One Point Ahead

There are different reasons why a developer transitions to a Project/Program manager role. After some time, there could be a moment in your career when you want to move back to a developer role. If you think moving to a PM role was a right choice, ignore reading this further. If you think you miss technical hands-on development in that you excelled, it’s never late to switch back. Here are some tips to get back on a hands-on development track and take your career to the next level:

1. Find out why you want to be a developer again: 

It’s important to assess your whys clearly. Let’s look at some common whys:

• Self-realization: Switching from a developer to a PM may not be easier for everyone. Some developers will find the ecstasy in a PM role. A PM who was an excellent developer, may have two possible thoughts on two extremes: 

1. Oh, I wish, I was born as a PM. I like leading people towards a goal. I love meeting people. I love high level integration, without going in deep of the code (then again, you don’t need to read it further).
2. Oh, did I really work today? Am I really delivering any value? I heard I led that meeting well, but I didn’t do anything at all. I just presented what others did. Am I going to get any credit for any of the work? If yes, is it fair to get the credit for something I didn’t do? Does anyone really appreciate scheduling a meeting and asking people to work towards a goal? Don’t they already know why, how, and what to work towards their goals? I don’t think I did anything. Did I have to pull up my sleeve to get into anything deep technical, to solve a problem? Why are people thanking me as if I did all the magic to make the project successful? Is it a fake thank you and they really meant to say: you were not needed, you wasted our time with many useless meetings.

• A step to be a technical manager: Many times, a belief is that to be a development manager, you must excel in technical skills, leadership skills, and operational/business skills. Getting into a PM role may provide you a right combination of leadership and operational/business skills.

2. Acknowledge what you learned as a PM:

The years you worked as a PM were a great investment. You learned these skills:

• How to lead and communicate: This is a great skill to have. As a developer, the tendency is to know all the details about a system. PM skills are great in understanding and leading the integration of systems as a black box (not knowing what’s inside).
• Influencing stakeholders: As a developer, your job generally is to complete the assigned tasks. There may be opportunities to influence technical teams for a technical solution. But, as a PM, you get more assigned tasks to influence users. How many developers will be motivated to read a book on influencing stakeholders? If we ask the same question to a PM community, the question should be opposite: can you be a PM without reading the book on influencing stakeholders?
• Respect what PMs do: To appreciate a skill, it’s the best to be in that role yourself. As a PM, do you recall your scariest moment when you were not sure to get a buy-in from your stakeholders? If you were wrong (they showed up to your meeting and respected your engagement) and you got their buy-in, will you ever forget that moment of joy? You clearly remember the number of stakeholders you invited who showed up to your meeting. And yes, majority of them agreed to your point of view.

3. Finally, how to be a developer again:

• You’re here with the real interest: Congratulations. You clarified your whys and made a decision. You’re learning the development with your true interest. This is a critical step. 
• Don’t give up and don’t lean back: As it’s your interest and your strong desire, you’ll succeed if you don’t give up. So, first thing first: don’t give up in your uncomfortable journey ahead, of becoming a developer again. Here are some common feelings you’ll encounter as your daemons and you must not deviate from your goal:
• Are you too old to be a developer ? Will people laugh and will you feel bad at your moderate and old technical skills?
• Did you fail as a PM? Many people may ask you, why are you transitioning back to a developer role? Did you not perform well as a PM? Is it a demotion? You may hear people saying: the grass is greener on the other side.
• Will you excel as a developer again? There’re many smart developers in the market who’re young, probably with less family responsibilities. Will you be able to spend that much time again? Are you still that sharp to learn new technical skills quickly?
• What if you become an average developer who’s not able to cope up with newer technologies? There are many intelligent new age developers. You quickly recalled an incidence. That day, a developer was cursing himself to be a developer. He was feeling overwhelmed with so many new technologies to learn.
• Work/life balance. Development tasks are very time consuming. It feels like two 40 hours a week sets are needed (at the same time). But will you be paid for 80 hours a week? You may feel it was nice to be a PM. As a PM, you guided many people how to manage their time within 40 hours a week.
• Decide a skills set: List out what skills you acquired earlier that are still in demand. If not the same, at least, do you find equivalent skills set in the market? Once you find your strengths, it’s important to decide a new technical skills set that you want to master. Stay with the planned skills set.
• Join forums and communities: Find opportunities inside and outside your company, to learn new technical development skills.
• Show your curiosity of technical skills: Show your curiosity of technical development skills within your network. You know how to communicate, make relationships, and it’s the time to ask for the help of others to help you learn technical skills.
• Find the development opportunities: Find a development opportunity in your area. Here are key ideas:
• Do you see a gap of technical resources in your project? If yes and if you can do the task, dive into it, work beyond your comfort zone, and own the technical task.
• Work on a prototype code that’s not mission critical.
• Develop your side project you have been dreaming for years. There are no limits to the possibilities. It could be your pet project to organize your family members list, your investments, your documents, or a simple utility that your family & friends would like to use.
• Review your progress: Review your development skills progress after six months. Then, follow a quarterly review routine. Rome wasn’t built in a day.
• Will you be an excellent developer again: You are skilled in communication skills, operational/business skills, and you’re progressing in your development skills. It’s not fair to assess yourself in one dimension. Do what you love to. A better question would be: am I an all-rounder professional who loves development as the core skill set?
• By now, you failed many times: But. You already made a decision. Don’t look back. Stay on the journey. You’ll succeed if you don’t give up.

The Gantt Chart is simply a breakdown illustration of project schedule. It was named after Henry Grant, American mechanical engineer and management consultant who invented this chart in 1910s. A Gantt diagram represents the project or tasks in the horizontal bar chart form. This cascading format with the various project activities listed helps project managers to track the tasks against their scheduled time and predefined milestones. The Gantt chart could also be considered as a scrum artifact as the burndown chart is used by many teams to communicate and track progress towards the sprint goal.

What to consider when making a Gantt chart

• What are the major deliverables?
• Who is on the team and what role will they play in those deliverables?
• Identify the stakeholders?
• What is the project plan to get to those deliverables and deadline?
• What are the milestones?
• Are there road blockers that could impact the timeline?

Who should read it: It is for you if you are looking for an overview of this topic for a project, to conduct/appear in an interview, or in general. As I learn more, we will update this article.

MongoDB is a document based, schema-less, and a highly available NOSQL database. Let’s look at some high level details about it.

Basic Terms:

• document: is a basic unit of data equivalent of a row in an RDBMS table.
• collection: is equivalent to a table in an RDBMS database.
• database: A single MongoDB instance can have multiple instances of databases.
• mongo shell: it’s a shell that helps in administrative tasks.

Basic Operations:

CREATE:

• Use insertOne() operation.
• If we need to insert many documents into a collection, use insertMany().
• MongoDB also provide a Bulk Write API, that affects a single collection. It has db.collection.bulkWrite() method which by default performs ordered operations. It also has an option to turn off ordering.

READ:

• Use find() or findOne() operation.

DELETE:

• Use deleteOne() to delete a single document.
• Use deleteMany() to delete all eligible matching documents.

UPDATE:

• For update, we can use updateOne(), updateMany(), or replaceOne().
• updateOne() and updateMany() takes a filter document and a modifier document, as the second parameter.
• replaceOne() expects a document with which it will replace the document with the first input document.

DROP:

• It is possible to use deleteMany() to drop all matching documents in a collection. It can also be used to delete all documents in a collection.
• To clear an entire collection, use of drop() is faster.

UPSERT:

• It is equivalent to update-else-insert. Means, update a matching document. If no matching document found, insert a new document.

Supported Data types: Null, Boolean, Number, String, Date, Regular expression, Array, Embedded document, Object ID, Binary Data, Code

ACID operations: ACID (Atomicity, Consistency, Isolation, Durability) operations in MongoDB are at a document level. Below are some basics of ACID operations:

• Atomicity: zero or none operations.
• Consistency: ensure data is persisted in all nodes.
• Isolation: Any reads or writes are not impacted with other reads or writes.
• Durability: Commits are performed successfully.

References:

• MongoDB: The Definitive Guide, 3rd Edition by by Kristina Chodorow; Eoin Brazil; Shannon Bradshaw
• https://docs.mongodb.com/manual/core/bulk-write-operations/

References:

• https://aws.amazon.com/about-aws/global-infrastructure/
• AWS Certified Solutions Architect Official Study Guide by Joe Baron, Hisham Baz, Tim Bixler, Biff Gaut, Kevin E. Kelly, Sean Senior, John Stamper

References:

• https://aws.amazon.com/about-aws/global-infrastructure/
• AWS Certified Solutions Architect Official Study Guide by Joe Baron, Hisham Baz, Tim Bixler, Biff Gaut, Kevin E. Kelly, Sean Senior, John Stamper

References:

• https://aws.amazon.com/about-aws/global-infrastructure/
• AWS Certified Solutions Architect Official Study Guide by Joe Baron, Hisham Baz, Tim Bixler, Biff Gaut, Kevin E. Kelly, Sean Senior, John Stamper

Who should read it: It is for you if you are looking for a quick overview of this topic for a project, to conduct/appear in an interview, or in general. As we learn more, we will update this article. What is Cloud computing: Cloud computing is an on-demand IT resources and applications via the internet with the pay-as-you-go solution. In a simpler way, cloud computing provides ways to access servers, databases, storage, and many application services over the internet. Why cloud infrastructure matters:  As of today, AWS has 81 availability zones within 25 geographic regions. On a high level, AWS cloud infrastructure these main benefits:

• Security
• Availability
• Performance
• Global Footprint
• Scalability
• Flexibility

Advantages of cloud computing:  Six major advantages are below:

• Variable versus Capital Expense: Instead of setting up servers and paying the cost of it, we can pay for the infrastructure per the usage.
• Economies of Scale: Using cloud resources like AWS can reduce the cost.
• Stop guessing capacity: Companies can gain as little or as much per the requirement, within a short notice.
• Increase speed and agility: new IT resources can be made available very quickly.
• Focus on business differentiators: Businesses can stop focusing on maintaining the infrastructure and focus on main business items.
• Go global in minutes: it’s easy to expand the applications globally, in few minutes.

Cloud computing models:

• All-in cloud based applications:  everything on cloud.
• Hybrid deployment: A hybrid solution with some parts on cloud and some on on-premises.

AWS compute and networking services:

• Amazon Elastic Compute Cloud (EC2): it’s a service that provides resizable compute capacity in the cloud. Organization can select memory, CPU, etc. per their need.
• AWS Lambda: It’s a platform that allows developers to have zero maintenance of infrastructure. AWS deploys the code on Amazon EC2 instances.
• Auto-scaling: Auto scaling allows companies to scale up or down the resources as needed.
• Elastic load balancing: Elastic load balancing allows automatic distribution of traffic across Amazon load balancers.
• AWS elastic Beanstalk: To deploy a web application faster, this service handles resource provisioning, monitoring, etc. automatically.
• Amazon Virtual private Cloud (Amazon VPC): Amazon VPC allows organizations to control the AWS infrastructure, by allowing them to choose IP address, etc.
• AWS Direct Connect: This provides direct network connections between a company\’s owned data centers and AWS.
• Amazon Route 53: It’s a highly scalable DNS service. For example, using Route 53, I configured my own domain name with AWS.

 Storage and Content delivery:

• Simple Storage Service (Amazon S3): Amazon S3 provide the storage for various usages like storing files, code backups, etc.
• Amazon Glacier: It’s a low cost service that allows data storage for the long term backups.
• Amazon Elastic Block Store (Amazon EBS): Amazon EBS provide block-level storage volume for use within Amazon EC2 instances.
• AWS Storage Gateway: AWS Storage Gateway service connects on-premises software appliances with AWS infrastructure.
• Amazon CloudFront: It’s a content delivery web service.

Databases:

• Amazon Relational Database Service (Amazon RDS): It’s a fully managed relational database service.
• Amazon DynamoDB: It’s a NOSQL database service.
• Amazon RedShift: It’s a petabyte-scale data warehouse service.
• Amazon ElastiCache: It’s a service that provides in-memory cache in the cloud. It supports Memcached and Redis cache engines.

Management Tools:

• Amazon CloudWatch: It’s a monitoring service for cloud resources and cloud hosted applications.
• AWS CloudFormation: It provides a way to effective manage a collection of AWS resources.
• AWS CloudTrail: It records logs for the audit and review.
• AWS Config: This service provides configuration history and configuration change notifications.

Security and Identity services:

• AWS Identity and Access Management (IAM): It allows organization users to securely access AWS cloud services.
• AWS Key Management Service (KMS): It allows users to create encryption keys to encrypt the data. It uses Hardware Security Modules (HMS) to protect the security of the keys.
• AWS Directory Service: AWS Directory Service uses Microsoft Active Directory. Using AWS Directory Service, organization users and user groups can manage single sign-on, group user accounts, etc.
• AWS Certificate Manager: It’s a service that manages SSL/TLS certificates for use with AWS cloud services.
• AWS Web Application Firewall (WAF): WAF allows to manage security and allow/deny access of web applications, for the security attacks prevention.

Application Services:

• Amazon API Gateway: It is a managed service that helps developers to create, publish, maintain, and secure APIs.
• Amazon Elastic Transcoder: It’s a media transcoding in the cloud. Transcoding is a process to convert an audio or a video file from one format to another.
• Amazon Simple Notification Service (SNS): Amazon SMS is a service to delivery messages to recipients.
• Amazon Simple Email Service (SES): It is an email service, to send any kind of emails to their customers.
• Amazon Simple Workflow Service (SWS): SWS is a workflow service that can run jobs in parallel or in a sequential steps. It has retry features.
• Amazon Simple Queue Service (SQS): SQS is a messaging queueing service.

Five pillars of Amazon Web Services (AWS):

• Operational excellence:
  • Infrastructure as a Code (IaC): There are two main services: CloudFormation and Cloud Development Kit (CDK)
  • Observability: it’s a process of monitoring infrastructure metrics at three levels: ◦ Infrastructure level ◦ Application level ◦ Account level
  • Three things:
    • PRINCIPAL(S) for WHO has permissions to
    • ACTION(S) for WHAT to perform
    • RESOURCE(S) specifies which properties to access
• Network Security: A zero trust on Network Security involves a defense in search approach. It involves Network Level Security and Resource Level Security. Data Encryption is about a plan to encrypt the data in the transit and at rest.
• Reliability: this pillar focuses on building services resilient to both service and infrastructure disruptions

References:

• https://aws.amazon.com/about-aws/global-infrastructure/
• AWS Certified Solutions Architect Official Study Guide by Joe Baron, Hisham Baz, Tim Bixler, Biff Gaut, Kevin E. Kelly, Sean Senior, John Stamper

References:

• https://aws.amazon.com/about-aws/global-infrastructure/
• AWS Certified Solutions Architect Official Study Guide by Joe Baron, Hisham Baz, Tim Bixler, Biff Gaut, Kevin E. Kelly, Sean Senior, John Stamper

References:

• https://aws.amazon.com/about-aws/global-infrastructure/
• AWS Certified Solutions Architect Official Study Guide by Joe Baron, Hisham Baz, Tim Bixler, Biff Gaut, Kevin E. Kelly, Sean Senior, John Stamper

Who should read it: It is for you if you are looking for a quick overview of this topic for a project, to conduct/appear in an interview, or in general. As we learn more, we will update this article.

Below are some technology/framework terms and basic definitions:

Customer Data Platform: As per CDP institute, Customer Data Platform is a  packaged software that creates a persistent,  unified customer database that is accessible to other systems. CDP is usually controlled by business users. It makes it different from data ware houses or data lakes, that are set-up by corporate IT teams. CDP creates a comprehensive view of each customer by capturing data from multiple sources. It tracks customer behavior over time. Data stored in CDP can be used for analysis and to manage customer interactions. There are different types of CDPs like Data CDPs, Analytics CDPs, Campaign CDPs, and Delivery CDPs.

Difference between CDP and CRM (Customer Relationship Management):

• CRMs maintain the customer interactions. CDP maintains the 360 degree view of the customer behavior for the used products. 
• CRM data is gathered manually via the service/support/other customer specific interactions. CDP data is usually collected automatically using integrations and code snippets. 
• CRMs are to improve interactions with the customers. CDPs are for understanding customers and their behavior.

Segment IO: Segment is a CDP service that looks after data governance, data integration, and audience management at once place.

Optimizely: Optimizely is a technology company that provides multiple options to support A/B testing experiments. 

Split IO: It allows the feature delivery for the apps. By using split IO, a feature can be enabled or disabled. It can also use A/B testing.

Elasticsearch: It is an open source, search and analytics engine. It is accessible using RESTful web services and stores data in JSON format. It is developed in Java, which makes it compatible with other platforms.

Splunk: Splunk is a software platform widely used for monitoring, searching, analyzing, visualizing machine generated data. It offers real-time visibility of data into a dashboard. It is best suited to understand the root-causes.

Distributed tracing: It is also known as distributed request tracing. This is a method that is used to monitor applications, especially built around micro services architecture. IT and DevOps teams use it to monitor applications.

Open Tracing: Open tracing is a vendor agnostic API to achieve distributed tracing. These APIs are build to support many languages.

API Gateways: Just like servers support web applications, API gateways support APIs. There are many proxy servers in front of the API to support various features like authentication, rate limiting, routing, load balancing, etc. API gateways are integral parts of microservices, nanoservices, and serveless components. 

Benefits of API gateways:

• Decoupling: API gateway allows you to decouple the public facing endpoint APIs from the underlying implementation.
  
• Reduce round trips: If some APIs need to join data across other services, an API gateway can save round trips.
  
• Security: API gateways provide centralized services like authentication, CORS, rate limiting, bot detection, etc.
  
• Cross cutting concerns: API gateways can provide a way to centrally plan the logging, caching, and other cross cutting concerns.
  

Distributed caching: There are two common technologies for distributed caching: redis and memcached.

• Redis: It is an open source in-memory remote database that uses disk space for the data storage.
• Memcached: It is also an open source in-memory database.
• Redis versus Memchached:
  • Both are no-SQL storage types that store key-vaue pairs.
  • Both are open-source databases.
  • Redis supports more data types. Memchached support string types.

MuleSoft:  Mule ESB (Enterprise Service Bus) is a highly scalable Java-based enterprise service bus and integration platform provided by MuleSoft. It has two concepts: Bus and Adapter. The concept of Bus is achieved through a messaging server like JMS or AMQP. By using Bus, applications decouple from one another. The concept of Adapter is responsible to convert application specific backend data into the Bus format. Data from one application to another is exchanged using the bus format, which is a consistent message format.

Micro services: Micro service architecture is the strategy to implement independent services for a larger application. It is becoming a way to build APIs.

Solr: Solr is a search server which is an open source, Java-based information retrieval library.

Serverless: It is a cloud based code execution model in that cloud providers deal with the servers. A developer is not needed to work on server infrastructure. Cloud providers provide a way to pay per use model, to execute the serverless components. That way, there is no idle cost. Using serverless components features no hassle of maintaining an psychical machines, easy to scale, cost efficient, easy to maintain, and easy to deploy. Testing a serverless component is challenging because it is not easy to replicate the environment for the testing needs. There are two types of serverless components: BaaS (Backend as a Service) and FaaS (Frontend as a Service).

In 1990s, if a developer had to deploy an application into production, he/she had to plan to servers,  networking, databases, and all related end to end solutions, to deploy a solution. In 2000s, we had virtual machines, to build the infrastructure. In 2008, Amazon released EC2 instances that made things more easier. But with EC2, we had to maintain servers. We still had to take care of OS and other elements. S3 and SQS also helped further. But now, we can use cloud infrastructure without worrying anything about server infrastructures. AWS lambda providers a great way. A serverless application involves multiple microservices. With serverless, scaling down is also easy.

URL Shortner: URL shortner is a service to create short links from very long URLs. Converting URLs to a short URL makes it easy to share, tweet, and for other purposes. Clicking on a short URL redirects the user browser to the original URL. Below are some ways to convert a URL to a short URL:

• Hash original URLs with a hash function (like MD5 or SHA-2).
• Generate short links using UUID.
• Convert numbers from base 10 to base 62.
  

gRPC: gRPC is a newer approach for RPC (Remote Procedure Protocol). It is an open source technology. It is a method to execute a procedure on a remote server. gRPC added a concept of protocol buffers (also known as protbufs). It can run on any platform and supported by many programming languages.

GraphQL: With GraphQL, client determines which data, in which format, and how the client wants it. By default, it typically sends the smallest possible request.

Webhooks: It’s an HTTP POST request that is triggered when an event occurs. It updates the client when there is an update. Webhooks provide instant, real-time notifications.

Common Java Libraries:

• Lombok API: Lombok API helps minimize boilerplate code. It reduces the line of code. To minimize the lines of code, it provides annotations. Below are some of the annotations:
  • Getter & Setter
  • No Arg Constructor
  • All Arg Constructor
  • Data
  • ToString
  • EqualsAndHashCode
• Resilience4j: It is an API designed for functional programming. It provides options to pick and choose what’s needed. For more details, read here. It was inspired by Hystrix. Hystrix helps in distributed services by adding latency tolerance and fault tolerance logic.
• AspectJ: AspectJ is a programming paradigm that increases the modularity by allowing the separation of concerns. For more, read here.
• Swagger: Swagger is a set of open source tools built around Open source API specification. Open API specification ( also known as Swagger specification) is an API specification for REST APIs.
• javatuples: javatuples is a Java API that allows Java programs to work with tuples. A tuple is a sequence of elements that are not related to each other. For example, it can contain an integer, string, and an object. Tuples can only contain specific number of elements. All elements are type safe.
• JDK, ASM, Javassist, and CGlib: These four are APIs to generate Java proxy classes. JDK dynamic proxy is easiest to use. CGLib and javassist are advanced libraries to generate byte codes.
• p6spy: p6spy is a dynamic monitoring framework for database operations.
• Spring Cloud: It provides options to manage Spring applications on the cloud infrastructure.

Reference: 

• https://www.cdpinstitute.org/
• https://segment.com/blog/CRM-vs-CDP/
• https://segment.com/docs/guides/
  
• https://revium.com.au/blogs/december-2019/what-is-segment-cdp
• https://www.splunk.com/en_us/training/learning-path/courses-for-users/splunk-fundamentals-1.html
• https://opentracing.io/docs/overview/what-is-tracing/
• https://microservices.io/patterns/microservices.html
  
• https://www.scalyr.com/blog/what-is-opentracing/
• https://www.moesif.com/blog/technical/api-gateways/How-to-Choose-The-Right-API-Gateway-For-Your-Platform-Comparison-Of-Kong-Tyk-Apigee-And-Alternatives/
• https://www.tutorialspoint.com/mulesoft/index.htm
• https://solr.apache.org/guide/8_9/a-quick-overview.html
• https://relevant.software/blog/serverless-architecture/#What_is_a_serverless_architecture
• https://www.serverless.com
• https://bitly.com/
• https://dzone.com/articles/url-shortener-detailed-explanation#:~:text=Introduction,links%20from%20very%20long%20URLs.&text=Clicking%20on%20a%20short%20link,%2C%20cutt.ly%2C%20etc.
• https://nordicapis.com/when-to-use-what-rest-graphql-webhooks-grpc/
• https://grpc.io/
• https://www.geeksforgeeks.org/introduction-to-project-lombok-in-java-and-how-to-get-started/
• https://resilience4j.readme.io/docs/getting-started
• https://github.com/Netflix/Hystrix
• Redis implementation example with Spring boot: https://javatechonline.com/how-to-implement-redis-cache-in-spring-boot-application/#What_can_you_expect_from_this_Article
• Redis versus Memcached: https://www.instaclustr.com/blog/redis-vs-memcached

Who should read it: It is for you if you are looking for an overview of this topic for a project, to conduct/appear in an interview, or in general. As we learn more, we will update this article.

HTTP: It stands for Hyper Text Transfer Protocol. An HTTP response is a response on web client, received via internet, in answer to an HTTP request. It is an application layer protocol for transferring hypermedia documents like HTML. HTTP is a stateless protocol. Means, the server does not keep any data between two requests.

HTTP response status codes: response codes are categorized in five classes below:

Informational responses (100–199)
Successful responses (200–299)
Redirects (300–399)
Client errors (400–499)
Server errors (500–599)

Cross-Origin Resource Sharing (CORS): It is a mechanism to allow the requests for browsers from cross-origin sources.

HTTP cookies: HTTP cookie is a small information that a server sends to a browser. This is used to identify if two requests are coming from the same browser. HTTP is a stateless protocol. HTTP cookie helps to remember the states. Cookies are used for session management, personalization, and tracking.

HTTP rate limiting: HTTP 429 Too Many Requests response code indicates that the user has sent so many requests in a given amount of time. This is called rate limiting.

HTTP2: HTTP/2 makes applications more faster, robust, and simpler.

SPDY: It was an experimental protocol introduced by Google. It targeted for 50% reduction in page load time.

HTTPS: It is a secured HTTP protocol. This involves public and private key cryptography.

HTTP caching: Caching in general helps to get the data faster, without hitting the server every time. Browser has cache option. Proxy server also keeps a cache. We also have a reverse proxy server.  HTTP header plays the key role in cache mechanism. There are three types of headers: expires, pragma, and content-control. The content-protocol is a preferred caching header. There are properties to configure the duration of cache.

Related terms to learn:  HTTP tunneling, HTTP content negotiation, HTTP caching, and Certificates

Reference:

• https://developer.mozilla.org/en-US/docs/Web/HTTP
• https://developers.google.com/web/fundamentals/performance/http2
  
• https://www.cloudflare.com/learning/ddos/glossary/hypertext-transfer-protocol-http/
• https://www.w3schools.com/whatis/whatis_http.asp
  

Overview: Java 8 introduced functional programming. Let’s understand what it is. Basics of functional programming: it’s a paradigm that enables concurrent usage of code. Lambda expressions are pillars of functional programming. 

Pure Function: Pure functions should follow these rules:

• No state: it means a function should not refer any member of a class or an object.
• No side effects: a function can not change the state outside of the function.
• Immutable variables: use immutable variables.
• Prefer recursion over looping. Another option is to use stream API.

First class function: A first class function can be passed as a parameter to a function. It’s like a one-time use function with a function. In Java, it’s achieved using a lambda expression.

High order function: It takes a function as a parameter or returns a function. In Java, it’s achieved using a lambda expression.

Functional interface: An interface is a functional interface if it has a single abstract (unimplemented) method. This interface could also have a default method and a static method.

Functional composition: it is a technique to combine multiple functions into a single function.

Imperative versus Recursive function: Imperative is a simple way of writing logic. Recursion is a way to call function in a nested way. Recursion is of two types: Tail and Head Recursion. Tail recursion has a recursive method call at the end of the logic in a method. Head recursion has a recursive method at the beginning of the logic in a method.

Parallelism: In this concept, we split the task into multiple sub tasks. At the end, we combine the results of subtasks for the final result.

Monads: A monad is a design pattern that helps to represent a missing value.

Java Stream API: Java Stream API is a way that makes operations on data sources easier and convenient. It does not modify underlying data sources. Some examples of common stream operations are forEach, map, collect, filter, findFirst, flapMap, etc.

Lambdas: A Java lambda expression is a short code which takes input parameters and returns a value. These are like methods but without a name. Java Lambda expression provides the way to implement a functional interface.

References:

• https://www.baeldung.com/java-functional-programming
• http://tutorials.jenkov.com/java-functional-programming/streams.html
• https://stackify.com/streams-guide-java-8/
• http://tutorials.jenkov.com/java/lambda-expressions.html