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How to build flexible and scalable WebAPI, many novices are not very clear about this, in order to help you solve this problem, the following editor will explain for you in detail, people with this need can come to learn, I hope you can gain something.

Basic concept

The common WebAPI architecture is shown in the figure above, mainly including client (browser), server and database. WebAPI is provided by the server. At the same time, the server needs to complete load balancing and login authentication operations.

When the client traffic increases rapidly, the server can only increase and improve the service capacity by means of horizontal expansion and machine.

This general model has two main limitations:

In addition to developing business code, technical students have a large number of server operation and maintenance costs to ensure the stability and availability of services. Technical students have to spend a lot of time on operation and maintenance work, occupy development time and reduce the efficiency of project research and development.

When the traffic suddenly increases, you need to expand horizontally and add the machine, so the flexibility is poor, and the expansion speed often takes tens of minutes, which makes it impossible to achieve rapid expansion in seconds, resulting in insufficient service capacity for a period of time.

The WebAPI architecture based on function computing is shown in the figure above. Compared with the conventional WebAPI architecture, the client and database have not changed, but the server has changed greatly, mainly as follows:

The routing module and authentication module that need to be maintained by the development team will be connected to the API gateway system and authentication system provided by the service provider. The development team no longer needs to maintain the business code of these two parts, but only needs to maintain the relevant rules continuously.

Under this structure, the business code is also divided into function granularity, and different functions represent different functions.

We can no longer see the existence of the server because the purpose of Serverless is to allow users to focus only on their own business logic, so some security issues and resource scheduling problems (such as the surge in the number of users, how to achieve automatic capacity expansion, etc.) are all left to cloud vendors.

Compared with traditional projects, traditional projects have costs for running services regardless of whether they are accessed by users or not. for Serverless, the function will be activated and executed only when it is used to initiate a request, and it will be charged by quantity, which can be supported only when there is traffic, and there will be no expenditure when there is no traffic. Relatively speaking, the cost will be further reduced.

Development process 1. Log in to the function calculation console to create an application

You can create applications in two ways. If you have an existing Web project, you can choose the first one in the figure above: "Common Web applications"; for new projects, it is recommended to use the second: "create applications based on templates". We use templates here to choose Python-based Web applications.

Templates can be used as application scaffolding, select the appropriate template, and automatically complete the creation of related dependent resources, such as roles, OSS, domain name gateways, etc., reducing development costs.

two。 New function

In the application, to create a function, we are developing WebAPI, so we choose the "HTTP" function, which uses the specified http request as a trigger to schedule the execution of the corresponding function.

After the function is created, it is a demo that returns helloWorld, based on which we develop our business logic.

First of all, we introduce the handler function in the code above, which is the entry function. After receiving the call, the http trigger will start the entire function through this entry. The function has two input parameters, environ and start_response:

Environ

Environ mainly contains two parts: the input parameters of the http request and the function execution context fcContext. The function context parameters contain some information about the function runtime (such as request id, temporary AK), which you can use in your code. The information type is FCContext.

Start_response

This parameter is mainly used to generate the response of the http request.

3. Configure triggers, bind domain names

When you create a new function, a http trigger is automatically created. The path of this trigger is a test path of "aliyun.com" and can only be used for testing. Real applications need to bind the real domain name to the function through a custom domain name, so that when the specified domain name is accessed, the corresponding function will be triggered and executed.

4. Log and monitoring

On each function editing page, log and monitoring service, a unique requestId is generated for each execution of the function. The log is queried through requestId to see all the logs executed by this function.

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