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abnormal detection appears, the server sends out the detection 
signal. And the PC client downloads the newest detection 
information from the server through the internet, communicates 
with the field client, and disposes the event investigations and 
measures. The field client uses the portable digital equipment 
(PDA or intelligent cell phone), communicates with the server 
and PC client through mobile network, sends back the 
investigation data and information to the server, and completes 
the emergency response work. 
Figure 1. Structure design of collaborative surveillance and 
response system 
The collaborative server is an internet work station with 
powerful computing and storage abilities, employs large 
database systems (e.g. Oracle, SQL Server) for the storage of 
disease data, runs a full-time epidemical surveillance program, 
and with the multi-thread mode and the network protocol, 
implements the communication and information transmission 
between the server, the PC client and the field client. PC client 
has a collaborative operation program and a 3-D visual 
surveillance program, downloads the detection data from the 
server through the internet, completes the visualization of 
surveillance and detection, and provides directly visible effects 
about the detection which could help the operators make the 
correct and exact decisions. The portable digital equipment of 
the field client has a communication program which could 
connect to the server and PC client through mobile network, 
completes the data collecting and feedback in event 
investigation, and meanwhile has a program for event treatment, 
which could help the working people finish the emergency 
response conveniently and effectively. 
5. IMPLEMENTATION OF PROTOTYPE SYSTEM 
Prototype system of this paper is developed based on standard 
C/C++ programming language. Programs of server and PC 
client are developed by Microsoft Visual C++ IDE, and 
programs of PDA client are developed by Microsoft eMbedded 
C++ IDE. Collaborative server, whose operation system is 
Windows 2003 Server Edition, has CPU of Intel Core 2 T5600, 
2G memory and 1000M network card. Database system used in 
server is Microsoft SQL Server 2000. PC client is common 
microcomputer. PDA client is PDA with Windows Mobile 5. 
Collaborative server, which is the main part of epidemical 
surveillance subsystem, assumes the responsibility of whole 
time surveillance, and meanwhile provides collaborative service 
for PC client and PDA client. The prototype system uses a 
powerful computing and storage server in internet as the 
collaborative service, and disposes two services: PC service and 
PDA service which are responsible to the PC and PDA clients 
respectively. PDA service is a multi-thread program for data 
exchange based on Winlnet structure, and is in charge of the 
data exchange between collaborative service and PDA client. 
PC Service is a multi-thread service program developed with 
Socket protocol, and monitors and responds the requests of 
computer terminals in specified port. According to the function 
demands, PC Service could include terminal computing service, 
database service and information service of sending and 
receiving. Furthermore, according to the information types 
during the information sending and receiving, information 
service could be classified into three different types: message 
service, text service and file service. The service types and 
functions of collaborative server are shown in Table 1. 
PC client is the information bridge of collaborative work 
between surveillance and response subsystems. When the 
surveillance computing results of server terminal appear 
exceptions, collaborative server will send exception information 
to PC client. And then PC client directs PDA client to perform 
emergency response work in exception regions. PC client 
builds up the communication connection to collaborative server 
and PDA client by Socket and Winlnet respectively. 
PDA client accepts the directions from collaborative server and 
PDA, provides various functions of response subsystem for the 
response personnel to accomplish the epidemical fieldwork 
investigation and emergency response, and sends the response 
data back. The communication connection between PDA client 
and collaborative server is built up on the basis of Http protocol 
and GPRS mobile network. 
Service Name 
Service Function 
PDA Service 
Collaboration and data exchange 
between Server and PC Client 
PC 
Service 
Computing 
Service 
Terminal surveillance computing 
and information exchange of the 
computing results 
Database 
Service 
Database server and storage of 
geographical and epidemical data 
Information 
Service 
(Send and 
Receive) 
Message 
Service 
Information exchange 
of messages 
Text 
Service 
Information exchange 
of texts 
File 
Service 
Information exchange 
of binary datafiles 
Table 1. Service types and functions of collaborative server 
6. APPLICATION OF PROTOTYPE SYSTEM 
The terminal computing program of collaborative server uses 
spatial and space-time scan statistics methods, and implements 
the real-time epidemical surveillance according to the existed 
geographical and disease data. When the exceptions appears in 
both spatial and space-time scan statistics, collaborative server