Implementing a Highly Available Architecture: PHP Development Experience Sharing

In the development of the Internet, high availability has always been an extremely important issue. For many businesses, such as e-commerce, games, and even some SaaS, high availability is a standard that must be met. In implementing high-availability architecture, PHP, as a popular server-side language, also has its own development experience worth sharing.

1. Using load balancing

Load balancing is one of the key links in achieving a high-availability architecture. It can distribute requests to multiple servers to achieve the purpose of diverting traffic. In PHP development, commonly used load balancing software includes LVS, Nginx, HAproxy, etc.

Among them, Nginx is widely used and has the characteristics of lightweight and high flexibility. In Nginx, by setting up the upstream module and defining the IPs and ports of multiple servers, request forwarding can be achieved. Moreover, Nginx has excellent processing performance for static resources, which can further improve the access speed of the website.

2. Designing a stateless application

A stateless application means that the application server does not save the user's session state (session), but saves the state to a shared in storage. In this way, state data can be shared among multiple application servers, thereby achieving a high-availability architecture. Commonly used storages include Memcached, Redis, etc.

When implementing stateless applications, you need to pay attention to the following principles:

(1) The use of local storage is prohibited: In the application server, the use of local files, databases and other storage methods is prohibited. Because this will prevent the state from being shared among multiple servers.

(2) Use a globally unique ID: When a user logs in, a globally unique ID needs to be assigned to the user and this ID is saved to shared storage. On each request, the application server needs to get the ID from the shared storage in order to authenticate the user.

(3) Limit the size of user status data: Because the shared storage capacity is limited, it is necessary to limit the size of user status data.

3. Avoid single points of failure

When implementing a high-availability architecture, single points of failure must be avoided. Because once a single point of failure occurs, the service will be unavailable, thus affecting the user experience.

In PHP development, the commonly used methods to avoid single points of failure are as follows:

(1) Use dual-machine hot backup: You can copy the service to the backup through dual-machine hot backup On the server, when the main server fails, it is immediately switched to the backup server to ensure service continuity.

(2) Use master-slave replication: In database applications, you can use the master-slave replication method to allocate read and write requests to different database servers. When the master server fails, immediately switch to the slave server. on the server.

(3) Use distributed storage: Distributed storage can spread data across multiple servers to avoid single points of failure.

4. Quick recovery service

In a high-availability architecture, quick recovery service is also very important. Once a service fails, immediate measures need to be taken to restore the service to normal.

In PHP development, the following measures can be used to quickly restore services:

(1) Automated deployment: Through automated deployment tools, services can be quickly deployed to new servers.

(2) Grayscale release: When updating services, grayscale release can be used to release the new version to some users first to ensure the stability of the new version, and then gradually expand the scope of the release.

(3) Monitoring and alarming: In daily operation and maintenance, services need to be monitored and alarms issued in a timely manner to quickly switch to the backup server to ensure service continuity.

Summary:

To achieve a high-availability architecture, optimization needs to be carried out from many aspects. In PHP development, through measures such as load balancing, stateless application design, avoiding single points of failure, and rapid service recovery, we can effectively improve service availability and provide users with a better experience.

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