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There are lots of practical problems in building resource discovery solutions. One of the biggest, and most ubiquitous is incorporating metasearching functionality into existing web-sites -- for example, content-management systems, library catalogues or intranets. In general, even when access to core metasearching functionality is provided by simple web-services such as Pazpar2, integration work is seen as a major part of most projects.

Index Data provides several different toolkits for communicating with its metasearching middleware, trading off varying degrees of flexibility against convenience:

All but the last of these approaches require programming to a greater or lesser extent. Against this backdrop, we introduce MKWS (the MasterKey Widget Set) -- a set of simple, very high-level HTML+CSS+JavaScript components that can be incorporated into any web-site to provide MasterKey searching facilities. By placing <div>s with well-known MKWS classes in any HTML page, the various components of an application can be embedded: search-boxes, results areas, target information, etc.

Simple example

The following is a complete MKWS-based searching application:

    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    <title>MKWS demo client</title>
    <script type="text/javascript" src="//"></script>
    <link rel="stylesheet" href="//" />
    <div class="mkws-search"></div>
    <div class="mkws-results"></div>

Go ahead, try it! Simply put the above in a file (e.g. index.html), drop it into a folder accessible with an ordinary web-server (e.g. Apache HTTP Server) and load it in your web browser. Just like that, you have working metasearching.

How the example works

If you know any HTML, the structure of the file will be familiar to you: the <html> element at the top level contains a <head> and a <body>. In addition to whatever else you might want to put on your page, you can add MKWS elements.

These fall into two categories. First, the prerequisites in the HTML header, which are loaded from the tool site

Second, within the HTML body, <div> elements with special classes that begin mkws- can be provided. These are filled in by the MKWS code, and provide the components of the searching UI. The very simple application above has only two such widgets: a search box and a results area. But more are supported.

Defining widget elements

Widget type

An HTML element is made into an MKWS widget by including an MKWS class-name. These names begin mkws- and what follows that prefix specifies the type of the widget. The type can be any sequence of alphanumeric characters and hyphens except something beginning team -- see below.

The main widgets are:

To see all of these working together, just put them all into the HTML <body> like so:

<div class="mkws-switch"></div>
<div class="mkws-lang"></div>
<div class="mkws-progress"></div>
<div class="mkws-search"></div>
<div class="mkws-results"></div>
<div class="mkws-targets"></div>
<div class="mkws-stat"></div>

The full set of supported widgets is described in the reference guide below.

Widget team

In general a set of widgets work together in a team: in the example above, the search-term that the user enters in the mkws-search widget is used to generate the set of records that are displayed in the mkws-results widget.

Sometimes, it's desirable to have multiple teams in a single page. A widget can be placed in a named team by giving it (in addition to its main class) a class that begins with mkws-team- and what follows that prefix specifies the team that the widget is part of. For example, <div class="mkws-search mkws-team-aux"> creates a search widget that is part of the aux team.

Widgets that do not have a team specified (as in the examples above) are placed in the team called AUTO.

Configuring widgets

Global configuration

Many aspects of the behaviour of MKWS can be modified by setting parameters into the mkws_config object. So the HTML header looks like this:

<script type="text/javascript">
  var mkws_config = {
    lang_options: [ "en", "da" ]
    lang: "da",
    sort_default: "title",
<script type="text/javascript" src=""></script>

This configuration restricts the set of available UI languages English and Danish (omitting German), sets the default to Danish (rather than the English), and initially sorts search results by title rather than relevance (though as always this can be changed in the UI).

The full set of supported configuration settings is described in the reference guide below.

Per-widget configuration

In addition to the global configuration provided by the mkws_config object, individual widgets' behaviour can be configured by providing configuration settings as attributes on their HTML elements. For example, a records widget might be restricted to displaying no more than three records by setting the maxrecs parameter as follows:

<div class="mkws-records" maxrecs="3">

Although this works well, HTML validators will consider this element unacceptable, since the maxrecs attribute is not part of the HTML schema. However, attributes beginning data- are always accepted as HTML extensions, much like email headers beginning with X-. Therefore, the widget set also recognises configuration attributes prefixed with data-mkws-, so:

<div class="mkws-records" data-mkws-maxrecs="3">

The first form is more convenient; the second is more correct.

Because some configuration settings take structured values rather than simple strings, they cannot be directly provided by inline attributes. To allow for this, the special attribute data-mkws-config, if provided, is parsed as JSON and its key-value pairs used as configuration settings for the widget in question. For example, the value of lang_options is an array of strings specifying which of the supported UI languages should be made available. The following invocation will limit this list to only English and Danish (omitting German):

<div class="mkws-lang" data-mkws-config='{ "lang_options": [ "en", "da" ] }'></div>

(Note that, as JSON requires double quotes around all strings, single quotes must be used to contain the entire attribute value.)

Control over HTML and CSS

More sophisticated applications will not simply place the widgets together, but position them carefully within an existing page framework -- such as a Drupal template, an OPAC or a SharePoint page.

While it's convenient for simple applications to use a monolithic mkws-results area which contains record, facets, sorting options, etc., customised layouts may wish to treat each of these components separately. In this case, mkws-results can be omitted, and the following lower-level widgets provided instead:

Customisation of MKWS searching widgets can also be achieved by overriding the styles set in the toolkit's CSS stylesheet. The default styles can be inspected in mkws.css and overridden by any styles that appear later in the HTML. At the simplest level, this might just mean changing fonts, sizes and colours, but more fundamental changes are also possible.

To properly apply styles, it's necessary to understand how the HTML is structured, e.g. which elements are nested within which containers. The structures used by the widget-set are described in the reference guide below.

Customised display using Handlebars templates

A lot can be done by styling widgets in CSS and changing basic MKWS config options. For further customisation, MKWS allows you to change the markup it outputs for any widget. This is done by overriding the Handlebars template used to generate it. In general these consist of {{things in double braces}} that are replaced by values from the system. For details of Handlebars template syntax, see the online documentation.

The templates used by the core widgets can be viewed in our git repository. Parameters are documented in a comment at the top of each template so you can see what's going where. If all you want to do is add a CSS class to something or change a span to a div it's easy to just copy the existing template and make your edits.

Overriding templates

To override the template for a widget, include it inline in the document as a <script> tag marked with a class of mkws-template-foo where foo is the name of the template you want to override (typically the name of the widget). Inline Handlebars templates are distinguished from JavaScript via a type="text/x-handlebars-template" attribute. For example, to override the pager template you would include this in your document:

<script class="mkws-template-pager" type="text/x-handlebars-template"> Pager template

The Facet template has a special feature where you can override it on a per-facet basis by adding a dash and the facet name as a suffix e.g. facet-subjects. (So class="mkws-template-facet-subjects".) When rendering a facet for which no specific template is defined, the code falls back to using the generic facet template, just called facet.

You can also explicitly specify a different template for a particular instance of a widget by providing the name of your alternative (e.g. special-pager) as the value of the template key in the MKWS config object for that widget: for example, <div class="mkws-pager" template="special-pager"/>.

Templates for MKWS can also be precompiled. If a precompiled template of the same name is found in the Handlebars.templates object, it will be used instead of the default.

Inspecting metadata for templating

MKWS makes requests to the Service Proxy or Pazpar2 that perform the actual searching. Depending on how these are configured and what is available from the targets you are searching, there may be more data available than what is presented by the default templates.

Handlebars offers a convenient log helper that will output the contents of a variable for you to inspect. This lets you look at exactly what is being returned by the back-end without needing to use a JavaScript debugger. For example, you might prepend {{log hits}} to the Records template in order to see what is being returned with each search result in the list. In order for this to work, you will need to enable verbose output from Handlebars which is done by including this line or similar:

<script>Handlebars.logger.level = 1;</script>


If you would like your template to use the built-in translation functionality, output locale specific text via the mkws-translate helper like so: {{{mkws-translate "a few words"}}}.


Rather than use the toolkit's included AJAX helpers to render record details inline, here's a summary template that will link directly to the source via the address provided in the metadata as the first element of md-electronic-url:

<script class="mkws-template-summary" type="text/x-handlebars-template">
  <a href="{{md-electronic-url.[0]}}">
  {{#if md-title-remainder}}
  {{#if md-title-responsibility}}

For a more involved example where markup for multiple widgets is decorated with Bootstrap classes and a custom Handlebars helper is employed, take a look at the source of topic.html.

Some Refinements

Message of the day

Some applications might like to open with content in the area that will subsequently be filled with result-records -- a message of the day, a welcome message or a help page. This can be done by placing an mkws-motd division anywhere on the page. It will initially be moved into the mkws-results area and displayed, but will be hidden as soon as the first search is made.

The jQuery UI library can be used to construct MKWS applications in which the only widget generally visible on the page is a search box, and the results appear in a popup. The key part of such an application is this invocation of the MKWS jQuery plugin:

<div class="mkws-search"></div>
<div class="mkws-popup" popup_width="1024" popup_height="650">
  <div class="mkws-results"></div>

The necessary scaffolding can be seen in an example application, popup.html.

The relevant properties (popup_width, etc.) are documented below in the reference section.

MKWS target selection


MKWS accesses targets using the Pazpar2 metasearching engine. Although Pazpar2 can be used directly, using a statically configured set of targets, this usage is unusual. More often, Pazpar2 is fronted by the Service Proxy (SP), which manages authentication, sessions, target selection, etc. This document assumes the SP is used, and explains how to go about making a set of targets (a "library") available, how to connect your MKWS application to that library, and how to choose which of the available targets to use.

By default MKWS configures itself to use an account on a service hosted by By default, it sends no authentication credentials, allowing the appropriate account to be selected on the basis of referring URL or IP address.

If no account has been set up to recognise the referring URL of the application or the IP address of the client, then a default "MKWS Demo" account is used. This account (which can also be explicitly chosen by using the username mkws, password mkws) provides access to about a dozen free data sources.

In order to search in a customised set of targets, including subscription resources, it's necessary to create an account with Index Data's hosted Service Proxy, and protect that account with authentication tokens (to prevent unauthorised use of subscription resources).

Maintaining the library

The Service Proxy accesses sets of targets that are known as "libraries". In general, each customer will have their own library, though some standard libraries may be shared between many customers -- for example, a library containing all open-access academic journals. A library can also contain other configuration information, including the set of categories by which targets are classified for the library.

Libraries are maintained using MKAdmin (MasterKey Admin). Specifically, those used by MKWS are generally maintained on the "MKX Admin" installation at In general, Index Data will create a library for each customer, then give the customer a username/password pair that they can use to enter MKAdmin and administrate that library.

Once logged in, customers can select which targets to include (from the list of several thousand that MKAdmin knows about), and make customer-specific modifications to the target profiles -- e.g. overriding the titles of the targets.

Most importantly, customers' administrators can add authentication credentials that the Service Proxy will use on their behalf when accessing subscription resources -- username/password pairs or proxies to use for IP-based authentication. Note that it is then crucial to secure the library from use by unauthorised clients, otherwise the customer's paid subscriptions will be exploited.

Access to libraries is managed by creating one or more "User Access" records in MKAdmin, under the tab of that name. Each of these records provides a combination of credentials and other data that allow an incoming MKWS client to be identified as having legitimate access to the library. The authentication process, described below, works by searching for a matching User Access record.

Authenticating your MWKS application onto the library

Some MKWS applications will be content to use the default library with its selection of targets. Most, though, will want to define their own library providing a different range of available targets. An important case is that of applications that authenticate onto subscription resources by means of back-end site credentials stored in MKAdmin: precautions must be taken so that such library accounts do not allow unauthorised access.

Setting up such a library is a process of several stages.

Create the User Access account

Log in to MKAdmin to add a User Access account for your library:

If your MWKS application runs at a well-known, permanent address --, say -- you can set the User Access record so that this originating URL is recognised by setting it into the "Referring URL" field. Then the application will always use the library that this User Access record is associated with (unless it sends a username/password pair to override this default).

Or if your application's users are coming from a well-known range of IP-address space, you can enter the range in the "IP Ranges" field. The format of this field is as follows: it can contain any number of ranges, separated by commas; each range is either a single IP address or two addresses separated by a hyphen; each IP address is four small integers separated by periods. For example,,,

Alternatively, your application can authenticate by username and password credentials. This is a useful approach in several situations, including when you need to specify the use of a different library from the usual one. To arrange for this, set the username and password as a single string separated by a slash -- e.g. mike/swordfish -- into the User Access record's Authentication field.

You can set multiple fields into a single User Access record, or create multiple User Access records. For example, a single User Access record can specify both a Referring URL and a username/password pair that can be used when running an application from a different URL. But if multiple Referring URLs are needed, then each must be specified in its own User Access record.

(Optional): embed credentials for access to the library

When credential-based authentication is in use (username and password), it's necessary to pass these credentials into the Service Proxy when establishing the session. This is done by providing the sp_auth_credentials configuration setting as a string containing the username and password separated by a slash:

mkws_config = { sp_auth_credentials: "mike/swordfish" };

(Optional): conceal credentials from HTML source

Using credential-based authentication settings such as those above reveals the credentials to public view -- to anyone who does View Source on the MKWS application. This may be acceptable for some libraries, but is intolerable for those which provide authenticated access to subscription resources.

In these circumstances, a different approach is necessary. Referer-based or IP-based authentication may be appropriate. But if these are not possible, then a more elaborate approach can be used to hide the credentials in a web-server configuration that is not visible to users.

The idea is to make a Service Proxy authentication URL local to the customer, hiding the credentials in a rewrite rule in the local web-server's configuration. Then local mechanisms can be used to limit access to that local authentication URL. Here is one way to do it when Apache2 is the application's web-server, which we will call

Step 1: add a rewriting authentication alias to the configuration:

RewriteEngine on
RewriteRule /spauth/\
    ?command=auth&action=check,login&username=U&password=PW [P]

Step 2: set the MKWS configuration setting service_proxy_auth to

Step 3: protect access to the local path (e.g. using a .htaccess file).

Choosing targets from the library

MKWS applications can choose what subset of the library's targets to use, by means of several alternative settings on individual widgets or in the mkws_config structure:

For example, a Records widget can be limited to searching only in targets that have been categorised as news sources by providing an attribute as follows:

<div class="mkws-records" targetfilter='categories=news'/>

Reference guide


The following widgets are provided in the core set. (Others can be added: see the MKWS developers' guide.)

Name Description
auth-name Initially empty, it updates itself to shows the name of the library that the application is logged in as when authentication is complete.
builder A button which, when pressed, analyses the current settings of the team that it is a part of, and generates the HTML for an auto-searching element that will replicate the present search. This HTML is displayed in an alert box: it is intended that this widget be subclassed to store the generated widget definitions in more useful places.
button The search button. Usually generated by a search widget.
categories Obtains from the Service Proxy a list of the target categories associated with the library in use, and displays them in a drop-down list. When a category is selected, searches are limited to the targets that are part of that category.
config This widget has no functionality of its own, but its configuration is copied up into its team, allowing it to affect other widgets in the team. This is the only way to set configuration settings at the team level.
console-builder Like the builder widget, but emits the generated HTML on the JavaScript console. This exists to provide an example of how to subclass the builder widget.
cover-art Displays cover art for a book by searching in Amazon. Often used with an autosearch attribute to indicate what book to display. For example, <div class="mkws-cover-art" autosearch="isbn=1291177124"></div> displays cover art for All Yesterdays: Unique and Speculative Views of Dinosaurs and Other Prehistoric Animals. For this widget to work, a library that includes the AmazonBooks target must be used. For example, the "DEMO AmazonBooks for MKWS" account, which can be selected with sp_auth_credentials="mkws-amazon/mkws".
details This widget is generated by the toolkit itself to hold the full details of records that are initially listed in summary form.
done Initially empty, this widget is set to display "Search complete: found n records" when all targets have completed their work, either returning a hit-count or an error. The message displayed can be changed by overriding the done template using <script class="mkws-template-done" type="text/x-handlebars-template">.
facet A facet that displays the frequency with which a set of terms occur within a specific field. The specific field whose contents are analysed must be specified by the widget's facet configuration setting, which may conveniently be done by means of the data-mkws-facet attribute on the HTML element. The supported facets are "subject", "author", and "xtargets" -- the latter a special case which treats the target providing a record as a facet. Most often, facet widgets are generated by a facets widget, which knows which facets are required, but they can also be placed individually.
facets An area that contains a "Facets" heading and several facet widgets. The set of facet widgets generated is specified by the facets configuration setting, which may be set globally or at the level of the widget or the team. The value of this configuration setting is an array of zero or more strings, each naming a facet.
google-image A specialisation of the images widget which defaults to the Google_Images target.
images A specialisation of the records widget which defaults to the images template. Unlike the default summary template, this displays an image from the URL specified by the md-thumburl field of each record.
lang Provides a selection between the supported set of languages (which defaults to English, German and Danish, but can be configured by the lang configuration setting, whose value is an array of two-letter language codes).
log Initially empty, this widget accumulates a log of messages generated by the widget set, similar to those emitted on the JavaScript console.
lolcat A specialisation of the google-image widget which defaults to the search-term "kitteh" and auto-executes.
motd-container An empty container, which the motd widget (if there is one) is moved into for initial display. Usually generated as part of the results widget.
motd May be provided, containing content to appear in the area where records will later appear. It is moved into this area (the motd-container widget) and initially displayed; then hidden when the first search is run. It can be used to provide a "message of the day".
navi Shows a list of the facets that have been selected, and allows them to be deselected.
pager Shows a list of the available pages of results, and allows the user to navigate to a selected page.
per-page Provides a dropdown allowing the user to choose how many records should appear on each page. The available set of page-sizes can be specified as the perpage_options configuration setting, whose value is an array of integers. The initial selected value can be specified by the perpage_default configuration setting.
progress Shows a progress bar which indicates how many of the targets have responded to the search.
query The input area for a query. Usually generated by a search widget.
ranking The result-ranking area, consisting of a sort widget and a per-page widget. These may instead be specified separately if preferred.
record A detailed display of a single record, usually appearing when the user clicks on a summary record. This is generated by the records widget.
records The area in which summary records appear. (Clicking on a summary record make it pop up as a detailed record.)
reference A short summary about a subject specified by the autosearch configuration setting. This is created by drawing a picture and a paragraph of text from Wikipedia. To work correctly, this widget must be used in a library that provides the wikimedia_wikipedia_single_result target.
results A large compound widget used to provide the most important results-oriented widgets in a pre-packaged framework: facets, ranking, pager, navi and records.
search-form The search form, containing the query area and the button. Usually generated by a search widget.
search The search box, consisting of a form containing a query area and a button.
sort Provides a dropdown allowing the user to choose how the displayed records should be sorted. The available set of sort criteria can be specified as the sort_options configuration setting, whose value is an array of two-element arrays. The first item of each sub-array is a Pazpar2 sort-expression such as data:0 and the second is a human-readable label such as newest. The initial selected value can be specified by the sort_default configuration setting.
stat A summary line stating how many targets remain active, how many records have been found, and how many of them have been retrieved for display. For most purposes, the progress widget may be preferable.
summary A short record, included in the list shown when a search is run. When clicked, this generally pops up a detailed record widget. This widget is generated by the toolkit, in response to search results.
switch A pair of buttons allowing the user to switch between viewing the search results (the usual case) or the target list.
targets A list of all targets in the present library, showing their ID, the number of records they have found for the current search, any diagnostics they have returned, the number of records that have been returned for display, and the connection state.
waiting An image, defaulting to unless overridden with the src configuration item, which is initially invisible, appears when a search is submitted, and disappears when the search is complete.

Configuration settings

Configuration settings may be provided at the level of a individual widget, or a team, or globally. Per-widget configuration is described above; per-team settings can be placed in a config widget belonging to the relevant team, and will be applied to that team as a whole; and global settings are provided in the global variable mkws_config. This structure is a key-value lookup table, and may specify the values of many settings.

Some settings apply only to specific widgets; others to the behaviour of the toolkit as a whole. When a widget does not itself have a value specified for a particular configuration setting, its team is consulted; and if that also does not have a value, the global settings are consulted. Only if this, too, is unspecified, is the default value used.

The supported configuration settings are described in the table below. For those settings that apply only to particular widgets, the relevant widgets are listed. All entries are optional, but if specified must be given values of the specified type. Long default values are in footnotes to keep the table reasonably narrow.

Setting Widget Type Default Description
autosearch facet, facets, record, records, results string If provided, this setting contains a query which is immediately run on behalf of the team. Often used with an indirect setting.
facet facet string For a facet widget, this setting is mandatory, and indicates which field to list terms for. Three fields are supported: subject, author, and xtargets -- the latter is a special case which treats the target (that is providing a record) as a facet. Any other field may also be used, but the default caption and maximum term-count may not be appropriate, needing to be overridden by facet_caption_* and facet_max_* settings.
facet_caption_* facet string Specifies what on-screen caption is to be used for the named facet: for example, if a date facet is generated, then facet_caption_date can be used to set the caption to "Year".
facet_max_* facet int Specifies how many terms are to be displayed for the named facet: for example, if a publisher facet is generated, then facet_max_publisher can be used to limit the list to the top six.
facets team array Note 1 Ordered list of names of facets to display.
freeze_opacity records float If defined, a fractional value between in the range 0.0 (transparent) to 1.0 (opaque). During the short period after a mouse-move over the records when the display will not be updated, the widget is faded to that opacity (reverting to full opacity when the period elapses or the mouse leaves the area).
lang team string The code of the default language in which to display the UI. Supported language codes are en = English, de = German, da = Danish, and whatever additional languages are configured using language_* entries (see below).
lang_options lang array [] A list of the languages to offer as options. If empty (the default), then all configured languages are listed.
language_* global hash Support for any number of languages can be added by providing entries whose name is language_ followed by the code of the language. See the separate section below for details.
limit facet, facets, record, records, results string Allows a partial search to be included in the specification of an auto-executing widget. This is ANDed with the submitted query, as though it had been selected from a facet. See the Search section in the Protocol chapter of the Pazpar2 manual
log_level global string info The lowest level of logging output to emit. Acceptable values are trace, debug, info, warn, error, and fatal.
maxrecs facet, facets, record, records, results int Limits the metasearching middleware to retrieving no more than the specified number of records from each target.
newsearch_opacity records, facets float If defined, a fractional value between in the range 0.0 (transparent) to 1.0 (opaque). When a new search is submitted, the widget fades to that opacity (reverting to full opacity when data arrives).
paragraphs reference int Limits the number of paragraphs rendered to the specified number. If omitted, there is no limit.
pazpar2_url global string If specified, this is the URL used to access the metasearch middleware. This service must be configured to provide search results, facets, etc. It may be either unmediated Pazpar2 or the MasterKey Service Proxy, which mediates access to an underlying Pazpar2 instance. When not specified, the URL is assembled from pp2_hostname and pp2_path. See the Assembling Pazpar2 URLs section below.
perpage facet, facets, record, records, results int Specifies the number of records to show per page in an auto-executing widget. Contrast with perpage_default, which is used to prime the dropdown with which a user chooses the page-size in an interactive session.
perpage_default team string 20 The initial value for the number of records to show on each page.
perpage_options ranking array Note 2 A list of candidate page sizes. Users can choose between these to determine how many records are displayed on each page of results.
pp2_hostname global string Note 3 Unless overridden by the pazpar2_url setting, this is used together with pp2_path to construct the URL to the Pazpar2 service (or Service Proxy). Set this to connect to a service on a different host from the default.
pp2_path global string Note 4 Unless overridden by the pazpar2_url setting, this is used together with pp2_hostname to construct the URL to the Pazpar2 service (or Service Proxy). Set this to connect to a service on a different host from the default.
scan_all_nodes global bool false An internal setting that changes how MKWS scans the HTML document to discover widgets. If set to true, a different approach is used which may be faster under some circumstances.
sentences reference int Limits the number of sentences rendered to the specified number. If omitted, there is no limit.
service_proxy_auth global url If defined, this is the URL which, when use_service_proxy is true, is fetched once at the beginning of each session to authenticate the user and establish a session that encompasses a defined set of targets to search in. When not defined, the URL is assembled from sp_auth_hostname or pp2_hostname, pp2_path or sp_auth_path, sp_auth_query, and sp_auth_credentials. See the Assembling Pazpar2 URLs section below.
service_proxy_auth_domain global domain When the server used for authentication -- e.g. the one identified by the service_proxy_auth URL -- proxies for different server, this can be set to the domain of the server that it proxies for, so that cookies are rewritten to appear to be from this domain.
show_lang lang bool true Indicates whether or not to display the language menu.
show_perpage ranking bool true Indicates whether or not to display the perpage menu.
show_sort ranking bool true Indicates whether or not to display the sort menu.
show_switch switch bool true Indicates whether or not to display the switch menu.
sort facet, facets, record, records, results string Specifies the order in which to sort the records retrieved by an auto-executing widget. Must be one of those in the sort_options array. Contrast with sort_default, which is used to prime the dropdown with which a user chooses the sortorder in an interactive session.
sort_default team string relevance The default sort criterion to use. Must be one of those in the sort_options array.
sort_options ranking array Note 5 List of supported sort criteria. Each element of the list is itself a two-element list: the first element of each sublist is a Pazpar2 sort-expression such as data:0 and the second is a human-readable label such as newest.
sp_auth_credentials global string If defined, this must be a slash-separated combination of username and password, which is sent as the authentication credentials on session initialisation. See the Assembling Pazpar2 URLs section below.
sp_auth_hostname global string If provided, overrides the pp2_hostname setting when constructing the Service Proxy authentication URL. This need only be used when authentication is performed on a different host from the remaining operations (search, retrieve, etc.)
sp_auth_path global string Part of the URL used for authentication. See the Assembling Pazpar2 URLs section below.
sp_auth_query global string Note 6 Part of the URL used for authentication. See the Assembling Pazpar2 URLs section below.
src waiting url The address of an image to use in the waiting widget in place of the default spinning wheel. Used to indicate that a search is in progress.
target facet, facets, record, records, results string One of three ways to select which targets are used by an auto-searching widget. See the Choosing targets from the library section above.
targetfilter facet, facets, record, records, results string One of three ways to select which targets are used by an auto-searching widget. See the Choosing targets from the library section above.
targets facet, facets, record, records, results string One of three ways to select which targets are used by an auto-searching widget. See the Choosing targets from the library section above.
template details, done, facet, facets, images, lang, navi, pager, progress, ranking, records, reference, results, search, stat, switch, targets string Numerous widgets use Handlebars templates to render HTML. In general, each of these by default uses a template with the same name as the widget itself. Individual widgets can be customised to use a template of a different name, by means of their template setting. The records widget (and record: an equivalent that shows only a single record) use the summary template as well as the records template.
text builder string "Build!" Specifies what text to use for the Builder button.
use_service_proxy global bool true If true, then a Service Proxy is used to deliver searching services rather than raw Pazpar2. An authentication phase is run during initialisation.

The show_lang, show_perpage, show_sort, and show_switch configuration settings are technically redundant, as the relevant widgets, like all widgets, are displayed only when they are provided. But they are retained as an easier route to lightly customise the display, than by providing a full HTML structure.


  1. The default for facets is ["xtargets", "subject", "author"]

  2. The default for perpage_options is [10, 20, 30, 50]

  3. The default for pp2_hostname is ""

  4. The default for pp2_path is "service-proxy/"

  5. The default for sort_options is [["relevance"], ["title:1", "title"], ["date:0", "newest"], ["date:1", "oldest"]]

  6. The default for sp_auth_query is "command=auth&action=perconfig"

Indirect settings

The values of any setting are generally interpreted literally. However, it is possible to specify a value indirectly -- for example, by reference to a query parameter -- and this is often useful in contexts such as specifying an autosearch query. Settings of this kind have values beginning with an exclamation mark, and take the form !type!value.

The currently supported types are:

    <script>var _reversedParam = extractAndReverse("term");</script>
    <div class="mkws-results" autosearch="!var!_reversedParam">

Assembling Pazpar2 URLs

Most of MKWS's functionality is achieved by use of the Pazpar2 middleware. This is accessed on an endpoint URL which is usually assembled from the two configuration settings pp2_hostname and pp2_path. However, if for some reason an unusual Pazpar2 endpoint must be used, that endpoint can be specified in the pazpar2_url setting, and that will be used instead.

In the common case where Pazpar2 is accessed via the Service Proxy, an authentication call is made during initialisation. The call is generally made to the same endpoint as the other requests. However, the hostname used for authentication may if necessary be overridden using the sp_auth_hostname setting, and the path overridden by sp_auth_path. In any case, the value of sp_auth_query is appended; and if sp_auth_credentials is set, then it is used to add username and password parameters.

So in the absence of any configuration added by an application, the Service Proxy authentication URL is made up of pp2_hostname ( since sp_auth_hostname is undefined; and pp2_path (service-proxy/) since sp_auth_path is undefined; and sp_auth_query (command=auth&action=perconfig); and no credentials, since sp_auth_credentials is undefined. Therefore the URL is generated.

Language specification

Support for another UI language can be added by providing an entry in the mkws_config object whose name is language_ followed by the name of the language: for example, language_French to support French. The value of this entry must be a key-value lookup table, mapping the English-language strings of the UI into their equivalents in the specified language. For example:

var mkws_config = {
  language_French: {
    "Authors": "Auteurs",
    "Subjects": "Sujets",
    // ... and others ...

The following strings occurring in the UI can be translated:

In addition, facet names can be translated:

and whatever field captions are defined by facet_caption_* settings.

And sort-orders:

and whatever sort-orders are defined by the sort_options setting.

Finally, the names of fields in the full-record display can be translated. These include, but may not be limited to:

jQuery UI popup invocation

The MasterKey Widget Set can be invoked in a popup window at the top of the page.

Note that the popup widget uses facilities from the jQuery UI, so it's necessary to include both CSS and JavaScript from that toolkit. The relevant lines are:

<script src=""></script>
<link rel="stylesheet" type="text/css"
      href="" />

<div class="mkws-search"></div>
<div class="mkws-popup" popup_width="1024" popup_height="650" popup_autoOpen="0">
  <div class="mkws-switch"></div>
  <div class="mkws-lang"></div>
  <div class="mkws-results"></div>
  <div class="mkws-targets"></div>
  <div class="mkws-stat"></div>

Popup windows can contain any HTML, not just MKWS widgets.

The properties of the popup widget are as follows:

Setting Type Default Description
popup_width int 880 Width of the popup window, in pixels.
popup_height int 760 Height of the popup window, in pixels.
popup_button string input.mkwsButton A jQuery selector identifying the element which, which clicked, pops up the window.
popup_modal bool 0 Indicates whether the popup is modal (blocks access to the background page until dismissed). Set to 1 if a modal popup is required.
popup_autoOpen bool 1 Indictaes whether to pop up the window automatically when the page is loaded.

Multiple popup widgets can co-exist on a page. In this case, different popup_button values must be used for each.

Structure of HTML generated by widgets

In order to override the default CSS styles provided by the MasterKey Widget Set, it's necessary to understand the structure of the HTML elements that are generated within the widgets. The HTML structure is as follows. As in CSS .class indicates an instance of a class. A trailing * indicates zero or more instances; a trailing ? indicates zero or one instance.





Appendix: compatibility roadmap

Wherever possible, we ensure that all functional changes in MKWS are backwards-compatible, so that applications written against old versions of the toolkit will continue to work when running against newer versions.

However, a few aspects of functionality may unavoidably change in backwards incompatible ways. We ensure that this only happens with new major versions -- so it should always be safe to upgrade to a new minor version. As an aid to porting old applications, we here note the specific backwards-incompatible changes in the various major releases, and those planned for future major releases:

Major version 1.x

Versions of MKWS before v1.0 (including the only prior release, v0.9.1) used camel-case class-names: without hyphens and with second and subsequent words capitalised. So instead of mkws-search, it used to be mkwsSearch. And the classes used to specify team names used an mkwsTeam_ prefix (with an underscore). So instead of mkws-team-foo, it used to be mkwsTeam_foo.

The 1.x series of MKWS releases recognise these old-style class-names as well as the canonical ones, as a facility for backwards compatibility. However, these old class-names are deprecated, and support will be removed in v2.0. Existing applications that use them should be upgraded to the new-style class names as soon as is convenient.

Copyright (C) 2013-2016 Index Data ApS.