Note: Descriptions are shown in the official language in which they were submitted.
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EMAIL SERVER WITH
LEAST RECENTLY USED CACHE
Field of the Invention
[0001] The present invention relates to the field of
communications systems, and, more particularly, to
electronic mail (email) communications systems and
related methods.
Background of the Invention
[0002] Electronic mail (email) has become an
integral part of business and personal communications.
As such, many users have multiple email accounts for
work and home use. Moreover, with the increased
availability of mobile cellular and wireless local area
network (LAN) devices that can send and receive emails,
many users wirelessly access emails from mailboxes
stored on different email storage servers (e.g.,
corporate email storage server, Yahoo, Hotmail, AOL,
etc.).
[0003] Yet, email distribution and synchronization
across multiple mailboxes and over wireless networks
can be quite challenging, particularly when this is
done on a large scale for numerous users. For example,
different email accounts may be configured differently
1
CA 02622409 2008-03-17 ,~ r
--
. --- - --. - .. .--. . ~o, 654-
~
US2005034531 =
24-08-2006 1 1 . QAM --- . - --
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= and with nOn-unifar'm aecess criteria, Moreaver~ as
emails ar~ received at the wireless commUnications
devica, copies Of the amaila may still be present in
the originaJ, rnailhox~~, which cari ma]~e it dif f icult for
users to keep their emai,l organa.zed,
[0004] One particularly advantageous '-push" type
email distribution and synchronization system is
disclased in U. S, Patent No. 6,779,019 to Mouss~au et
al., whxch is assigned t,ra the present Assignea. This
system pushes user-selected data items from a host
syst~m, ta a user' s mobila wire1~ss coztriunicativns
device upon detecting the oGcurrence of One or more
user-'defir&ed avent triggers Th~ user m,ay then move (or
file) the data items to a particular folder within a
folcier hiararchy stored ln the rti.ohile wireless
cornmunicatians davice, or may execu,te sarne athet system
operatzQn on a data item. Software operating at the
deviGe arid the host system therr synchrOnizes the folder
hierarchy of the device with a folder hierarchy of the
hOst system, and any actions executsd 4n the data items
at the device are than autamatically replicated on, the
sa.ma data items stored at the ho5t system, thus
eliminating the nead for the user to manually replicata
actians at tha host system that have been executed at
tha mQbile wireless cor~munications device. W0
2005/046148 (D1) discloses a messaging server that
stares messages exchangad using a rneasaging systam.
Messages, and companents af messages~ are cached closer
to the rnessaging c1 ient s. The m.~ss agirlg client
different requests for messages are served frorn the
~
cache ratter than frQm the messaging sarvar. The
anessagas can be secured using security infQrmatian
stored at the messaging server. The messaging sarver
senda the sacurity inf orAmation d'irectly to the
IAeS~aging CZients. WO 03/036492 (D2) d'1SCloSeS 3
method to reduce tha network capaci,ty uaage
eceived at the EPO an Aug 24, 200616:51:13. P~ AMENDED SHEET
- = ~ ~, 654 r1 1 1 1 / / f . -- -
24-1 I I08-n n 200fin n~1 f 1 ~I ;(1 ~AM CA 02622409 2006-03-17
U[t1} Un I U US2005034531
~f eleetxanie email eontaxning MIME-~nooded
attachments. A prexy server is looatad between the
ema31 client and the seuree emazl server and separates
the MIME parts of the rnessage. Zt remeves one or more
M1ME attaohments, then insext link~ coxraspending to
tha ene or mera MYME attaehments znto the email
mesaage. The prexy se~ver transmxts the emai.l message
to tha eliant using a 7-bit text forinat. The end uaer
may elick on a link oorrespondLng ta a MYME attachment .
The attachment is trar~smitted to the elient u.eing a
non-'7-bit forrn,at. The proxy a~rvar ean act as a
protQcol proxy, retrieving and transmitting massagas in
real time, er it ean retrieve, transform, and cache
messagos before cl.ients request them+ Eg 1331791 (D3)
disc1Qses a cache handeff method arnd systam for
rnanaging a caeheable streamLrnq content xequested by a
mabile node within a network architecture. The network
arohitecture includas a first subnet and asecond
subnet. The cache handoff syatem includes a first
oaching proxy in the fir5t subnet tv supply acentent
streain in response ta a request of the rnobi1a node,
e. g., a mobile IP node in the f irst subnet. In
additian, the cache handoff system inelucte5 aseeand
eaching proxy iri the secQnd aubnet.Tha first cae"hing
prexy may initiata a cache handoff of the request to
the seeend caching proxy whan the mebila nede relacates
to the secend subnet. The seeand eaehing proxy may
seamless1 y cantinue to supply the requested content
strearn as a functien of tha cache handeff.
C0005] The foregaing sy5tem advantageeusI,y provides
graat convenience to usera of wireless amail
eommunication devices for erganizing.and managing their
email messagas. Yet, f urther convenience arnd, e f f Yciency
features may ba desired in email distribution and
synchroriization syst~ms as email usaga cQntiriues to
grew in popularitry s
eceived at the EPO an Aug 24, 2006 16:57:13. P~ AMENDED SHEET
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Brief Description of the Drawings
[0006] Other objects, features and advantages of the
present invention will become apparent from the
detailed description of the invention which follows,
when considered in light of the accompanying drawings
in which:
[0007] FIG. 1 is schematic block diagram of a direct
access electronic mail (email) distribution and
synchronization system in accordance with the present
invention.
[0008] FIG. 2 is a schematic block diagram of an
exemplary embodiment of user interface components of
the direct access proxy of the system of FIG. 1.
[0009] FIG. 3 is a schematic block diagram of an
exemplary embodiment of the Web client engine of the
system of FIG. 1.
[0010] FIGS. 4 is a schematic block diagram of an
exemplary embodiment of the mobile office platform
engine machine for use in the system of FIG. 1.
[0011] FIG. 5 is a schematic block diagram of an
exemplary embodiment of the database module of the
system of FIG. 1.
[0012] FIGS. 6A and 6B are high-level flowcharts
illustrating operation of an electronic mail (email)
server that obtains mappings for mapping message
identifiers.
[0013] FIG. 7 is a high-level flowchart illustrating
a process for reducing UID mappings in cache.
[0014] FIG. 8 is a high-level flowchart illustrating
a basic process of improving a Least Recently Used
(LRU) cache.
[0015] FIG. 9 is a schematic block diagram
illustrating an exemplary mobile wireless
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communications device that can be used with the Direct
Access system shown in FIG. 1.
Detailed Description of the Preferred Embodiments
[0016] The present invention will now be described
more fully hereinafter with reference to the
accompanying drawings, in which preferred embodiments
of the invention are shown. This invention may,
however, be embodied in many different forms and should
not be construed as limited to the embodiments set
forth herein. Rather, these embodiments are provided
so that this disclosure will be thorough and complete,
and will fully convey the scope of the invention to
those skilled in the art. Like numbers refer to like
elements throughout, and prime notation is used to
indicate similar elements in alternative embodiments.
[0017] Generally speaking, the present application
is directed to a direct access electronic mail system,
and more particularly, to an electronic mail (email)
server. The email server may include a proxy that
obtains mappings for unique identifiers (UID's)
corresponding to new electronic messages that had been
determined from a polling operation. A Least Recently
Used (LRU) cache caches each new message and releases
from cache least recently used messages. A memory is
included in which all messages within the LRU cache are
spooled.
[0018] This memory could be formed as a disk memory
having an input/output through which new messages are
input and output. The input/output varies in its
requests per second based on the number of proxies per
partition. The input/output also has fewer requests
per second when a greater number of proxies per
partition exists on the disk memory. The proxy is also
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operative for filtering out received headers from a new
message to aid in reducing the overall size of a new
message.
[0019] A communications system, electronic mail
(email) processing method, and computer-readable medium
having computer-executable modules is set forth. The
computer-readable medium can include a Least Recently
Used (LRU) cache and memory, such as disk memory.
[0020] Referring initially to FIG. 1, a direct
access (DA) email distribution and synchronization
system 20 allows direct access to different mail
sources, allowing messages to be transferred directly
to a mobile wireless handheld device from a source
mailbox. As a result, different mail stores need not be
used for integrated external source mail accounts, and
a permanent copy of an email in a local email store is
not required.
[0021] Although this diagram depicts objects as
functionally separate, such depiction is merely for
illustrative purposes. It will be apparent to those
skilled in the art that the objects portrayed in this
figure can be arbitrarily combined or divided into
separate software, firmware or hardware components.
Furthermore, it will also be apparent to those skilled
in the art that such objects, regardless of how they
are combined or divided, can execute on the same
computing device or can be arbitrarily distributed
among different computing devices connected by one or
more networks.
[0022] The direct access system 20 enables email
users or subscribers to have email from third party
email services pushed to various mobile wireless
communications devices 25. Users need not create a
handheld email account to gain direct access to an
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existing external email account. The direct access
system 20 may operate without performing aggregation as
used in some prior art systems, in which emails are
aggregated from multiple different source mailboxes to
a single target mailbox. In other words, email need not
be stored in an intermediate target mailbox, but
instead may advantageously be accessed directly from a
.source mail store.
[0023] As illustrated in FIG. 1, the direct access
system 20 illustratively includes a Web client (WC)
engine 22 and a mobile office platform (MOP) 24. These
Web client engine 22 and mobile office platform 24
operate together to provide users with direct access to
their email from mobile wireless communications devices
25 via one or more wireless communications networks 27,
for example. Both the Web client engine 22 and the
mobile office platform 24 may be located at the same
location or at separate locations, and implemented in
one or more servers. The web client engine 22
illustratively includes a port agent 30 for
communicating with the wireless communications devices
25 via the wireless communications network(s) 27, a
worker 32, a supervisor 34, and an attachment server
36, which will be discussed further below. An alert
server 38 is shown in dashed lines, and in one
preferred embodiment, is not used, but could be part of
the system in yet other embodiments.
[0024] The mobile office platform 24 illustratively
includes a DA proxy 40, and a proxy application
programming interface (API) 42 and a cache 44
cooperating with the DA proxy. The mobile office
platform 24 also illustratively includes a load balance
and cache (LBAC) module 46, an event server 48, a
universal proxy (UP) Servlet 54, an AggCron module 56,
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a mobile office platform (MOP) engine 58, and a
database (DB) engine 60, which will be discussed in
further detail below. The Least Recently Used (LRU)
cache 41 caches new messages, and can release messages
and objects that were least recently used.
[0025] The supervisor 34 processes new mail
notifications that it receives from the direct access
proxy 40. It then assigns a job, in the form of a User
Datagram Protocol (UDP) packet, to the least-loaded
worker 32, according to the most recent UDP heartbeat
the supervisor 34 has received. For purposes of this
description, heartbeat is a tool that monitors the
state of the server. Additionally, the supervisor 34
will receive a new service book request from the direct
access proxy 40 to send service books to the mobile
wireless communication device for new or changed
accounts. A service book can be a class that could
contain all service records currently defined. This
class can be used to maintain a collection of
information about the device, such as connection
information or services, such as an email address of
the account.
[0026] The worker 32 is an intermediary processing
agent between the supervisor 34 and the port agent 30,
and responsible for most processing in the Web client
engine 22. It will retrieve e-mail from a universal
proxy 54, via a direct access proxy, and format e-mail
in Compressed Multipurpose Internet Mai1. Extension
(CMIME) as a type of Multipurpose Internet Mail
Extension, and send it to the port agent 30, for
further processing. Its responsibilities include the
following tasks: (1) messages sent to and received from
the handheld; (2) message reply, forward and more
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requests; (3) Over The Air Folder Management operation
(OTAFM); (4) attachment viewing; and (5) service book.
[0027] The port agent 30 acts as a transport layer
between the infrastructure and the rest of the Web
client engine 22. It is responsible for delivering
packets to and from the mobile wireless communications
device. To support different integrated mailboxes with
one device, more than one service book can be used, and
each service book can be associated with one integrated
mailbox. A port agent 30 can include one Server Relay
Protocol (SRP) connection to a relay, but it can also
handle multiple SRP connections, and each connection
may have a unique Globally Unique Identifier (GUID)
associated with a service book. The attachment server
36 provides service for document/attachment conversion
requests from workers 32.
[0028] The direct access proxy 40 provides a Web-
based Distributed Authoring and Versioning (WebDAV)
interface that is used by the worker 32 to access
account and mailbox information. This provides
functionality to create, change and move documents on a
remote server, e.g., a Web server. The direct access
proxy 40 typically will present an asynchronous
interface to its clients. The LBAC module 46 is used by
a notification server and the Web client engine 22
components to locate the proper DA proxy for the
handling of a request. The universal proxy Servlet 54
abstracts access to disparate mail stores into a common
protocol. The event server 48 responds to notifications
of new messages from corporate servers 52 and/or mail
service providers 50, which may be received via the
Internet 40, for example. The notifications are
communicated to the direct access proxy 40 by the
AggCron module 56 and the event server 48 so that it
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may initiate checking for new mail on source mailboxes
51, 53 of the mail service providers 50 and/or
corporate servers 52. The proxy API can be a Simple
Object Access Protocol (SOAP) Daemon 42 and is the
primary interface into a database 60, which is the
primary data store for the mobile office platform 24.
The AggCron module 56 may also periodically initiate
polling for new messages as well.
[0029] FIG. 2 is a high-level block diagram showing
user interface components of the direct access proxy
40. More particularly, the direct access proxy 40
illustratively includes an identifier module 72 with
various downstream proxy modules for different
communication formats, such as a Wireless Application
Protocol (WAP) proxy module 74 and a Hypertext Markup
Language (HTML) proxy module 76. Of course, it will be
appreciated by those skilled in the art that other
types of proxy modules for other communications formats
may also be used.
[0030] The identifier module 72 provides a
centralized authentication service for the direct
access system 20 and other services. An authentication
handshake may be provided between an ID service and
direct access system 20 to ensure that users have the
proper credentials before they are allowed access to
the direct access system 20. The ability to switch from
managing a Web client to a direct access system, or
vice versa, may occur without requiring the user to re-
enter any login credentials. Any Web client and direct
access may share session management information on
behalf of a user.
[0031] The WAP proxy 74 provides a wireless markup
language (WML)-based user interface for configuring
source mailboxes with the mobile office platform 24.
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The HTML proxy 76 provides an HTML-based user interface
for configuring of source mailboxes in the MOP 24. The
proxy API 42 (SOAP Daemon) is the primary interface
into the database 60. The engine 58 is a protocol
translator that-connects to a source mailbox to
validate configuration parameters. The database 60 is
the primary user data store for the mobile office
platform 24.
[0032] FIGS. 3, 4 and 5 illustrate respective Web
client engine machines 80 (FIG. 3), an engine machine
82 (FIG. 4), and database machine 84 (FIG. 5). The Web
client engine machine 80 illustratively includes the
supervisors 34, workers 36, and port agents 38. Relays
86 cooperate with the port agents 38 using a GUID.
[0033] The engine machine 82 illustratively includes
a direct access proxy 40, HTML proxy 76, WAP proxy 74,
PDS module 88, UP Servlet 54, LBAC module 46, a
sendmail module 90, an secure mail client (SMC) server
92, a secure sockets layer (SSL) proxy 94, an
aggregation engine 96, and event server 48. The SMC
server 92 cooperates with corresponding SMC modules
resident on certain corporate networks, for example, to
convey email data between the mobile office platform 24
and source mailboxes. The database machine 84 may
include an aggregation application programming
interface (API) 100 as a SOAP Daemon, an administration
console 102, an aggregation database 104, the AggCron
module 56, an SMC directory server 106, and a send mail
module 90.
[0034] The various components of the Web client
engine 22 may be configured to run on different
machines or servers. The component binaries and
configuration files may either be placed in a directory
on the network or placed on a local disk that can be
CA 02622409 2008-03-17
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accessed to allow the appropriate components to run
from each machine. In accordance with one exemplary
implementation, deployment may include one supervisor,
two workers, and one port agent for supporting 30,000
external source mailboxes, although other
configurations may also be used. Actual production
deployment may depend on the results of load,
performance and stress testing, as will be appreciated
by those skilled in the art.
[0035] For the mobile office platform 24 direct
access components, modules and various functions,
machines are typically installed in two configurations,
namely engine machines (FIG. 4) and database machines
(FIG. 5). While these machines may have all of the
above-described components installed on them, not all
of these components need be active in all applications
(e.g., aggregation may be used with systems that do not
support push technology, etc.). Once again, actual
production deployment may depend on the results of
load, performance and stress testing.
[0036] The mobile office platform 24 architecture in
one known technique advantageously uses a set of
device/language-specific eXtensible Stylesheet Language
(XSL) files, which transform application data into
presentation information. In one non-limiting example,
a build process takes a non-localized XSL and generates
a localized XSL for each supported language. When the
XSL is used, it is "compiled" in memory and cached for
repeated use. The purpose of pre-localizing and caching
the templates is to reduce the CPU cycles required to
generate a presentation page.
[0037] Branding may also be performed. Initially, a
localized XSL may build a WAP application to access
aggregated email accounts. A WAP proxy application may
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be localizable and support multiple WAP devices. For
each logical page of an application, a device-specific
XSL may be created, which may be localized for each
language/country supported. This rendering scheme may
support not only WAP devices, but also SMTP, HTML and
POP proxies, for example. In branding, each page of a
given application may be customized for each different
brand.
[0038] The branding of a page may be accomplished
through XSL imports, including the use of a Java
application programming interface (API) for XML
processing (JAXP) feature to resolve the imports
dynamically. This need not require that each combined
page/brand template be compiled and cached. By way of
example, in a sample template directory, first and
second pages for a single language/country may be
combined with branded counterparts to generate a
plurality of distinct template combinations. It is also
possible to profile memory requirements of an
application by loading templates for a single language,
device/application and brand. An HTML device may
include a set of templates that are large compared to
other devices.
[0039] In one known technique, the mobile office
platform 24 advantageously builds processes and takes
non-localized files and language-specific property
files and combines them to make each non-localized XSL
into an XSL for each supported language. A separate
XSL for each language need not be used, and the
language factor may be removed from the memory usage
equation. A JAXP API may be used to extend XSL with
Java classes. The extensions may take various forms,
for example, including extension elements and extension
functions. A template may be transformed by creating
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and initializing an extension object with a locale and
passing an object to a transformer. The system can
remove multiple imports and use less memory. HTML
templates can use template importing to enable template
reuse, much like Java classes, and reuse other Java
classes through a mechanism like derivation or
importing.
[0040] In the direct access system 20, users receive
email on their mobile wireless communications devices
25 from multiple external accounts, and when replying
to a received message, the reply-to and sent-from
address integrity is preserved. For example, for a user
that has an integrated Yahoo! account (user@yahoo.com)
and a P0P3 account (user@pop3.com), if they receive an
email at user@yahoo.com, their replies generated from
the device 25 will appear to come from user@yahoo.com.
Similarly, if a user receives an email at
user@pop3.com, their replies will appear to come from
user@pop3.com.
[0041] Selection of the "sent from" address is also
available to a user that composes new messages. The
user will have the ability to select the "sent from"
address when composing a-new message. Depending on the
source mailbox type and protocol, the message may also
be sent through the source mail service. This
functionality can be supported by sending a
configuration for each source mailbox, for example, as
a non-limiting example, a service book for each source
mailbox 51, 53 to the mobile wireless communications
device 25.
[0042] As noted above, a service book is a class
that may include all service records currently defined.
This class may be used to maintain a collection of
information about the device, such as connection
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information. The service book may be used to manage
HTTP connections and mail (CMIME) information such as
account and hierachy. At mobile wireless communications
devices 25, a delete service book request may be sent
when a source mailbox 51, 53 is removed from the
account. The service book may also be resent to the
device 25 with a viewable name that gives the user some
indication that the selection is no longer valid.
[0043] A sent items folder may also be
"synchronized." Any device-originated sent messages
may be propagated to a source account and stored in a
sent mail folder, for example. Also, messages deleted
on the device 25 may correspondingly be deleted from
the source mailbox 51, 53. Another example is that
device-originated marking of a message as read or
unread on the device 25 may similarly be propagated to
the source mailbox 51, 53. While the foregoing features
are described as source-dependent and synchronizing
one-way, in some embodiments certain synchronization
features may in addition, or instead, propagate from
the source mailbox/account to the handheld device, as
will be appreciated by those skilled in the art.
[0044] When available, the mail service provider or
corporate mail server may be used for submission of
outgoing messages. While this may not be possible for
all mail service providers or servers, it is
preferrably used when available as it may provide
several advantages. For example, subscribers to AOL
will get the benefit of AOL-specific features like
parental controls. Furthermore, AOL and Yahoo users,
as non-limiting examples, will see messages in their
sent items folder, and messages routed in this manner
may be more compliant with new spam policies such as
Sender Policy Framework (SPF) and Sender Id. In
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addition, messages sent via corporate mail servers 52
will have proper name resolution both at the global
address list level and the personal level. It should be
understood, however, that the use of the mail service
provider 50 to deliver mail may be dependant on partner
agreements and/or protocol, depending upon the given
implementation.
[0045] The architecture described above also
advantageously allows for features such as on-demand
retrieval of message bodies and attachments and,
multiple folder support. Morever, a "this-is-spam"
button or indicator may be used allowing company labels
and other service provider-specific features when
supported by an underlying protocol, as will be
appreciated by those skilled in the art.
[0046] One particular advantage of the direct access
system 20 is that,a user need not configure an account
before integrating additional accounts. However, a
standalone email address may be used, and this address
advantageously need not be tied to a mailbox size which
the subscriber is required to manage. For example, the
email account may be managed by an administrator, and
any mail could be purged from the system after a pre-
determined period of time (i.e., time-based auto-aging
with no mailbox limit for all users).
[0047] Additionally, all aspects of any integrated
email account creation, settings and options may
advantageously be available to the user from their
mobile wireless communications device 25 Thus, users
need not visit an HTML site and change a setting,
create a filter, or perform similar functions, for
example. Of course, an HTML site may optionally be
used.
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[0048] As a system Internet email service with the
direct access system 20 grows, ongoing emphasis may
advantageously be placed on the administrative site to
provide additional information to carrier
administrators, support teams, and similar functions.
However, in some instances-a mail connector may be
installed on a personal computer, and this
functionality may not always be available from the
mobile wireless communications device.
[0049] The Web client engine 22 may advantageously
support different feature,s including message to
handheld (MTH), message from handheld (MFH),
forward/reply a message, request to view more for a
large message (e.g., larger than 2K), request viewing
message attachment, and over the air folder management
(OTAFM). These functions are explained below.
[0050] For an MTH function, each email account
integrated for a user is linked with the user device
through a Web client service book. For each new message
that arrives in the Web client user mailbox, a
notification that contains the new message information
will typically be sent to a Web client engine
supervisor component (FIG. 3), which in turn will
assign the job to an available worker with the least
load in the system. The chosen worker 32 will validate
the user information and retrieve the new message from
the user source mailbox and deliver it to the user
device.
[0051] In an MFH function, MFH messages associated
with a Web client service book are processed by the Web
client engine 22 and delivered to the Internet 49 by
the worker 32 via the simple mail transfer protocol
(SMTP) or native outbox. If a user turns on the option
to save the sent message to the sent items folder, the
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direct access proxy will save a copy of the sent
message to this folder.
[0052] In a Forward/Reply/More function, the user
can forward or reply an MTH or MFH message from the
mobile wireless communications device 25 as long as the
original message still existed in the direct access
proxy cache or in user mailbox. For MTH, the worker 32
may send the first 2K, for example, or the whole
message (whatever is less) to the user device. If the
message is larger than 2K, the user can request MORE to
view the next 2K of the message. In this case, the
worker 32 will process the More request by retrieving
the original message from the user source mailbox, and
send back the 2K that the device requests. Of course,
in some embodiments more than 2K of message text (or
the entire message) may be sent.
[0053] In an attachment-viewing function, a user can
view a message attachment of a popular document format
(e.g., MS Word, MS Power Point, MS Excel, Word Perfect,
PDF, text, etc.) or image format (GIF, JPEG, etc). Upon
receiving the attachment-viewing request, which is
implemented in a form of the More request in this
example, the worker 32 can fetch the original message
from the user source mailbox via the direct access
proxy, extract the requested attachment, process it and
send result back to the user device. The processing
requires that the original message has not been deleted
from the user Web client mailbox.
[0054] In the save sent message to sent items folder
function, if the user turns this option on, the worker
32 places a copy of each MFH message sent from the user
device in the user sent items folder in the mailbox. In
over the air folder management, the Web client OTAFM
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service maintains any messages and folders in the user
mailbox synchronized with the user device over the air.
[0055] Whenever a message in the user source mailbox
is Moved/Deleted, the associated message on the device
may also be Moved/Deleted accordingly, and vice-versa.
When a message is Moved/Deleted on the device, the
associated message in the user Web client mailbox may
also be Moved/Deleted accordingly. Similarly, when a
folder is Added/Removed/Renamed from the user Web
client mailbox, the associated folder on the device may
be Added/Removed/Renamed, and vice-versa.
[0056] The system 20 may advantageously support
different subsets of various messaging features. For
example, in the message to handheld function, the
mobile office platform 24 may be responsible for
connecting to the various source mailboxes 51, 53 to
detect new emails. For each new mail, a notification
is sent to the Web client engine 22 and, based on this
notification, the supervisor 34 chooses one of the
workers 32 to process that email. The chosen worker
will fetch additional account information and the
contents of the mail message from the direct access
proxy 40 and deliver it to the user device 25.
[0057] In a message sent from handheld function, the
MFH could be given to the direct access proxy 40 from
the Web client worker 32. In turn, the mobile office
platform 24 delivers a message to the Internet 49 by
sending through a native outbox or sending it via SMTP.
It should be understood, however, that the native
outbox, whenever possible, may provide a better user
experience, especially when taking into account current
anti-spam initiatives such as SPF and sender Id.
[0058] In a message deleted from handheld function,
when a message is deleted from the device 25, the Web
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client engine 22 notifies the mobile office platform 24
via the direct access proxy 40. As such, the mobile
office platform 24 can delete the same message orr) the
source mailbox.
[0059] When handling More/Forward/Reply/Attachment
viewing requests, the Web client worker 32 may request
an original mail from the direct access proxy 40. It
will then process the request and send the results to
the mobile wireless communications device 25. The
architecture may additionally support on-demand
retrieval of message parts and other upgrades, for
example.
[0060] Upon the integration of a new source mailbox
51, 53, the service book notification from the alert
server 38 may be sent to the supervisor 34, which
assigns this notification to a worker 32 for sending
out a service record to the device. Each source mailbox
51, 53 may be associated with a unique service record.
In this way, each MFH message is linked with a source
mailbox 51, 53 based on the service record on the
device.
[0061] The system 20 may also poll the integrated
external mailboxes periodically to check for new mail
and to access any messages. The system 20 may further
incorporate optimizations for polling bandwidth from an
aggregation component allowing a quick poll. The system
20 can also advantageously support a large active user
base and incorporate a rapidly growing user base.
[0062] The topology of load balancing can be based
on the size of a component's queue and its throughput.
These load statistics can be monitored by a mechanism
in one example called the UDP Heartbeat, as described
before. If a component is overloaded or has a large
queue size, the component will have less chance to get
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an assigned job from other components. In contrast, a
component will get more assigned jobs if it completes
more jobs in the last few hours than other components.
With this mechanism, the load could distribute over
heterogeneous machine hardware, i.e., components
running on less power machines will be assigned fewer
jobs than those on machines with more power hardware.
[0063] General load balancing for any mobile office
platform components can be accomplished through the use
of a load balancer module, for example, a BIG-IP module
produced by F5 Networks of Seattle, Washington. BIG-IP
can provide load balancing and intelligent layer 7
switching, and can handle traffic routing from the
Internet to any customer interfacing components such as
the WAP and HTML proxies. The use of a BIG-IP or
similar module may provide the application with pooling
capabilities, fault tolerance and session management,
as will be appreciated by those skilled in the art.
[0064] Typically, access to a single source mailbox
51, 53 can be from a single direct access proxy 40 over
a persistent connection. Any requests on behalf of a
particular user could persist to the same machine in
the same direct access clustered partition. As certain
components are system-wide and will be handling work
for users across many partitions, these components can
be designed to determine which direct access partition
to communicate with on a request-by-request basis.
[0065] The load balancer and cache (LBAC) 46 may
support this function. The LBAC 46 is a system-wide
component that can perform two important functions. The
first of these function is that it provides a mapping
from the device PIN to a particular direct access proxy
40, while caching the information in memory for both
fast access and to save load on the central database.
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Secondly, as the direct access proxy 40 will be run in
clustered partitions, the LBAC 46 may distribute the
load across all direct access proxies within any
partition..
[0066] The LBAC 46 can be formed of different
components. For example, the code which performs the
load balancing can be an extended version of a secure
mail connector. The code can also perform lookups to
the central database and cache the results (LBAC).
[0067] In one non-limiting example, when a worker
requires that a direct access proxy 40 perform work, it
provides the LBAC 46 with a device PIN. The LBAC 46
will discover which partition that PIN is associated
with by looking in its cache, or retrieving the
partition identifier from a central database (and
caching the result). Once the partition is knoian, the
LBAC 46 then consults its cache to see which direct
access proxy in that partition has been designated to
handle requests for that PIN. If no mapping exists, the
LBAC requests the PDS to create a new association on
the least loaded DA proxy 40 (again caching the
result). Finally, the LBAC 46 responds to the worker 32
with the connection information for the proper direct
access proxy to handle that particular request.
[0068] The secure mail connector 88 may run in
failover pairs, where one is an active master and the
other is a secondary standby. Internal data structures
may be replicated in real-time from the master to the
standby. Multiple LBACs 46 can be run for scalability
and fault tolerance, but typically would require an
external connection balancing component, such as the
BIG-IP component as explained before.
[0069] A receiving component in the Web client
engine 22 saves the job that has been assigned to it
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from other components to a job store on the disk before
processing. It can update the status of the job and
remove the job from the job store when the job
processing is completed. In case of component failure
or if the process is restarted, it can recover the jobs
from the job store and, based on the current statuses
of these jobs, continue processing these jobs to the
next state, saving the time to reprocess them from the
beginning.
[0070] Any recovery from the standpoint of MTH/MFH
can be achieved through current polling behavior and on
the Web client engine 22 recovery mechanisms. From
within the mail office platform components, until a
message has been successfully delivered to a Web client
engine 22, that message is not recorded in the
partition database 60. During the next polling
interval, the system can again "discover" the message
and attempt to notify the Web client engine 22. For new
mail events, if an event is lost, the system can pick
up that message upon receiving the next event or during
the next polling interval. For sources supporting
notifications, this interval could be set at six hours,
as one non-limiting example. For messages sent from the
Web client engine 22, and for messages that have been
accepted by the Web client engine, recovery can be
handled by different Web client engine components.
[0071] The Web client engine 22 may advantageously
be horizontally and vertically scalable. Multiple
supervisors 34 can be registered/configured with direct
access proxies 40 to provide the distribution of the
notification load and the availability of engine
service. Multiple workers 32 and port agents 30 can run
on the same machine or across multiple machines to
distribute load and achieve redundancy. As the number
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of users grows, new components can be added to the
system to achieve high horizontal scalability.
[0072] It is possible for a new component to be
added/removed to/from the system automatically without
down time. Traffic can automatically be delegated to a
new component and diverted away from failed components.
Each component within.the mobile office platform 24 can
be deployed multiple times to achieve horizontal
scalability. To achieve vertical scalability, each
mobile office platform 24 component can be a multi-
threaded process with a configurable number of threads
to scale under heavy load. Pools of connections can be
used to reduce the overhead of maintaining too many
open connections.
[0073] Currently, every time the DA proxy 10
receives a "check for new mail" notification, it
obtains all the message identifiers, unique
identifiers, and Href attributes as a"path" or
"handle" to a message (msgId, uid, and href) mappings
from the database 60 and caches them. In this
description, HREF is a mechanism used to identify and
retrieve a particular message from a source mailbox.
It typically has meaning to a UP Servlet. Similarly,
in case the DA proxy 10 receives a Get/Delete/Move
request for a MsgId and it does not find it in the
cache 44, it accesses the database and obtains all the
msgId, uid, and href mappings and caches them. Once
cached, these mappings will reside for the life of the
user session. The database 60 can include a disk
memory in which messages or portions of messages can be
spooled. A disk memory to which messages or portions
of messages can be spooled could be separate from the
database physical structure, of course.
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[0074] The Href attribute is operative to retrieve a
destination universal resource locator (URL), e.g.,
anchor point can jump to the bookmarks of any other
object identification attributes. A link could
possibly display any directory containing a current
page, or could generate an error depending on other
elements on the web page and the server environment.
When an anchor is specified, the link to that address
is represented by the text between opening and closing
anchor tags. The Href could also be considered a
uniform resource locator being linked, making the
anchor into a link. The message identifiers can be
unique identifiers (UID) as are known to those skilled
in the art. The Href, msgID and UID terms can be
called by different names as known by those skilled in
the art.
[0075] It should be understood that some mailboxes
have 1000+ messages and others have up to 10,000+
messages in an Inbox and there could also be certain
optimizations. In the database, (msgId, davUid,
davHref) are declared as (int, varbinary(64),
varbinary(255), typically about a maximum of 327 bytes
per mapping. DAV can refer to distributed authoring
and versioning, and in one implementation, data sizes
and names could change.
[0076] In one optimization example, instead of
fetching all the msgId mappings, the system could
retrieve a smaller number, for example, the latest 100,
when the system is about to perform a quick poll. The
system does not require a full reconcile, and it is
able to retrieve all UID's only when the system is
about to make a full poll. If the system observes a
Get/Delete/Move request on a msgld that is not cached,
the system could add another stored procedure call that
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gives it the mapping for this particular msgId and, as
an example, another 100 mappings around it.
[0077] Sample data suggests that the average mailbox
size on a Work Client production is 200. A typical
mailbox, however, has 2000 UID's. Each DA proxy
partition typically can support at least about 30,000
mailboxes. If the system deploys three proxies per
partition, then each proxy can support about 10,000
mailboxes in this non-limiting example.
[0078] As an example, the average mailbox size is
typically about 200. The average UID mapping. will
occupy 200 bytes (60% of 327). Hence, each mailbox
will require (200*200=) 40KB, and each proxy will
require (40KB*10,000=) 400MB to store these mappings.
If 30% of all users will be active at any given time,
the memory requirement reduces to 30% of 400MB = 120MB.
Similarly, if the system uses four proxies per
partition, then the total memory requirement comes down
to about 30% of (40KB*7,500) = 90 MB in this example.
[0079] In one embodiment, three out of four polls in
the DA system 10 are quick polls. If the system
introduces this optimization, it does not have to cache
all the UID mappings 75% of the time, and thus, the
system can significantly reduce the total memory
requirement to cache these mappings.
[0080] The main issue with fetching a subset, for
example, 100, of all UID's in order to check for new
mail is that it can give the system false positives.
If a UID from a remote server is a new, or is a visible
UID by checking for existence in the list of seen
UID's, the system could obtain a false positive, since
we will be checking against a subset of seen UID's and
not the entire set of seen UID's. False positives will
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result in duplicate mails being delivered to the device
as new mail.
[0081] One way of getting around this problem is to
fetch all the UID's from the database if the system
comes across a new mail while doing a quick poll in
order to make sure it is a new UID. This approach
could introduce an additional database hit every time a
new mail is discovered. The extra database hit would
not be necessary if a quick poll does not discover any
new mail.
[0082] Another optimization can be introduced in
case the DA proxy 10 receives a Get/Delete/Move request
for a msgId and it does not find that in the cache. In
this case, the system will fetch and cache all mappings
irrespective of the poll type, quick or full. This
approach does not affect the total memory requirement
to cache these mappings during polling but will provide
some benefit if a session does not see any polling
requests during its life, in which case it would not
fetch all the mappings and cache them but cache only a
subset.
[0083] A different approach would be to fetch all
the UID mappings from the database and store them in a
file-based cache instead of in memory. This would not
only address the concern the system has about memory
consumed, but also eliminate the need for an extra
database hit. On the other hand, this type of system
is much more complex to implement as opposed to storing
the mappings in memory. It also could possibly
decrease the performance since the list has to be
accessed from disk.
[0084] Another possible approach makes a stored
procedure (proc) call with a batch of UID's in the
right order, and implements the quick poll logic in the
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stored proc call. This approach is available since the
quick poll logic is rather straightforward, and it
would eliminate a requirement to read all the UID
mappings into memory. The quick poll logic, however,
requires the system to look at the top and the bottom
of the mailbox to check for new mail, in which case it
would result in two separate hits to the database, once
with the batch of UID's from the top, and a second time
with the UID's from the bottom of the mailbox.
[0085] One method to reduce the memory requirement
would be to purge the UID's that have been read into
memory after the polling step is over. Once the quick
or full poll is done, the system can proactively remove
the UID's that have been read into memory. This
polling logic requires only the UID's, and it does not
require the msgId or the davHref. These are no longer
read from the database into memory. The new UID
mappings that have been discovered in the polling step
are cached into memory, in order to avoid a database
hit when the worker asks for them.
[0086] If a Get/Delete/Move request is evident on a
msgId that is not cached, another stored procedure call
gives the system the mapping for this particular msgId,
and 20 other mappings around it are added. These
mappings are subsequently cached in memory. When the
system asks the database to return the mappings for a
particular msgId, the system retrieves mappings for 20
other msgIds around it, assuming that the user might
operate on other messages around the one that the user
is currently operating on. Checks are placed to make
sure that the number of cached mappings do not keep
growing and the cache is cleared if the number exceeds
a certain threshold. The memory consumed by each user
session to cache the UID mappings is greatly reduced.
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[0087] In the DA proxy architecture 40, there is a
LRU cache 41 that caches all new messages that it
finds. Each DA proxy partition could see up to one
million new messages a day, for example, 30,000 users
each receiving 30 messages a day, and the memory
requirements of this data structure are large. For
example, if the system decides to cache 1K of each
message in memory and spool anything over 1K to disk,
and assuming every message is at least 1K in size, the
cache would require one gigabyte of memory. In order
to improve upon this, one possible approach is to add a
weight/value to each message based on a heuristic,
e.g., its message size or the number of times it would
be accessed. Every time a message is accessed, its
associated value could be decremented. When this value
turns zero, the system would proactively delete this
message item from the cache, instead of waiting for the
LRU to operate. The total memory consumption of this
data structure could be reduced.
[0088] This approach relies on knowledge of the
internal workings of the system. For example, messages
less than 3K in size are pushed in their entirety to
the device, and are likely to be accessed only twice,
i.e., once the first time it is pushed to the device,
and the second time if the user decides to reply or
forward the mQssage. Messages greater than 3K in size
can be accessed once for every "More" request by the
user, indicating that the user desires to view
additional portions of the message. Messages with
attachments, however, may follow a different pattern of
requests unique to the working of the attachment
server.
[0089] If the resulting heuristic is narrow, the
system may end up deleting a message from the cache
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prematurely, and thus, have to download the message a
second time. This could possibly increase bandwidth
usage. On the other hand, if the heuristic is wide,
the system may not delete messages until the LRU forces
them out, thus failing to derive any benefit from the
optimization.
[0090] Instead of keeping a certain portion of a
message, for example, up to 1K, in memory and spooling
the rest onto disk, it is also possible that messages
can be retained entirely in memory or entirely on disk.
Since these are new messages that the worker is going
to retrieve in their entirety, keeping some portion in
memory does not aid the overall response time of this
request if the remaining portion will require a disk
read.
[0091] One example data sample from the Work Client
production finds the distribution of message sizes.
The data indicated that 37% of all messages were less
than 3K in size. One approach would be to keep
messages less than 3K entirely in memory, and messages
greater than 3K entirely on disk. In this case, the
memory requirements would still be considerably high,
3K * 370K(37% of 1M messages) = 1.1G.
[0092] This example data also indicated that
typically 2% of all messages are about less than 1K.
Since the percentage of these messages is small,
storing only messages less than 1K entirely in memory
would not significantly affect the overall performance.
In one embodiment, then, messages in cache can be
spooled entirely on disk. This not only reduces the
main memory requirements of the cache to zero, but not
having any heuristic and relying on plain LRU reduces
the likelihood of deleting messages prematurely and
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then having to download them a second time, increasing
bandwidth usage.
[0093] An example DA system request rate performance
spreadsheet indicates the following requirements that
the DA proxy 40 (per partition) can support. Those
requests that involve reading or writing to the message
cache in this example are:
New mail 621,000 msg / day
Reply/Forward 124,000 msg / day
More 31,000 msg / day
Total 776,000 msg / day
[0094] 776,000 requests over a 12 hour period
amounts to about 18 requests/sec. It is possible to
use multiple proxies. If the system uses one DA proxy
40 per partition, as long as the disk I/O can give the
system 18 requests per second, the system should be
operable in its intended manner. If the system uses
two DA proxies 40 per partition, then the system may
require about 9 requests/second.
[0095] It is also possible to filter out the
"Received" headers from the downloaded messages and
reduce the overall size of the message, and hence the
memory consumed by each message in the cache.
[0096] FIGS. 6A, 6B, 7 and 8 are high-level
flowcharts illustrating examples of the processes for
obtaining mappings for new UID's and mapping new
message ID's (FIG. 6), reducing UID mappings in cache
(FIG. 7), and improving the LRU cache (FIG. 8).
[0097] FIG. 6A shows that a polling function can
start (block 200). The UID's and message ID's of new
mail are stored in a persistent store such as a
database (block 202). The message ID's of new mail are
cached to a cache memory (block 204) and the polling is
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complete. As shown in FIG. 6B, a mail job is received
(block 210) and a determination is made if a message ID
is in cache (block 212). If so, a mapping is obtained
from cache (block 214) and the mail job processed
(block 216). The mail job is complete (block 218).
Alternatively, the message ID and adjacent message ID's
can be retrieved from the persistent store as a data
store (block 220) and the message ID is cached in the
cache memory (block 222).
[0098] As shown in FIG. 7 in this function, the
polling can start (block 230). All previously existing
UID's can be fetched and cached from the persistent
store as a database (block 232). The UID's and message
ID's for new mail can be stored in the persistent store
(block 234). The message ID's for new mail can be
stored in a message ID cache (block 236). All
previously existing UID's can be cleared from the cache
(block 238) and the polling is complete (block 240).
[0099] As shown in FIG. 8, the polling can start
(block 250). The UID's and message ID's of new mail
can be stored in a persistent store as a database
(block 252). The message ID's or new mail can be
cached to a cache memory (block 254). Each message can
be retrieved and added into the LRU (block 256). The
messages can be spooled to a disk (block 258). The
polling is complete (block 260).
[00100] An example of a hand-held mobile wireless
communications device 1000 that may be used is further
described in the example below with reference to FIG.
9. The device 1000 illustratively includes a housing
1200, a-keypad 1400 and an output device 1600. The
output device shown is a display 1600, which is
preferably a full graphic LCD. Other types of output
devices may alternatively be utilized. A processing
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device 1800 is contained within the housing 1200 and is
coupled between the keypad 1400 and the display 1600.
The processing device 1800 controls the operation of
the display 1600, as well as the overall operation of
the mobile device 1000, in response to actuation of
keys on the keypad 1400 by the user.
[00101] The housing 1200 may be elongated vertically,
or may take on other sizes and shapes (including
clamshell housing structures). The keypad may include a
mode selection key, or other hardware or software for
switching between text entry and telephony entry.
[00102] In addition to the processing device 1800,
other parts of the mobile device 1000 are shown
schematically in FIG. 9. These include a
communications subsystem 1001; a short-range
communications subsystem 1020; the keypad 1400 and the
display 1600, along with other input/output devices
1060, 1080, 1100 and 1120; as well as memory devices
1160, 1180 and various other device subsystems 1201.
The mobile device 1000 is preferably a two-way RF
communications device having voice and data
communications capabilities. In addition, the mobile
device 1000 preferably has the capability to
communicate with other computer systems via the
Internet.
[00103] Operating system software executed by the
processing device 1800 is preferably stored in a
persistent store, such as the flash memory 1160, but
may be stored in other types of memory devices, such as
a read only memory (ROM) or similar storage element. In
addition, system software, specific device
applications, or parts thereof, may be temporarily
loaded into a volatile store, such as the random access
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memory (RAM) 1180. Communications signals received by
the mobile device may also be stored in the RAM 1180.
[00104] The processing device 1800, in addition to
its operating system functions, enables execution of
software applications 1300A-1300N on the device 1000. A
predetermined set of applications that control basic
device operations, such as data and voice
communications 1300A and 1300B, may be installed on the
device 1000 during manufacture. In addition, a personal
information manager (PIM) application may be installed
during manufacture. The PIM is preferably capable of
organizing and managing data items, such as e-mail,
calendar events, voice mails, appointments, and task
items. The PIM application is also preferably capable
of sending and receiving data items via a wireless
network 1401. Preferably, the PIM data items are
seamlessly integrated, synchronized and updated via the
wireless network 1401 with the device user's
corresponding data items stored or associated with a
host computer system.
[00105] Communication functions, including data and
voice communications, are performed through the
communications subsystem 1001, and possibly.through the
short-range communications subsystem. The
communications subsystem 1001 includes a receiver 1500,
a transmitter 1520, and one or more antennas 1540 and
1560. In addition, the communications subsystem 1001
also includes a processing module, such as a digital
signal processor (DSP) 1580, and local oscillators
(LOs) 1601. The specific design and implementation of
the communications subsystem 1001 is dependent upon the
communications network in which the mobile device 1000
is intended to operate. For example, a mobile device
1000 may include a communications subsystem 1001
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designed to operate with the MobitexTM, Data TACTM or
General Packet Radio Service (GPRS) mobile data
communications networks, and also designed to operate
with any of a variety of voice communications networks,
such as AMPS, TDMA, CDMA, PCS, GSM, etc. Other types of
data and voice networks, both separate and integrated,
may also be utilized with the mobile device 1000.
[00106] Network access requirements vary depending
upon the type of communication system. For example, in
the Mobitex and DataTAC networks, mobile devices are
registered on the network using a unique personal
identification number or PIN associated with each
device. In GPRS networks, however, network access is
associated with a subscriber or user of a device. A
GPRS device therefore requires a subscriber identity
module, commonly referred to as a SIM card, in order to
operate on a GPRS network.
[00107] When required network registration or
activation procedures have been completed, the mobile
device 1000 may send and receive communications signals
over the communication network 1401. Signals received
from the communications network 1401 by the antenna
1540 are routed to the receiver 1500, which provides
for signal amplification, frequency down conversion,
filtering, channel selection, etc., and may also
provide analog to digital conversion. Analog-to-digital
conversion of the received signal allows the DSP 1580
to perform more complex communications functions, such
as demodulation and decoding. In a similar manner,
signals to be transmitted to the network 1401 are
processed (e.g. modulated and encoded) by the DSP 1580
and are then provided to the transmitter 1520 for
digital to analog conversion, frequency up conversion,
filtering, amplification and transmission to the
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communication network 1401 (or networks) via the
antenna 1560.
[00108] In addition to processing communications
signals, the DSP 1580 provides for control of the
receiver 1500 and the transmitter 1520. For example,
gains applied to communications signals in the receiver
1500 and transmitter 1520 may be adaptively controlled
through automatic gain control algorithms implemented
in the DSP 1580.
[00109] In a data communications mode, a received
signal, such as a text message or web page download, is
processed by the communications subsystem 1001 and is
input to the processing device 1800. The received
signal is then further processed by the processing
device 1800 for an output to the display 1600, or
alternatively to some other auxiliary I/0 device 1060.
A device user may also compose data items, such as e-
mail messages, using the keypad 1400 and/or some other
auxiliary I/0 device 1060, such as a touchpad, a rocker
switch, a thumb-wheel, or some other type of input
device. The composed data items may then be transmitted
over the communications network 1401 via the
communications subsystem 1001.
[00110] 'In a voice communications mode, overall
operation of the device is substantially similar to the
data communications mode, except that received signals
are output to a speaker 1100, and signals for
transmission are generated by a microphone 1120.
Alternative voice or audio I/0 subsystems, such as a
voice message recording subsystem, may also be
implemented on the device 1000. In addition, the
display 1600 may also be utilized in voice
communications mode, for example to display the
CA 02622409 2008-11-18
identity of a calling party, the duration of a voice call, or other
voice call related information.
[00111] The short-range communications subsystem enables
communication between the mobile device 1000 and other proximate
systems or devices, which need not necessarily be similar devices.
For example, the short- range communications subsystem may include
an infrared device and associated circuits and components, or a
BluetoothTm communications module to provide for communication with
similarly-enabled systems and devices.
[00112] This application is related to copending Canadian Patent
Application No. 2,621,649 entitled, "EMAIL SERVER WITH PROXY CACHING
OF UNIQUE IDENTIFIERS" and Canadian Patent Application No. 2,622,316
"EMAIL SERVER WITH PROXY CACHING OF MESSAGE IDENTIFIERS AND RELATED
METHODS," which are filed on the same date and by the same assignee
and inventors.
[00113] Many modifications and other embodiments of the invention
will come to the mind of one skilled in the art having the benefit
of the teachings presented in the foregoing descriptions and the
associated drawings. Therefore, it is understood that the invention
is not to be limited to the specific embodiments disclosed, and that
modifications and embodiments are intended to be included within the
scope of the appended claims.
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