Google Desktop indexes, caches, and searches content on your computer. Through the Google Desktop Query API, your applications can send search queries directly to Google Desktop and process its search results.
Examples:
samples/search/query_api/js_samples
(in the SDK)The Query API described in the first part of this document was introduced with Google Desktop 3. We cover how to use it with both native plug-ins and script-based plug-ins, and assume that you are familiar with the general principles of how to write Desktop plug-ins.
The latter part of this document describes methods for issuing Desktop search queries using HTTP and XML. This XML-based API is supported by both the Windows and Mac OS X versions of Google Desktop. Mac OS X support was added in Google Desktop Mac 1.0.3.
You can only use the Query API if you have registered with it and thus obtained a Query API registration cookie. Note that this is in addition to the general registration of your plug-in with Google Desktop.
There are two types of Query API registration cookies, read-only and read-write. Usually, you'll only need a read-only cookie. The read-write cookie is only needed when you remove an item from the Google Desktop index.
We recommend that your plug-in encrypt the registration cookie when it saves it, and, of course, be able to decrypt it when you pass it to the various Query API methods and objects.
You'll need a global identifier (GUID) for your
plug-in to pass to the registration method. You can use a tool such
as guidgen.exe
to generate
one.
If you are writing a native plug-in, the
following summarizes the registration interface and its
method. All method return values are of type
HRESULT
.
interface IGoogleDesktopRegisterQueryPlugin: IDispatch
Note: Components are required to call this interface to register themselves with the Google Desktop Query API before they can make use of that API.
RegisterPlugin
: Must be invoked by any
component to register with the Query API.
BSTR plugin_class
: The
component's GUID or ProgID.VARIANT_BOOL read_only
:
If true
, you can
do search queries but cannot delete items from the
index. A false
value gives you both read and write access, allowing
you to delete index items.[out, retval] long* cookie
: Returns the registration cookie. Save
this value, as you will have to use it whenever
you make a query or remove an item from the
Desktop index via the Query API.S_OK
if successful.If you are writing a script-based plug-in,
see register_script_sample.js
for a complete example of registering with the Query API using
JavaScript. The gist is the following code:
try { // Instantiate the Google Desktop registrar component by creating // an ActiveX registration object. var registrar = new ActiveXObject("GoogleDesktop.Registrar"); // Give it our plug-in GUID and description registrar.StartComponentRegistration(g_scriptSampleId, componentDescription); // Ask for the specific registration object that gives us Query API access. var regObj = registrar.GetRegistrationInterface("GoogleDesktop.QueryRegistration"); // Now ask that registration object to give us a cookie representing // our Query API access. Note the read_only flag argument here; // if false, then we're asking for read-write access instead of // just read-only access. cookie = regObj.RegisterPlugin(g_scriptSampleId, read_only); // Now submit and hope the user will accept this component. // If not, then an error will be thrown registrar.FinishComponentRegistration(); } catch (e) { // We hit an error message("Couldn't register the script samples.\n" + new String(e.number) + "\n" + e.description); return 0; }
Note that you need to save the cookie value, as you will have to use it whenever you make a query or remove an item from the Desktop index via the Query API.
The Query API has one root object,
IGoogleDesktopQueryAPI
for
native plug-ins, GoogleDesktop.QueryAPI
for script plug-ins, that supports two methods:
Query
: Immediately executes the
specified desktop search query and returns a result object that
contains all the search results for the query.QueryEx
: Returns a query object
which does not (yet) actually execute the query. Instead, you can
tweak some custom parameters first, then execute the revised query.
When executed, it returns the same type of result object as
Query
.The Query
and QueryEx
root object methods both
take the following arguments:
cookie
: The security
cookie created when you registered your plug-in with the Query
API.query
: The search query string,
which can include the same
set of query operators that you could use
in a query typed into a Google Desktop search box.category
: Optional string argument
that lets you restrict results to those of a particular type. Valid
values are email
,
web
,
im
,
file
,
contact
,
calendar
,
task
,
note
,
or journal
.ranking
: Optional numeric
argument specifying whether the search results will be ranked by
date (RECENCY_RANKING
= 1), the
default, or by relevance (RELEVANCE_RANKING
= 0).interface IGoogleDesktopQueryAPI: IDispatch
Query
: Immediately takes the
specified search query and executes it with default option values.
long cookie
: The
component's Query API security cookie.BSTR query
:
The search query string, which can contain any of the
allowed Desktop search operators.VARIANT category
: [Optional]
VARIANT ranking
: [Optional]
[out, retval] IGoogleDesktopQueryResultSet**
results
: The search results from
having automatically executed a desktop search for the
search query.S_OK
if successful.QueryEx
: Returns a query object
that does not automatically execute a search. Instead, you
can alter the query's properties and exert finer control
over the search, and then execute the query.
long cookie
: The
component's Query API security cookie.BSTR query
:
The search query string, which can contain any of the
allowed Desktop search operators.VARIANT category
: [Optional]
VARIANT ranking
: [Optional]
[out, retval] IGoogleDesktopQuery** q)
: An unexecuted query object, which
you can alter the default properites and parameters of
before running a search on its search query.S_OK
if successful.In JavaScript, you just create the base object and then create and run the Query in one step.
// Instantiate the main query api object var qapi = new ActiveXObject("GoogleDesktop.QueryAPI"); // Perform the query and get a recordset object back containing the // search results. var set = qapi.Query(cookie, search_string);
See the simple_query.js
example for a detailed example.
If you run the QueryEx()
method, it returns a Query object for which you can change any or all of
these four options before executing the query:
async
: By setting this to
false
, all result items are
fetched before the Execute()
method completes. The default value is
true
.filter_duplicates
: By
setting to false
, you'll get
all the items that match, including any duplicates of already
matched items. Default
is true
.match_all_terms
: When set
to false
, if there are
multiple query terms, any item matching just one of the query
terms is returned. Otherwise, a result must match all of the query
terms. Default is true
.blacklisting
: By setting
to false
, items in the search
results do not go through the default blacklisting filters.
Default is true
.
If you turn this off, you'll most likely see spam email, secure
content, bad urls such as about:, res:, etc. in addition to
your good results.To change an option value, use the
SetOption()
method, one of four
methods associated with Query objects. These are:
SetOption
: Takes arguments, in
this order, of what option to set and what value to set it
to.GetOption
: Takes an option name,
returns its value.query
: Takes no arguments,
returns a string containing the search query.Execute
: Once you've finished
setting the Query object's options, run this method to actually
run the search. Returns a query result set.QueryEx
's returned object,
IGoogleDektopQuery
, has the following
interface:
interface IGoogleDesktopQuery: IDispatch
SetOption
: Set an option value.
BSTR name
: Which option to
set.VARIANT value
:
What value to set the option to.S_OK
if successful.GetOption
: Get an option value.
BSTR name
: Which option to
get the value of.[out, retval] VARIANT* value
:
The option's value.S_OK
if successful.query
: Get the search query string.
[out, retval] BSTR* ret
:
The search query string.S_OK
if successful.Execute
: Execute the search as
specified by the QueryEx object's query string and option values.
[out, retval] IGoogleDesktopQueryResultSet**
results
: Results from the search.S_OK
if successful.The following code using
QueryEx
comes from the
item_count.js
example. It shows
the usual series of events when using
QueryEx
; call
QueryEx
on the
base Query API object to get a Query object, set Query object
options with SetOption()
, then
call Execute()
on the Query object and
get back a recordset of the search results.
var q = new ActiveXObject("GoogleDesktop.QueryAPI"); // Call the QueryEx method so that we can turn off the asynchronous // loading of record items. var qx = q.QueryEx(g_securityCookie, query); // Turn off the default asynchronous behavior. qx.SetOption("async", false); // Execute the query synchronously and get back a recordset object var set = qx.Execute();
When you execute a Query
or QueryEx
, it
returns a result set object. This object contains individual result item
objects, each of which represents a single search result.
Unless you used QueryEx
and changed the default value of the Query object's
async
option to
false
from its default value
true
before executing the
query, you can access search results before the search has completely
finished. To find out if a search has completed, check the resultset's
readystate
property, which can
have three values:
GD_QRS_UNITIALIZED = 0
: Search
has not yet started.GD_QRS_LOADING = 1
: Search
is still in progress.GD_QRS_COMPLETE = 2
: Search
is complete, with all results received and in the resultset.There are four methods associated with result set objects:
readystate
: Takes no arguments,
returns the current readystate
value.count
: Takes no arguments,
returns the total number of individual search result items in
the recordset. Note that this number will change as long as
results are still arriving. Until
readystate
is
GD_QRS_COMPLETE
, this value
is an estimate.Next
: Takes no arguments, returns
the next individual search result in the set. If results are
still arriving and Next()
is
at the end of the current results, it will wait until the next
result arrives. If you reach the end of the results after all
results are in the recordset, Next()
returns null
.
available_count
: Takes no arguments,
returns how many individual results can be fetched via calls to
next()
without it blocking
while waiting for more results.interface IGoogleDesktopQueryResultSet: IDispatch
Next
: Returns the next individual
search result in the set. If results are still arriving, it
waits for the next result to arrive before returning it. If
called after reaching the final result, it returns
S_FALSE
and
null
.
[out, retval] IGoogleDesktopQueryResultItem**
next
: An individual search result.
S_OK
if successful.S_FALSE
and
null
if called after the
last result has already been returned.readystate
: Returns the current
readystate
value, which
can be
GD_QRS_UNINITIALIZED = 0
GD_QRS_LOADING = 1
(Still receiving results)GD_QRS_COMPLETE = 2
(All results received)[out, retval] QRSReadyState* state
: readystate
's value.S_OK
if successful.count
: Returns the total number
of individual search result items. Note that this number
will change so long as individual results are still
arriving. Until the readystate
value becomes GD_QRS_COMPLETE
,
this value is an estimate. After that, it is the
exact and total number of individual search results.
[out, retval] long* ret
: Number of results
S_OK
if successful.available_count
: Returns the
value of how many individual results can currently be
fetched via calls to next()
without blocking.
[out, retval] long* available_count
: Current remaining number of available
search results.S_OK
if successful.To iterate through a result set's individual results in JavaScript, you'd write something like:
var item; while ((item = results.Next()) != null) { // process item here }
Result item objects each contain a single search
result. The key method is GetProperty
,
which takes a property name and returns its value for the
result. The complete list of valid property names is quite long; the
ones you'll probably use most often are
content
,
uri
,
summary
, and for email
from
, to
, and subject
.
To avoid errors due to trying to get a value for a
property that doesn't exist for a result type (for example, a file
doesn't have a from
property), you
should first use the schema
method
to determine the result's type. The following schemas are defined in
the Desktop SDK IDL:
- "web"
- "text"
- "media"
- "office"
- "file"
- "calendar"
- "contact"
- "email"
- "im"
- "note"
- "journal"
- "task"
- "shortcut"
If you try to get a value for a property the result doesn't have, an error is returned. For scripts, that means an exception is thrown, so remember to use exception handling in your script plug-ins.
There are four methods associated with result item objects:
GetProperty
: Takes a property
name argument, returns that property's value.schema
: Takes no arguments,
returns the name of the item's schema.versions
: Takes no arguments, returns
either a list of emails in this item's thread (if the item is an
email) or a list of all file versions (if the item is a file) in
the Desktop index. These are returned as a document versions object.
RemoveFromIndex
: Takes one
argument, which if true
(the default value)
removes this item and all its versions from the Desktop index.
If false
, only this
individual item is removed.
Remember, you must have a read-write Query API
registration cookie for this method to work. If you don't have
one, you'll get an "Access Denied" error.The complete property set is:
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The following is the interface for
IGoogleDesktopQueryResultItem
,
the native plug-in individual result item.
interface IGoogleDesktopQueryResultItem: IDispatch
GetProperty
: Looks up and returns
property values.
BSTR prop_name
:
Property name to look up the value of.[out, retval] VARIANT* value
: Value of the property argument for this result.
S_OK
if successful.RemoveFromIndex
: Removes either
only this item or all versions of this item from the Desktop
index (for email items, the latter means removing all messages
in its thread). Note that you must have a read-write Query API
registration cookie for this method to work; if not you'll get
an "Access Denied" error.
VARIANT_BOOL remove_all_related_versions
: If
VARIANT_TRUE
, all
versions are removed. If
VARIANT_FALSE
,
only this single item is removed.S_OK
if successful.schema
: Returns the name of the
item's schema.
[out, retval] BSTR* schema_name
: Name of this item's schema
S_OK
if successful.versions
: Returns either a list
of emails in this item's thread (if the item is an email) or
a list of all file versions (if the item is a file) in the
Desktop index.
[out, retval] IGoogleDesktopDocumentVersions**
ret
: List of item's versions or
other messages in its thread.S_OK
if successful.The following code from the
lucky.js
example shows how to
get various properties from each individual result item in a result
set. The message()
method is a
basic output method defined early in the script.
//Get the next individual search result item from the recordset var item = set.Next() if (item != null) { // First output the URI of the item we found message(item("uri")); // Now output the text representation of the content message(item("text_content")); // Alternatively, we could output the content in its native form // message(item("content")); } else { message("no item found!"); }
The remove_from_index.js
example shows first how to build a query whose results
are restricted by being a specific filename in a specific folder, as
well as a script that removes from the Desktop index all result items
from a search query.
The result item's version
property requires a bit of explanation. Its value is a
document versions object, which is a collection of individual query
result items. These are the same individual result items described
in the previous section; in other words, an individual search result
object can contain other individual result objects in its
version
property.
For an email message, its version contents are the other email messages in the same thread. For a file, its version contents are any other versions of that file, either from an earlier or a later time, indexed by Desktop.
The method of accessing individual versions is different from how
individual results are gotten from a search result recordset. The
count
property's value is
the number of versions in the document versions object.
The Item()
method takes a 0-based
index value and returns the result item object at that location.
Note that the versions are not ordered other than by their index
value; version 0 is not necessarily the earliest or latest version,
version 1 may be earlier or later than version 0, etc.
interface IGoogleDesktopDocumentVersions: IDispatch
count
: Number of separate
versions in this object.
[out, retval] long* ret
: Number of indexed versions of this item.
S_OK
if successful.Item
: Takes an index value and
returns the result item stored at that location in the
document versions list.
long index
: Index value of the version to be
returned.[out, retval] IGoogleDesktopQueryResultItem**
ret
: The item at the position
provided by the index
argument.S_OK
if successful.The versions collection has one function,
Item(index)
and one property,
count
, which function as described
above.
From here to the end of the document, we cover how to use the HTTP/XML-based Query API.
To issue Google Desktop HTTP/XML search queries you will need to know, in addition to the information in this document:
Your application requests a desktop search by sending an HTTP
request that includes a &format=xml
parameter
to Google Desktop. For example, to search for "Google" you'd send something
like:
http://127.0.0.1:4664/search&s=1ftR7c_hVZKYvuYS-RWnFHk91Z0?q=Google&format=xml
To break this down:
http://127.0.0.1:4664/
is the localhost address and
Google Desktop port.
search&s=1ftR7c_hVZKYvuYS-RWnFHk91Z0
is the search command and a security token.
?q=Google
is the query term(s) parameter.
+
s. For example, to search for both "Google" and "Desktop", use:?q=Google+Desktop
+
s and surround the phrase with %22
s.
For example, to search for the phrase "Google Desktop", use:?q=%22Google+Desktop%22
?q=%22Google+Desktop%22+%22Copyright+2007%22
.
&format=xml
specifies that the HTTP response
returns the search results in XML format, as described in the next section.
Note: These requests perform only a desktop search, not both a web and desktop search.
By default, an HTTP search response will only return the first
ten results. You can specify a larger number by appending the &num=
parameter, followed by the maximum number of results you'd like returned, to
your query. There is no problem if the maximum number argument value is greater
than the total number of search results; only the total number of results is
returned, with no null "results".
You can also specify at what point in the results the returned
ones start. For example, if you're using the default value of 10 returned
results and want to get back results 11-20 instead of the default results 1-10,
append the &start=
parameter, followed
by the position you want the results to start from. In this example, you'd
specify &start=1
0
to
indicate you want your returned results to start with the one after overall
result 10. The &start=
and
&num=
parameters can both be used in a single query.
To create a query, first get the query URL
that Google Desktop stores.
Then append your query terms,
any optional parameters,
and the &format=xml
parameter.
The stored query URL has the first part of the URL that you need to perform any Google Desktop query. It looks something like the following:
http://127.0.0.1:4664/search&s=1ftR7c_hVZKYvuYS-RWnFHk91Z0?q=
How you get the stored query URL depends on whether your code is running on Windows or Mac OS X.
Get the query URL from the registry using the following value name:
HKEY_CURRENT_USER\Software\Google\Google Desktop\API\search_url
Use CFPreferences to fetch the stored query URL
from the user preferences domain
com.google.Desktop.WebServer
using the key
search_url
.
For example:
CFStringRef val = CFPreferencesCopyValue( CFSTR("search_url"), CFSTR("com.google.Desktop.WebServer"), kCFPreferencesCurrentUser, kCFPreferencesAnyHost); if (val) { // act on the value CFRelease(val); }
When a search request has the &format=xml
parameter, Google Desktop returns results in an XML format. For example:
<?xml version="1.0" encoding="UTF-8" standalone="yes" ?> <results count="24945"> <result> <category>web</category> <!-- ... optional internal, implementation-specific elements such as ids and flags... --> <title>Developer Knowledge Base - Read the Google Desktop blog</title> <url>http://code.google.com/support/bin/answer.py?answer=66869&topic=10434</url> <time>128243290079530000</time> <snippet>Desktop engineers regularly post development articles and announce updates to the <b>SDK</b> and documentation. Here are some interesting posts from the past: New</snippet> <thumbnail>/thumbnail?id=6%5Fvwps3QA4FIYGAAAA&s=wgQCmjGl0VEzw3KVhm3mxBG_x48</thumbnail> <icon>/icon?id=http%3A%2F%2Fcode%2Egoogle%2Ecom%2F&s=kKR1by-QXDMlb5vEhxkDZhCv3eE</icon> <cache_url>http://127.0.0.1:4664/...</cache_url> </result> ... </results>
The one meta-results tag is <results>
,
which contains the total number of items that matched the query as the value of
a count
parameter; e.g. <results
count=42>
. This will be the largest number of
possible <result>
...</result>
entries in the <results>
element.
However, if the number of returned results (which defaults to at most 10 if you
don't specify an &num=
parameter with a
larger value) is different from the count
value,
the number of returned <result>
...</result>
entries will be the smaller of the two conflicting values.
For example, let's say the <count>
value is 42. But you didn't give an &num=
argument in the query. So, despite there being 42 items that matched the query,
the XML response will only contain 10 <result>
...</result>
entries. If the <count>
value was 6,
which is smaller than the default 10 value, the XML response will only contain
6 <result>
...</result>
entries.
If you want to be sure to obtain all search results, your
component will have to parse out the <count>
value and then issue additional HTTP Google Desktop search requests to retrieve that many
results via use of either the &start=
or
&num=
parameters.
Each <result>
may
include the following fields, which may appear in any order. Which fields
appear will depend on the result type; for example, the <from>
entry should only show up in email or chat results. Each tag will
contain a value; any tags not containing a value are not shown.
<cache_url>
is the Google Desktop-relative URL
of this result's internal cache page.
<category>
contains the result's type.
The following table shows the possible result types for each platform.
Result Type | Windows | Mac OS X |
---|---|---|
application | ![]() |
|
bookmark | ![]() |
|
calendar | ![]() |
![]() |
chat | ![]() |
|
contact | ![]() |
![]() |
![]() |
![]() |
|
file | ![]() |
![]() |
journal | ![]() |
|
media_file | ![]() |
|
note | ![]() |
|
task | ![]() |
|
web | ![]() |
![]() |
<folder>
is the name of the folder containing an email message.
This field is not used on Mac OS X.
<from>
is the name of either the person an
email message was from, or the other party in an Instant Message chat.
<icon>
is a Google Desktop-relative URL to an
icon representing this result or its type. This will either be one of the
standard Google Desktop Search result type icons (envelope for email, Word icon
for a Word file, etc.) or a favicon obtained from a website.
<snippet>
is a snippet from the result's
content that contains at least one of the search terms.
<thumbnail>
is a relative URL to the icon for
this result at the Google Desktop webserver
<time>
is the time
value from the event that put this content into Google Desktop. Usually this will be the
time the content was indexed by Google Desktop, but, for example, it could also be a file's
last modified time. The format is per the Windows FILETIME structure; the
number of 100-nanosecond intervals since January 1, 1601 represented as a
64-bit number.
<title>
is the result's title, which
varies depending on its type, for example:
<url>
is the result's URL. For files and web
pages, this is the usual path to the result. For chats and email messages,
Google Desktop generates a URL for the location where it has stored its cached
copy.
If you want to experiment with queries to see what their XML
format results look like, just do a desktop search from the browser. Then
append ?format=xml
to the result's URL, hit
Enter, and the same results will display in XML format in the browser. Two
caveats: first, only the number of results that originally appeared on one
results page will show up in the browser in XML. So, for example, if only 10
HTML format results show up in the browser on one results page, only 10 XML
format results will appear in the browser, even if the value of the <results>
tag's
count
parameter
is, say, 42. Second, your browser must include an XML viewer, which IE and
Firefox do by default.
Finally, note that the XML results do not include the search terms. If your application wants to also make use of the search terms, as well as the results, it will have to keep track of what they were.