Design Problem: Pacing Rate Limited API

Today, most applications are API-driven. Whether creating a weather forecast, a financial ticker, a sports score alert, or translating a local language, you’ll need to connect 3rd party APIs to access the required data.

APIs are typically metered, and consumption is limited through Rate Limiting. A rate-limited API defines an API rate. It is usually expressed in terms of the number of requests made in a given timeframe; for example, the API rate of stock price quotes API is 100 per second, implying that you can only make 100 calls in a second.

A pacer mechanism must handle the gap between the application demand rate and API acceptance rate.

What is Parsing?

Parsing is a process of converting formatted text into a data structure. A data structure type can be any suitable representation of the information engraved in the source text.

• Tree type is a common and standard choice for XML parsing, HTML parsing, JSON parsing, and any programming language parsing. The output tree is called Parse Tree or Abstract Syntax Tree. In HTML context, it is called Document Object Model (DOM).

• A CSV file parsing can result in a List of List of values or a List of Record objects.

• Graph Type is a choice for natural language parsing.

A piece of program that does parsing is called Parser.

How it works?

Parser analyses source text against the format* prescribed. If source text does not match against format error is thrown or returned.

• If source text does not match against format error is thrown or returned.

• If matches then “data structure” is returned.

*format is coded inside the parser.

Format is the DNA of a parser.

Patterns of reading JSON

JavaScript Object Notion (JSON) is a de-facto standard for exchanging data over Web API. JSON is a recursive data structure and can be visualized as a key-value pairs tree.

There are two broad categories of APIs for reading information from JSON :

• Streaming Based: It is parsing or visiting of JSON part by part. With each part iteration, you skip or map part to Object/s. Part maybe {, [, field, value, : , } , and ] (JSON Tokens!).

• Binding based: Binding is mapping of JSON field to Programming Objects; these may be domain or abstract. JSON is entirely parsed and mapped to objects.

This article goes through different patterns of Reading JSON data. Java is chosen for demonstrating these patterns.

Continue Reading these patterns in details

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Finding Balance in Software Development

Software development is not only about code. It is also about the process and the people around it. At the core, Product (Business) Managers and Developers turn the idea of Software into reality.

In the philosophical view of Software development, there exist, two realms that affect the reality of Software: Product end and Technology end.

These are different in the perception of an application:

An Application is a set of features that support a business function. - Product View

An Application is a set of code, framework, libraries, services. - Developer View

In contrast, these are also associated in a way that a change in one realm introduces change(s) in another realm.

Tap in Product Realm

Customer Grievances, Competition Edge, UX improvements, Feedbacks and Law Changes: all these introduce changes. After a rigorous thought process (cost-benefit analysis), these changes are passed to developers to transform into code. At developers end, they might have to write new code or adjust with the existing codebase. 

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Recap | April - 2020

I hope you are doing well in this uncertain time and complying with your Local Government guidelines for best of all.

Stay at Home && Stay Healthy.

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Article > Uploading file over the web

Uploading files over the network is not an easy task. It involves considerable challenges in developing a solution that works for all file sizes. Uploading files are prone to failures, users drop, and security risks. On each failure, the file needs to be re-uploaded: which adversely affect associated user experience.

There are many techniques and design decisions you can choose while developing the functionality of upload files. This article goes through some of them.

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Snippet > Frequency Map in Java 8+

Calculating the frequency of items is a recurring problem, especially in competitive programming. A frequency map of array or List can be constructed succinctly using Stream.