EP1393517A2 - Compression de contenu basee sur le service au sein d'un systeme de communication de reseau - Google Patents

Compression de contenu basee sur le service au sein d'un systeme de communication de reseau

Info

Publication number
EP1393517A2
EP1393517A2 EP02729251A EP02729251A EP1393517A2 EP 1393517 A2 EP1393517 A2 EP 1393517A2 EP 02729251 A EP02729251 A EP 02729251A EP 02729251 A EP02729251 A EP 02729251A EP 1393517 A2 EP1393517 A2 EP 1393517A2
Authority
EP
European Patent Office
Prior art keywords
email
client
server
email message
compression
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP02729251A
Other languages
German (de)
English (en)
Inventor
Chris Koopmans
Nicholas Stavrakos
Constantine Polychronopoulos
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Bytemobile Inc
Original Assignee
Bytemobile Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US10/095,551 external-priority patent/US7024460B2/en
Application filed by Bytemobile Inc filed Critical Bytemobile Inc
Publication of EP1393517A2 publication Critical patent/EP1393517A2/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L51/00—User-to-user messaging in packet-switching networks, transmitted according to store-and-forward or real-time protocols, e.g. e-mail
    • H04L51/06—Message adaptation to terminal or network requirements
    • H04L51/066—Format adaptation, e.g. format conversion or compression
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L67/00—Network arrangements or protocols for supporting network services or applications
    • H04L67/50—Network services
    • H04L67/56—Provisioning of proxy services
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L67/00—Network arrangements or protocols for supporting network services or applications
    • H04L67/50—Network services
    • H04L67/56—Provisioning of proxy services
    • H04L67/565—Conversion or adaptation of application format or content
    • H04L67/5651—Reducing the amount or size of exchanged application data
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L69/00—Network arrangements, protocols or services independent of the application payload and not provided for in the other groups of this subclass
    • H04L69/04—Protocols for data compression, e.g. ROHC
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L51/00—User-to-user messaging in packet-switching networks, transmitted according to store-and-forward or real-time protocols, e.g. e-mail
    • H04L51/58—Message adaptation for wireless communication

Definitions

  • the present invention generally relates to network communication systems, and more particularly, to systems and methods for performing service- based compression of content within a network communication system.
  • heterogeneous wireless/wireline networks for example, the wireless channels are typically characterized by a relatively low bandwidth and a relatively high occurrence of random packet loss and deep fades. Because conventional Internet-based architectures typically assume that physical channels have a relatively high bandwidth and a relatively low occurrence of random packet loss, these architectures may erroneously conclude that packet loss was caused by congestion, rather than a temporary degradation in the signal quality of the wireless channel. For systems employing a TCP/IP architecture, this erroneous detection of congestion loss may cause the server to significantly decrease the rate at which data is transmitted to the wireless client, resulting in under- utilization of the limited bandwidth resources of the wireless channel. As a result, heterogeneous wireless/wireline networks typically exhibit sub-optimal performance and typically provide inefficient or ineffective use of limited wireless bandwidth resources.
  • Embodiments of the present invention provide systems and methods for reducing the amount of data communicated over a wireless (or other low bandwidth) channel by compressing content based on the type of requested service.
  • a service module intercepts packets communicated between a client and a server and selectively processes packets corresponding to email services.
  • the service module may be configured to classify a connection between the client and the server to determine whether the connection corresponds to an email service, such as Post Office Protocol (POP) or Internet Message Access Protocol (IMAP).
  • POP Post Office Protocol
  • IMAP Internet Message Access Protocol
  • This process may involve examining the packet headers of incoming packets and comparing the destination port field with a predetermined set of destination port numbers, such as 110 (the designated port assignment for the POP email protocol) and 143 (the designated port assignment for the IMAP email protocol). If a connection between the client and the server corresponds to an email service, the service module breaks the connection between the client and the server by terminating the connection with the client at the service module and opening a separate connection between the service module and the server. This process breaks the end-to-end connection between the client and the server to form two separate connections: a client-side connection between the client and the service module and a server-side connection between the service module and the server.
  • a predetermined set of destination port numbers such as 110 (the designated port assignment for the POP email protocol) and 143 (the designated port assignment for the IMAP email protocol).
  • the service module may be configured to intercept subsequent packets addressed between the client and the server and redirect the packets via the client-side connection and the server-side connection to an email compression application associated with the service module. For example, the service module may be configured to modify the packet headers of incoming packets to replace the original destination address and destination port with a destination address and destination port associated with the email compression application. Packets addressed from the client may then be redirected to the email compression application via the client-side connection, and packets addressed from the server may be similarly redirected to the email compression application via the server-side connection.
  • the service module may be configured to generate connection control parameters, such as TCP control block parameters, for the client-side connection and the server-side connection in response to the service module determining that the connection between the client and the server corresponds to an email service.
  • connection control parameters store the original source and destination information associated with the end-to-end connection (along with a redirected destination address and destination port associated with the email compression application) and enable the operating system and networking stack of the service module to recognize packets corresponding to the end-to-end connection and redirect packets to the email compression application.
  • the email compression application may examine messages communicated between the client and the server and process the messages in accordance with the state of the email session. For example, the email compression application may be configured to forward messages corresponding to connection establishment, user authentication or other non-transaction related commands to the originally intended destination by reading the message from the client-side connection and writing the message to the server-side connection or vice versa. On the other hand, if the email session enters a transaction state, messages corresponding to email message data may be buffered within the email compression application.
  • the service module sends acknowledgement packets back to the source in response to each received packet so that the source will continue to send data corresponding to the email message.
  • the email compression application strips the message headers and any protocol-specific data, compresses the data and attaches new message headers corresponding to the compressed email message. The compressed and reformatted email message is then reinserted into the data stream for transmission to the originally intended destination.
  • the operating system and networking stack of the service module may treat the outgoing data as though the data originated from the email compression application.
  • the operating system and networking stack may generate packets having a source address and source port associated with the email compression application.
  • the service module may be configured to generate outgoing packets using the network addresses and ports associated with the end- to-end connection.
  • the service module may be configured to maintain a table (or linked list structure) that stores the original packet header information associated with the client-side connection and the server-side connection.
  • the service module For outgoing packets sent through the client-side connection, the service module searches the table based on the information included in the packet header of the outgoing packet to determine the original packet header information associated with the client-side connection. The service module then modifies the outgoing packet to replace the source address and source port with the original network address and port associated with the server. Similarly, for outgoing packets sent through the server-side connection, the service module searches the table based on the information included in the packet header of the outgoing packet to determine the original packet header information associated with the server-side connection. The service module then modifies the outgoing packet to replace the source address and source port with the original network address and port associated with the client.
  • the service module may be configured to generate connection control parameters, such as TCP control block parameters, for the client-side connection and the server-side connection that incorporate the original network address and port associated with the end-to-end connection.
  • connection control parameters such as TCP control block parameters
  • connection control parameters may then be used by the operating system and networking stack of the service module to generate outgoing packets having a network address and port corresponding to the original end-to-end connection between the client and the server.
  • the connection control parameters for the client-side connection may be configured to store the original source and destination addresses and the original source and destination ports associated with the client and server.
  • the service module uses the connection control parameters to generate outgoing packets having a source address and source port associated with the server.
  • the connection control parameters associated with the server-side connection may be similarly configured such that the operating system and network stack of the service module automatically generates outgoing packets addressed to the server using the original source address and source port associated with the client. Because packets transmitted from the service module include the original source and destination addresses and the original source and destination ports associated with the end-to-end connection, the client and the server are unaware that the service module intercepted the packets and (possibly) performed intermediate processing on the transmitted data.
  • the email compression application may be configured to compress email messages in a format that can be readily decompressed using decompression libraries already incorporated within the operating system of the client device, such as the Microsoft Cabinet (CAB) format incorporated in the Microsoft Windows 95, 98, CE and NT operating systems and the GZIP format incorporated in the Unix operating system.
  • CAB Microsoft Cabinet
  • This aspect of the present invention exploits the fact that most operating systems already support and recognize certain file formats and compression types in a default configuration.
  • the CAB format for example, is incorporated within the Microsoft Windows 95, 98, CE and NT operating systems to support decompression of backup system configuration files in the event of a system malfunction and decompression of operating system and user software files during initial installation and setup operations.
  • files compressed in a CAB format using a recognized compression type are automatically recognized and decompressed by the operating system in response to a user attempting to open a file having the associated ".cab" extension.
  • a recognized compression type such as MSZip (default), Quantum or LZX
  • the client may then decompress received email messages utilizing software already incorporated within the operating system of the client device, without requiring download or installation of special decompression modules and/or coordination of compression/decompression of email messages with the server or sending party.
  • the email compression application may also change the file extensions associated with compressed email attachments so that the client's operating system will automatically recognize and decompress the attachment (by executing the decompression module associated with the applicable file extension) in response to the user attempting to open the email attachment.
  • the service module may be configured to provide a transparent end-to- end email compression service without requiring installation of special software modules at the client (other than modules already incorporated in the operating system of the client device).
  • the service module may be configured to select between a first compression mode and a second compression mode based on a determination of whether the client includes a compatible decompression unit.
  • the service module performs socket compression on data transmitted to the client.
  • the service module forwards uncompressed messages corresponding to signaling messages, such as connection establishment, user authentication or other connection control commands, and compresses data corresponding to an email message.
  • the service module may be configured to classify a connection to determine whether the source address associated with a source matches a predetermined source address or falls within a predetermined range of source addresses (which may comprise the source addresses of registered users of a peer decompression unit or registered client modules of a network carrier that incorporate a peer decompression unit). If so, the service module performs socket compression on data communicated on the downlink from the service module to the source. If the source address associated with the source does not match the predetermined source address or predetermined range of source addresses, the service module processes email messages using the second compression mode.
  • a predetermined source address or falls within a predetermined range of source addresses which may comprise the source addresses of registered users of a peer decompression unit or registered client modules of a network carrier that incorporate a peer decompression unit.
  • the email compression application may be configured to selectively compress email messages in accordance with the type of content.
  • the email compression application may associate each type of content supported by an email protocol, such as text, application, audio, video or application data, with a corresponding compression type, such as lossless compression, lossy compression or no compression.
  • the association between the compression type and the type of content may be stored in a configuration file that may be modified to register new types of content or change an existing association without requiring the email compression application to be recompiled.
  • the configuration file may also associate each compression type with a compression format, such as a CAB format, a GZIP format or no compression, in order to enable a user to modify the compression format without modifying the association between the compression type and the type of content.
  • the email compression application may be configured to extract each part of the email message and individually process each part in accordance with the type of content. Once each part of the message has been compressed, the email compression application may then attach new message headers to each part (corresponding to the compressed and reformatted data) and reassemble the individual parts in the same order as the original uncompressed message. Because each part of the message may be individually processed, the email compression application may be configured to selectively compress email attachments and forward the email message body in an uncompressed format. This process also enables the client's email application to recognize each compressed part by examining the associated uncompressed message headers.
  • FIGS. 1 A and IB illustrate exemplary network communication systems in which the principles of the present invention may be advantageously practiced
  • Figure 2 illustrates an exemplary service module platform that may be used in accordance with the present invention
  • Figures 3 A and 3B illustrate functional block diagrams of an exemplary email compression system in accordance with a first and a second embodiment of the present invention
  • Figure 4 illustrates a signal flow diagram showing exemplary signals passed between a wireless client, service module and server during an exemplary email session
  • Figure 5 illustrates a functional block diagram of an exemplary email compression application for processing email messages
  • Figure 6 illustrates a functional block diagram of an exemplary email compression handler in accordance with one embodiment of the present invention
  • Figures 7A and 7B illustrate exemplary methods in flowchart form for redirecting received packets and reinserting packets into a data stream, respectively;
  • Figure 8 illustrates an exemplary method in flowchart form for establishing a client side connection and a server-side connection
  • Figure 9 illustrates an exemplary method in flowchart form for compressing received email messages in accordance with one embodiment of the present invention.
  • the exemplary system includes a wireless client 110, such as a personal digital assistant or laptop computer equipped with a wireless modem, that communicates with a server 180 via a wireless backbone network 125 and the Internet 170.
  • the wireless backbone network 125 employs a General Packet Radio Service (GPRS) architecture.
  • GPRS General Packet Radio Service
  • the wireless client 110 communicates with a base station 120 located within the wireless client's assigned cell.
  • the base station 120 then forwards data and signaling information received from the wireless client 110 through the wireless backbone network 125 via a base transceiver station 130, a serving
  • GPRS General Packet Radio Service
  • the gateway 160 acts as an interface between the wireless backbone network 125 and nodes within the Internet 170 and enables information to be transceived between wireless clients 110 coupled to the wireless backbone network 125 and servers 180 coupled to the Internet 170.
  • information is routed through the Internet 170 and wireless backbone network 125 from the server 180 toward the wireless client 110. Once the information is received by the base station 120, the information is transmitted to the wireless client 110 over a wireless channel 115.
  • a wireless channel 115 is typically characterized by a relatively low bandwidth and a relatively high occurrence of random packet loss and deep fades. These random packet losses and periods in which the wireless client 110 is unavailable may be erroneously interpreted by the network as congestion loss (rather than a mere temporary degradation in the signaling quality of the wireless channel 115). For networks implementing a TCP/IP architecture, this erroneous detection of congestion loss may cause the server 180 to significantly reduce the transmission rate of information sent to the wireless client 110, resulting in under-utilization of limited bandwidth resources of the wireless channel 115.
  • the service module 190 may be incorporated within the network infrastructure between the wireless client 110 and server 180 in order to enable the service module 190 to process email messages as the corresponding packets flow through the network. As illustrated in Figure 1 A, for example, the service module 190 may be deployed in an offload configuration that enables the service module 190 to process packets forwarded from a network node, such as a GGSN 150.
  • a network node such as a GGSN 150.
  • the configuration of Figure 1A may be advantageous in that it enables the service module 190 to conform to less stringent reliability requirements, and allows the service module 190 to be periodically taken off-line for hardware or software upgrades or periodic maintenance without disabling links between adjacent nodes.
  • the service module 190 may be arranged in an inline configuration between network nodes such that packets are routed through the service module 190.
  • This inline configuration may also be advantageous in that it may minimize packet processing delays by enabling the service module 190 to process packets without traversing through an intermediate network node.
  • the service module 190 may directly incorporate functionalities of the service module 190 within a network node, such as a GGSN 150, SGSN 140, gateway 160, base transceiver station 130 or the like, in order to enhance the processing capabilities of conventional network nodes or reduce the overhead associated with maintaining separate pieces of equipment.
  • the service module 190 may be configured to reduce the amount of data transmitted over a wireless channel 115 by intercepting packets communicated between the server 180 and the wireless client 110 and selectively processing packets corresponding to email services.
  • the service module 190 may be configured to classify a connection between the wireless client 110 and the server 180 to determine whether the connection corresponds to an email service, such as Post Office Protocol (POP) or Internet Message Access Protocol (IMAP).
  • POP Post Office Protocol
  • IMAP Internet Message Access Protocol
  • This process may involve examining packet headers and comparing the destination port field with a predetermined set of destination port numbers, such as 110 (the designated port assignment for the POP email protocol) and 143 (the designated port assignment for the IMAP email protocol). If a connection between the wireless client 110 and the server 180 corresponds to an email service, the service module 190 breaks the connection between the wireless client 110 and the server 180 by terminating the connection with the wireless client 110 at the service module 190 and opening a separate connection between the service module 190 and the server 180. This process breaks the end-to-end connection between the wireless client 110 and the server 180 to form two separate connections: a client-side connection between the wireless client 110 and the service module 190 and a server-side connection between the service module 190 and the server 180.
  • a predetermined set of destination port numbers such as 110 (the designated port assignment for the POP email protocol) and 143 (the designated port assignment for the IMAP email protocol).
  • Packets communicated between the wireless client 110 and the server 180 are then redirected through the client-side connection and the server-side connection to an email compression application associated with the service module 190 that examines messages communicated between the wireless client 110 and the server 180 and processes the messages in accordance with the state of the email session.
  • the service module 190 may be configured in one embodiment to redirect the packets to the email compression application by replacing the original destination address and destination port associated with the server 180 with a destination address and destination port associated with the email compression application. This redirection process enables incoming packets to be treated by the operating system and networking stack of the service module
  • connection control parameters such as TCP control block parameters
  • the service module 190 may be configured to generate connection control parameters, such as TCP control block parameters, for the client-side connection that stores the original source and destination information associated with the end-to-end connection (along with the redirected address and port associated with the email compression application) in response to the service module detecting that the connection corresponds to an email service.
  • connection control parameters may then be used by the operating system and networking stack of the service module 190 to recognize and redirect subsequent packets communicated between the wireless client 110 and the server 180 to the email compression application.
  • the email compression application may then examine the data communicated from the wireless client 110 to the server 180, update the state of the email session, and forward the data to the server 180 by writing the data to the server- side connection.
  • the data then flows through the operating system and networking stack of the service module 190 to generate an outgoing packet addressed to the server 180. Because the operating system and networking stack of the service module 180 may treat the packet as though the packet originated at the email compression application, the outgoing packet may have source address and source port fields associated with the email compression application.
  • the service module 190 may be configured in one embodiment to modify the packet header of outgoing packets to replace the source address and source port associated with the email compression application with the original source address and source port associated with the end-to-end connection.
  • the service module 190 may be configured to maintain a lookup table (or linked-list structure) that stores the original packet header information initially received from the wireless client 110 before the packet header information is modified during the redirection process.
  • the service module 190 may then search the lookup table to determine the original source address and source port and modify the packet header of the outgoing packet to replace the source address and source port associated with the email compression application with the source address and source port associated with the wireless client 110.
  • the service module 190 may be configured to maintain connection control parameters, such as TCP control block parameters, for the server-side connection that incorporate the original network address and port associated with the wireless client 110.
  • the connection control parameters may then be used by the operating system and networking stack of the service module 190 to automatically generate outgoing packets addressed to the server 180 using the original source address and source port associated with the wireless client 110.
  • the server 180 Because the outgoing packets received by the server 180 have a source address and source port associated the wireless client 110, the server 180 does not and cannot know that the service module 190 has broken the end-to-end connection and (possibly) performed intermediate processing on the transmitted data. As a result, the server 180 treats the connection as though the connection was between the server 180 and the wireless client 110.
  • the service module 190 may similarly redirect the incoming packets through the server-side connection by either replacing the destination address and destination port associated with the wireless client 110 with the destination address and destination port associated the email compression application, or maintaining connection control parameters for the server-side connection that enables the operating system and networking stack of the service module 190 to recognize and redirect packets associated with the end- to-end connection to the email compression application.
  • the email compression application may then examine the data communicated from the server 180 to the wireless client 110, update the state of the email session, and process the data in accordance with the state of the email session.
  • the email compression application forwards the messages to the wireless client 110 by writing the data to the client-side connection.
  • the email session enters a transaction state, the data corresponding to the email message data is buffered within the email compression application. Because these data packets are received on a separate server-side connection, the operating system and networking stack automatically sends "fake" acknowledgement packets back to the server 180 in response to each received packet so that the server 180 will continue to send data corresponding to the email message.
  • the email compression application strips the message headers and any protocol-specific data, compresses the data and attaches new message headers corresponding to the compressed email message.
  • the compressed and reformatted email message is then written to the client-side connection for transmission to the wireless client 110.
  • the service module 190 also performs a reverse-redirection process on outgoing packets communicated to the wireless client 110 through the client-side connection.
  • the service module 190 may be configured in one embodiment to perform a search of the lookup table to determine the original network address and port assignment associated with the server 180.
  • the service module 190 may then modify the packet headers of outgoing packets transmitted to the wireless client 110 to replace the source address and source port associated with the email compression application with the original network address and port associated with the server 180.
  • the service module 190 may be configured to maintain connection control parameters for the client-side connection that stores the original source and destination information associated with the end-to-end connection and enables the operating system and networking stack of the service module 190 to generate outgoing packets communicated to the wireless client 110 using a source address and source port associated with the server 180. Because the outgoing packets received by the wireless client 110 include a source address and source port associated with the server 180, the wireless client 110 is similarly unaware that the service module 110 has broken the end-to-end connection. As a result, the wireless client 110 also treats the connection as though the connection was between the wireless client 110 and the server 180.
  • the email compression application may be configured to compress the email messages in a format that can be readily decompressed using decompression libraries already incorporated within the operating system of the wireless device, such as the Microsoft Cabinet (CAB) format incorporated in the Microsoft Windows 95, 98, CE and NT operating systems and the GZIP format incorporated in the Unix operating system.
  • CAB Microsoft Cabinet
  • This aspect of the present invention exploits the fact that most operating systems already support and recognize certain file formats and compression types in a default configuration.
  • the CAB format for example, is incorporated within the Microsoft Windows 95, 98, CE and NT operating systems to support decompression of files during installation and setup operations and to decompress backup registration files in the event of a system malfunction.
  • Files compressed in a CAB format using a recognized compression type, such as MSZip (default), Quantum or LZX, are automatically recognized and decompressed by the operating system in response to a user attempting to open a file having the associated ".cab" extension.
  • the wireless client 110 may decompress received email messages utilizing software already incorporated within the operating system of the wireless device, without requiring download or installation of special decompression modules and/or coordination of compression/decompression of email messages with the server 180 or sending party.
  • the email compression application may also change the file extensions associated with compressed email attachments so that the wireless client's operating system will automatically recognize and decompress the attachment (by executing the decompression module associated with the applicable file extension) in response to the user attempting to open the email attachment.
  • the service module 190 may be configured to provide a transparent end-to-end email compression service without requiring special processing by the server 180 or installation of special software modules at the wireless client 110 (other than modules already incorporated in the operating system of the wireless device).
  • an exemplary service module platform that may be used in accordance with the present invention is depicted generally at 200.
  • the exemplary platform includes one or more network interface cards 210 for interfacing with other nodes within the network, such as a base transceiver station, a SGSN, a GGSN, a gateway or the like.
  • the network interface cards 210 are coupled to a processor 220 via a system bus 225.
  • the processor 220 is also coupled to a memory system 240, such as a random access memory, a hard drive, a floppy disk, a compact disk, or other computer readable medium, which stores an operating system and networking stack 260 and an email compression application 250.
  • the exemplary platform may also include a management interface 280, such as a keyboard, input device or port for receiving configuration information, that may be used to selectively modify configuration parameters within the operating system and networking stack 260 and the email compression application 250 without requiring the modules to be re-compiled.
  • a management interface 280 such as a keyboard, input device or port for receiving configuration information, that may be used to selectively modify configuration parameters within the operating system and networking stack 260 and the email compression application 250 without requiring the modules to be re-compiled.
  • the network interface cards 210 generate a system interrupt to the interrupt controller 230 in response to the network interface card 210 receiving a packet.
  • the interrupt controller 230 then passes the interrupt to the processor 220 in accordance with the interrupt' s assigned priority.
  • the interrupt causes the processor 220 to execute interrupt handlers incorporated within the operating system and networking stack 260 to process the received packet.
  • These modules may provide operating system functions and other functions associated with the applicable protocol, such as TCP/IP or UDP/IP.
  • Embodiments of the present invention may also incorporate other functionalities within the operating system and networking stack 260, such as functionalities for classifying the connection, breaking the connection between the wireless client and the server, and generating source addresses for outgoing packets.
  • the operating system and networking stack 260 may also interact with the email compression application 250 to provide email compression services.
  • the exemplary system includes a service module 190 having a physical layer 320, an operating system and networking stack 260 and an email compression application 250.
  • the physical layer 320 initiates a interrupt to the operating system and networking stack 260 to process the received packet.
  • An IP filter layer 322 within the operating system and networking stack 260 then initiates a classifier 325 to classify the received packet in accordance with a set of classification rules 330 to determine whether the packet corresponds to an email service supported by the service module 190.
  • classification rules 330 may comprise one or more masks that are applied to the packet header.
  • the classification rules 330 may mask the source address, source port, destination address, and device (or VLAN) ID fields within the packet header and determine whether the protocol field equals TCP and whether the destination port equals either 110 (for POP email protocol) or 143 (for IMAP email protocol). If the packet does not match a classification rule 330, the classifier 325 either drops the packet or returns the packet to the IP filter layer 322 without modification. If the packet corresponds to an email service supported by the service module 190, however, the classifier 325 redirects the packet to the email compression application 250 by modifying the packet header to replace the original destination address and destination port with a destination address and destination port associated with the email compression application 250.
  • the classifier 325 then returns the modified packet to the IP filter layer 322, which forwards the modified packet to the IP and TCP layers 335, 340 for processing.
  • the classifier 325 also stores the original packet header information (along with the redirected destination address and destination port) within a classification table 332 to enable the classifier 325 and the email compression application 250 to access the original packet header information at a later time, as will be described hereinbelow.
  • the IP and TCP layers 335, 340 process the modified packet as though the packet were terminated at the email compression application 250. As a result, the IP and
  • TCP layers 335, 340 unpack the modified packet and pass the packet data to the operating system and networking stack 260.
  • the operating system and networking stack 260 forwards the packet data to a client socket 350 that the email compression application 250 previously established to receive new connections.
  • the operating system and networking stack 260 also sets a flag to inform the email compression application 250 that a new connection has been requested. Once the email compression application 250 accepts the new comiection, subsequent packets from the same source to the same destination are forwarded by the operating system and networking stack 260 to that client socket 350.
  • the classifier 325 redirects the packets to the email compression application 250.
  • the IP and TCP layers 335, 340 then process the redirected packets based on the source and modified destination information, and the operating system and networking stack 260 passes the data to the client socket 350.
  • the email compression application 250 may then access data communicated from the source by performing a read operation on the client socket 350 and send data to the source by performing a write operation on the client socket 350.
  • the email compression application 250 initiates a socket API 352 that searches the classification table 332 based on the source address and redirected destination address associated with the client socket 350. This search of the classification table 332 enables the email compression application 250 to recover the original packet header information before the destination information was modified by the classifier 325 during the redirection process.
  • the email compression application 250 may then open a server socket 360 using the original destination address and destination port. This process opens a separate connection between the email compression application 250 and the original destination to enable data to be communicated between the destination and the email compression application 250.
  • the email compression application 250 also initiates another call to the socket API 352 to create a new entry within the classification table 332 that stores the original packet header information (that was retrieved by email compression application 250), along with the redirected destination address and destination port associated with the server socket 360. Once the server socket 360 is established, the email compression application 250 may then receive data from the destination by performing a read operation on the server socket 360 and send data to the destination by performing a write operation on the server socket 360.
  • the corresponding data flows through the TCP and IP layers 340, 335 as though the data originated from the email compression application 250.
  • the TCP and IP layers 340, 335 may generate packets having a source address and source port associated with the email compression application 250.
  • the IP filter layer 322 initiates a call to the classifier 325 to modify outgoing packets to replace the source address and source port with the original source address and source port associated with the end-to-end connection.
  • the classifier 325 For packets addressed from the client socket 350, for example, the classifier 325 searches the classification table 332 based on the information included in the packet header of the outgoing packet to determine the original packet header information associated with the client socket 350. The classifier 325 then modifies the outgoing packet to replace the source address and source port with the original network address and port associated with the destination and returns the modified packet to the IP filter layer 322 such that the outgoing packet to the source appears to originate from the destination.
  • the classifier 325 similarly searches the classification table 332 for the original packet header information associated with the server socket 360 (that was stored by email compression application 250) and modifies the packet header of the outgoing packet by replacing the source address and source port fields with the original network address and port associated with the source such that the outgoing packet to the destination appears to originate from the source. Accordingly, because packets transmitted from the service module 190 include the original source and destination addresses and original source and destination ports, the original source and the original destination are unaware that the service module 190 intercepted the packets and (possibly) performed intermediate processing on the transmitted data.
  • the classifier 325 may then classify subsequent packets by searching the classification table 332 to determine whether the packets correspond to an on-going connection. If the packet header of an incoming packet matches an entry stored in the classification table 332, the classifier 325 may then access the redirected destination address and destination port stored in the classification table 332 and modify the destination address and destination port of the packet header as described above. If the incoming packet does not match an entry stored in the classification table 332, the classifier 325 may classify the packet in accordance with the classification rules 330 to determine whether to redirect the packet to the email compression application 250. By performing an initial search of the classification table 332, however, the classifier 325 may avoid the need to re-classify additional packets corresponding to an on-going connection (which may comprise the majority of packets forwarded to or through the service module 190).
  • packets addressed from a client email application 305 to a server email application 380 flow through the client operating system and networking stack 310 and physical layer 315 of the wireless client 110 and across the wireless portion of the communications network.
  • the communications network then forwards the packets to or through the service module 190 depending on whether the service module 190 is arranged in an inline or offload configuration.
  • the IP filter layer 322 calls the classifier 325 to classify the received packets to determine whether the packets correspond to an email service by either searching the classification table 332 or classifying the packets in accordance with the classification rules 330. If the packets correspond to an email service, the classifier 325 terminates the connection with the client email application 305 at the email compression application 250 to form a client-side connection 356 between the email compression application 250 and the client email application
  • the email compression application 250 may then receive data from the client email application 305 by performing a read operation on the client-side connection 356 and send data to the client email application 305 by performing a write operation on the client-side connection 356.
  • packets addressed from the server email application 380 to the client email application 305 flow through the server operating system and networking stack 370 and physical layer 365 of the server 180 and across the wireline portion of the communications network.
  • the IP filter layer 322 calls the classifier 325 to classify the received packets to determine whether the packets correspond to an email service by either searching the classification table 332 or applying the classification rules 330.
  • the classifier 325 redirects the packets to the email compression application 250 through a separate server-side connection 357 that the email compression application 250 opened in response to the initial packet received from the client email application 305.
  • the email compression application 250 may then receive data from the server email application 380 by performing a read operation on the server-side connection 357 and send data to the server email application 380 by performing a write operation on the server-side connection 357.
  • the IP filter layer 322 calls the classifier 325 to search the classification table 332 and replace the source address and source port associated with the email compression application 250 with the network address and port associated with the server email application 380.
  • the modified outgoing packets are then routed through the wireless portion of the communications network and are transmitted to the wireless client 110.
  • the client operating system and networking stack 310 processes the packets as though the packets originated directly from the server email application 380 and passes the processed packets to the client email application 305.
  • the classifier 325 similarly modifies outgoing packets sent by the email compression application 250 through the server-side connection 357 by replacing the source address and source port associated with the email compression application 250 with the network address and port assignment associated with the client email application 305.
  • the outgoing packets are then routed to the server 180 through the wireline portion of the communications network.
  • the server operating system and networking stack 370 processes the packets as though the packets originated directly from the client email application 305 and passes the processed packets to the server email application 380.
  • the email compression application 250 may monitor data received from the client- . side connection 356 and the server-side connection 357 and process the data in accordance with the state of the email session. For example, the email compression application 250 may be configured to forward connection-related data, such as connection establishment and user authentication messages, between the client-side connection 356 and the server-side connection 357 by reading the data from the client-side connection 356 and writing the data to the server-side connection 357 and vice versa, as indicated generally by line 354.
  • connection-related data such as connection establishment and user authentication messages
  • the email compression application 250 may buffer the corresponding email message data within a compressor 355 until the entire message has been received. Because these email message data packets are received through a separate connection, the TCP and IP layers 340, 335 automatically send acknowledgement messages back to the source of the data (typically the server 180) so that the source will continue to send data corresponding to the email message. Once the entire email message is received, the compressor 355 strips the message headers and any protocol-specific data, compresses the data and attaches new message headers corresponding to the compressed email message.
  • the compressed and reformatted email message is then reinserted into the data stream by writing the compressed email message to the appropriate client-side connection 356 or server-side connection 357.
  • the service module 190 may be configured to intercept packets corresponding to email messages and provide an email compression service in a manner transparent to the wireless client 110 and the server 180.
  • some embodiments of the present invention may configure the service module 190 to support only pull-type email services, such as POP or IMAP. These pull-type email services are generally initiated by clients for the purpose of downloading email messages. Because clients are the more likely end host to be connected to the communications network via the low bandwidth channel, these embodiments of the present invention may ensure that email messages are compressed and transmitted toward the low bandwidth channel.
  • pull-type email services such as POP or IMAP.
  • the compressor 355 may be configured to compress email message data in a manner that can be readily decompressed by the wireless client 110.
  • One of the problems generally associated with sending compressed email messages is ensuring that the recipient has the appropriate decompression software to decompress the email messages.
  • Embodiments of the present invention alleviate these problems by exploiting the fact that most operating systems already recognize and support certain file formats and compression types in a default configuration.
  • these operating systems incorporate decompression libraries to perform functions associated with operating system, such as decompression of backup system configuration files or decompression of operating system files or user software files during initial installation and setup operations. For example,
  • the client operating system and networking stack 310 may incorporate a decompressor 312 for decompressing file formats, such as the CAB format or GZIP format.
  • the file extension associated with the decompressor 312 is registered within the registry 314 or other operating system configuration file when the client operating system and networking stack 310 is installed so that the client operating system and networking stack 310 will automatically execute the decompressor 312 in response to a user attempting to open a file having the associated file extension.
  • the wireless client 110 can decompress received email messages utilizing software already incorporated within the client operating system and networking stack 310, without requiring download or installation of special decompression modules by the user and/or coordination of compression/decompression of email messages with the server 180 or sending party.
  • the compressor 355 may also change the file extensions associated with compressed email attachments so that the client operating system and networking stack 310 will automatically recognize and decompress the attachment (by executing the decompressor 312 associated with the applicable file extension) in response to the user attempting to open the email attachment.
  • the service module 190 may be configured to provide a transparent end-to-end email compression service without requiring installation or configuration of special decompression modules at the wireless client 110.
  • FIG. 3B a functional block diagram of an exemplary email compression system in accordance with a second embodiment of the present invention is illustrated generally at 300.
  • the embodiment of Figure 3B is substantially similar to the embodiment of Figure 3 A and incorporates many of the principles discussed above.
  • the embodiment of Figure 3B utilizes a more efficient mechanism for classifying connections and redirecting incoming and outgoing data.
  • the service module 190 receives packets communicated between the wireless client 110 and the server 180, the packets may be directed through the IP filter and IP layers 322, 335 to the TCP layer 340 of the service module 190.
  • the TCP layer 340 calls the classifier 325 to classify the connection establishment packets in accordance with a set of classification rules 330. If the connection establishment packets match a classification rule 330, the classifier
  • the TCP layer 340 modifies a TCP control block 342 to store the original packet header information received from the source, such as the original source and destination addresses and the original source and destination ports, and a redirected destination address and destination port associated with the email compression application 250.
  • the operating system and networking stack 260 passes data to a client socket 360 and notifies the email compression application 250 that a new connection has been requested.
  • the email compression application 250 accepts the new connection, the email compression application calls a socket API 352 that accesses the TCP control block 342 associated with the client socket 350 to retrieve the original packet header information.
  • the email compression application 250 then opens a server socket 360 using the original destination address and destination port, and calls the socket API 352 to store the original packet header information, along with the redirected address and redirected port associated with the server socket 360, within a TCP control block 342 associated with the server socket 360.
  • the TCP layer 340 uses the TCP control block 342 to redirect incoming packets addressed from the source to the client socket 350 and to redirect incoming packets addressed from the destination to server socket 360.
  • the email compression application 250 may then examine messages communicated between the source and destination by reading the client socket 350 and the server socket 360, and may send messages to the source and destination by writing data to the appropriate client socket 350 and server socket 360.
  • the data is passed to the TCP layer 340, which accesses the TCP control block 342 associated with the client socket 350 and generates packets having a source address and source port associated with the original destination.
  • the TCP layer 340 similarly accesses the TCP control block 342 associated with the server socket 360 and generates packets having a source address and source port associated with the original source.
  • the embodiment of Figure 3B offers advantages over the embodiment of Figure 3 A in that classification only needs to be performed on connection establishment packets, and the modification of the TCP control block 342 associated with the client socket 350 and the server socket 360 enables the TCP layer 340 to redirect incoming packets to the appropriate client socket 350 or server socket 360 and to automatically generate outgoing packets having a source address and source port associated with the original end-to-end connection.
  • the email compression application 250 may monitor messages communicated between the wireless client 110 and the server 180 and transparently compress email message data as described above.
  • Patent Application No. __/ entitled "Systems and Methods for
  • a signal flow diagram showing exemplary signals passed between a wireless client, service module and server during an exemplary email session is illustrated generally at 400.
  • packets communicated between the wireless client 110 and the server 180 may be intercepted by the service module 190 and redirected to an email compression application.
  • the email compression application may be configured to monitor messages communicated between the wireless client 110 and the server 180 and to update the state of the email session.
  • the email compression application may then process received messages in accordance with the current state of the email session.
  • the wireless client 110 may initiate an email session with the server 180 by attempting to engage in a three-way handshake with the server
  • the service module 190 classifies the connection between the wireless client 110 and the server 180, and terminates the connection with the wireless client 110 at the email compression application.
  • the operating system and networking stack of the service module 190 then completes the three-way handshake with the wireless client 110.
  • the email compression application opens a separate server-side connection with the server 180 using the original destination address and destination port.
  • the operating system and networking stack of the service module 190 similarly completes a three-way handshake with the server 415 as indicated generally at 415.
  • This process breaks the end-to-end connection between the wireless client 110 and the server 180 to form a client side- connection between the wireless client 110 and the service module 190 and a server-side connection between the service module 190 and the server 180.
  • the email session may then enter a user authentication state as indicated generally at 420.
  • the messages communicated between the wireless client 110 and the server 180 during this state vary depending on the particular email protocol.
  • the server 180 may send a greeting packet to the wireless client 110 requesting an appropriate user name and password, and the wireless client 110 responds by sending the requested information to the server 180.
  • the email compression application maintains end-to-end semantics by forwarding messages between the client-side connection and the server-side connection. This process may involve reading the message from the client-side connection and writing the message to the server-side connection and vice versa. Because the service module 190 uses the original source and destination address and source and destination ports for outgoing packets, the wireless client 110 and server 180 respond as though they are communicating with one another.
  • the email session may then enter a transaction state as indicated generally at 430.
  • the wireless client 110 may request retrieval of a particular email message as indicated by a FETCH (for an IMAP email protocol) or RETR (for a POP email protocol) command.
  • the email compression application forwards this message to the server 180 by reading the message from the client-side connection and writing the message to the server-side connection.
  • the email compression application then knows that the data received from the server 180 in response to the FETCH or RETR command will correspond to an email message.
  • the email compression application then buffers the email message data received from the server 180.
  • the server-side connection is a separate connection
  • the operating system and networking stack of the service module 190 sends acknowledgement messages back to the server 180 in response to each received packet so that the server 180 will continue to send data corresponding to the email message.
  • the email compression application strips the message headers and any protocol-specific data, compresses the data and attaches new message headers corresponding to the compressed email message.
  • the compressed and reformatted email message is then sent to the wireless client 110 by writing the compressed email message to the client-side connection.
  • the client-side connection is a separate connection
  • the operating system and networking stack of the service module 190 suppresses acknowledgement packet received from the wireless client 110 and retransmits lost packets without notifying the server 180.
  • the email session may then enter into an update state (as indicated generally at 440) that closes the email session and a close state (as indicated generally at 450) that closes the connection between the wireless client 110 and the server 180.
  • the email compression application maintains end-to-end semantics by forwarding messages between the client-side connection and the server-side connection.
  • the operating system and networking stack of the service module 190 responds to messages received by the wireless client 110 in order to close the client-side connection.
  • the operating system and networking stack then notifies the email compression application that the client-side connection has been closed, and the email compression application responds by initiating closure of the server-side connection.
  • the operating system and networking stack of the service module 190 then engages in conventional closure handshakes with the server 180 in order to close the server-side connection as indicated generally at 455.
  • the exemplary email compression application includes a proxy engine 510, a data handler 520, an email protocol handler 530 and an email compression handler 540.
  • the proxy engine 510 acts as an interface between the data handler 520 and the operating system and networking stack and manages communication between the client socket and the server socket.
  • the proxy engine 510 interacts with the operating system and networking stack to break the connection between the wireless client and the server to form the client-side connection and the server-side connection. For example, the proxy engine 510 may monitor the available client sockets and accept new connection requests received from the operating system and networking stack. The proxy engine 510 may then request the original packet header information associated with the client socket from the socket API and open the server socket using the original destination address and destination port. The proxy engine 510 also calls the socket API to either create a new entry in the classification table or modify the TCP control block to store the connection information associated with the server socket. Once the client socket and the server socket have been established, the proxy engine 510 listens to the client socket and server socket for new messages.
  • the proxy engine 510 then passes data received from the client socket and server socket to the data handler 520 and writes the data returned by the data handler 520 to the appropriate client socket or server socket.
  • the data handler 520 inspects the data to determine the corresponding handler that processes data of that type. For example, the proxy engine 510 may pass the source port from which the data was received to enable the data handler 520 to determine the applicable handler. Because the service module may associate each source port with a corresponding service (e.g., source port 4000 may correspond to POP and source port 4001 may correspond to socket compression), the data handler 520 may then determine the particular service associated with the data.
  • source port 4000 may correspond to POP and source port 4001 may correspond to socket compression
  • the data handler 520 may then call the email protocol handler 530 to process the incoming data.
  • the service corresponds to a socket compression service
  • the data handler 520 forwards the incoming data to the socket handler 525.
  • the service module may be configured to support two modes of compression, the socket compression performed by the socket handler 525 and the email compression performed by the email compression handler 540.
  • the service module may need to determine whether the wireless client has a peer decompression unit for performing socket decompression.
  • the service module may make this determination by adding a classification rule to the classifier that classifies incoming packets to determine whether the source address associated with a wireless client matches a predetermined source address or falls within a predetermined range of source addresses (which may comprise the source addresses of registered users of the peer decompression unit or designated subscribers of a network carrier who are issued a peer decompression unit).
  • the service module may search a local or external database that stores the source addresses of registered users of a compatible socket decompression unit.
  • the service module may then redirect data to the socket handler 525 to perform socket compression and transmit the compressed socket to the wireless client in accordance with the above described principles.
  • the email protocol handler 530 processes the data to perform the protocol- specific functions associated with managing the email session.
  • the email protocol handler 530 may be configured to monitor the data received from the data handler 520 and maintain a state machine for the email session. Based on the state of the email session, the data may take two paths through the email protocol handler 530 as indicated generally by paths 532 and 534.
  • the email protocol handler 530 may update the state machine and pass the data back to the data handler 520, which forwards the data to the proxy engine 510.
  • the proxy engine 510 then forwards the messages to the originally intended destination by writing the messages to the client socket or server socket.
  • This transfer of data up to the email protocol handler 530 enables the email protocol handler 530 to monitor the state of the email session and detect initiation of an email message transaction.
  • the transfer of data down to the proxy engine 510 enables the proxy engine 510 to maintain the end-to-end semantics between the wireless client and the server. If the email protocol handler 530 detects the initiation of an email message transaction (e.g.
  • the email protocol handler 530 buffers the email message data. Once the entire email message is received, the email protocol handler 530 extracts the email message by removing protocol specific data, such as POP byte-stuffing, to form a protocol independent RFC822 compliant email message. The email protocol handler 530 then passes the RFC822 compliant email message to the email compression handler 540.
  • protocol specific data such as POP byte-stuffing
  • the email compression handler 540 parses the message header to determine the content type and encoding type. The email compression handler 540 may then decode the email message, compress the email message in accordance with the content type, encode the message and attach a new message header to match the newly formatted message body. As mentioned previously, the email compression handler 540 may utilize a compression format commonly incorporated within the operating system of wireless devices, such as the CAB format, so that the wireless client can decompress the email message and any associated attacliments, without requiring special decompression modules (other than those already included within the operating system of the wireless device).
  • the email compression handler 540 may also change the file extension associated with the compressed file to ".cab" to enable the operating system of the wireless client to automatically decompress the file in response to a user attempting to open the file.
  • the email message handler 540 returns an RFC822 compliant message to the email protocol handler 540, which reformats the message with any protocol specific data, such as POP byte-stuffing.
  • the resulting message is passed to the data handler 520 and proxy engine 510, where the compressed and reformatted email message is transmitted to the intended destination.
  • the service module may include different email compression applications (with separate proxy engines, data handlers, email protocol handlers and email compression handlers) for each email protocol.
  • the service module may include a first email compression application for handling the POP email protocol and a separate email compression application for handling the IMAP email protocol.
  • the classifier may then be configured to redirect incoming email data streams to the destination port associated with appropriate email compression application, without requiring the data handler to determine the email protocol associated with the incoming data stream.
  • a message handler 610 receives a protocol independent message from protocol handler.
  • the message handler 610 may initially parse the message header of the received message to determine the content type, encoding type, data type and other information.
  • the message handler 610 then passes the email message and the encoding type to a decoder 620, which decodes the email message in accordance with the encoding type.
  • the decoder 620 may support the conventional encoding types used to encode email messages, such as Base64 and Quoted Printable. Based on the content type indicated in the message header, the message handler 610 will pass the decoded message to the compression engine 630, the multipart/mixed handler 636 or the message/RFC822 handler 635.
  • the message handler 610 passes the email message to the compression engine 630. Because compression generally includes some overhead, the compression engine 630 may initially determine whether the size of the received email message exceeds a predetermined threshold. If the size falls below the threshold, the compression engine 630 passes the email message back to the message handler 610. Otherwise, the compression engine 630 proceeds with compression of the email message.
  • the compression engine 630 may initially determine whether the size of the received email message exceeds a predetermined threshold. If the size falls below the threshold, the compression engine 630 passes the email message back to the message handler 610. Otherwise, the compression engine 630 proceeds with compression of the email message.
  • the compression engine 630 may be configured to automatically pass the email message to the CAB formatter 650, which compresses the email message in accordance with a CAB format using the compression library 680 and passes the compressed email message back the compression engine 630.
  • the compression engine 630 may be configured to compress email messages in accordance with the type of content.
  • the compression engine 630 may associate each type of content supported by an email protocol, such as "rtf ', "vnd.ms-excel" and "gif ', with a corresponding compression type, such as lossless compression, lossy compression or no compression.
  • the association between the compression type and the type of content may be stored in a configuration file 640 that may be modified to register new types of content or change an existing association without requiring the email compression handler to be recompiled.
  • the configuration file 640 may also associate each compression type with a compression format, such as a CAB format, a GZIP format or no compression, in order to enable a user via a management interface (illustrated in Figure 2) to modify the compression format without modifying the association between the compression type and the type of content. For example, assuming the type of content associated with the email message equals "vnd.ms-exel", the compression engine 630 compresses the data using the CAB formatter 650 and passes the compressed data back to the message handler 610. If the content type of the email message equals "message/RFC 822"
  • the message handler 610 passes the email message to a message/RFC822 handler 635, which separates the email message into its component messages and passes each message back to the message handler 610.
  • the message handler 610 then decodes each message and compresses each message as though the message were a single part message.
  • the message handler 610 then encodes the compressed message and passes each compressed message back to the message/RFC822 handler 635, which modifies the message header for each message to correspond to the compressed message (e.g., by changing the file name and file type parameters) and reassembles the compressed messages and modified message headers in the same order as the original uncompressed message.
  • the message/RFC822 handler 635 then passes the reassembled message back to the message handler 610. If the content type of the email message equals "multipart/mixed" (e.g., the email message has one or more attachments that may be of a different type of content), the message handler 610 passes the email message to a multipart/mixed handler 636, which extracts each part of the email message and passes each part back to the message handler 610. The message handler 610 then decodes each part and compresses each part as though the part were a separate (or stand-alone) message.
  • multipart/mixed e.g., the email message has one or more attachments that may be of a different type of content
  • the message handler 610 then encodes each compressed part and passes each compressed part back to the multipart/mixed handler 636, which modifies the message header for each part to correspond to the compressed part (e.g., by changing the file extension to an extension corresponding to the compression format, such ".cab") and reassembles the parts and modified message headers in the same order as the original uncompressed message.
  • the multipart/mixed handler 636 then passes the reassembled message back to the message handler 610.
  • the message handler 610 receives the compressed messages from the compression engine 630, message/RFC822 handler 635 or multipart/mixed handler 636, the message handler 610 creates and attaches a new message header to match the newly formatted email message to form an RFC822 compliant email message. The message handler 610 then passes the compressed message back to the protocol handler, which reformats the message with any protocol specific data.
  • an exemplary method in flowchart form for classifying and redirecting received packets in accordance with one embodiment of the present invention is illustrated generally at 700.
  • the exemplary method determines at step 715 whether the packet corresponds to a connection request packet, such as a SYN packet, indicating that the packet corresponds to a new connection that has not been previously classified. If the packet corresponds to a connection request packet, the exemplary method proceeds to step 720, where the packet is classified in accordance with one or more classification rules to determine whether the packet corresponds to an email service, such as POP or IMAP.
  • the classification rules may comprise one or more masks that are applied to the packet header.
  • Exemplary classification rules may mask the source address, source port, destination address, and device ID fields within the packet header and determine whether the protocol field equals TCP and whether the destination port equals either 110 (for POP email protocol) or 143 (for IMAP email protocol). Other exemplary classification rules may mask source port, destination address, destination port and device ID and protocol fields and determine whether the source address match a predetermined source address or falls within a range of source addresses. If the packet does not match a classification rule, the method does not terminate the packet, and either drops the packet, forwards the packet to the operating system and networking stack without modification, or performs other default services on the packet.
  • the method stores the original packet header information and redirected destination address and destination port within the classification table at step 740, and redirects the packet to an email compression application associated with the service module at step 745 by replacing the original destination address and destination port with the redirected destination address and destination port associated with the classification rule.
  • the modified packet is then forwarded through the operating system and networking stack of the service module to the email compression application at step 760.
  • the method searches the classification table at step 750 to determine whether the packet corresponds to an on-going connection. This process may involve searching the classification table to determine whether the packet header of the incoming packet corresponds to an entry stored in the classification table. If so, the method proceeds to step 745 where the packet header is modified to replace the original destination address and destination port with the redirected destination address and destination port associated with the entry stored in the classification table. The modified packet is then forwarded through the operating system and networking stack of the service module to the email compression application at step 760.
  • step 720 classify the packet in accordance with the above-described process.
  • an exemplary method in flowchart form for reinserting packets into a data stream is illustrated generally at 710.
  • the method searches the classification table at step 765 based on the packet header of the outgoing packet to determine the original source address associated with the end-to-end connection. The method then replaces the source address and source port of the outgoing packet with the original source address and source port at step 770.
  • the method would replace the source address and source port of the outgoing packet with the source address and source port associated with the wireless client. Conversely, for outgoing packets addressed to the client, the method would replace the source address and source port of the outgoing packet with the source address and source port associated with the server.
  • the method then reinserts the modified outgoing packet into the data stream at step 775.
  • the outgoing packet may then be routed through the communications network to the originally intended destination. Because the original source address and source ports are incorporated within the packet header, the destination will treat the packet as though the originated from the source.
  • the foregoing process may be performed on all outgoing packets communicated to the source and destination so that the source and destination are unaware that the packets were processed by the server module.
  • an exemplary method in flowchart form for establishing a client side connection and a server-side connection is illustrated generally at 800.
  • the exemplary method of Figure 8 may be performed by an email compression application in order to break a connection between the wireless client and the server by terminating the connection with the wireless client at the email compression application and opening a new connection between the email compression application and the server.
  • the exemplary method may be initiated in response the operating system and networking stack setting a flag informing the email compression application that a new connection has been requested.
  • the method may accept the connection from the source (typically the client) to form a client-side connection between the email compression application and the source.
  • the method then retrieves the original packet header information from the classification table at step 820 by calling an associated socket API to enable the email compression application to open a new connection to the original destination address and destination port at step 830 to form a server-side connection between the email compression application and the original destination. Furthermore, in order to enable the service module to redirect incoming packets to the email compression application on the server-side connection and replace the original source address and source port for outgoing packets, the method also calls the socket API to create a new entry within the classification table at step 840 that stores the connection information associated with the server-side connection. The email compression application may then read messages from and write messages to the source and destination connections at step 850.
  • Figure 9 illustrates an exemplary method in flowchart form for compressing received email messages in accordance with one embodiment of the present invention.
  • the exemplary method of Figure 9 may be performed by the email compression application once the entire email message has been received.
  • the email compression application may initially extract the email message by removing protocol specific data, such as POP byte- stuffing, at step 905.
  • the email compression application decodes the message in accordance with the encoding type at step 910 to form a decoded email message.
  • the email compression application then reads the message header to determine the content type at step 915 and compresses the email message in accordance with the content type.
  • email messages having a simple or single part content type may be initially examined to determine whether the size of the email message exceeds a predetermined threshold. If so, the email compression application compresses the single part email message at step 920 and encodes the compressed message at step 930. The email , compression application then attaches new headers corresponding to the compressed and reformatted message at step 940, and reformats the message with any protocol specific data, such as POP byte-stuffing, at step 945.
  • any protocol specific data such as POP byte-stuffing
  • the email compression application extracts each part of the email message at step 940 and performs a function call to step 910 to process the extracted part as though the part were a separate message.
  • the email compression application extracts each message at step 945 and performs a function call to step 910 to process the extracted message as though the message were a separate message.
  • Each extracted part or extracted message is then decoded at step 910, and the content type of each extracted part or extracted message is determined at step 915.
  • the email compression application will either compress the extracted part or extracted message as indicated above or perform another function call to step 910 in the event the extracted part or extracted message contains additional parts or messages. This recursive process enables each part of the message to be compressed and then reassembled in the same order as the original message.

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  • Information Transfer Between Computers (AREA)

Abstract

Un module de service intégré à une infrastructure de réseau intercepte des paquets qui transitent entre un client et une serveur de manière à déterminer si la connexion correspond à un service de messagerie électronique. Lorsque tel est le cas, le module de service rompt la connexion en mettant fin à cette connexion avec le client au niveau du module de service et en établissant une connexion séparée entre le module de service et le serveur. Les paquets qui transitent entre le client et le serveur peuvent être re-dirigés vers une application de compression de message électronique qui gère les messages transitant entre le client et le serveur et traite ces messages conformément à l'état de la session de messagerie électronique. En ce qui concerne les messages correspondant à l'établissement d'une connexion et à l'authentification des utilisateurs ainsi que les autres messages spécifiques d'un protocole, l'application de compression de messagerie électronique peut être configurée pour acheminer les messages vers la destination prévue à l'origine. Les messages correspondants à des données de message électronique sont, cependant, mis en mémoire tampon au sein de l'application de compression des messages électroniques. Une fois que la totalité du message a été reçue, l'application de compression des messages électroniques peut retirer les entêtes du message et toute donnée spécifique du protocole, comprimer les données et adjoindre de nouveaux entêtes de message correspondant au message électronique comprimé. Le message électronique comprimé et reformaté est ensuite réintroduit dans le train de données en vue de sa transmission vers la destination prévue. Parce qu'elle peut être effectuée entre le serveur et le client, la compression peut être exécutée sans recours à aucun traitement spécial par le serveur avant l'émission des messages électroniques. En outre, étant donné que les messages électroniques peuvent être comprimés dans un format pouvant être facilement décomprimé au moyen de bibliothèques de décompression intégrées au système d'exploitation des dispositifs clients, tel que le format CAB ou le format GZIP, le client peut décomprimer les messages électroniques reçus au moyen d'un logiciel déjà intégré au système d'exploitation du dispositif client, sans recours ni à un téléchargement ou à une installation de logiciel de décompression spécial ni à une coordination de la compression/décompression des messages électroniques avec le serveur ou la partie émettrice.
EP02729251A 2001-05-16 2002-05-16 Compression de contenu basee sur le service au sein d'un systeme de communication de reseau Withdrawn EP1393517A2 (fr)

Applications Claiming Priority (7)

Application Number Priority Date Filing Date Title
US29191801P 2001-05-16 2001-05-16
US291918P 2001-05-16
US30921801P 2001-07-31 2001-07-31
US309218P 2001-07-31
US10/095,551 US7024460B2 (en) 2001-07-31 2002-03-11 Service-based compression of content within a network communication system
US95551 2002-03-11
PCT/US2002/015758 WO2002093867A2 (fr) 2001-05-16 2002-05-16 Compression de contenu basee sur le service au sein d'un systeme de communication de reseau

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EP1393517A2 true EP1393517A2 (fr) 2004-03-03

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AU (1) AU2002259255A1 (fr)
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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2468179A (en) * 2008-11-14 2010-09-01 Zeus Technology Ltd Electronic mail attachment compression
US9384204B2 (en) 2013-05-22 2016-07-05 Amazon Technologies, Inc. Efficient data compression and analysis as a service
US10019457B1 (en) 2013-01-22 2018-07-10 Amazon Technologies, Inc. Multi-level compression for storing data in a data store

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6640301B1 (en) * 1999-07-08 2003-10-28 David Way Ng Third-party e-mail authentication service provider using checksum and unknown pad characters with removal of quotation indents
EP1798929A1 (fr) * 2005-12-19 2007-06-20 Thomson Licensing Serveur de compression individuel de réseau, méthode, station de réseau et serveur DHCP
US7886014B2 (en) * 2007-12-31 2011-02-08 International Business Machines Corporation Maintaining communication continuity
JP6389280B2 (ja) 2014-05-28 2018-09-12 華為技術有限公司Ｈｕａｗｅｉ Ｔｅｃｈｎｏｌｏｇｉｅｓ Ｃｏ．，Ｌｔｄ． プロトコルスタック適合方法および装置
US12052326B2 (en) * 2019-07-03 2024-07-30 Telefonaktiebolaget Lm Ericsson (Publ) Packet acknowledgment techniques for improved network traffic management

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5557749A (en) * 1992-10-15 1996-09-17 Intel Corporation System for automatically compressing and decompressing data for sender and receiver processes upon determination of a common compression/decompression method understood by both sender and receiver processes
US6112250A (en) * 1996-04-11 2000-08-29 America Online, Inc. Recompression of files at an intermediate node in a network system
DE19929232A1 (de) * 1999-06-25 2000-12-28 Siemens Ag Verfahren und Telekommunikationsendgerät zur automatisierten Datenkomprimierung in Funkkommunikationssystemen

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO02093867A2 *

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2468179A (en) * 2008-11-14 2010-09-01 Zeus Technology Ltd Electronic mail attachment compression
US10019457B1 (en) 2013-01-22 2018-07-10 Amazon Technologies, Inc. Multi-level compression for storing data in a data store
US11494339B2 (en) 2013-01-22 2022-11-08 Amazon Tehnologies, Inc. Multi-level compression for storing data in a data store
US9384204B2 (en) 2013-05-22 2016-07-05 Amazon Technologies, Inc. Efficient data compression and analysis as a service
US9934235B2 (en) 2013-05-22 2018-04-03 Amazon Technologies, Inc. Efficient data compression and analysis as a service
US10901950B2 (en) 2013-05-22 2021-01-26 Amazon Technologies, Inc. Efficient data compression and analysis as a service

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WO2002093867A2 (fr) 2002-11-21
AU2002259255A1 (en) 2002-11-25

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