Rpc Quotes

SOA Microservices Inter-service communication Smart pipes, such as Enterprise Service Bus, using heavyweight protocols, such as SOAP and the other WS* standards. Dumb pipes, such as a message broker, or direct service-to-service communication, using lightweight protocols such as REST or gRPC Data Global data model and shared databases Data model and database per service Typical service Larger monolithic application Smaller service

SOA and the microservice architecture usually use different technology stacks. SOA applications typically use heavyweight technologies such as SOAP and other WS* standards. They often use an ESB, a smart pipe that contains business and message-processing logic to integrate the services. Applications built using the microservice architecture tend to use lightweight, open source technologies. The services communicate via dumb pipes, such as message brokers or lightweight protocols like REST or gRPC.

Here are a couple of simple, practical tricks to determine if a service is not RESTful: If the name of the service is a verb instead of a noun, the service is likely RPC and not RESTful. If the name of the service to be executed is encoded in the request body, the service is likely RPC and not RESTful. If the back-button in the web-application does not work as expected, the service is not stateless and not RESTful. If the service or website does not behave as expected after turning cookies off, the service is not stateless and not RESTful.

RPC API

Avoid database integration at all costs. Understand the trade-offs between REST and RPC, but strongly consider REST as a good starting point for request/response integration. Prefer choreography over orchestration. Avoid breaking changes and the need to version by understanding Postel’s Law and using tolerant readers.

The Richardson Maturity Model can be used for determining the degree to which services are RESTful. The following levels are defined: Level 0: Services use an RPC style. Level 1: Services expose resources. Larger services are broken down into resources. Level 2: Services use HTTP methods correctly. Services use HTTP infrastructure efficiently. Level 3: Hypermedia is used according to HATEOAS. The service is self-documenting and flexible.

Figure 2-4 shows how a user’s request is serviced: first, the user points their browser to shakespeare.google.com. To obtain the corresponding IP address, the user’s device resolves the address with its DNS server (1). This request ultimately ends up at Google’s DNS server, which talks to GSLB. As GSLB keeps track of traffic load among frontend servers across regions, it picks which server IP address to send to this user. Figure 2-4. The life of a request The browser connects to the HTTP server on this IP. This server (named the Google Frontend, or GFE) is a reverse proxy that terminates the TCP connection (2). The GFE looks up which service is required (web search, maps, or—in this case—Shakespeare). Again using GSLB, the server finds an available Shakespeare frontend server, and sends that server an RPC containing the HTTP request (3).

All of Google’s services communicate using a Remote Procedure Call (RPC) infrastructure named Stubby; an open source version, gRPC, is available. 3 Often, an RPC call is made even when a call to a subroutine in the local program needs to be performed. This makes it easier to refactor the call into a different server if more modularity is needed, or when a server’s codebase grows. GSLB can load balance RPCs in the same way it load balances externally visible services.