view mod_pubsub_subscription/README.markdown @ 5468:14b5446e22e1

mod_http_oauth2: Fix returning errors from response handlers This would either redirect the user back to the client along with the error code, or show the error HTML template. Previously this would just show some JSON to the user.
author Kim Alvefur <zash@zash.se>
date Thu, 18 May 2023 12:57:23 +0200
parents 97fac0ba0469
children
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# Introduction

This module lets you programmatically subscribe to updates from a
[pubsub][xep0060] node, even if the pubsub service is remote.

## Example

``` {.lua}
module:depends("pubsub_subscription");
module:add_item("pubsub-subscription", {
    service = "pubsub.example.com";
    node = "otter_facts";

    -- Callbacks:
    on_subscribed = function()
        module:log("info", "Otter facts incoming!");
    end;

    on_item = function(event)
        module:log("info", "Random Otter Fact: %s", event.payload:get_text());
    end;
});
```

## Usage

Ensure the module is loaded and add your subscription via the
`:add_item` API. The item table MUST have `service` and `node` fields
and SHOULD have one or more `on_<event>` callbacks.

The JID of the pubsub service is given in `service` (could also be the
JID of an user for advanced PEP usage) and the node is given in,
unsurprisingly, the `node` field.

The various `on_event` callback functions, if present, gets called when
new events are received. The most interesting would be `on_item`, which
receives incoming items. Available events are:

`on_subscribed`
:   The subscription was successful, events may follow.

`on_unsubscribed`
:   Subscription was removed successfully, this happens if the
    subscription is removed, which you would normally never do.

`on_error`
:   If there was an error subscribing to the pubsub service. Receives a
    table with `type`, `condition`, `text`, and `extra` fields as
    argument.

`on_item`
:   An item publication, the payload itself available in the `payload`
    field in the table provided as argument. The ID of the item can be
    found in `item.attr.id`.

`on_retract`
:   When an item gets retracted (removed by the publisher). The ID of
    the item can be found in `item.attr.id` of the table argument..

`on_purge`
:   All the items were removed by the publisher.

`on_delete`
:   The entire pubsub node was removed from the pubsub service. No
    subscription exists after this.

``` {.lua}
event_payload = {
    -- Common prosody event entries:
    stanza = util.stanza;
    origin = util.session;

    -- PubSub service details
    service = "pubsub.example.com";
    node = "otter_facts";

    -- The pubsub event itself
    item = util.stanza; -- <item/>
    payload = util.stanza; -- actual payload, child of <item/>
}
```

# Compatibility

Should work with Prosody \>= 0.11.x