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CREATE_BRIDGE.md
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# Howto create a bridge
A bridge is an interface that allows rss-bridge to create a RSS feed from a website.
The bridge is a PHP file, located in the `bridges/` folder.
A bridge is an class that allows rss-bridge to create a RSS feed from a website.
The bridge is a PHP file, located in the [`bridges/`](bridges/) folder.
##Specifications
Read the following chapters an make sure to read the [Guidelines](#guidelines)!
A rss bridge must extend the `BridgeAbstract` class, and implement the following functions :
## Specifications
* The `loadMetadatas` function, described below,
* The `getCacheDuration` function, describing the time during which rss-bridge will output cached values instead of re-generating a RSS feed.
* The `collectData` function, also described below.
A rss bridge must extend the `BridgeAbstract` class and implement the following functions :
##The `collectData` function
* [`loadMetadatas`](#the-loadmetadatas-function)
* [`collectData`](#the-collectdata-function)
* [`getName`](#the-getname-function)
* [`getURI`](#the-geturi-function)
* [`getCacheDuration`](#the-getcacheduration-function)
This function takes as a parameter an array called `$param`, that is automatically filled with values from the user, according to the values setted in `loadMetadatas`.
This function is the place where all the website scrapping and the RSS feed generation process will go.
Find a [template](#template) at the end of this file.
The RSS elements are stored in the class variable `items[]`.
## The `loadMetadatas` function
Every RSS element is an instance of the `Item` class.
This function is used by rss-bridge to determine the name, maintainer name, website, last updated date... of the bridge, and the user parameters.
##The `loadMetadatas` function
### Basic metadatas
This function is the one used by rss-bridge core to determine the name, maintainer name, website, last updated date... of the bridge, and the user parameters.
### Basic metadatas.
The basic metadatas are the following :
The basic metadatas are :
```PHP
$this->maintainer
$this->name
$this->uri
$this->description
$this->update
$this->maintainer // Name of the maintainer
$this->name // Name of the bridge
$this->uri // URI to the target website of the bridge ("http://....")
$this->description // A brief description of the bridge
$this->update // Date of last change in format "yyyy-mm-dd"
$this->parameters // (optional) Definition of additional parameters
```
The default values are the following :
Find a description of `$this->parameters` [below](#parameters)
The default values are :
```PHP
$this->maintainer = 'No maintainer';
$this->name = "Unnamed bridge";
$this->uri = "";
$this->description = 'No description provided';
$this->maintainer = 'No maintainer';
$this->parameters = array();
```
### Parameters
Parameters use a JSON-like format, which is parsed and transformed to HTML `<form>` by rss-bridge.
Parameters are defined in a JSON-like format, which is parsed and transformed into a HTML `<form>` by rss-bridge.
These datas goes into the `$this->parameters` array, which is not mandatory if your bridge doesn't take any parameter.
@ -59,47 +60,188 @@ The array can be a key-based array, but it is not necessary. The following synta
$this->parameters[] = ...
$this->parameters['First usage of my bridge'] = ...
```
It is worth mentionning that you can also define a set of parameters that will be applied to every possible utilisation of your bridge.
To do this, just create a parameter array with the `global` key.
To do this, just create a parameter array with the `global` key :
```PHP
$this->parameters['global'] = ...
```
### Format specifications
Every `$this->parameters` element is a JSON array (`[ ... ]`) containing every input.
Every `$this->parameters` element is a JSON array of cluster (`[ ... ]`) containing all input fields.
It needs the following elements to be setted :
* name, the input name as displayed to the user
* identifier, which will be the key in the `$param` array for the corresponding data.
Following elements are supported :
Hence, the most basic parameter definition is the following:
Parameter Name | Required | Type | Supported values | Description
---------------|----------|------|------------------| -----------
`name`|**yes**|Text||Input name as displayed to the user
`identifier`|**yes**|Text||Identifier, which will be the key in the `$param` array for the [`collectData`](#the-collectdata-function) function
`type`|no|Text|`text`, `number`, `list`, `checkbox`|Type of the input, default is text
`required`|no|Boolean|`true`, `false`|Set this if you want your attribute to be required
`values`|no|Text|`[ {"name" : option1Name, "value" : "option1Value"}, ... ]`| Values list, required with the '`list`' type
`title`|no|Text||Will be shown as tooltip when mouse-hovering over the input
Hence, the most basic parameter definition is the following :
```PHP
$this->parameters =
...
$this->parameters[] =
'[
{
"name" : "Username",
"identifier" : "u"
}
]';
...
```
####Optional parameters
## The `collectData` function
Here is a list of optional parameters for the input :
This function takes as a parameter an array called `$param`, that is automatically filled with values from the user, according to the values defined in the parameters array in `loadMetadatas`.
This function is the place where all the website scrapping and the RSS feed generation process must be implemented.
Parameter Name | Parameter values | Description
---------------|------------------|------------
type|text, number, list, checkbox| Type of the input, default is text
required| true | Set this if you want your attribute to be required
values| [ {"name" : option1Name, "value" : "option1Value"}, ...] | Values list, required with the 'list' type
title| text | Will be shown as tooltip when mouse-hovering over the input
RSS elements collected by this function must be stored in the class variable `items[]`.
#### Guidelines
Every RSS element is an instance of the `Item` class.
* scripts (eg. Javascript) must be stripped out. Make good use of `strip_tags()` and `preg_replace()`
* bridge must present data within 8 seconds (adjust iterators accordingly)
* cache timeout must be fine-tuned so that each refresh can provide 1 or 2 new elements on busy periods
* `<audio>` and `<video>` must not autoplay. Seriously.
* do everything you can to extract valid timestamps. Translate formats, use API, exploit sitemap, whatever. Free the data!
* don't create duplicates. If the website runs on WordPress, use the generic WordPress bridge if possible.
* maintain efficient and well-commented code :wink:
## Items
The `Item` class is used to store parameter that are collected in the [`collectData`](#the-collectdata-function) function. Following properties are supported by rss-bridge :
```PHP
$item->uri // URI to reach the subject ("http://...")
$item->thumbnailUri // URI for the thumbnail ("http://...")
$item->title // Title of the item
$item->name // Name of the item
$item->timestamp // Timestamp of the item in numeric format (use strtotime)
$item->author // Name of the author
$item->content // Content in HTML format
```
In order to create a new item you'll have to escape the **I** in **I**tem like this :
```PHP
$item = new \Item();
```
### Item usage
Which items are necessary depends on the output format. There are two formats that support literally any property in the `$item`:
* JSON
* Plaintext
The following list provides an overview of the parameters used by the other formats :
Parameter | ATOM | HTML | (M)RSS
----------|------|------|-------
`uri`|X|X|X
`thumbnailUri`||X
`title`|X|X|X
`name`|X||
`timestamp`|X|X|X
`author`|X|X|X
`content`|X|X|X
## The `getName` function
This function returns the name of the bridge as it will be displayed on the main page of rss-bridge or on top of the feed output (HTML, ATOM, etc...).
```PHP
public function getName(){
return ''; // Insert your bridge name here!
}
```
## The `getURI` function
This function returns the URI to the destination site of the bridge. It will be used on the main page of rss-bridge when clicking your bridge name.
```PHP
public function getURI(){
return ''; // Insert your URI here!
}
```
## The `getCacheDuration` function
This function returns the time in **seconds** during which rss-bridge will output cached values instead of re-generating a RSS feed.
```PHP
public function getCacheDuration(){
return 3600; // 1 hour
}
```
# Bridge Abstract functions
All bridges extend from `BridgeAbstract` and therefore are able to make use of functions defined in `BridgeAbstract`.
Following functions should be used for good practice and will support you with your bridge :
* [`returnError`](#the-returnerror-function)
* [`file_get_html`](#the-file_get_html-function)
## The `returnError` function
This function aborts execution of the current bridge and returns the given error message with the provided error number :
```PHP
$this->returnError('Your error message', 404)
```
Check the [list of error codes](https://en.wikipedia.org/wiki/List_of_HTTP_status_codes) for applicable error numbers.
## The `file_get_html` function
This function is a wrapper around the simple_html_dom file_get_html function in order to provide context by design. It is considered good practice to use this function.
```PHP
$html = $this->file_get_html('your URI');
```
# Guidelines
* scripts (eg. Javascript) must be stripped out. Make good use of `strip_tags()` and `preg_replace()`
* each bridge must present data within 8 seconds (adjust iterators accordingly)
* cache timeout must be fine-tuned so that each refresh can provide 1 or 2 new elements on busy periods
* `<audio>` and `<video>` must not autoplay. Seriously.
* do everything you can to extract valid timestamps. Translate formats, use API, exploit sitemap, whatever. Free the data!
* don't create duplicates. If the website runs on WordPress, use the generic WordPress bridge if possible.
* maintain efficient and well-commented code :wink:
# Template
This is a template for a new bridge:
```PHP
<?php
class MySiteBridge extends BridgeAbstract{
public function loadMetadatas(){
$this->maintainer = 'No maintainer';
$this->name = $this->getName();
$this->uri = $this->getURI();
$this->description = 'No description provided';
$this->parameters = array();
}
public function collectData(array $params){
// Implement your bridge here!
}
public function getName(){
return ''; // Insert your bridge name here!
}
public function getURI(){
return ''; // Insert your URI here!
}
public function getCacheDuration(){
return 3600; // 1 hour
}
}
```