1. A method for implementing an online mutual aid question-answer service, the method comprising: a questioning user device uploading a question to an extensible markup language document management (XDM) server; after uploading the question to said XDM server, said questioning user device further choosing a frequency for sending an answer notification and a number of answers included in each answer notification, and uploading the frequency and the number to said XDM server; an answering user device subscribing for questions from said XDM server, said XDM server sending the question to said answering user device; after said answering user device receives the question, said answering user device answering the question, and informing said questioning user device about an answer to the question; after answering said question, said answering user device uploads the answer to the question to said XDM server, said XDM server sends down the answer to the question to said questioning user device through the answer notification; said XDM server sending down said answer notification to said questioning user device according to the frequency for sending said answer notification chosen by the questioning user device and the number of answers included in each answer notification; after said answering user device answers the question, said answering user device obtaining presence information of the questioning user device, choosing a synchronous communication mode available to the questioning user device according to said presence information, and sending a communication request with the synchronous communication mode; and the questioning user device receiving said communication request, and communicating with said answering user device after choosing to accept the communication request to receive the answer to said question.
1. A method for implementing an online mutual aid question-answer service, the method comprising: a questioning user device uploading a question to an extensible markup language document management (XDM) server; after uploading the question to said XDM server, said questioning user device further choosing a frequency for sending an answer notification and a number of answers included in each answer notification, and uploading the frequency and the number to said XDM server; an answering user device subscribing for questions from said XDM server, said XDM server sending the question to said answering user device; after said answering user device receives the question, said answering user device answering the question, and informing said questioning user device about an answer to the question; after answering said question, said answering user device uploads the answer to the question to said XDM server, said XDM server sends down the answer to the question to said questioning user device through the answer notification; said XDM server sending down said answer notification to said questioning user device according to the frequency for sending said answer notification chosen by the questioning user device and the number of answers included in each answer notification; after said answering user device answers the question, said answering user device obtaining presence information of the questioning user device, choosing a synchronous communication mode available to the questioning user device according to said presence information, and sending a communication request with the synchronous communication mode; and the questioning user device receiving said communication request, and communicating with said answering user device after choosing to accept the communication request to receive the answer to said question. 4. The method as claimed in claim 1 , further comprising: said question uploaded to said XDM server by said questioning user device including a rewarded score of the question, after the questioning user device of said question receives the answer of said question, the questioning user device of the question sending a questioning ending request to said XDM server if determining that the question has been solved; after receiving the questioning ending request, the XDM server sending a question ending notification to a question-answer service server, wherein the question ending notification carries a user ID of the questioning user device of said question, a user ID of said answering user device and said rewarded score; after receiving said question ending notification, the question-answer service server deducting the rewarded score from an account of said questioning user device, and accumulating the rewarded score to an account of said answering user device.