![]() ![]() ![]() ![]() The API gateway pattern has some drawbacks: Translates from a “standard” public web-friendly API protocol to whatever protocols are used internally.Simplifies the client by moving logic for calling multiple services from the client to API gateway.An API gateway is essential for mobile applications. Fewer requests also means less overhead and improves the user experience. For example, the API gateway enables clients to retrieve data from multiple services with a single round-trip. Reduces the number of requests/roundtrips.Provides the optimal API for each client.Insulates the clients from the problem of determining the locations of service instances.Insulates the clients from how the application is partitioned into microservices.Using an API gateway has the following benefits: A simple Java/Spring API gateway from the Money Transfer example application.In this example, there are three kinds of clients: web application, mobile application, and external 3rd party application.Įach one is provides an API for its client. It defines a separate API gateway for each kind of client. verify that the client is authorized to perform the request Variation: Backends for frontendsĪ variation of this pattern is the Backends for frontends pattern. The API gateway might also implement security, e.g. For example, the Netflix API gateway runs client-specific adapter code that provides each client with an API that’s best suited to its requirements. Rather than provide a one-size-fits-all style API, the API gateway can expose a different API for each client. It handles other requests by fanning out to multiple services. Some requests are simply proxied/routed to the appropriate service. The API gateway handles requests in one of two ways. Implement an API gateway that is the single entry point for all clients. Services might use a diverse set of protocols, some of which might not be web friendly Partitioning into services can change over time and should be hidden from clients The number of service instances and their locations (host+port) changes dynamically The server-side web application can make multiple requests to backend services without impacting the user experience where as a mobile client can only make a few. This means that a native mobile client uses a network that has very difference performance characteristics than a LAN used by a server-side web application. And, of course, any WAN is much slower than a LAN. For example, a mobile network is typically much slower and has much higher latency than a non-mobile network. ![]() Network performance is different for different types of clients. For example, the desktop browser version of a product details page desktop is typically more elaborate then the mobile version. For example, as described above, a client needing the details for a product needs to fetch data from numerous services.ĭifferent clients need different data. Microservices typically provide fine-grained APIs, which means that clients need to interact with multiple services. The granularity of APIs provided by microservices is often different than what a client needs. How do the clients of a Microservices-based application access the individual services? Forces Inventory service - product availabilityĬonsequently, the code that displays the product details needs to fetch information from all of these services.Order service - purchase history for product.Product Info Service - basic information about the product such as title, author.Since the online store uses the Microservice architecture pattern the product details data is spread over multiple services. Other items bought by customers who bought this book.Other items that are frequently bought with this book.Basic information about the book such as title, author, price, etc.In addition, the online store must expose product details via a REST API for use by 3rd party applications.Ī product details UI can display a lot of information about a product.įor example, the details page for POJOs in Action displays: Native Android and iPhone clients - these clients interact with the server via REST APIs.HTML5/JavaScript-based UI for desktop and mobile browsers - HTML is generated by a server-side web application.You need to develop multiple versions of the product details user interface: Let’s imagine you are building an online store that uses the Microservice architecture pattern and that you are implementing the product details page. Pattern: API Gateway / Backends for Frontends Context ![]()
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