The Service Oriented Architecture (SOA) is not a technology instead it is a collection of Services. Precisely it is an architectural style for building business applications using loosely coupled services which communicates with each other.
SOA = Messages + Services
Services – Self-contained business functionality and communicate using messages.
Messages – It is a discrete unit of communication. It should be cross-platform, secure, asynchronous, reliable, follow the industry standard, and able to describe and discover the service.
The SOA shifts your thinking from classes and objects to messages.
The webserviceis nothing but a service available over the web (Or method of communication between two devices over a network) while API(Application Programming Interface)acts as an interface between two different applications so that they can communicate with each other. The API may or may not be web-based. Having said that all the all the web services are APIs but all APIs are not web services. The webservice always needs a network while for API it may/may not be needed.
WebServices are mainly of two types
Let’s understand the differences between SOAP and REST
SOAP stands for Simple Object Access Protocol. REST stands for Representation State transfer.
SOAP is an XML based protocol which uses WSDL for communication between source and recipient. REST is an architecture style protocol which uses XML and JSON to communicate between consumer and provider.
SOAP uses RPC while REST directly uses URL.
The transfer is over HTTP, FTP, SMTP and other protocol for SOAP while for REST it is HTTP only.
SOAP is hard to implement over REST.
The performance is slower compared to REST.
SOAP is more secure since it does define its own security. The REST is less secure. The transport defines the security. (Smart consumer and provide while dumb pipe).
The SOAP message is large. The core element of SOAP message is a SOAP envelope. The SOAP envelope defines the start and end of the message. It has two parts 1. SOAP HEADER 2. SOAP BODY
WSDL – Web Service Description Language
The WSDL is an XML based interface that is used to describe the functionalities of the webservices .
Microservices is one of the newer concepts and a variant of a Service Oriented Architecture (SOA). Although SOA has been there for almost two decades while the Microservices came into existence in 2012.
The idea is to have small autonomous services to work together to build a large complex application. The approach focuses on individual business sub-domains and building small services making them easier to maintain, and promotes independently deployable pieces thus ensuring that internal changes in one service do not affect or require the redeployment of other services. In today’s software development landscape, most applications are monolithic and one of the drawbacks of this approach is that business owners get to take a very limited number of decisions in a year (slower response times because of dependencies). For instance, upgrading a product, adding newer functionality that is significant in size, etc within a set of related services requires a concerted effort of all concerned parties to deliver changes in a synchronized manner. Microservices allow you to take more far-reaching business decisions more spontaneously as each microservice works independently and an individual team who is managing that has a good control over the changes. This is also helped by the fact that well-implemented microservices attempt to steer clear of the ‘shared database’ model of development (mentioned later in this post).
The microservices architecture allows each team to decide the technology and infrastructure that works best for them, which may be completely different from other microservices that it interacts with for the very same product. Another aspect of choice is seen when attempting to scale a Monolith application, where you need to scale every component as all components under one product typically run under the same process. This usually reduces flexibility that may require only a small subset of the features to be scaled (eg. performance bottleneck in one piece of a payment processing pipeline). Given such circumstances, scaling a monolithic application as a whole may soon turn into an expensive affair. On the other hand, each set of microservices can (potentially) be scaled independently of the others, thus helping focus resources on areas where the problem truly lies.
I have been reading building microservices by Sam Newman and really liked the 8 keys principles explained by him. In this post, I am attempting to provide a high-level overview of those principles and I highly encourage you to read his book to get a more detailed understanding of these concepts.
You can buy this book by clicking it on below book
The eight key principles are
1. Modeled around business domain
Focus on your business domain and identify individual subdomains and build services. A good way to start would be to follow the principles of Domain-Driven Design.
2. Culture of automation
Infrastructure automation is what smart companies are focusing on today. Provisioning a new machine, operating system and service should be automated.
Automation testing and continuous delivery are critical as well so as to deploy/release your software frequently and reliably.
3. Hide implementation details.
Hide your database, and hide your functionality. Each service should have its own database and if shared information is needed from other services, leverage service endpoints designed for the specific subdomain to extract what is expected. While migrating a monolithic application to a microservice(ish) structure, it is often considered easiest to tease apart application level code while leaving the (shared) underlying database as is. There is often a variety of rationale provided for doing this ranging from a lack of confidence in the success of this migration to potential issues faced for data analysis and report aggregation purposes. However, this shared database continues to serve as a source of coupling between the independent services far greater than the decoupling achieved by spinning off the application level services.
4. Decentralize all the things
Focusing on autonomy (giving people as much freedom as possible to do the job in hand), self-service (do you have to create a ticket to provision a machine or you can do it all by your self), shared governance (making architecture work) and avoiding complex messaging is important.
5. Deploy independently
If you have 4 services and all of them have to be deployed together due to dependency then fix that before you create 5th service. Having one service per host makes life very easy for everyone. Docker is getting a lot of traction for such isolation of operating environments.
In such an environment of independent deployments, consumers drive contracts where when you make a change, the consumer service has expectations about not facing challenges when you deploy changes.
When there are co-existing endpoints, for instance in an upgrade scenario, the consumer service would switch to a newer version while the provider continues supporting the existing version for a limited time period this providing some time for other services to migrate without holding the entire system hostage to its changes.
6. Consumer First
As the creator of an API, it is very important that you make your service easy to consume. The documentation plays an important role here.
7. Isolate Failures
Microservice architecture doesn’t automatically make your systems more stable. To the contrary, it makes the overall system more vulnerable to certain types of network and hardware related issues (more points of failure). You should have ways to isolate failures and look for ways to recover such as failover caching and retry logic.
8. Highly observable
It is very important to know what is happening in your system with so many moving parts. Each service may depend on multiple services and vice versa. There needs to be constant observation and monitoring to ensure the whole integration is smooth.
Microservices often communicate via HTTP/REST (Synchronous) or utilizes Asynchronous protocols like JMS, RabbitMQ etc. It is perfectly fine and acceptable to use Synchronous protocols for public APIs while when dealing with microservices internal communications, you should go with Asynchronous protocols.
In a typical monolith application when you want to fetch the data to show in search functionality, all you have to do is join multiple tables and present it to a user. If you want to achieve the same using microservices, there is going to be a big performance hit as you need to retrieve it from each and every microservices which may not be a good idea. In this situation, I would recommend you to go with Elasticsearch. You can display the high-level data coming from one table. When a user clicks on an individual item, you can always go to all microservices. Moreover, you can run them all in parallel on top of it. This can significantly reduce the pain of performance bottlenecks in homegrown solutions. There are multiple scenarios like this that entice teams and organizations to avoid going with microservices while an easier way out exists. I would be discussing some of the very common challenges and their resolution in details in my upcoming blogs
Microservices architecture gives you enormous benefits when done right. When implementing a microservices architecture, you certainly want to keep your services small. Most of the companies and teams I have come in contact with having a tendency to do so with the backend, primarily for two reasons.
It is expensive in terms of time and money.
Although you are better off going with a monolith application while you would not gain most of the benefits as you cant deploy your backend services independently without the front end. In such scenarios, not only is application scaling a challenge, you also need to update the front end whenever an API is deployed with breaking changes.
The idea with a Micro-Frontend is to decompose your application into smaller units based on screens representing domain-specific functionality instead of writing large monolithic front-end applications. The front-ends are self-contained and can be deployed independently. SPAs (single page applications) are the best way identified so far to go this route and domain driven architecture helps achieve this to a great extent. You can have backend, frontend, data access layer, and database, everything required for a subdomain in one service. Every piece of the service should be worked by an independent team. Collaboration and communication play an important role here and as long as you adhere to best practices and principles of microservices, you are most likely to get successful and gain maximum out of your product/software.
Benefits of Micro-Frontends
The individual development team can choose their own technology.
The development and the deployment are very quick.
The benefit of microservices can be leveraged in a much better way. The dependency is drastically reduced.
Helps in continuous deployment.
The maintenance and support are very easy as the individual team owns a specific area.
The testing becomes simple as well as for every small change, you don’t have to go and touch the entire application.
The UX consistency is an important aspect. The user experience may become a challenge if the individual team goes with their own direction hence there should be some common medium to ensure UX is not compromised.
The dependency needs to be managed properly. The collaboration becomes a challenge at a time. The multiple teams working on one product should be aligned and have a common understanding.
In business software applications, the domain objects (entities) are used to represent the business domain. As the application grows and adds more business logic, the service layer, mappers and other patterns gets applied. This sector has held promise for many software developing companies, and has often been touted as the future of work. Often this leads to domain object becomes bloated and the related components become huge & un-maintainable.
CQRS solves the common problem of having a bloated Domain objects. The domain objects get bloated largely because of bounded context. The series of contexts which makes developers think that a single domain object is sufficient to handle all the related things. For example, a large Invoice object for handling Invoice, Shipment and handling change of address for customer . But in reality, these contexts (invoicing, shipment and change) need not be related to same Invoice entity.
What is Command, Query Responsibility segregation (CQRS)?
In order to simplify the Domain objects, CQRS proposes to have two types of domain entities.
those serving the command (ordering/assertion services) – For example, SaveCustomer, CreateInvoice, ShipProduct etc
those serving a Query (request) – examples include GetCustomerAddress, SearchCustomer etc
With this separation, the complexity (number of fields, methods) of entities used becomes simplified. And hence the Data mapper layers & the service layers becomes more simplified.
Where can I use CQRS?
Largely complex system: Applying CQRS on a simple CRUD operation based system is a over kill. When there is a domain heavy system, like banking and financing systems, LOB applications where business logic, lots of boundary conditions are heavy. Where it makes DDD (Domain driven design) provides high value.
Situations where you will apply Microservices, Eventual consistency and Event Sourcing. When we have separation of concerns using CQRS, the microservices becomes much simpler to design and maintain. With Event sourcing we are focused on getting the data (query) from other related sources and is what CQRS propagates.
CQRS is a carefully thought out pattern for simplifying & solving large and complex systems.
In this video, Jatinder talks about Six fundamental principles for improving web application performance. He also talks a lot about how we go about Decreasing CPU time and increasing parallelism on the client machine to achieve faster web performance.
While I went through the video, I captured all the tricks he talks about. And thought will be useful for others while they watch it. Please find below the tricks.
Quickly respond to network request
Avoid 3XX Redirections (63% of top websites use redirect)
Avoid Meta refresh
Minimise Server time for Requests
Use Content distribution Networks (CDN)
Maximise concurrent connections.
Reuse connections – don’t sent connection close.
Know your other servers – you are only fast as your weakest link
Use window.requestAminationFrame(renderLoop) for Animations
Know when your application is visible (document.hidden, Visibilitychange (event))
The web optimisation is not easy and needs exhaustive, deep look and hopefully this check list helps while optimising your pages. Enjoy coding high performing applications. If you have more tips please provide them in the comments.
Microservices is a really becoming a famous architectural pattern that most of the new software written these days, just apply them. One of the most important differentiation between the traditional web services and micro-services pattern is the amount of common stuff across different subject areas. This calls for a discussion on how Eventual Consistency pattern is mandatory for successfully implementing microservices.
The micro frontend if gaining lots of popularity. You can read about microservices principles and micro frontends at
Generally, in a micro-service pattern, the API’s are split into small subject areas. For example for a CRM application, the subject areas are
Customer information – like name, address, email, phone
Appointment information – which customer, salesperson, when, where
Relationship management – sales/manager, what products, interests
Campaign data – offers, deals etc
Then micro-services are built for each of the subject areas. The microservices are logically and physically separated from each other. ie there is no sharing (code, database, component etc) between any of these micro-services of these subject areas. Pictorially its looks something like this.
Applying Eventual Consistency Pattern
In Micro-services, there is no data that is shared across the micro services. In order to synchronize the data across these isolated storages of these services, we need to apply the eventual consistency pattern. You can read more about applying the pattern correctly here. The simpler way we can achieve consistency across these micro-services is through Event Sourcing pattern.
Event sourcing is a process of capturing application state changes in the form of events. An example of events are customer created, customer updated, Deal created, etc. Other systems listen to these events and they take relevant action. You can read more about event sourcing here.
Event sourcing is the new way of storing changes to systems and help in making micro-services eventually consistent. These patterns together form well maintainable, reliable and scalable systems in the modern world.
This is the second post in the Getting started with MEAN series where we start looking at the Node ecosystem for stable web application frameworks for our application. A brief glance through the Express framework showed that express by itself would be time consuming start off with from scratch. On the other hand, the Express.js website links to a number of frameworks built on top of Express. This looked like a good place to start exploring.
Going through the list of frameworks mentioned there, however, we quickly noticed that a number of options were either targeted only (or primarily) towards APIs, lacked sufficient documentation for our needs, or did not appear to have a sufficiently large community behind them. Mind you, the assessment wasn’t entirely objective, as I did have previous experience with generator angular fullstack.
Generator angular fullstack is a Yeoman generator that provides an application skeleton as well as sub generators that allow the developer to quickly scaffold various UI and API components. The generator supports a number of customizations through questions asked before generating the app. The ones I found most useful were:
Html templating : HTML, PUG (previously Jade)
Angular Router : ngRouter, ui-router
Stylesheets : css, stylus, sass, less
CSS frameworks : bootstrap (with the option to include UI Bootstrap)
Databases : none, Mongodb, SQL
oAuth integration with Facebook, Twitter and Google Plus
Socket IO integration
Phew! That was a lot of options built into the generator itself, stuff that teams and products usually like to customize according to their convenience. This by itself is a strong reason to select the framework, because none of the other frameworks that we evaluated came anywhere close in terms of customizability and out of the box functionality. The generator also comes with built in hooks to deploy your application to Heroku or Openshift, although I found that part to be a little broken (more on that later)
Anyway, coming back to getting started with the application.
npm install -g yo
Installing the angular fullstack generator and its prerequisites
npm install -g yo gulp-cli generator-angular-fullstack
On a side note, please read node-gyp’s installation guide before going any further to get the application to run successfully. Node-gyp is required to compile native drivers for each platform and on windows, there are a couple of different ways to support the compilation process. Personally, I was able to get option 2 on the link mentioned above working (see: “Option 2: Install tools and configuration manually”)
Initializing the App
Finally! Coming down to the crux of the matter. Initializing the app
Run : yo angular-fullstack
The installer asks a number of questions about customization, including the ones mentioned above, and once the installer has completed, you have a fully functional app (with authentication if you selected it during install) ready for you to work on.
Running the app is as simple as running : gulp serve
You just need to make sure that if you selected a database, it is running on your local box so the node API can connect to it. If the DB is not found, the application will simply crash, but you already knew that would happen 🙂
Stay tuned for the next article about the getting familiar with the code generated by the Yeoman generator