The machines running PAID will be interconnected via the Daimler Benz intranet and the public Internet.
There will be two major types of machines within the PAID network, servers and clients. Server machines will require large internal storage capacity and fast internet connections. Client machines require minimal storage capacity (though more can be advantageous) and can range from handheld PDAs to desktop machines.
Response time, or latency, of a request for information stored locally would only be limited by the speed of the local machine, whereas the latency of a request for remote server data would be limited by connection speed, network load, and the size of the update.
The desired time for completion of remote database queries is one minute. Local queries should take under 10 seconds. The expected rate of transactions is 2.5/sec to accommodate the case when all dealers access their servers within the span of 1 minute (widespread update). The number comes from 6000 dealer and an estimated 40 database servers resulting in 150 dealers per server.
4.1.2 Input/OutputPerformance
All data generation will be managed by the actual client and server
machines, so no additional hardware will be needed.
The response time or information flow rate does not exceed the available
communication bandwidth between subsystems or between tasks and hardware.
Queries should be responded to within seconds.
4.1.3 Processor allocation
Software running on dealer machines can easily be dealt with by a single processor. Server side machines may require additional processors depending on the implementation of the Learning subsystem.
4.1.4 Memory allocation
The PAID servers should contain enough memory to buffer a large number of requests. If performance suffers due to insufficient memory, additional memory can easily be added for a minimal cost.
There will be an interconnected collection of database servers, which are connected via the Diamler Benz Intranet. Dealers' desktop machines will connect to these servers through the public Internet (via ethernet, ISDN, modems, etc). Handheld clients (ie PDAs) will connect to the dealers' desktop machines.
The database server will be duplicated on geographically distributed machines in order to improve the response time of the system. The data on these servers will be synchronized with the central database servers such as those at MBNA and the Daimler-Benz headquarters in Germany. These servers shall be interconnected via high-bandwidth network connections.
Figure 4.2.1 - Connectivity Diagram
Connection channels will use the TCP/IP protocol to establish reliable communication between client and server machines. A public key encryption scheme, such as Secure Sockets Layer (SSL), may be added to increase security by encrypting data before tranmission. Interaction between a client and a server is asynchronous, as dictated by TCP/IP.
Assuming that an average document to be tranmitted is no greater than 1 MB and that ideal time to download take no longer than one minute, the minimum throughput would have to be 17 KB/sec per machine at a given dealership. If no more than three machines at a dealership are downloading files at a given time, then 50 KB/sec is the required available bandwidth into the dealership. Any bandwidth can be accommodated, however connection speeds below that of a 19kb modem on a given machine are not recommended.