Replication Web Hosting System
There are essentially three different kinds of aspects related to Replication Web Hosting System.
- Latency metrics: By which the time measured for an action to take place for example: Fetching a document.
- Spatial metrics: It mainly consists of measuring the distance between nodes in terms of the number of network-level routing hops or hops between autonomous systems.
- Network usage metrics: It computes consumed bandwidth in terms of the number of bytes to transfer.
- Consistency metrics: It tells us to what extent a replica is deviating from its master copy.
- Financial metrics: It closely related to the actual infrastructure of the Internet.
- The important question that needs to address when and how adaptations are to triggered.
- A simple model is to periodically estimate metrics and subsequently take measures as needed.
- Special processes located at the servers collect information and periodically check for changes.
There are essentially only three measures that can take to change the behavior of a Replication Web Hosting System:
- Changing the placement of replicas
- Changing consistency enforcement
- Deciding on how and when to redirect client requests
Replication of web applications
- It complicated to improve the performance of Web applications through caching and replication.
- To improve performance, we can apply full replication of the data stored at the origin server.
- This scheme works well whenever the update ratio is low and when queries require an extensive database search.
- Replicating for performance will fail when update ratio is high.
- An alternative a partial replication in which only a subset of the data stored at the edge server.
- The problem with partial replication is that it may be very difficult to manually decide which data needed at the edge server.