In a microservices architecture, each microservice exposes a set of typically fine-grained endpoints. This fact can impact the client-to-microservice communication, as explained in this section. A possible approach is to use a direct client-to-microservice communication architecture. In this approach, a client app can make requests directly to some of the microservices, as shown in Figure In this approach, each microservice has a public endpoint, sometimes with a different TCP port for each microservice.

In a production environment based on a cluster, that URL would map to the load balancer used in the cluster, which in turn distributes the requests across the microservices. This acts as a transparent tier that not only performs load balancing, but secures your services by offering SSL termination. In any case, a load balancer and ADC are transparent from a logical application architecture point of view.

A direct client-to-microservice communication architecture could be good enough for a small microservice-based application, especially if the client app is a server-side web application like an ASP. However, when you build large and complex microservice-based applications for example, when handling dozens of microservice typesand especially when the client apps are remote mobile apps or SPA web applications, that approach faces a few issues.

Interacting with multiple microservices to build a single UI screen increases the number of round trips across the Internet. This increases latency and complexity on the UI side.

Ideally, responses should be efficiently aggregated in the server side. This reduces latency, since multiple pieces of data come back in parallel and some UI can show data as soon as it's ready. Implementing security and cross-cutting concerns like security and authorization on every microservice can require significant development effort. A possible approach is to have those services within the Docker host or internal cluster to restrict direct access to them from the outside, and to implement those cross-cutting concerns in a centralized place, like an API Gateway.

Protocols used on the server side like AMQP or binary protocols are usually not supported in client apps. A man-in-the-middle approach can help in this situation. The API of multiple microservices might not be well designed for the needs of different client applications. For instance, the needs of a mobile app might be different than the needs of a web app. For mobile apps, you might need to optimize even further so that data responses can be more efficient.

You might do this by aggregating data from multiple microservices and returning a single set of data, and sometimes eliminating any data in the response that isn't needed by the mobile app.In this post in the microservices series we will talk about API gateways and how they can help us solve some important concerns in a microservice-based architecture.

We described these and other issues in our first post in the series. In all service-based architectures there are several concerns that are shared among all or most services.

Amazon API Gateway

A microservice-based architecture is not an exception. As we said in the first post, microservices are developed almost in isolation. Cross-cutting concerns are dealt with by upper layers in the software stack. The API gateway is one of those layers. Here is a list of common concerns handled by API gateways:. Most gateways perform some sort of authentication for each request or series of requests.

According to rules that are specific to each service, the gateway either routes the request to the requested microservice s or returns an error code or less information. Most gateways add authentication information to the request when passing it to the microservice behind them. This allows microservices to implement user specific logic whenever required.

Many gateways function as a single entry point for a public API. In such cases, the gateways handle transport security and then dispatch the requests either by using a different secure channel or by removing security constraints that are not necessary inside the internal network. Under high-load scenarios, gateways can distribute requests among microservice-instances according to custom logic.

Each service may have specific scaling limitations. Gateways are designed to balance the load by taking these limitations into account. For instance, some services may scale by having multiple instances running under different internal endpoints. Gateways can dispatch requests to these endpoints or even request the dynamic instantiation of more endpoints to handle load.

Even under normal-load scenarios, gateways can provide custom logic for dispatching requests. In big architectures, internal endpoints are added and removed as teams work or new microservice instances are spawned due to topology changes, for instance.

This provides exceptional flexibility to development teams. Additionally, faulty services can be routed to backup or generic services that allow the request to complete rather than fail completely.

As microservices deal with very specific concerns, some microservice-based architectures tend to become "chatty": to perform useful work, many requests need to be sent to many different services. For convenience and performance reasons, gateways may provide facades "virtual" endpoints that internally are routed to many different microservices.

As we learnt in the first post of this series, microservices are usually developed in isolation and development teams have great flexibility in choosing the development platform.There are no minimum fees or upfront commitments. There are no data transfer out charges for Private APIs.

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API Gateway also provides optional data caching charged at an hourly rate that varies based on the cache size you select. Pay only for the API calls you receive. Pay for messages transferred and connection minutes. If you exceed this number of calls per month, you will be charged the API Gateway usage rates.

These free tier offers are only available to new AWS customers, and are available for 12 months following your AWS sign-up date. When your 12 month free usage term expires or if your application use exceeds the tiers, you simply pay standard, pay-as-you-go service rates.

Which API Gateway to choose?

Pay only for the API calls you make. Pay only for the API calls you receive and the amount of data transferred out. Pay only for messages sent and received and the total number of connection minutes.

You may send and receive messages up to kilobytes KB in size. Messages are metered in 32 KB increments. So, a 33 KB message is metered as two messages. Links to pricing for some of the commonly used services are listed below. If you use external data transfers, you will be charged at the EC2 data transfer rate. The API is called 25 times per minute to upload documents which on average is 4.

Chat Application: users connected to the chat application for 12 hours in a day. Each user sends messages and receives messages per day. Each message size is 3KB.

api gateway

Learn through tutorials. Start building with AWS. Product Pricing Glossary. Sign up for the Free Tier. Data transfer If you use external data transfers, you will be charged at the EC2 data transfer rate. AWS Lambda Includes pricing for requests and duration. Amazon CloudWatch Includes pricing for metrics and dashboards. Example below reflects pricing in US East N. Sign up for an AWS account.

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Explore and learn with simple tutorials. Page Content.Amazon API Gateway is a fully managed service that makes it easy for developers to create, publish, maintain, monitor, and secure APIs at any scale.

APIs act as the "front door" for applications to access data, business logic, or functionality from your backend services. API Gateway supports containerized and serverless workloads, as well as web applications.

API Gateway handles all the tasks involved in accepting and processing up to hundreds of thousands of concurrent API calls, including traffic management, CORS support, authorization and access control, throttling, monitoring, and API version management.

API Gateway has no minimum fees or startup costs. Build real-time two-way communication applications, such as chat apps and streaming dashboards, with WebSocket APIs. API Gateway maintains a persistent connection to handle message transfer between your backend service and your clients.

Run multiple versions of the same API simultaneously with API Gateway, allowing you to quickly iterate, test, and release new versions. You pay for calls made to your APIs and data transfer out and there are no minimum fees or upfront commitments. Provide end users with the lowest possible latency for API requests and responses by taking advantage of our global network of edge locations using Amazon CloudFront. Throttle traffic and authorize API calls to ensure that backend operations withstand traffic spikes and backend systems are not unnecessarily called.

Monitor performance metrics and information on API calls, data latency, and error rates from the API Gateway dashboard, which allows you to visually monitor calls to your services using Amazon CloudWatch.

How to build an API with Lambdas and API Gateway

Learn with step-by-step tutorials. Start building with AWS. Performance at any scale Provide end users with the lowest possible latency for API requests and responses by taking advantage of our global network of edge locations using Amazon CloudFront.

Easy monitoring Monitor performance metrics and information on API calls, data latency, and error rates from the API Gateway dashboard, which allows you to visually monitor calls to your services using Amazon CloudWatch. Sign up for an AWS account.

Explore and learn with simple tutorials. Ready to build? Have more questions?If you've got a moment, please tell us what we did right so we can do more of it.

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Thanks for letting us know this page needs work. We're sorry we let you down. If you've got a moment, please tell us how we can make the documentation better. Or you can make your APIs available to third-party app developers.

Adhere to the WebSocket protocol, which enables stateful, full-duplex communication between client and server.

API management

This diagram illustrates how the APIs you build in Amazon API Gateway provide you or your developer customers with an integrated and consistent developer experience for building AWS serverless applications. API Gateway handles all the tasks involved in accepting and processing up to hundreds of thousands of concurrent API calls.

These tasks include traffic management, authorization and access control, monitoring, and API version management. API Gateway acts as a "front door" for applications to access data, business logic, or functionality from your backend services, such as workloads running on Amazon Elastic Compute Cloud Amazon EC2code running on AWS Lambda, any web application, or real-time communication applications.

Developer portal for publishing your APIs. Canary release deployments for safely rolling out changes. CloudWatch access logging and execution logging, including the ability to set alarms.

Support for custom domain names. SDKs simplify authentication, integrate easily with your development environment, and provide access to API Gateway commands. For more information, see Tools for Amazon Web Services. AWS Lambda runs your code on a highly available computing infrastructure. It performs the necessary execution and administration of computing resources. Javascript is disabled or is unavailable in your browser.

Please refer to your browser's Help pages for instructions. Did this page help you?

api gateway

Thanks for letting us know we're doing a good job! Are HTTP-based. Enable stateless client-server communication. Route incoming messages based on message content. Document Conventions. API Gateway use cases.API gateways are a lot like a multi-lingual traffic cop, who not only knows where people want to go, but also speaks their language, no matter what country they come from!

As a point-of-entry for requests for application services sent by end-user applications, gateways sit between APIs Application Programming Interfaces and the application services running on a server. Instead of the APIs sending requests directly to individual services, they go through the gateway, i. APIs that receive authorized access from the gateway are then directed to a range of services.

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Here are some of the most common services:. During the process, the gateway translates the various protocols used by the APIs and then directs each request to the appropriate application service. In addition to accommodating direct requests, gateways can invoke requests for multiple back-end services and aggregate the results. Because developers must update an API gateway each time a new service is added or removed, the update process should be lightweight, without putting a drain on the gateway CPU and memory.

This allows the gateway to keep functioning properly as changes are made. API gateways include several functional components. Access Control manages which APIs can connect to each application service and the rules for how data requests are handled. This ensures only authenticated user applications can connect to back-end services. Another key function is Rate-Limitingwhich reduces the load on APIs to prevent misuse by permitting only a certain number of requests at one time.

In some cases, higher rate limits are set, such as services offered to customers. Threat Detection is also key. This provides protection against hackers who try to upload malware, SQL injection and other forms of cybercriminal activity such as DDoS Distributed Denial-of-Service attacks.

api gateway

The image above depicts an end-user managing a warehouse order-fulfillment process. The front-end application interacts with the API gateway to gain access to three separate application services that allow the end-user to check an order request, pull stock from inventory, and arrange for shipping. With the gateway directing connections to the services, everything happens all at once from the end-user viewpoint.

From a performance standpoint, Auto-Scaling handles spikes in activity while High Availability allows gateways to automatically failover to another gateway in the event of a system crash.

This is particularly important for maintaining access to mission-critical application services. This requires replicating API gateways across multiple data centers. In addition to making business continuity possible, replication gives you the ability to provision application services from the multiple data centers, thus providing lower latency to end-users. The gateway organizes requests processed by the microservices architecture to create simplified experiences for end-users.So, what even is an API gateway?

There are many ways to describe an API gateway. Whether you want to call it a reverse proxy, a single point of entry, or an interface, the idea is the same: an API gateway is a layer that goes between your clients and services.

Instead of clients sending requests directly to individual services, they send them to an API gateway. Then, the API gateway passes the requests on to the appropriate service. API gateways are getting increasingly popular with the trend towards using microservices architectures.

In a microservices architecture, an application is divided up between a handful of loosely-coupled services dubbed microserviceseach of which has its distinct functionality. While microservices offer a good number of benefits — most notably making it easier to develop, deploy, and maintain distinct parts of an application — they make it difficult for clients to access the information they need in a fast and secure fashion.

An API gateway can solve some of these problems by acting as a central interface for clients using these microservices. Instead of having to access dozens of individual services, a client can send a single request to the API gateway, which will itself recruit the microservices. This primary function of the API gateway is known as routingbut there are plenty more reasons to use an API gateway….

As a central interface connecting clients with services, an API gateway can handle crucial security and administration tasks such as authentication, input validation, metrics collection, and response transformation:.

Together, these features make the API gateway a very sensible way to package up your microservices. Some of the exact benefits you get from this are:. In understanding these benefits, you might find the concept of granularity quite useful. Typically, we talk about resources being fine-grained or coarse-grained. Wrapping a handful of resources together makes accessing those resources easier and faster, which is why API gateways have those first two benefits.

Despite some similarities between the two, service meshes are actually quite different from API gateways. The main difference is that API gateways facilitate communication between clients and services, while service meshes facilitate communication between internal services only.

There is overlap in how both patterns often contain routing, authentication, rate limiting, and metrics functionality, though.

The service mesh is a newer pattern, and it might one day be sufficient on its own. For now, some practitioners combine the two approaches, using an API gateway to handle external traffic and a service mesh to handle the interaction between the individual microservices within the application.

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And so Zuul 2. One of the main traits of the Netflix API gateway is how it routes requests from more than device typesproviding just the right information to clients depending on the hardware and software they are running. There you have it, API gateways in plain English. With growing popularity due to the rise of the microservice architecture, API gateways offer serious advantages from an API management perspective. Thomas Bush is an enthusiastic freelance writer from the United Kingdom, who loves breaking down tough topics into bite-sized articles.

Also read: The Business Caveats of Microservices. About Thomas Bush Thomas Bush is an enthusiastic freelance writer from the United Kingdom, who loves breaking down tough topics into bite-sized articles. Why DevOps Tooling Relies on Subscribe to our API Digest. Create With Us.


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