Compressing and decompressing electronic messages in message threads

A method performed by a system that includes one or more data processing devices, the method comprising:

• receiving, at the system, an outgoing electronic message;
• determining, by the system, that the outgoing electronic message is a follow-up message in an electronic message thread that includes a previously-transmitted electronic message that is separate from the outgoing electronic message;
• identifying, by the system, textual content that is in the previously-transmitted electronic message, and that is available to the system;
• determining, by the system, a correspondence between symbols or groups of symbols in the textual content of the previously-transmitted electronic message, and code words in accordance with a coding scheme that uses content of the previously-transmitted electronic message as a seed dictionary;
• compressing, by the system, content in the outgoing electronic message using the determined correspondence between the symbols or groups of symbols in the previously-transmitted electronic message of the electronic message thread, and the code words;
• and
• transmitting, from the system, the compressed outgoing electronic message having code words that correspond to the symbols or groups of symbols in the textual content of the previously-transmitted electronic message of the electronic message thread,
• wherein determining the correspondence between the symbols or groups of symbols in the textual content of the electronic message of the electronic message thread and the code words comprises locating, in a data storage device, a preexisting mapping of the symbols or groups of symbols and the code words in accordance with the coding scheme, wherein the mapping was created using content of the previously-transmitted electronic message as a seed dictionary.

A method performed by a system the includes one or more data processing devices, the method comprising:

• receiving, at the system, an incoming electronic message;
• determining, by the system, that the incoming electronic message has been compressed using symbol/code word correspondences yielded by application of a coding scheme to a prior electronic message, wherein the prior electronic message and incoming electronic message both belong to a common electronic message thread and the prior electronic message preceded the incoming electronic message in the common electronic message thread;
• determining, by the system, a correspondence between symbols or groups of symbols in the textual content of the prior message of the common electronic message thread, and code words in accordance with the coding scheme, using the textual content of the prior message as a seed dictionary for the coding;
• and
• decompressing, by the system, content in the incoming electronic message using the determined correspondence between the symbols or groups of symbols in the textual content of the prior message of the common electronic message thread, and the code words,
• wherein the textual content is separate from the incoming electronic message.

A device comprising:

• a transmitter;
• and
• one or more data processing devices and associated memory programmed to implement:
• a seed dictionary selection module programmed to perform operations comprising selecting textual content in electronic messages that are separate from an outgoing electronic message but in a common message thread as the outgoing electronic message, for use as a seed dictionary for compressing the outgoing electronic message, wherein the outgoing electronic message includes at least some textual content absent from the selected textual content and some textual content from the selected textual content, and wherein the textual content is separate from the outgoing electronic message;
• and
• a message compression module programmed to perform operations comprising compressing content in the outgoing electronic message in accordance with code words determined using the textual content in electronic messages that are separate from but in a common message thread as the outgoing electronic message, selected by the seed dictionary selection module as the seed dictionary.

A device comprising:

• a receiver;
• and
• one or more data processing devices and associated memory programmed to implement:
• a compression recognition module programmed to perform operations comprising recognizing that an incoming electronic message is compressed using symbol/code word correspondences yielded by applying a coding scheme to a prior electronic message, wherein the prior electronic message and the incoming electronic message both belong to a common electronic message thread of messages and creation of the prior electronic message preceded creation of the incoming electronic message in time;
• a mapping determination module programmed to determine mapping between symbols or groups of symbols and code words used to compress the content in the incoming electronic message, wherein the mapping is determined using textual content that is part of the prior electronic message of the electronic message thread as a seed dictionary for an encoding scheme for the incoming electronic message;
• and
• a message decompression module programmed to perform operations comprising decompressing content in the incoming electronic message using the mapping determined by the mapping determination module, based at least in part on textual content of the prior electronic message of the electronic message thread.