Oracle Web Cache Administration and Deployment Guide Release 1.0.2 Part Number A86722-01 |
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Glossary

##### access log

A log file that contains information about the HTTP requests sent to Oracle Web Cache for a Web site. The access log has a file name of `access_log` and is stored by default in `$ORACLE_HOME/webcache/logs` and `ORACLE_HOME``\webcache\logs` on Windows NT.

##### application Web server

A server that manages data for a Web site, controls access to that data, and responds to requests from Web browsers. The application on the Web server interfaces with the database and performs the job requested by the Web server.

##### cache hit

A HTTP Web browser request that can be satisfied from the Oracle Web Cache cache without going to the application Web server.

##### cache miss

A HTTP Web browser request that cannot be satisfied from the Oracle Web Cache cache and most go to the application Web server.

##### CLF

See Common LogFile Format (CLF).

##### Common LogFile Format (CLF)

An industry-standard format for Web transaction log files.

##### cookie

A packet of state information sent by an application Web server to a Web browser during a HTTP request. During subsequent HTTP requests, the cookie is passed back to the application Web server, enabling the application Web server to remember the state of the last transaction. Some uses of cookies include:

- Identifying a registered user

- Maintaining a shopping cart selected during a session

- Session tracking

##### DNS

See Domain Name System (DNS).

##### Domain Name System (DNS)

A system for naming computers and network services that is organized into a hierarchy of domains. DNS is used in TCP/IP networks to locate computers through user-friendly names. DNS resolves a friendly name into an IP address, which is understood by computers.

##### Document Type Declaration (DTD)

Markup declarations that provide a grammar for a class of documents.

##### event log

A log file that contains Oracle Web Cache event and error information. The event log has a file name of `error_log` and is stored in `$ORACLE_HOME/webcache/logs` on UNIX and `ORACLE_HOME``\webcache\logs` on Windows NT.

##### expiration

Time when documents are no longer valid in the cache and are refreshed.

##### Extended LogFile Format (XLF)

An improved format for HTTP server logins since it is extensible, permitting a wider range of data to be captured. XLF allows you to configure the logger to generate different statistics of HTTP requests such as the IP address of clients, methods of the HTTP requests and response headers such as user agent and accept.

##### Extensible Markup Language (XML)

A language that offers a flexible way to create common information formats. XML is used for invalidation messages and responses.

##### failover

When an application Web server fails, Oracle Web Cache automatically distributes the load over the remaining application Web servers and polls the failed application Web server for its current up/down status every 60 seconds until it is back online.

##### GET method

A HTTP method used for simple requests for Web pages. A `GET` method is made up of a URL. Requests for pages that use the `GET` method are typically cached.

##### GET method with query string

A HTTP method made up of a URL and a query string containing parameters and values. An example of a HTTP `GET` with query string follows.

    http://www.myserver.com/setup/config/navframe?frame=default

This request executes a script named `navframe` in the `/setup/config` directory of the `www.myserver.com` server and passes the script a value of default for the frame variable.

Note: You should not cache pages with `GET` with query strings forms that make changes to the application Web server(s) or database. You should only cache pages that use `GET` with query strings if they are used in searches.

##### HTTP protocol

Hypertext Transport Protocol. A protocol that provides the language that enables browsers and application Web servers to communicate.

##### HTTP request header

A header that enables Web browsers to pass additional information about the request and about itself to the application Web server.

##### HTTP request method

A method included in the HTTP request that specifies the purpose of the client's request. HTTP supports many methods, but the ones that concern caching are `GET`, `GET` with query string, and `POST` methods.

##### HTTPS protocol

Secure Hypertext Transfer Protocol. A protocol that uses the Secure Sockets Layer (SSL) to encrypt and decrypt user page requests as well as the pages that are returned by the application Web server.

##### invalidation

Process that marks documents as invalid and then refreshes them with updated content from the application Web servers. Invalidation keeps the Oracle Web Cache cache consistent with the content on the application Web servers.

##### IP address

Used to identify a node on a network. Each computer on the network is assigned a unique IP address, which is made up of the network ID, and a unique host ID. This address is typically represented in dotted-decimal notation, with the decimal value of each octet separated by a period, for example 144.45.9.22.

##### latency

Networking roundtrip time.

##### load balancing

A feature by which HTTP requests are distributed among application Web servers so that no single server is overloaded.

##### Layer 4 (L4) switch

A networking switch that operates at Layer 4 of the Open Systems Interconnection (OSI) model--the Transport layer. L4 switches base their switching decisions on the TCP/IP protocol header and determine, based on the port number, where to pass traffic.

##### Layer 7 (L7) switch

A networking switch that operates at Layer 7 of the Open Systems Interconnection (OSI) model--the Application layer. L7 switches base their switching decisions on URL content.

##### Open Systems Interconnection (OSI)

A model of network architecture developed by ISO as a framework for international standards in heterogeneous computer network architecture.

The OSI architecture is split between seven layers, from lowest to highest:

1. Physical layer

2. Data link layer

3. Network layer

4. Transport layer

5. Session layer

6. Presentation layer

7. Application layer

Each layer uses the layer immediately below it and provides a service to the layer above.

##### OSI

See Open Systems Interconnection (OSI).

##### Oracle Web Cache Manager

A graphical user interface tool that combines configuration abilities with component control to provide an integrated environment for configuring and managing Oracle Web Cache.

##### performance assurance heuristics

Heuristics that enable Oracle Web Cache to assign a queue order to documents. These heuristics determine which documents can be served stale and which documents must be retrieve immediately. While documents with a higher priority are retrieved first, documents with a lower priority are retrieved at a later time.

The queue order of documents is based on the popularity of documents and the validity of documents assigned during invalidation. If the current load and capacity of the application Web server is not exceeded, the most popular and least valid documents are refreshed first.

##### personalized attributes

Pages that contain personalized attributes, such as personalized greetings in the form of "Welcome <your name>", on an otherwise generic page. You can configure Oracle Web Cache to cache the instructions for substituting values for personalized attributes based on the information contained within a cookie or the embedded URL parameter.

##### popularity

The number of requests for a document since entering the cache and the number of recent requests for the document.

##### POST method

A HTTP method used for requests that modify the contents of the data store on the application Web server, such as posting a message to a mailing list, submitting forms for registration purposes, or adding entries to the database.

Note: You should not cache pages with `POST` forms that make changes to the application Web server(s) or database. You should only cache pages that use `POST` forms if they are used in searches.

##### regular expression

Oracle Web Cache supports the POSIX 1003 extended regular expressions for URLs, as supported by Netscape Proxy Server 2.5.

See Also:: `http://www.cs.utah.edu/dept/old/texinfo/regex/regex_toc.html` for regular expression syntax

##### reverse proxy server

A proxy server that appears to be a normal server to browsers but internally retrieves its documents from other application Web servers as a proxy.

##### session-encoded URLs

`<A HREF=...>` HTML tags containing session information. Session-encoded URLs enable Web sites to keep track of user sessions. Oracle Web Cache can cache the instructions for replacing session information for one user with another based on the personal information contained within a cookie or as an embedded parameter in the URL.

##### session tracking

Session information passed back and forth between a Web browser and an application Web server. This is typically done with a unique sequential number and/or cookie.

##### Uniform Resource Identifier (URI)

The address syntax that is used to create URLs.

##### Uniform Resource Locator (URL)

A standard for specifying the location and route to a file on the Internet. URLs are used by browsers to navigate the World Wide Web and consist of a protocol, domain name, directory path, and the file name. For example, `http://otn.oracle.com/products/ias` specifies the location and path a browser will travel to find the Oracle Technology Network's Oracle9i Application Server site on the World Wide Web.

##### URI

See Uniform Resource Identifier (URI).

##### URL

See Uniform Resource Locator (URL).

##### validity

A level of validity assigned during invalidation or expiration.

The higher the validity level, the longer Oracle Web Cache serves these documents stale from the cache before invalidating them. For documents with lower validity levels, Oracle Web Cache serves these documents stale for a short amount of time before invalidating them.

Critical documents should be assigned a low validity level, and non-critical documents should be assigned a high validity level.

##### XLF

See Extended LogFile Format (XLF).

##### XML

See Extensible Markup Language (XML).

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