Data processing: database and file management or data structures – Database design – Data structure types
Reexamination Certificate
2000-08-14
2003-07-08
Robinson, Greta (Department: 2177)
Data processing: database and file management or data structures
Database design
Data structure types
C707S793000, C707S793000, C707S793000
Reexamination Certificate
active
06591266
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates, generally, to content delivery networks and, in preferred embodiments, to systems and methods for intelligent caching and refreshing of dynamically generated and static Web content to improve content delivery services.
2. Description of the Related Art
Web performance is a key point of differentiation among content providers. Crashes and slowdowns within major Web sites demonstrate the difficulties companies face in trying to deal with high Web traffic. As Internet backbone technologies have developed, many innovations in the area of service management have improved bandwidth and Web content retrieval response time. These improvements to infrastructure, however, cannot solve traffic problems at all points within the Internet.
For example, assume in
FIG. 1
that an end user
12
in a network
14
in Japan requests access to a page from a Web site
16
in a network
18
in the United States. The request must pass through several gateways
20
,
22
, and
24
before reaching Web site
16
. Although Web site
16
may have large bandwidth (the ability to rapidly communicate large quantities of data), the gateways connecting the network
14
in Japan to the network
18
in the United States may be slow, and thus, when end user
12
attempts to access the page from Web site
16
, the gateways may create a bottleneck. Such gateway bottlenecks may result in the access time for one page of data being on the order of 10 seconds or more. Because of the gateway bottlenecks, and because there are many uncertainties along the Internet paths from end user
12
to/from the Web site
16
, content delivery networks or systems are now being developed.
Fundamentally, content delivery systems may be designed and deployed for at least two major purposes; one is to achieve load balancing, and the other is to reduce response time. A content delivery system may be implemented using a high speed dedicated line to deliver content while bypassing all gateways or reducing the number of Internet gateways in the transmission path. However, such a dedicated network is expensive and cannot be deployed for all networks. Another approach to implementing content delivery systems is through the use of intelligent caching, mirroring, proxy servers, or other techniques which redirect end users to available servers that contain the desired content and are close to or easily accessible by the end users to ensure fast response time. With some of the traffic redirected, traffic surges will decrease and end users benefit from faster response time. The term generally used for the architecture and functionality of such networks or systems is content delivery services (CDS).
Many approaches and architectures have been proposed for CDS and most of these services, systems, and architectures have focused on static content. For example, CachePortal™ is a system providing CDS, and is described in pending U.S. patent application Ser. No. 09/545,805, entitled “System and Method for Efficient Content Delivery,” filed Apr. 7, 2000, the contents of which are incorporated herein by reference. CachePortal™ has access to mirror servers which are used as edge cache to provide content to end users with less network delay. CachePortal™ can distribute content among mirror servers as well as remove, refresh, or invalidate the content in the mirror servers. CachePortal™ can also modify the attributes of content in the mirror servers. For example, CachePortal™ may check whether an object has been updated. If CachePortal™ finds that it is not updated, then CachePortal™ may change the value of the refresh time stamp or last modified date time stamp.
However, for many e-business sites, Web pages are created dynamically based on the current state of business processes represented in application servers and databases. The techniques required are more complex than what are needed for static content delivery. Given the fact that based on current technology, the application servers, databases, and Web servers or cache which deliver Web pages are independent components, there has been no efficient mechanism to reflect database content changes in the cached Web pages. As a result, conventional application servers typically specify dynamically generated Web pages to be non-cacheable or expire immediately. By so doing, the processing time for such requests will be the time required for the network round trip—time to receive the current data from the Web servers, and time for the backend systems (i.e. application servers and databases) to perform the computations necessary to provide current data.
FIG. 2
shows an overview of a typical current Web page delivery mechanism
24
for Web sites with backend systems. For example, an e-business site may utilize a database management system (DBMS)
26
to maintain the price, item descriptions, and quantity of all products the e-business site sells through its Web site. It should be understood that a DBMS, as described herein, includes memory such as a database for storing content. As illustrated in
FIG. 2
, an end user
28
interacts with a Web browser
30
to access the Internet and requests information
32
on a product at the e-business site. Such a request may include parameters such as the product name and model number, and may include other items such as cookies
34
.
Cookies are small files that were sent by a particular Web site, and now reside in the end user's computer. The cookie is used by the Web site to keep track of what the end user is doing, or to identify the user. For example, when an end user clicks on a button at a particular Web site, that Web site may send a cookie to the end user's computer. This cookie may monitor the activity of the end user as the Web site is navigated. The next time that the user logs onto that Web site, the Web site may search for a cookie in a particular location. If it finds the cookie, it will know that the end user is a repeat customer. The Web site may also use the navigational information from the cookie to customize the Web page for that end user.
Referring again to
FIG. 2
, the Web page request
32
may be sent from the client browser
30
to a cache
36
. In
FIG. 2
, the cache block
36
is identified with dotted lines to indicate that it may be any one of a number of different types of cache. One type of cache is called edge cache. Edge cache is also called proxy cache and is typically managed and maintained by a third party content delivery service provider such as CachePortal™. Content providers can store content into this edge cache and make it available at locations that are close to the end user. Another type of cache is called reverse cache, which is cache that is owned by entities close to the end user and is typically located close to the end user. Another type of cache is called server side cache, which is cache that is owned by the content provider. Yet another type of cache is called Web server cache. Web server cache may be found in machines that typically would deliver Web server content from disk to the end user. However because disk access is slow, the content from the disk may be copied to another location within that Web server. This location would provide faster access to that content than the disk. These storage locations are known as Web server caches.
Referring again to
FIG. 2
, if the Web page request
32
is not serviced by the cache
36
because the page is not found in cache
36
, or is expired or invalidated in cache
36
, the request will be passed to the e-business Web server
38
. In some e-business applications, some frequently accessed pages, such as catalog pages, are pre-generated in advance and are put on the Web server
38
in advance. For example, a Web server machine
38
may have a sub-directory called HTTPD. Web pages that are static (do not change frequently) may be stored within that sub-directory. If those pages are requested by the client browser
30
and the HTTPD subdirectory contains an up to date copy of the Web p
Agrawal Divyakant
Candan Kasim Selouk
Li Wen Syan
Black Linh
NEC Corporation
Robinson Greta
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