Synchronous calls considered harmful "Microservices" - yet another new term on the crowded streets of software architecture.
Synchronous calls considered harmful "Microservices" - yet another new term on the crowded streets of software architecture. Although our natural inclination is to pass such things by with a contemptuous glance, this bit of terminology describes a style of software systems that we are finding more and more appealing.
In short, the microservice architectural style  is an approach to developing a single application as a suite of small services, each running in its own process and communicating with lightweight mechanisms, often an HTTP resource API. These services are built around business capabilities and independently deployable by fully automated deployment machinery.
There is a bare minimum of centralized management of these services, which may be written in different programming languages and use different data storage technologies. My Microservices Resource Guide provides links to the best articles, videos, books, and podcasts about microservices.
Enterprise Applications are often built in three main parts: The server-side application will handle HTTP requests, execute domain logic, retrieve and update data from the database, and select and populate HTML views to be sent to the browser.
This server-side application is a monolith - a single logical executable . Any changes to the system involve building and deploying a new version of the server-side application. Such a monolithic server is a natural way to approach building such a system.
All your logic for handling a request runs in a single process, allowing you to use the basic features of your language to divide up the application into classes, functions, and namespaces.
You can horizontally scale the monolith by running many instances behind a load-balancer. Monolithic applications can be successful, but increasingly people are feeling frustrations with them - especially as more applications are being deployed to the cloud.
Change cycles are tied together - a change made to a small part of the application, requires the entire monolith to be rebuilt and deployed. Scaling requires scaling of the entire application rather than parts of it that require greater resource. Monoliths and Microservices These frustrations have led to the microservice architectural style: As well as the fact that services are independently deployable and scalable, each service also provides a firm module boundary, even allowing for different services to be written in different programming languages.
They can also be managed by different teams. We do not claim that the microservice style is novel or innovative, its roots go back at least to the design principles of Unix. But we do think that not enough people consider a microservice architecture and that many software developments would be better off if they used it.
Characteristics of a Microservice Architecture We cannot say there is a formal definition of the microservices architectural style, but we can attempt to describe what we see as common characteristics for architectures that fit the label. As with any definition that outlines common characteristics, not all microservice architectures have all the characteristics, but we do expect that most microservice architectures exhibit most characteristics.
While we authors have been active members of this rather loose community, our intention is to attempt a description of what we see in our own work and in similar efforts by teams we know of. In particular we are not laying down some definition to conform to. When talking about components we run into the difficult definition of what makes a component.
Our definition is that a component is a unit of software that is independently replaceable and upgradeable. Microservice architectures will use libraries, but their primary way of componentizing their own software is by breaking down into services.
We define libraries as components that are linked into a program and called using in-memory function calls, while services are out-of-process components who communicate with a mechanism such as a web service request, or remote procedure call.
This is a different concept to that of a service object in many OO programs . One main reason for using services as components rather than libraries is that services are independently deployable. If you have an application  that consists of a multiple libraries in a single process, a change to any single component results in having to redeploy the entire application.
But if that application is decomposed into multiple services, you can expect many single service changes to only require that service to be redeployed.
Another consequence of using services as components is a more explicit component interface. Most languages do not have a good mechanism for defining an explicit Published Interface.
Services make it easier to avoid this by using explicit remote call mechanisms. Using services like this does have downsides. Remote calls are more expensive than in-process calls, and thus remote APIs need to be coarser-grained, which is often more awkward to use.
At a first approximation, we can observe that services map to runtime processes, but that is only a first approximation.Automation, digital platforms, and other innovations are changing the fundamental nature of work.
Understanding these shifts can help policy makers, business leaders, and workers move forward. Demographics and Automation Daron Acemoglu, Pascual Restrepo. NBER Working Paper No. Issued in March NBER Program(s):Aging, Economic Fluctuations and Growth, Labor Studies We argue theoretically and document empirically that aging leads to greater (industrial) automation, and in particular, to more intensive use and development of robots.
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Automation is the use of control systems to control processes, reducing the need for human intervention. Putting this into context, automation is having technology do things for you so that you don't have to.
Automation is all around us. When you're at a set of traffic lights, there isn't a traffic light operator. Application of information technology to the typical clerical and secretarial tasks such as communication, correspondence, documenting, and filing.
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