Electrical computers and digital processing systems: multicomput – Computer-to-computer session/connection establishing
Reexamination Certificate
1998-08-17
2002-08-20
Meky, Moustafa M. (Department: 2153)
Electrical computers and digital processing systems: multicomput
Computer-to-computer session/connection establishing
Reexamination Certificate
active
06438597
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention pertains to data access network systems. More particularly, this invention relates to a system and method for managing accesses to a data service system that supports persistent as well as non-persistent connections.
2. Description of the Related Art
Traditionally, an HTTP (Hyper Text Transport Protocol) transaction between a user terminal and a data service system is performed using the transaction's own TCP (Transmission Control Protocol) connection. Thus, to complete a transaction, the user's browser first establishes a TCP connection to a server within the data service system. The browser then sends the access request and waits for the reply from the server. Meanwhile, the access request received in the server of the data service system is processed by server applications in the server to generate the reply. Once the browser receives the reply from the server, the browser reads the reply and then the server closes the connection. When the browser then receives another access request, it repeats the above mentioned steps to complete another transaction.
One problem of this prior art is that when the server is under heavy load, creating a connection can be very slow. This slow connection creation impacts all users equally. Another problem is the waste in system resources when, for example, a subsequent access request accesses the same location in the server. In this case, connection does not need to be closed after the transaction for the prior access request has been completed and then re-established for the subsequent access request.
To alleviate the above mentioned problems, an improved version of HTTP protocol (i.e., HTTP/1.1) has been introduced which supports persistent connections. A persistent connection typically refers to a connection that is not closed (i.e., remains to be open) after its access request has been transferred, processed, and replied. In this case, a browser that supports persistent connections leaves the connection to the server open after handling the first transaction. As long as the connection remains open, the browser can reuse the connection for as many requests to the server as it desires. There are several advantages to using persistent connections. First, instead of many short-lived connections, a single long-lived connection allows the TCP to run better because its flow-control and congestion-control logic will have sufficient time to reach a stable state. Secondly, the connection overhead can be reduced dramatically. As is known, opening and closing a TCP connection typically involves the exchange of seven network packets of data. This is often a significant overhead as an access request typically fits into a single data packet and a reply to an access request is often just a few packets long. Thirdly, the persistent connections allow access requests to be pipelined on a persistent connection. This means that the network round-trip time can be amortized across multiple requests. This eliminates or at least reduces the need for creating multiple concurrent connections to the same server.
However, disadvantages are associated with this prior approach. One disadvantage is that a significant amount of system resources (e.g., CPU, memory) of the server is required to maintain the connections open (i.e., persistent). At the very least, a persistent connection occupies a TCP socket (e.g., Unix socket) and associated receiving and sending buffers. In the worst case, a persistent connection may keep an entire server process busy.
Another disadvantage associated is that a persistent connection may be idle for a long period of time before the next request is received in the server through this connection. This may become a problem if most of the persistent connections are idle most of the time. In other words, while persistent connections can greatly improve server performance as perceived by a user and reduce congestion in the network, server utilization may actually decrease due to idling persistent connections that occupy the server resources. In addition, an idling persistent connection may not allow a new access request from a new user since the server may limit the number of available connection slots to a fixed number.
SUMMARY OF THE INVENTION
One feature of the present invention is to classify access requests to a data service system as persistent connection requests and non-persistent connection requests.
Another feature of the present invention is to allow a data service system that supports persistent connections to provide services to its users based on the classes that the users belong to.
Another feature of the present invention is to improve the throughput and response time of a data service system that supports persistent connections.
A further feature of the present invention is to allow a data service system to take advantage of persistent connections while allowing maximized utilization of the server resources.
A still further feature of the present invention is to improve overload behavior of a data service system that supports persistent connections.
A connection management system for a data service system that is accessible through a plurality of access requests includes a request classifier that classifies each of the access requests as either a persistent connection request or a non-persistent connection request based on a predetermined classification policy. The connection management system also includes a persistent connection request processor that allows a connection established for a persistent connection request from a first remote user terminal to remain open after the request is processed by the data service system. A non-persistent connection request processor is also included in the connection management system that causes a connection established for a non-persistent connection request from a second remote user terminal to close after the request is processed by the data service system.
A method of managing connections to a data service system that is accessible through a plurality of access requests includes the step of classifying each of the access requests as either a persistent connection request or a non-persistent connection request based on a predetermined classification policy. The method then allows a connection established for a persistent connection request from a first remote user terminal to remain open after the persistent connection request is processed by the data service system. The method also causes a connection established for a non-persistent connection request from a second remote user terminal to be closed after the non-persistent connection request is processed by the data service system.
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Mosberger David
Salehi James D.
Edelman Bradley
Hewlett--Packard Company
Meky Moustafa M.
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