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Dynamic Content Delivery Network:What is EdgeRoutine?

Last Updated:Nov 15, 2023

EdgeRoutine (ER) is a JavaScript code runtime environment that runs on globally distributed points of presence (POPs). ER supports the ES6 syntax and standard Web Service Worker APIs. You can deploy your JavaScript code to ER. This way, your code is propagated across the DCDN global network. This allows DCDN to process requests on the POPs that are closest to the clients.

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Service activation

ER is in Beta release and available only to selected users. If the daily peak bandwidth of your DCDN service exceeds 500 Mbit/s, you can submit a ticket to activate ER. We apologize for the inconvenience this may have caused. For more information about public previews, visit the official website.

Benefits

  • Global deployment, near-site scheduling, and ultra-low latency: Compared with common cloud computing services, such as Function Compute and Elastic Compute Service (ECS), you do not need to deploy ER in a specific region. ER runs on points of presence (POPs) around the world. Client requests are automatically scheduled to the nearest POPs, which immediately run your code and process client requests. ER can significantly reduce the server response time, which helps you deliver low-latency services to your customers.

  • Automatic scale-out and pay-as-you-go billing: Alibaba Cloud has constructed an edge network that consists of more than 3,200 POPs around the world. These POPs provide unparalleled scalability. If the number of client requests in a region spikes, these requests are automatically scheduled to the nearest POPs that have sufficient compute resources. You are charged for ER based on the number of calls that are made to the service.

  • Easy-to-use serverless mode: ER allows you to focus on your business logic without having to manage underlying resources, such as CPU, memory, network, and operating system. You can upload your code by using the console or API to deploy applications. Serverless development can effectively reduce your development and O&M costs.

How it works

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  • Scenarios in which ER is not used: 1. Clients initiate requests to the gateways of the POPs. → 2. The POPs search for the requested content in the cache. If a request is a cache hit, the requested content is returned to the client. → 3. If a request is a cache miss, the request is redirected to the origin server.

  • Scenarios in which ER is used: 1. Clients initiate requests to the gateways of the POPs. → 4. The requests are managed by ER, and the relevant JavaScript code is triggered. → Fetch requests are sent to the cache and origin server (No. 5 or No. 3), or to other publicly-accessible services (No. 6).

    Note

    In the preceding figure, ER is executed behind the gateway. In this case, the configurations of DCDN-accelerated domain names that are configured in the console, such as HTTPS configurations, access control, performance optimization, and cache settings, will continue to take effect.

Terms

  • Routine: ER is a JavaScript code runtime environment that runs on Alibaba Cloud POPs. You can upload and run JavaScript code in ER. You need to create a routine before you can use ER. A routine consists of configurations and the JavaScript code script that you upload. The configurations specify information about the routine, such as the name, description, CPU and memory caps, and domain name whitelist.

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  • Version: Routines support version management. During the development of a routine, the JavaScript code is constantly modified and updated. After you complete testing for a stage, you can take a snapshot of the current state of the code by creating a code version. When you publish a routine, you need to select a code version. The system allows you to select earlier versions and manage historical code. Each version has a version number, which is automatically generated by the system.

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  • Environment: ER provides the staging environment, production environment, and canary release environment.

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    • Staging environment: A staging environment is an independent POP that is used to test code. The staging environment simulates the production environment but is isolated from the production environment. You can modify the routine configuration or code in the staging environment. This does not affect the production environment. You can access the staging environment only after you add the IP address that is provided on the page to your hosts file.

    • Production environment: The production environment, also known as the deployment environment, consists of a large number of POPs that are distributed around the world. After you test your code in the staging environment, you can deploy the code to the production environment. The preceding figure is provided for reference only. ER automatically adds or removes POPs based on your request volume. The POP distribution may vary based on actual scenarios.

    • Canary release environment: The canary release environment allows you to gradually expand the scope of your deployment. It is risky to deploy code or configuration changes directly to the production environment. If errors exist in your code or configurations, the errors may affect your users. If the scale of your business is large or you want to control risks when you make code or configuration changes, we recommend that you use the canary release environment to manage the deployment scope. The canary release environment is complex. We recommend that you understand the basics of the environment before you use the canary release environment. For more information, see Canary release environment (optional).

  • Domain name: After you create a routine and deploy code, you need to use a domain name as the portal of the routine that clients can access. ER supports only DCDN-accelerated domain names as portals. You can associate ER with domain names in the DCDN console.

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  • POP: POPs are used by DCDN for content delivery. Client requests are scheduled to the nearest POPs.

Limits

Feature

Limit

Description

CPU time

5 ms, 50 ms, and 100 ms

The CPU time slice that is allocated by ER for an execution. I/O wait is not included in the calculated CPU time. You can select one of the three options: 5 ms, 50 ms, and 100 ms. For more information, see Billing rules.

Memory size

128 MB

The memory size of a domain name on a physical machine (PM). All requests for the domain name share the memory. For example, the maximum JavaScript sandbox memory size on a PM is 128 MB.

Real time (RT)

120s

The response time of an execution for ER cannot exceed 120s. I/O wait is included in the calculated RT.

Waiting time

10s

The time during which the gateway waits for ER. If ER does not return data within 10s, the gateway disconnects from the server and returns the HTTP 504 status code to the client.

Code package size

4 MB

The maximum size of the JavaScript code file for each routine.

Number of fetch requests

4

The number of fetch requests that is allowed by ER in an execution.

Programming language

JavaScript (ES6 syntax)

Only JavaScript is supported. You need to know how to use JavaScript.

Number of routines

50

You can create up to 50 routines for each Alibaba Cloud account.

Number of versions

10

You can save up to 10 versions for each routine.

Supported protocol

Only HTTPS

WebSocket, TCP, and UDP are not supported.

Fetch requests

None

You cannot initiate a fetch request in a routine to a domain name of another routine.