Application Availability
Processes and strategies to ensure ebc supported applications are available at specified service levels.
The four basic components of application response time are:
- Client request generation - the time it takes for a client—a PC, PDA, or other application-layer device—to process a response before generating another request.
- Server response - server processing time. Client and server response time can be optimized at the local level. Clustering and high-availability technology can produce significant performance gains. When applications are deployed over a WAN, however, application response becomes susceptible to network and protocol delays.
- Network delays - include transmission delays, delays at hops, delays within the queue of a network device caused by packet loss, and network congestion.
Distance is a major factor, because packets have to traverse multiple hops and wait in
queues at multiple network devices. The farther the end user is from the application
server, the more pronounced these network delays become.
- Protocol delays - a result of transmission and flow control management by network
protocols. Even a LAN can have protocol delays: collisions can occur on an Ethernet
LAN, and force retransmission. However, protocol delays caused by HTTP and TCP, in
particular, are much more prevalent on a WAN.
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- improve the percentage of the time that applications are available
- application servers are generally available 98% of the time during business hours (7AM - 7PM, Monday through Friday)
- web services (including applications with web interfaces) will be available 99.9 % of the time during business hours (7AM - 7PM, Monday through Friday) and 99% of the time during non-business hours
How are we doing ?
Administrative costs are paid through an annual appropriation to the ebcIT Division through the Ministry of Labour as negotiated during the annual government-wide fiscal budgeting process.
6. Dependencies
- application availability is largely conditional upon network availability. if the network is not available the application is also not available to the majority of users
8. More Information
- Application Delivery Networks Accelerate Web Application Response Time and Availability
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