This topic describes the terms that are used in Serverless App Engine (SAE) to help you get familiar with SAE.
- application instance
An application instance is the minimum unit on which an application runs.
In most cases, an application runs on one or more instances and can have multiple deployment versions. Different versions of the application can run on different instances.
A namespace is a logically isolated runtime environment.
Namespaces can be categorized into two types: Kubernetes namespace and microservices namespace. Namespaces isolate different runtime environments, such as development, test, and production environments, based on the service calling and distributed configuration pushing of applications.
A container is the running entity of an image.
You can create, start, stop, delete, or suspend a container. The relationship between images and containers is similar to the relationship between classes and instances in object-oriented programming. Images are static whereas containers are dynamic.
- job instance
- Job instances are created based on job templates to execute business logic. A job instance is the minimum scheduling unit for an SAE job.
- job template
A job template can be used to automatically create jobs.
You can create, modify, copy, stop, or delete a job template. You can configure the job execution time, instance type, and number of concurrent jobs in a job template. The relationship between job templates and jobs is similar to the relationship between classes and objects in object-oriented programming. Task templates are static whereas jobs are dynamic. Multiple jobs can be created at the same time based on a job template.
- job record
A job record corresponds to an execution record of a job.
You can view or delete the execution records of created jobs. You can filter records based on the following states: Not Executed, Executed, Executed Failed, and Executing. In the job record list, you can view the information about a job. The information includes the job ID, execution status, creation time, end time, number of running instances, number of instances that succeeded to run, and number of instances that failed to run.
- startup commands
The startup commands are used to start and run containers.
When you start a container, the main process starts. Before you can start the main process, you must configure and initialize a MySQL database. Configure the ENTRYPOINT or CMD parameter in the Dockerfile file when you create an image. For example, if you specify
ENTRYPOINT ["top", "-b"]in the Dockerfile file, SAE automatically executes the command at the startup of the container.
- application health check
SAE performs scheduled health checks on application instances during the runtime of an application.
SAE provides the following methods to perform application health checks:
- SAE uses a liveness probe to check whether an application instance is running as expected. If the application instance is not running as expected, SAE restarts the application instance.
- SAE uses a readiness probe to check whether an application instance is ready to process requests. If the check fails, the application instance is not ready and SAE blocks access to the application instance. If the check is successful, the application instance is ready and SAE allows access to the application instance.
- Application Configuration Management
Application Configuration Management is a distributed architecture-based tool that allows you to manage and push application configurations in a centralized manner.
In SAE, you can use Application Configuration Management to manage and push application configurations in a centralized manner. You can also isolate and synchronize configurations between different environments by using namespaces.
- EDAS Container
Enterprise Distributed Application Service (EDAS) Container is developed by using the High-speed Service Framework (HSF) architecture and is used to run applications. EDAS Container includes Ali-Tomcat and Pandora containers.
In addition to microservice frameworks such as Spring Cloud and Dubbo, SAE supports Alibaba Cloud HSF.