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Hack 36. Get More Search Tools
Update the Search bar with more search engines,
and add some other search tools as well.
Searching the Web has never been easier in Firefox. All you need to
do is enter one or more terms into the search box in the upper-right
corner, press Return, and you're on your way. But
the searching capabilities of Firefox are far more than a single
field.
4.5.1. Adding Search Engines
By default, the Search box queries the Google search engine. You can
tell this from the small G icon that appears on
the left side of the box. If you click on that icon, however,
you'll see a list of several other available
engines, such as Yahoo!, Dictionary.com, and Amazon.com. You can
change which search engine is used. Just select a different engine
from this list before hitting Return to launch your
query.
If the site you want to query isn't listed,
you'll want to visit the Mycroft
extension site at http://mycroft.mozdev.org.
You can also get there by selecting Add Engines from the bottom of
the search engine list and following the last link in the Add New
Search Engines section.
Mycroft is a project dedicated to collecting a wide variety of search
plug-ins for Mozilla-based browsers. You
can find plug-ins for hundreds of sites, from
4.5.2. Searching Without the Search Box
There are various extensions you can explore that add more searching
flexibility to Firefox. For example, the
Dict extension
(available at http://dict.mozdev.org/) allows you to select
a word on a page and query a Dict server with the selected word by
right-clicking the selected word and choosing
"Define...." The results appear in
a pop-up window.
One of the most useful search extensions is one called
Conquery (http://conquery.mozdev.org/). This tool adds
a context menu that allows you to select an area of text from the
page you are viewing and send that directly to
any of the search engines you have installed, as
shown in Figure 4-5. The effect is almost the same
as if every piece of text on a web page were instantly linked to the
search engine of your choice!
Figure 4-5. Using Conquery's context menu to search with any engine you have installed
4.5.3. Anatomy of a Search Plug-in
Under the covers, the Search box is simple. By selecting an engine
from the drop-down list, you choose a search plug-in. Each
plug-in consists of two files, located
in the searchplugins subdirectory where Firefox
is installed: a .src file, and an image file
(either GIF, JPG, or PNG format).
The .src file contains the real meat of the
plug-in. It contains information about the site itself, how the site
builds the URL for a search query, and how it displays its results.
Its syntax is based on Apple's Sherlock
specification, with a few extensions. (The project name
Mycroft, a character from Sherlock Holmes
stories, is a play on that name.)
The image file must have the same base name as the source file, and
it is displayed as the small icon displayed next to each site name on
the search box and the drop-down list.
The easiest way to create your own plug-in is to copy an existing
plug-in and modify it to suit your needs. Many of the parameters
expose functionality for Mozilla's Search sidebar,
which is not available in Firefox by default but is still easy to
provide.
Let's start by looking at a sample plug-inthe
one for Creative Commonsand go through it line by line to see
how it works.
Nearly all plug-ins have four major sections: the
search tag, one or more input
tags, the interpret tag, and the
browser tag.
4.5.3.1 The <search> tag
The search tag defines what the
plug-in is and what site it will query.
Looking at our sample Creative Commons plug-in, we see the following:
#
# Mozilla/Netscape 6+ MyCroft Plugin for search.creativecommons.org ...
# Created by Ben Snider on April 1, 2004.
# E-Mail: stupergenius@columbus.rr.com.
#
# Updated by Matt Haughey on August 26, 2004.
# E-Mail: matt@creativecommons.org
#
<search
version="7.1"
name="Creative Commons"
description="Find photos, movies, music, and text to rip, sample, mash,
and share"
action="http://search.creativecommons.org/"
searchForm="http://search.creativecommons.org/"
method="GET"
The version, name, and
description parameters identify this particular
search plug-in. name is what is displayed in the
search box drop-down list.
The action and method
parameters indicate how the query is submitted and the base part of
the URL to be queried. At the time of writing, only
GET methods are supported, so if you are building
a plug-in for a site that works using POST forms
only, you might be out of luck.
Actually, you can try using a bookmarklet (a
special bookmarked URL starting with javascript:)
to change the form from POST to
GET and use that information to construct your
plug-in. However, if the site explicitly checks for
POSTed values or includes user-specific cookies,
you're definitely stuck.
The searchForm parameter denotes the main search
page for the site, and is not strictly necessary.
4.5.3.2 The <input> tags
Next, the input values define
the query parameters for the URL:
<input name="q" user>
<input name="sourceid" value="Mozilla-search">
There is only one argument passed to the plug-in, which is the search
term. The term user in the first
input tag is replaced with this value. For
example, this plug-in will add &q=searchterm
to the query URL. This parameter is URL-encoded automatically by the
browser, so "firefox
browser" will become
&q=firefox+browser.
The sourceid value is included in all plug-ins, to
help webmasters identify how many users are conducting searches from
a Gecko-based browser. If any other parameters need to be sent to the
search engine, you should include them here as well.
4.5.3.3 The <interpret> tag
The interpret tag
tells us how the search results are
displayed, so the browser can parse the results into individual items
in the sidebar:
<interpret
browserResultType="result"
resultListStart="<!-- start results -->"
resultListEnd="<!-- end results -->"
resultItemStart='<p class="resultitem">'
resultItemEnd="</p>"
>
The browserResultType parameter indicates whether
the page being returned lists actual search results or a list of
categories for browse-oriented searches. You can typically omit this
parameter from most searches.
The remaining parameters indicate the HTML code that denotes the
beginning and end of the list of items and the beginning and end of
each individual item. You can usually figure this out by examining
the HTML source of the page returned by the search engine. If the
HTML is essentially tag soup and there is no easily definable way to
delineate individual results, don't worry about this
tag. This isn't real XML, by the way;
don't encode your quotes or angle brackets, unless
they appear that way on the results page.
4.5.3.4 The <browser> tag
Last is the browser
tag, which provides information about this
plug-in:
<browser
update="http://mycroft.mozdev.org/plugins/creativecommons.src"
updateIcon="http://mycroft.mozdev.org/plugins/creativecommons.png"
updateCheckDays="3"
>
</search>
The update and updateIcon
parameters indicate where the browser should check for updates of
this plug-in, while the updateCheckDays parameter
says how many days it should wait in between checks. This tag is
strictly optional if you aren't planning to make
your search plug-in available to others.
Finally, don't forget to close the
search tag we used to open the file.
Keith M. Swartz
