Shulou(Shulou.com)06/02 Report--

4. What are the family buckets of Spring Cloud microservices?

In addition to common components, Spring Cloud also integrates micro-service home buckets, which can be used right out of the box:

Service registration discovery classes, including: Eureka, Consul, Zookeeper, Etcd, etc. Service registration: each micro-service component registers its own services with the registry, including the host, port number, version number, communication protocol and other information of the service. The registry organizes the service list according to the service type, and monitors whether the service in the list is available by heartbeat detection, and if it is not available, it needs to be removed from the service list to achieve the effect of troubleshooting services. Service discovery: under the framework of service governance, the invocation between services is no longer realized by the specific instance address, but by the request invocation initiated by the service name. The service caller obtains the list list of service instances from the service list of the registry through the service name, and takes out a service instance location for service invocation through the specified load balancing strategy.

Service invocation framework classes, including: Ribbon, Feign, etc. The client load balancer integrates the load balancing logic into the consumer. The consumer learns which instances of the service are available from the registry, and then selects a service instance from these addresses for access according to a certain policy.

Service fault-tolerant component classes, including: Hystrix and so on. Service breaker: if a target service is unavailable or a large number of access times out, the system will disconnect the call to the service, and for subsequent call requests, the system will no longer forward to this service and directly return a failed response, thus quickly releasing resources; if the target service is improved, the call is resumed. Service degradation: in the case of emergency shielding or service fuse, return directly to the local default response.

Unified configuration center class, including: Spring Cloud Config, Spring Cloud Bus and so on. In the service construction phase, cooperate with the construction pipeline to provide configuration for service software packages or images; in the service operation and maintenance phase, dynamically adjust the service configuration to meet the flexibility needs of operation and maintenance; in the service development phase, provide configuration API to externalize the configuration for other systems to call.

Service gateway proxy class, including: Zuul, Spring Cloud Gateway, etc. It mainly provides the service routing function, that is, it receives all the requests from the consumer and forwards the requests to the service provider according to a certain policy. At the same time, a series of cross-sectional functions are completed in the service gateway, such as authority verification, request measurement, flow control, quality of service, request management, response management, version management and so on.

Call the link monitoring class, including Spring Cloud Sleuth, which encapsulates Dapper, Zipkin, HTrace, and so on. There are a large number of components in the micro-service architecture, and a business request may need to invoke multiple services. The complexity of the invocation determines that errors and exceptions are difficult to locate. We need to know which services are involved in each request and what the order of invocation is, so that each invocation step can be clearly identified and problems can be quickly located.

Usually we use Eureka as the service registration center to achieve service registration and discovery; through Ribbon and Feign to achieve service consumption and client load balancing; through Spring Cloud Config to achieve external configuration and version management in different environments. In order to make the service cluster more robust, the break mechanism of Hystrix is used to avoid fault spread and avalanche caused by individual service anomalies in the micro-service architecture. The service gateway Zuul is a micro-service architecture portal, which migrates heavy non-business logic contents such as access control, metering and billing to the service routing level, so that the main body of the service cluster can have higher reusability and testability.

5. How does Spring Cloud integrate DevOps?

Next, let's take a look at what Spring Cloud can do to integrate with DevOps, and how can it make continuous application delivery faster? As we all know, DevOps has created a continuous delivery process, including: development, compilation, testing, release, operations and other nodes. How to make the application pass through the above nodes more smoothly? Spring Cloud can do some coordination and optimization at each R & D node:

In the development process, all of us should have tried Spring Initializer to create Spring Boot project projects. In addition, we can also use Maven Archetype to quickly generate project projects. Archetype is a template toolkit for Maven projects. An Archetype defines the basic skeleton of a certain type of project and provides users with sample projects as quickly as possible. In the testing stage, micro-services usually provide RESTful API for various types of clients to call, but in the past, we need to record these API information with the help of documents for other people to consult and test. If API changes, we need to update the documents synchronously, which reduces the efficiency of continuous delivery, and Swagger can help us automatically generate API online documents to keep pace with the code implementation. On this basis, we can also automate the testing of API. Integrate Swagger through Spring Boot to make interface testing more automated. In the release process, projects developed with Spring Boot can be embedded into application servers such as Jetty, Tomcat, etc., and are most suitable for publishing as Docker images. Instead of using the Docker Maven plug-in, we can create a new Dockerfile file in the root directory of the current project. After writing the code, users only need to modify some parameters and manually execute the command to image the application, so that there is no need to learn container-related technologies in depth. In the operation part, we can access the unified configuration center, log cloud, full-link tracking and other platforms to facilitate the location and solution of the problem. 6. How does Spring Cloud fit into the cloud infrastructure?

Just now we have introduced Spring Cloud in detail in terms of development framework, service integration and converged DevOps, so let's take a look at what Spring Cloud can do to adapt to the cloud platform. Usually in order to make various cloud computing technology stacks transparent to application developers and reduce the difficulty of cloud on applications, we need to adapt to different types of cloud infrastructure, such as virtual machines, containers and so on.

Virtual machine is the abstraction of physical machine, including operating system, memory and storage, etc. When making VM image, you can install software, such as WEB server and database, etc. These software will also appear in the virtual machine started with this image. VM is isolated from its host and other VM on the host. Containers only need the space needed by the code runtime environment in the system, and containers on the same operating system share the host kernel. Due to different implementation principles, the resources required to run virtual machines and containers are also different. A virtual machine is essentially a complete computer that requires more resources than a container, which is only part of the operating system. Container clusters are generally less resource intensive, so running multiple containers on a single server is more appropriate than running multiple VM on a single server.

What kind of infrastructure is suitable for our applications to deploy on? In general, public applications are suitable for virtual machine deployment, such as message queues, registries, databases, etc., which require high running resources and do not have too many components; business applications are suitable for container deployment. We can split business applications into a large number of micro-service components with a single responsibility, each of which requires relatively definite resource requirements and requires elastic scaling under different traffic.

Therefore, our DevOps system needs to abstract the management interfaces that operate different infrastructure, and implement application life cycle management, service governance and other functions based on these management interfaces. This piece can learn from foreign vendors to specify a cloud application management standard CAMP (Cloud Application Management for Platform), which defines the API of application construction, operation, management, monitoring and update, as well as resource model and interaction protocol. Anisebo

7. Spring Cloud application development mode of filling in blanks

In the construction of individual micro-services, Spring has provided us with rich components from the presentation layer, domain layer and data source layer, and we only need to pay attention to the writing of business logic code. In terms of service integration, Spring Cloud has already provided the whole bucket of micro-services, so we only need to reference these services and do not need to build these public services. In docking DevOps and cloud infrastructure, we can do some optimization and adaptation. With its support, we can more easily embrace microservices, DevOps and cloud computing to better meet the challenges of new technologies. Following the concept of division of labor and cooperation, Spring Cloud provides us with a blank-filling development model, in which we only need to focus on business and users, so as to polish excellent products at a faster iterative speed.

8. Summary

The Spring family is getting bigger and bigger, including Spring Framework, Spring Boot, Spring Cloud and so on. If we don't have a global understanding of it, it's easy for us to get lost in the technical details and make good use of this product. This paper is the experience and cognition accumulated by the author in the process of participating in the research and development of the company's micro-service framework, which can be used as an index of Spring Cloud knowledge system, and can be followed by in-depth learning of certain characteristics.

The main value of this article is to help you sort out the knowledge framework related to Spring Cloud, that is, the global perspective or God perspective. With this framework, we can according to our own needs to find clues to find the relevant node information to study, so as not to fall into the details can not find the direction. Of course, considering that each of us has different work and study conditions and different problems we usually encounter, this article cannot cover the problems encountered by everyone. You are welcome to leave messages and ask questions, and you are also welcome to follow the exchange and interaction of "IT veterans". Thank you!

The index of other articles in this series is as follows:

How to use Spring Cloud correctly? [above] Please add a link description

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.