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[mkws-moved-to-github.git] / doc / mkws-developer.markdown

diff --git a/doc/mkws-developer.markdown b/doc/mkws-developer.markdown
index 3d92fc3..a299eeb 100644 (file)
--- a/doc/mkws-developer.markdown
+++ b/doc/mkws-developer.markdown
@@ -1,16 +1,27 @@
 % The MasterKey Widget Set developer's guide
 % Mike Taylor
 % The MasterKey Widget Set developer's guide
 % Mike Taylor

-% 11 August 2014
+% November 2014
+
+
+Introduction
+============
+
+This manual is for people who want to build the widget set from
+source, develop the widget set's core code, or (more likely) create
+their own widgets as extensions to the main set.
+
+Those who want to use existing widgets should read
+[The MKWS manual: embedded metasearching with the MasterKey Widget
+Set](mkws-manual.html) instead.

 
 
 Required development tools
 ==========================
 
 
 
 Required development tools
 ==========================
 

-If you are building the widget set, as opposed to just using it, you
-will need the following Debian packages (or their equivalents on your
-operating system):
+If you are building the widget set, you will need the following Debian
+packages (or their equivalents on your operating system):

 
 

-       $ sudo apt-get install curl git make unzip \
+       $ sudo apt-get install curl git make unzip apache2 \

            pandoc yui-compressor libbsd-resource-perl
 
 You also need Node.js, but unfortunately the `node-js` package is not
            pandoc yui-compressor libbsd-resource-perl
 
 You also need Node.js, but unfortunately the `node-js` package is not

@@ -20,42 +31,86 @@ http://nodejs.org/download/ and build it yourself. You need both Node
 itself and its package manager NPM: `make install` puts them into
 `/usr/local/bin`.
 
 itself and its package manager NPM: `make install` puts them into
 `/usr/local/bin`.
 

-To compile the default templates you'll need to install the stable
-version of Handlebars. Currently it's at 2.0.0 and available by npm:

 
 

-       $ npm install handlebars@2.0.0 -g
+Concepts
+========
+
+Code structure
+--------------

 
 

+The code of the widget set is in four main layers, described here from
+the bottom up:

 
 

-Overview
-========
+1. The core code, which manages the set of widget teams, default
+options, authentication onto the Service Proxy, and the creation of
+widgets from HTML elements.
+This code is in `mkws-core.js`
+
+2. The team code, which manages teams of widgets. This is responsible
+for the collections of widgets that make up teams, event queues, and
+handling search-and-retrieval events
+This code is in `mkws-team.js`
+
+3. The generic widget code, which handles the creation of widget
+objects, parsing configuration attributes from their HTML elements,
+and firing off automatic searches.
+
+4. The code for individual widgets, which is specific to those
+widgets. It often involves subscribing to events and responding to
+them by setting the HTML of the widget element, but need not do
+so. The code for many of the most important widgets is in
+`mkws-widget-main.js`, but certain other widgets are defined in other
+files beginning with the prefix `mkws-widget-`.

 
 

-Core concepts
--------------
+In addition to this code, there are several source files containing
+support code:
+
+* `mkws-filter.js` contains support routine implementing the
+filter-set data structure, which contains information about which
+filters (e.g. by target, or by facet) are in force.
+
+* `mkws-handlebars.js` contains Handlebars helpers which can be used
+by the HTML templates.
+
+* `mkws-popup.js` defines a special widget for creating popup
+  windows. These may, but need not, contain other MKWS widgets,
+  forming a popup searching application.
+
+The final component of the source code is the set of Handlebars
+templates, in the `templates` directory, which are used to emit the
+HTML of the various widgets' contents. These are compiled into the
+file `mkws-templates.js`.
+
+
+
+Defining new types of widget
+----------------------------

 
 Development with MKWS consists primarily of defining new types of
 
 Development with MKWS consists primarily of defining new types of

-widgets. These can interact with the core functionality is several
-defined ways.
+widgets. This is done using exactly the same API as the the widgets
+that come as part of the set: they have no privileged access.

 
 You create a new widget type by calling the `mkws.registerWidgetType`
 function, passing in the widget name and a function. The name is used
 to recognise HTML elements as being widgets of this type -- for
 
 You create a new widget type by calling the `mkws.registerWidgetType`
 function, passing in the widget name and a function. The name is used
 to recognise HTML elements as being widgets of this type -- for

-example, if you register a `Foo` widget, elements like
-`<div class="mkwsFoo">` will be widgets of this type.
+example, if you register a `foo` widget, elements like
+`<div class="mkws-foo">` will become widgets of this type.

 
 

-The function promotes a bare widget object (passed as `this`) into a
+The function promotes a bare widget object (which is created by the
+core widget code and passed in as `this`) into a

 widget of the appropriate type. MKWS doesn't use classes or explicit
 prototypes: it just makes objects that have the necessary
 behaviours. There are _no_ behaviours that Widgets are obliged to
 provide: you can make a doesn't-do-anything-at-all widget if you like:
 
 widget of the appropriate type. MKWS doesn't use classes or explicit
 prototypes: it just makes objects that have the necessary
 behaviours. There are _no_ behaviours that Widgets are obliged to
 provide: you can make a doesn't-do-anything-at-all widget if you like:
 

-       mkws.registerWidgetType('Sluggard', function() {});
+       mkws.registerWidgetType('sluggard', function() {});

 
 More commonly, widgets will subscribe to one or more events, so that
 they're notified when something interesting happens. For example, the
 
 More commonly, widgets will subscribe to one or more events, so that
 they're notified when something interesting happens. For example, the

-`Log` widget asks to be notified when a `log` event happens, and
+`log` widget asks to be notified when a `log` event happens, and

 appends the logged message to its node, as follows:
 
 appends the logged message to its node, as follows:
 

-       mkws.registerWidgetType('Log', function() {
+       mkws.registerWidgetType('log', function() {

          var that = this;
 
          this.team.queue("log").subscribe(function(teamName, timestamp, message) {
          var that = this;
 
          this.team.queue("log").subscribe(function(teamName, timestamp, message) {

@@ -77,11 +132,11 @@ This simple widget illustrates several important points:
 * You can add functionality to a widget by subscribing it to an
   event's queue using `this.team.queue("EVENT").subscribe`. The
   argument is a function which is called whenever the event is
 * You can add functionality to a widget by subscribing it to an
   event's queue using `this.team.queue("EVENT").subscribe`. The
   argument is a function which is called whenever the event is

-  published. The arguments to the function are different for different
-  events.
+  published. The arguments to the event-callback function are
+  different for different events.

 
 * As with so much JavaScript programming, the value of the special
 
 * As with so much JavaScript programming, the value of the special

-  variable `this` is lost inside the `subscribez` callback function,
+  variable `this` is lost inside the `subscribe` callback function,

   so it must be saved if it's to be used inside that callback
   (typically as a local variable named `that`).
 
   so it must be saved if it's to be used inside that callback
   (typically as a local variable named `that`).
 

@@ -90,13 +145,13 @@ Widget specialisation (inheritance)
 -----------------------------------
 
 Many widgets are simple specialisations of existing widgets. For
 -----------------------------------
 
 Many widgets are simple specialisations of existing widgets. For

-example, the `Record` widget is the same as the `Records` widget
-except that it defaults to displaying a single record. It's defined as
-follows:
+example, the `images` widget is the same as the `records` widget
+except that it defaults to using the `images` template for displaying
+its result list. It's defined as follows:

 
 

-       mkws.registerWidgetType('Record', function() {
-         mkws.promotionFunction('Records').call(this);
-         if (!this.config.maxrecs) this.config.maxrecs = 1;
+       mkws.registerWidgetType('images', function() {
+         mkws.promotionFunction('records').call(this);
+         if (!this.config.template) this.config.template = 'images';

        });
 
 Remember that when a promotion function is called, it's passed a base
        });
 
 Remember that when a promotion function is called, it's passed a base

@@ -106,11 +161,11 @@ that you want to specialise from -- in this case, `Records` -- using
 the promotion function that's been registered for that type.
 
 Once this has been done, the specialisations can be introduced. In
 the promotion function that's been registered for that type.
 
 Once this has been done, the specialisations can be introduced. In

-this case, it's a very simple matter of changing the `maxrecs`
-configuration setting to 1 unless it's already been given an explicit
-value. (That would occur if the HTML used an element like `<div
-class="mkwsRecord" maxrecs="2">`, though it's not obvious why anyone
-would do that.)
+this case, it's a very simple matter of changing the `template`
+configuration setting to `'images'` unless it's already been given an
+explicit value. (That would occur if the HTML used an element like
+`<div class="mkws-images" template="my-images">` to use a customised
+template.

 
 
 Reference Guide
 
 
 Reference Guide

@@ -125,7 +180,8 @@ that is passed into `registerWidgetType`'s callback function, and can
 be used by the derived widget.
 
 * `String this.type` --
 be used by the derived widget.
 
 * `String this.type` --

-       A string containing the type of the widget.
+       A string containing the type of the widget (`search`,
+       `switch`, etc.)

 
 * `Team this.team` --
        The team object to which this widget belongs. The team has
 
 * `Team this.team` --
        The team object to which this widget belongs. The team has

@@ -133,7 +189,8 @@ be used by the derived widget.
        below.
 
 * `DOMElement this.node` --
        below.
 
 * `DOMElement this.node` --

-       The DOM element of the widget
+       The DOM element of the widget. Most often used for inserting
+       HTML into the widget element.

 
 * `Hash this.config` --
        A table of configuration values for the widget. This table
 
 * `Hash this.config` --
        A table of configuration values for the widget. This table

@@ -142,7 +199,7 @@ be used by the derived widget.
        inherits from the default configuration. Instances of widgets
        in HTML can set configuration items as HTML attributes: for
        example, the HTML element
        inherits from the default configuration. Instances of widgets
        in HTML can set configuration items as HTML attributes: for
        example, the HTML element

-       `<div class="mkwsRecords" maxrecs="10">`.
+       `<div class="mkwsRecords" maxrecs="10">`

        creates a widget for which `this.config.maxrecs` is set to 10.
 
 * `String this.toString()` --
        creates a widget for which `this.config.maxrecs` is set to 10.
 
 * `String this.toString()` --

@@ -164,16 +221,6 @@ be used by the derived widget.
        widgets such as `Records` and `Facet` that display some part
        of a search result.
 
        widgets such as `Records` and `Facet` that display some part
        of a search result.
 

-* `VOID hideWhenNarrow()` --
-       Registers that this widget should hide itself when the page
-       becomes "narrow" -- that is, fewer pixels in width that the
-       threshhold value specified by the top-level configuration item
-       `responsive_design_width`. Should be used for "unimportant"
-       widgets that can be omitted from the mobile version of a site.
-
-* `expandValue()` --
-       TODO: either document this or remove it from the API.
-

 * `subwidget(type, overrides, defaults)` --
        Returns the HTML of a subwidget of the specified type, which
        can then be inserted into the widget using the
 * `subwidget(type, overrides, defaults)` --
        Returns the HTML of a subwidget of the specified type, which
        can then be inserted into the widget using the

@@ -182,20 +229,15 @@ be used by the derived widget.
        except where overrides are passed in. If defaults are also
        provided, then these are used when the parent widget provides
        no values. Both the `overrides` and `defaults` arguments are
        except where overrides are passed in. If defaults are also
        provided, then these are used when the parent widget provides
        no values. Both the `overrides` and `defaults` arguments are

-       hashes: the latter is optional.
-  
-       See for example the `Credo` widget defined in the example
-       area's `mkws-widget-credo.js` file. This uses several
-       invocations of `subwidget` to create a complex compound widget
-       with numerous text, facet and image panes. TODO: rename this
-       widget and everything related to it.
+       hashes: the latter is optional. This can be used to assemble
+       compound widgets containing several subwidgets.

 
 In addition to these properties and methods of the bare widget object,
 some kinds of specific widget add other properties of their own. For
 
 In addition to these properties and methods of the bare widget object,
 some kinds of specific widget add other properties of their own. For

-example, the `Builder` widget uses a `callback` property as the
+example, the `builder` widget uses a `callback` property as the

 function that it use to publish the widget definition that it
 constructs. This defaults to the builtin function `alert`, but can be
 function that it use to publish the widget definition that it
 constructs. This defaults to the builtin function `alert`, but can be

-overridden by derived widgets such as `ConsoleBuilder`.
+overridden by derived widgets such as `console-builder`.

 
 
 Team methods
 
 
 Team methods

@@ -276,7 +318,7 @@ API should get simpler.
 Events
 ------
 
 Events
 ------
 

-TODO: list of events that can be usefully subscribed to.
+FIXME: list of events that can be usefully subscribed to.

 
 
 - - -
 
 
 - - -