Diffusion/API/front end

Clare

Hello! We are making good progress with our numismatic catalogue, but we really are struggling to set up the diffusion section to create a front end website. We have read everything and are still confused I am afraid. Can anyone provide a reasonably detailed example of setting up a diffusion to MySQL for web api use? Thanks!

PaCo

Hi Clare

It would be helpful to have more information and to know where you are right now in this regard. That is to say:
Do you have the publication database (MySQL/MariaDB) set up and working?
Are you going to use the default numisdata diffusion domain (config DEDALO_DIFFUSION_DOMAIN) or will you use a custom one?
What type of website are you planning to create (catalogue of types, findings, etc.)?

Alex

Clare We have read everything and are still confused I am afraid

Don't worry... is normal, diffusion is hard.
But, we are here to help you... Putting on some light to scare away the monsters... 👾 🦂 🙀

Best.

Alex

Dédalo has two different system, work system and diffusion system. Work system needs to process data to feed publication system.
The process is controlled by the diffusion ontology.

Previously, you had to install MariaDB or MySQL and create a database with two users: first owner and the second as read-only user.

Then, change the Dédalo configuration.

1.- Review the config_db.php. Here you need to define the connection from Dédalo to MariaDB, the user here has to access as owner of the database. It will used to create tables, fields, indexes, etc. and insert the publication records.

2.- Review the Diffusion variables in config.php. Here you need to set how Dédalo will process your data in the publication process. The most important definition is DEDALO_DIFFUSION_DOMAIN, because is the link to the diffusion ontology node, with the definition of how your data will be transformed, in other words, what is the schema of MariaDB and how Dédalo will transform the original data to flat data in MariaDB. If you are using numisdata you can use the default definition: numisdata48 as:

define('DEDALO_DIFFUSION_DOMAIN', 'numisdata_default')

This point requires more information, but for now, set it to test if you can complete the publication process.

At this point, you will see that you can publish records for example in the numismatic object.

If you don't see the diffusion tool button in the inspector, SOMETHING IS WRONG in the config files. Review previous points.

If the tool is ready, you will see something as:

With your configuration. At this point, you can proceed to publish your record, and test if the record was created in MariaDB.

If all works:

3.- Review the API configuration. server_config_api.php, it will be set with a READ ONLY user of the MariaDB (only SELECT table and columns). This user access to MariaDB and provides the result via publication API REST.

4 Set your API code in config files:

4.1. in config.php

define('API_WEB_USER_CODE_MULTIPLE' , [
        [
            'db_name' => 'dedalo_public',
            'code'  => 'My_code_for_public_API'
        ]
    ]);

4.2 in the server_config_api.php

define('API_WEB_USER_CODE', 'My_API_code');

Both codes must be identical.

Open the API Rest interface. You can open it in Administration->Maintenance and locate the PUBLICATION SERVER API panel:

Click in the Open Swagger UI xxxxxx. button.

Test the API.
Review the ontology behind diffusion, to understand how it works. Because the main idea is that you can create different schemes for different uses, or you can expand the diffusion ontology by your own, with local definitions. (but right now try to use the default to test all process)

Best

Graham

Hello Alex,

This little snippet would be useful in the main docs:
define('DEDALO_DIFFUSION_DOMAIN', 'numisdata_default')

However, getting an error that not able to connect to the database:

I had initially created my own db with the name 'web_dedalo' but wondered if, as using the default numisdata needed to create a db as named: 'web_numisdata_default'. But no change. Swagger reports same issue:

Both users added with appropriate permissions on both tables and put the appropriate settings in the api config as well. So at a bit of loss as to what I have missed.

Alex

Hi Graham

Okay, let me explain how it works.

1 Diffusion is an ontology definition.

2 You can access it in the Ontology menu, but only if you log in as root, developer, or global admin (with permission granted). Any other users are prohibited from accessing it.

3 The ontology defines the diffusion_domain, diffusion_group, and diffusion_element in this manner:

4 In your case, you are using the numisdata_default as the diffusion_domain, so your installation is pointing to this node within the ontology numisdata_default numisdata48.

5 This diffusion_domain contains two diffusion_groups.
- RDF export
- Web publication
Both are displaying in your diffusion tool. So far, everything is fine.

6 The diffusion_group Web publication contains a diffusion_element named Web numisdata default numisdata700.

This node is defined for SQL because it has a yellow P property as;

{
  "diffusion": {
    "class_name": "diffusion_mysql"
}

7 Inside the diffusion_element you have the database schema definition with tables, fields, etc. and the map with the ontology definition for the numismatic objects, types, mints, etc. As you can see the database node is named: web_numisdata_default numisdata869
And this is the name of the database when you are pointing to the numisdata_default as diffusion_domain.
of course, this definition can be changed locally, to create your own schema with a custom database, tables, fields... but, for now, you only need to understand how it works, and make the connections.

Until here is how it is defined. Now, go with the error.

I see in your screenshots that you have the api_web_user_code_multiple --> db_name as web_default

So, it appears that the error lies in the configuration. Okay, first, you need to establish a connection between Dédalo and MariaDB.

1- Review your config_db.php

define('MYSQL_DEDALO_DATABASE_CONN' , 'web_numisdata_default'); // check the name
define('MYSQL_DEDALO_USERNAME_CONN', 'username'); // check the user of MariaDB, it has to be owner
define('MYSQL_DEDALO_PASSWORD_CONN', 'password'); // check the user password
define('DEDALO_DB_PORT_CONN' , 3306); // check the port

If everything is fine, you should use the diffusion tool to populate the database. However, if you keep encountering the same connection error in the diffusion tool: Unable to connect to database web_numisdata_defautl. check your current PHP error log path to see if there are any errors.

tail -f /var/log/php_error.log

Open the diffusion tool and fire the error. If you can't find the error in the log, you can share it here. I'll check it.

2 Check your diffusion multiple: in /config/config.php

it has to be as:

define('API_WEB_USER_CODE_MULTIPLE', [
    [
        'db_name'  => 'web_numisdata_default', // it needs to be the database name
        'code'     => 'Yhf13likE459QwkG987pErl87x' // use your own code
    ]
]);

And I think that all will be ok. If you need help or more explanations, you kwon... 😉

Best

Graham

Thank you, Alex.

Clarity on the DB name to use helped sort this out.

Regards, Graham

Clare

Hi All!

We have managed to use the diffusion to publish a small base set of data, and this worked, and we are now trying to publish the remaining data, but it is now not working - is there anything we need to do for republishing items? All seems fine, but when you press publish it only takes 2 seconds (too short) and nothing has updated.

Alex

Clare we are now trying to publish the remaining data, but it is now not working

Hi Clare

With the information you're providing, it's difficult to determine the issue. Could you please share your PHP error log? When you're setting up the publication, it's crucial to monitor your PHP error log to identify and resolve any problems. Sometimes could be a permissions, sometimes could be a wrong data, sometimes could be a small RAM allocation to PHP, sometimes could be a ?????

To monitor the PHP error, you can use the tail command with the -f flag and reproduce the error in Dédalo.

tail -f /var/log/php/php_error_log

Note: The path and name may vary depending on your GNU/Linux distribution and implementation.

Best

Clare

Are we doing anything wrong? We are struggling to see the error. We are using the standard diffusion ontology for numismatics.

Clare

Any guidance welcome! :-)

Clare

Hi Alex - many thanks for the suggestion of looking at the php. We have used some fields which don't seem to be in the standard diffusion ontology and are getting errors there - I guess we then need to add them to the ontology in the UI to get everything to work? The fields are object (object1)
technique (technique1)
numisdata300
rsc332
numisdata41
numisdata38
material1
numisdata6
I did do some reading on this but I confess I remain a bit bewildered (and scared of breaking things!) Is there any guidance on how to add these, if this is indeed the issue? (I thought maybe things not in the ontology would just not be published, but anyhow).

Alex

Clare

Hi Clare,

I'm a bit confused about your comment regarding the fields you mentioned.

object1 -> thesaurus section for object names as coin or anphorae
technique1 -> thesaurus section for techniques as Struck
material1 -> thesaurus section for materials as gold or silver
numisdata6 -> mints section
rsc332 -> Bibliographic resource section
numisdata41 -> Legend section
numisdata38 -> Design section
numisdata300 -> the thesaurus for catalog.

They are ready to be processed by the default definition of numisdata. I'll show you some of them.

Could you please explain what Dédalo is referring to in the PHP error log regarding these fields?

Best

Clare

We also have (a lot) of this in the logs, but the docs don't say what it needs to be set to, and comment in the file says "// dedalo_entity_id . (From Dédalo private list. You need to be register before but it's not mandatory fill this)" Note that config file default is 0 (Zero) for DEDALO_ENTITY_ID. Review your config
[seq]: diffusion_sql:update_record > diffusion_sql:build_table_columns_data > diffusion_sql:build_data_field > diffusion_sql:generate_rdf > diffusion_rdf:update_record > diffusion_rdf:build_rdf_data > diffusion_rdf:build_rdf_node > diffusion_rdf:build_rdf_node > diffusion_rdf:resolve_base_u>
[03-Mar-2026 09:21:04 Europe/London] ^[[43mDEBUG_LOG [ERROR]
diffusion_rdf::resolve_base_uri Error . this->entity_locator is empty
this->entity_locator: null
constant config DEDALO_ENTITY_ID: 0
base_uri_entity: {
"title": "nomisma",
"section_tipo": "dd1010",
"component_tipo": "dd1014"
}
so we don't think this is the issue? Thanks!

PaCo

Hi Clare

DEDALO_ENTITY_ID is not required in most cases, but it is necessary for RDF export to create the entity publication service locator to use for get the URL base.

The official list is supported by the Dédalo community in the master repository.
E.g. for the MIB installation, DEDALO_ENTITY_ID = 5 (MIB entity id).

Maybe you need to request your own DEDALO_ENTITY_ID (estable URL is needed).

For now, if it is not essential, you can disable RDF from the publication.

I hope this helps.
Let us know how it went.

Best

Clare

PaCo Thanks for the suggestion. We are just using a temporary url at the moment so we don't think we need this (it works as any should?) Let me know if this is not the case. Otherwise we will continue to try and figure out where our error is coming from. :-)

Alex

Hi Clare.

The DEDALO_ENTITY_ID is used to match it with the nomisma ID. When you want to share data in OCRE or any other aggregated portal that uses Nomisma, you need to have a Nomisma ID, which is the URI representing your identification in the Nomisma ontology.

For example, Moneda Ibérica has this Nomisma ID:
https://nomisma.org/id/mib

This ID must be included in the RDF of your data, so the DEDALO_ENTITY_ID indicates where this Nomisma's unique ID resides within the Dédalo ontology, because you can share your data in others standards that use others ID, the DEDALO_ENTITY_ID is the unique identifier for all of them.

If you don't want to share your data in RDF Nomisma format, you can use any existing ID as @PaCo suggests. However, if you want to share your data with RDF, you'll need both the Nomisma ID (ask any Nomisma members) and your DEDALO_ENTITY_ID.

I hope is clear.

Best

Clare

Thanks that makes sense, thanks! Ok we think then the issue may be we have used fields that are not in the standard numisdata ontology UI - we will try and put these in and try again. :-)

Graham

Hello Alex,

Here is the output from the diffusion:
{ "pid": 180549, "pfile": "process_-1_2026-03-04_17-36-27_219586143820478", "is_running": false, "data": { "result": true, "msg": [ "EXCEPTION caught [export_list]: $uri is null and EasyRdf\\Graph object has no URI either.", "Warning. Request done with some errors: 1" ], "errors": [ "$uri is null and EasyRdf\\Graph object has no URI either." ], "diffusion_data": [], "memory": "64 MB", "last_update_record_response": { "result": true, "msg": [ "Record updated section_id: 2. Number of references: 11 in levels: 2" ], "errors": [], "class": "diffusion_mysql" }, "time": "2 sec" }, "time": "2026-03-04 17:36:29", "total_time": "2 sec", "update_rate": 1000, "errors": [] }

Too much mess in the .log file, to include here, will e-mail separately.

Regards, Graham

Alex

Graham "EXCEPTION caught [export_list]: $uri is null and EasyRdf\Graph object has no URI either.",
"Warning. Request done with some errors: 1"

Okay, I understand. The issue lies in the RDF process. Some resources lack an URI or have an invalid URI, making it impossible to create the graph.

In RDF is mandatory that every resource has its own URI. If your data doesn't define a nomisma URI for each resource, the process will fail. And it stop all diffusion process. Nothing is wrong for the MariaDB process, but the RDF creation stop all and nothing is saved into the SQL.

DEDALO_ENTITY_ID provides a safe way to solve it, because it defines a common base uri for all your data.

Okay, here's a question: would you like your Dédalo to create the RDF graph?

Since I suppose you'd like that, we've opened the DEDALO_ENTITY_ID for you as a provisional config. It currently has a fake URI that can be replaced with the "correct" one once you have your nomisma ID and final URI.

Your DEDALO_ENTITY_ID is 16

Add it into your configuration, locate it into /dedalo/config/config.php

define('DEDALO_ENTITY_ID', 16);

And update your ontology to obtain the configuration, of your DEDALO_ENTITY_ID

https://dedalo.dev/docs/management/updates/updating_ontology/

I hope that it resolves the RDF situation... 😉

Best