KEY:!ChangeThisMercureHubJWTSecretKey!}
            subscriber_jwt {$MERCURE_SUBSCRIBER_JWT_KEY:!ChangeThisMercureHubJWTSecretKey!}
        }
        php_server
    }
}
❯❯ symfony-demo git:(main) 18:32 frankenphp start -c Caddyfile
2026/01/31 17:32:09.634 INFO    maxprocs: Leaving GOMAXPROCS=32: CPU quota undefined
2026/01/31 17:32:09.634 INFO    GOMEMLIMIT is updated   {"package": "github.com/KimMachineGun/automemlimit/memlimit", "GOMEMLIMIT": 30248169062, "previous": 9223372036854775807}
2026/01/31 17:32:09.634 INFO    using config from file  {"file": "Caddyfile"}
2026/01/31 17:32:09.635 INFO    adapted config to JSON  {"adapter": "caddyfile"}
2026/01/31 17:32:09.635 WARN    Caddyfile input is not formatted; run 'caddy fmt --overwrite' to fix inconsistencies    {"adapter": "caddyfile", "file": "Caddyfile", "line": 2}
2026/01/31 17:32:09.648 INFO    admin   admin endpoint started  {"address": "localhost:2019", "enforce_origin": false, "origins": ["//[::1]:2019", "//127.0.0.1:2019", "//localhost:2019"]}
2026/01/31 17:32:09.648 INFO    http.auto_https server is listening only on the HTTPS port but has no TLS connection policies; adding one to enable TLS {"server_name": "srv0", "https_port": 443}
2026/01/31 17:32:09.648 INFO    http.auto_https enabling automatic HTTP->HTTPS redirects        {"server_name": "srv0"}
2026/01/31 17:32:09.648 INFO    tls.cache.maintenance   started background certificate maintenance      {"cache": "0xc000760680"}
2026/01/31 17:32:09.652 INFO    pki.ca.local    root certificate is already trusted by system   {"path": "storage:pki/authorities/local/root.crt"}
2026/01/31 17:32:09.652 INFO    pki     intermediate expires soon; renewing     {"ca": "local", "time_remaining": -1932344.652885874}
2026/01/31 17:32:09.659 INFO    pki     renewed intermediate    {"ca": "local", "new_expiration": "2026/02/07 17:32:09.000"}
2026/01/31 17:32:09.747 INFO    frankenphp      FrankenPHP started 🐘   {"php_version": "8.5.1", "num_threads": 64, "max_threads": 64}
2026/01/31 17:32:09.749 WARN    http    HTTP/2 skipped because it requires TLS  {"network": "tcp", "addr": ":80"}
2026/01/31 17:32:09.749 WARN    http    HTTP/3 skipped because it requires TLS  {"network": "tcp", "addr": ":80"}
2026/01/31 17:32:09.749 INFO    http.log        server running  {"name": "remaining_auto_https_redirects", "protocols": ["h1", "h2", "h3"]}
2026/01/31 17:32:09.760 INFO    http    enabling HTTP/3 listener        {"addr": ":443"}
2026/01/31 17:32:09.771 INFO    failed to sufficiently increase receive buffer size (was: 208 kiB, wanted: 7168 kiB, got: 416 kiB). See https://github.com/quic-go/quic-go/wiki/UDP-Buffer-Sizes for details.
2026/01/31 17:32:09.772 INFO    http.log        server running  {"name": "srv0", "protocols": ["h1", "h2", "h3"]}
2026/01/31 17:32:09.772 INFO    http    enabling automatic TLS certificate management   {"domains": ["localhost"]}
2026/01/31 17:32:09.773 INFO    autosaved config (load with --resume flag)      {"file": "/home/m/.config/caddy/autosave.json"}
2026/01/31 17:32:09.773 INFO    serving initial configuration
Successfully started Caddy (pid=4800) - Caddy is running in the background
2026/01/31 17:32:09.776 INFO    tls.obtain      acquiring lock  {"identifier": "localhost"}
2026/01/31 17:32:09.777 INFO    tls     storage cleaning happened too recently; skipping for now        {"storage": "FileStorage:/home/m/.local/share/caddy", "instance": "c8634587-9fb2-421a-bdc9-0abd4a3da1ba", "try_again": "2026/02/01 17:32:09.777", "try_again_in": 86399.99999952}
2026/01/31 17:32:09.777 INFO    tls     finished cleaning storage units
2026/01/31 17:32:09.778 INFO    tls.obtain      lock acquired   {"identifier": "localhost"}
2026/01/31 17:32:09.778 INFO    tls.obtain      obtaining certificate   {"identifier": "localhost"}
2026/01/31 17:32:09.786 INFO    tls.obtain      certificate obtained successfully       {"identifier": "localhost", "issuer": "local"}
2026/01/31 17:32:09.786 INFO    tls.obtain      releasing lock  {"identifier": "localhost"}
2026/01/31 17:32:09.786 WARN    tls     stapling OCSP   {"identifiers": ["localhost"]}
❯❯ symfony-demo git:(main) 18:32 curl -d 'topic=songs' -d 'data={"foo": "updated Value"}' -H 'Authorization: Bearer eyJhbGciOiJIUzI1NiJ9.eyJtZXJjdXJlIjp7InB1Ymxpc2giOlsiKiJdLCJzdWJzY3JpYmUiOlsiaHR0cHM6Ly9leGFtcGxlLmNvbS9teS1wcml2YXRlLXRvcGljIiwie3NjaGVtZX06Ly97K2hvc3R9L2RlbW8vYm9va3Mve2lkfS5qc29ubGQiLCIvLndlbGwta25vd24vbWVyY3VyZS9zdWJzY3JpcHRpb25zey90b3BpY317L3N1YnNjcmliZXJ9Il0sInBheWxvYWQiOnsidXNlciI6Imh0dHBzOi8vZXhhbXBsZS5jb20vdXNlcnMvZHVuZ2xhcyIsInJlbW90ZUFkZHIiOiIxMjcuMC4wLjEifX19.KKPIikwUzRuB3DTpVw6ajzwSChwFw5omBMmMcWKiDcM' -X POST https://localhost/.well-known/mercure -k
2026/01/31 17:32:27.255 INFO    http.handlers.mercure   Update published        {"update": {"id": "urn:uuid:019c151c-fcf6-7279-99c0-653bd918d103", "type": "", "retry": 0, "topics": ["songs"], "private": false}}
2026/01/31 17:32:27.255 INFO    http.log.access handled request {"request": {"remote_ip": "::1", "remote_port": "47386", "client_ip": "::1", "proto": "HTTP/2.0", "method": "POST", "host": "localhost", "uri": "/.well-known/mercure", "headers": {"User-Agent": ["curl/8.16.0"], "Accept": ["*/*"], "Authorization": ["REDACTED"], "Content-Length": ["41"], "Content-Type": ["application/x-www-form-urlencoded"]}, "tls": {"resumed": false, "version": 772, "cipher_suite": 4865, "proto": "h2", "server_name": "localhost"}}, "bytes_read": 41, "user_id": "", "duration": 0.001802698, "size": 45, "status": 200, "resp_headers": {"Alt-Svc": ["h3=\":443\"; ma=2592000"], "X-Frame-Options": ["DENY"], "X-Content-Type-Options": ["nosniff"], "X-Xss-Protection": ["1; mode=block"], "Content-Security-Policy": ["default-src 'self'"], "Server": ["Caddy"]}}

As an example how you can use your own keys in the console:

❯❯ symfony-demo git:(main) 18:44 export MERCURE_PUBLISHER_JWT_KEY="Bsalasfoi231ijsajifijji231joSAFSAASAAsafasFF"
❯❯ symfony-demo git:(main) 18:45 frankenphp start -c Caddyfile
- snip -
Successfully started Caddy (pid=8112) - Caddy is running in the background
❯❯ symfony-demo git:(main) 18:45 HEADER=$(echo -n '{"alg":"HS256","typ":"JWT"}' | openssl base64 -e -A | tr -d '=' | tr '/+' '_-')
❯❯ symfony-demo git:(main) 18:46 EXP=$(($(date +%s) + 86400))
❯❯ symfony-demo git:(main) 18:46 PAYLOAD=$(echo -n "{\"mercure\":{\"publish\":[\"songs\"]},\"exp\":$EXP}" | openssl base64 -e -A | tr -d '=' | tr '/+' '_-')
❯❯ symfony-demo git:(main) 18:46 SIGNATURE=$(echo -n "$HEADER.$PAYLOAD" | openssl dgst -sha256 -hmac "$MERCURE_PUBLISHER_JWT_KEY" -binary | openssl base64 -e -A | tr -d '=' | tr '/+' '_-')
❯❯ symfony-demo git:(main) 18:46 echo "$HEADER.$PAYLOAD.$SIGNATURE"
eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJtZXJjdXJlIjp7InB1Ymxpc2giOlsic29uZ3MiXX0sImV4cCI6MTc2OTk2Nzk3MH0.15xU6VA_6jn3QcRrt_-MdOIGdxODsOkgeLQxRp-8Nf8
❯❯ symfony-demo git:(main) 18:46 curl -d 'topic=songs' -d 'data={"foo": "updated Value"}' -H 'Authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJtZXJjdXJlIjp7InB1Ymxpc2giOlsic29uZ3MiXX0sImV4cCI6MTc2OTk2Nzk3MH0.15xU6VA_6jn3QcRrt_-MdOIGdxODsOkgeLQxRp-8Nf8' -X POST https://localhost/.well-known/mercure -k
2026/01/31 17:47:03.922 INFO    http.handlers.mercure   Update published        {"update": {"id": "urn:uuid:019c152a-5d71-7b8f-907d-5e8218b61d94", "type": "", "retry": 0, "topics": ["songs"], "private": false}}
2026/01/31 17:47:03.922 INFO    http.log.access handled request {"request": {"remote_ip": "::1", "remote_port": "46446", "client_ip": "::1", "proto": "HTTP/2.0", "method": "POST", "host": "localhost", "uri": "/.well-known/mercure", "headers": {"Accept": ["*/*"], "Authorization": ["REDACTED"], "Content-Length": ["41"], "Content-Type": ["application/x-www-form-urlencoded"], "User-Agent": ["curl/8.16.0"]}, "tls": {"resumed": false, "version": 772, "cipher_suite": 4865, "proto": "h2", "server_name": "localhost"}}, "bytes_read": 41, "user_id": "", "duration": 0.001667541, "size": 45, "status": 200, "resp_headers": {"Content-Security-Policy": ["default-src 'self'"], "Server": ["Caddy"], "Alt-Svc": ["h3=\":443\"; ma=2592000"], "X-Frame-Options": ["DENY"], "X-Content-Type-Options": ["nosniff"], "X-Xss-Protection": ["1; mode=block"]}}
urn:uuid:019c152a-5d71-7b8f-907d-curl -d 'topic=songs' -d 'data={"foo": "updated Value"}' -H 'Authorization: Bearer eyJhbGciOiJIUzI1NiJ9.eyJtZXJjdXJlIjp7InB1Ymxpc2giOlsiKiJdLCJzdWJzY3JpYmUiOlsiaHR0cHM6Ly9leGFtcGxlLmNvbS9teS1wcml2YXRlLXRvcGljIiwie3NjaGVtZX06Ly97K2hvc3R9L2RlbW8vYm9va3Mve2lkfS5qc29ubGQiLCIvLndlbGwta25vd24vbWVyY3VyZS9zdWJzY3JpcHRpb25zey90b3BpY317L3N1YnNjcmliZXJ9Il0sInBheWxvYWQiOnsidXNlciI6Imh0dHBzOi8vZXhhbXBsZS5jb20vdXNlcnMvZHVuZ2xhcyIsInJlbW90ZUFkZHIiOiIxMjcuMC4wLjEifX19.KKPIikwUzRuB3DTpVw6ajzwSChwFw5omBMmMcWKiDcM' -X POST https://localhost/.well-known/mercure -k
2026/01/31 17:47:34.126 INFO    http.log.access handled request {"request": {"remote_ip": "::1", "remote_port": "46448", "client_ip": "::1", "proto": "HTTP/2.0", "method": "POST", "host": "localhost", "uri": "/.well-known/mercure", "headers": {"Accept": ["*/*"], "Authorization": ["REDACTED"], "Content-Length": ["41"], "Content-Type": ["application/x-www-form-urlencoded"], "User-Agent": ["curl/8.16.0"]}, "tls": {"resumed": false, "version": 772, "cipher_suite": 4865, "proto": "h2", "server_name": "localhost"}}, "bytes_read": 0, "user_id": "", "duration": 0.000129447, "size": 13, "status": 401, "resp_headers": {"X-Xss-Protection": ["1; mode=block"], "Content-Security-Policy": ["default-src 'self'"], "X-Frame-Options": ["DENY"], "X-Content-Type-Options": ["nosniff"], "Content-Type": ["text/plain; charset=utf-8"], "Server": ["Caddy"], "Alt-Svc": ["h3=\":443\"; ma=2592000"]}}
Unauthorized # confirmation that the old example token doesn't work for this secret

[hgalt]

Thank you, but I didn't expect, that there is an problem with the Caddyfile. My current problem is, how send a POST message to the Mercure Hub.
To test it with Postman, or use it in my PHP program, I need a list of the required parameters. I'm not using symfony or any other implentation.
So what I need is a complete list of parameters which I have transfered in a funcional POST message to the Mercure Hub. Currently the Hub does not except my Host Header. Please, how has to look the value for a HOST header?

I think, if I'm able to create the right POST message, I have solved my implementation of the Mercure HUB, hopefully!

[henderkes]

I can't help you with Postman, I just don't use it much. You can see a fully working, minimal example in my comment above, using curl in the command line. I think you'll just have to figure this out on your own, since I can't reproduce your problems and the support only extends as far as the software working, not necessarily how to get it working in your specific circumstances.