A website usability metrics and assessment
1, the availability of measure: usually to describe the usability of the site with the number 9
2, availability assessment: availability index is an important indicator of site architecture design, foreign service commitment is internal assessment indicators.
Second, the availability of site architecture
Third, the high availability of applications
1, the failover stateless load balancing services through
2, Session management application server cluster. Under Cluster Management, Session Management are the following means
(1) Session replication: for the case of relatively small cluster size
(2) Session Binding
(3) the use of cookie record session: the session is stored in a cookie
(4) Session Server
Fourth, the availability of Service
1, hierarchical management
2, timeout setting
3, asynchronous calls: calls to applications and services via the message queue asynchronously complete the like, to avoid a service request failure results in failure of the entire application.
4, service degradation: denial of service and shut down services
The same time and must be called repeatedly generated call results in the service layer guaranteed service, and service idempotent: 5, idempotent design.
Fifth, the availability of data
Ensure high availability of data means that data backup and failover mechanisms
1, CAP principles:
(1) have the following highly available data several meanings: a persistent data, data accessibility, data consistency
(2) the consistency of the data is divided into the following points: strong data consistency, the user data is consistent, the final data is consistent
2, data backup
(1) cold standby
(2) Tracking: synchronous and asynchronous hot standby mode hot standby mode
1) Asynchronous Hot Standby:
2) Synchronization Hot Standby
3, failover: it consists of three parts: the failure to confirm, the access transfer, the data recovery
Failure to confirm two ways: heartbeat detection and application access failure report
Sixth, software quality assurance
1. Website launched
2, automated testing: selenium can complete compatibility testing and web browser functions at the same time
3, pre-release verification:
4, code control
(1) trunk development branch release
(2) development branch, trunk release
5, automatic release
6, gray release
Seven, site performance monitoring
1, the monitoring data acquisition
（1）用户行为日志收集：服务端日志收集和客户端浏览器日志收集
（目前许多网站逐步开发基于实时计算框架Storm的日志统计与分析工具）
（2）服务器性能监控：目前网站使用比较广泛的开源性能监控工具是Ganglia
（3）运行数据报告：
2、监控管理
（1）系统报警
（2）失效转移