Service Deployment

 Service Deployment

A Microservice based application consists of tens or hundreds of services. Services are written in a variety of languages, frameworks, and each service acts as a mini-application on its own

- Specific deployment
- Resource
- Scaling 
- Monitoring requirements 

The number of instances of each service is based on the demand for that service.

What is Microservice?

Microservice architectural style is a method to create an application as a set of small services that runs its process and interact with lightweight mechanisms, usually an HTTP resource API.

Microservice is developed based on business features and deployed independently by an automated deployment machinery.

There is less centralized management of Microservices that may be written in various programming languages and utilize diverse data storage technologies.

For example: In an ecommerce site, Payment service could be written in C++, while Order management service could be written in Java.

Microservice vs SOA

To quickly summarize, main difference between SOA and Microservices is

• Size (granularity)
• Scope.

Microservice could be considered as a subset of SOA.

Fact# 1

DID YOU KNOW - Amazon is regarded as the first company to get microservices and APIs right.

Microservice - Simple Understanding

Application functionality must be distributed into lightweight, discrete services, where every single service satisfies a particular business-focused interest. Learn more about Microservices in this video.

Deege U  -- youtube channel

https://youtu.be/PY9xSykods4

Fact# 2

Amazon delivers 50 million deployments annually, without coordination between teams when deploying services. Isn't that great?

Decomposition

The application is decomposed into microservices based on two categories.

• Decompose by business capability The services are created based on the business capabilities. For example, in Retailer Ecommerce - billing, payment, order management, and promotions are different business capabilities, which could be made into separate services.

• Decompose by subdomain Domain-driven design supports modeling based on the reality of business as akin to use cases.

Wrong decomposition could impact at the architectural level.

Application - Types

Applications are broadly classified into two types:

i) Monolithic Architecture, where an application is built as a single unit.

ii) Microservices Architecture, where many applications (microservices) handle a small portion of the functionality and data.

We will discuss both these types in detail.

Fact# 3

According to Gartner Hype Cycle for Application Services, 2016, Microservices is rated at the peak.

Monolithic Style

• A monolithic application is built as a single unit, i.e., one big application in a single language that handles all of the functionality, data, business logic etc. A load balancer distributes requests from the end user, across multiple machines, each running one instance of our application.

• All logic for handling a request runs in a single process, allowing you to utilize the primary features of the language to divide up the application into classes, functions, and namespaces.

Monolithic Style - Advantages

• Faster Initial Development - With one application, it would be relatively easy to add additional features, especially when the application is relatively small.
• Little User Confusion - Developers need not have to learn about different applications, but would be focused towards one application.
• Improved Integration - Features could integrate with each other well and easily.

Monolithic Style - Disadvantages

• Single Point of Failure - If any single application function or component fails, then the entire application goes down. For example - a web application with separate functions handling tasks like payment, login, and history; a function begins to consume more memory or CPU. In this scenario, the entire application will come to a halt.

• Horizontal Scaling - Scaling application can only be accomplished by deploying the same EAR/WAR packages in more servers. Every single copy of the application in different servers will use the same number of primary resources, which is usually not an effective way to design.

Monolithic Style - Disadvantages...

• As application grows, the code base grows with it, which can overload IDE every time it loads the application. This definitely reduces developer productivity.
• Substantially less iteration - a small change made to any part of the application, requires the entire monolith to be rebuilt and deployed.
• Maintenance costs will shoot up exponentially with site size.
• High set-up costs - In order to get each new volunteer up and running, the larger the application, the more difficult this would be.

Fact# 4

Cypherpath predicted that in 2017 onwards more vendors will specialize in supporting the deployment of microservices as a business model.

Microservice Style

Build applications as suites of services (Modular approach)

• Each microservice exposes a common API accessed through the network (as opposed to inter-process communication or shared memory on the same machine).

• API calls are stitched mostly on the server to produce a page, although few of this work is executed by the client querying individual microservices.

Microservice Style

Big enterprise players such as Amazon, Netflix, Uber, Yelp and eBay have adopted Microservices. Services are

• Independently deployable
• Scalable

Each service offers a secure module boundary, allowing different services to be written in different programming languages.

Microservice Style - Advantages

• Improved fault isolation: Larger applications can remain largely unaffected by the failure of a single module with microservice style adoption.
• Removes Dependency: Eliminates long-term commitment to any single technology stack.
• Easy Understanding: With the split of functionality, it gives more room for new developers to understand the functionality of a service and make enhancements easily.
• Easy Deployment: Microservices-based applications are deployed inside containers providing better management.

Microservice Style - Disadvantages

• Complexity - Deploying microservices can be a little complex, requiring coordination among multiple services, which may not be as straightforward as deploying a monolith.
• Multiple DBs - Managing multiple databases and transaction management could be painful.
• Testing - Testing could be little cumbersome, as each dependent service needs to be confirmed before one can start testing.
• Coordination - Handling requests across multiple independent services requires proper workflow management. There can be a scenario where one of the services may not be responding or remote calls experiencing latency.

Despite few disadvantages, the benefits of adopting Microservices are a lot more, pushing many enterprise leaders towards this journey.

How Does it Really Work?

Microservices are considered as the building blocks of modern applications. You will agree after watching this video.

https://youtu.be/gfWr2_H39N0