Most data providers suffers from performance and service availability issues. This system will address these issues using Asynchronous Request/Response and Queue-Based Load Leveling patterns.

• System Overview
• Requirements
• System Architecture
• Software Detailed Design
• External Interfaces
• Motivation For Choosing The API
• Setup
• Usage

The Currency Exchange Rate (CurExRate) Gateway is a software as a service (SAAS) solution that provides a single entry point for the latest and historical currency exchange rates from different data service providers.

The following diagram shows the system context view of the entire system.

This section documents a summary of those requirements that address aspects of the system besides functionality and that are relevant for the system architecture.

There are some key requirements that have a significant bearing on the architecture. They are:

• High Availability or Reliability - Service continuity will be addressed by supporting more than one (1) data service providers.
• Performance - Request and Response should have a throughput of more than 1000 per second.
• Scalability - On demand growth of service’s capacity and decreasing processing time will be addressed by applying the three dimensional scalability model of scale cube.

• CentOs Server
• JDK 1.8 or obove
• Spring Framework 1.4.1 or above
• RabbitMQ 3.5.7 or above
• MongoDB 3.4.5 or above

• Loosely Coupled
• High Cohesion
• Scale By Cloning
• Work Distribution

The general functionality of the CurExRate gateway can be seen in the following use case diagram:

As with any other things, a style may be used to satisfy any functional, non-functional or aesthetic needs in a software system. The CurExRate Gateway, follows the four-layer architectural style: user interface layer, application services layer, domain layer, and the infrastructure layer. The following is a simple description of what will be included in each of the layers:

This layer wraps access to the logic of the system. There are two categories of interface class - user interface (UI) classes that provide people access to the system and the system interface (SI) classes that allows service consumers to access the service provided by the system.

This layer implements business logic that involves collaborating with several domain classes or even other process and mediates between the various system/user interface components that is responsible for the flow and control of the application.

This is the layer where most objects found in an OO analysis and design will reside. Implementation of objects pertinent to your problem domain including the behaviors specific to individual objects that will drive the system.

This is where the objects that represent connections to entities outside the application (specifically those outside the object world) reside such as connections to databases or repositories and message broker.

This subsection will describe the overall decomposition of the CurExRate gateway design model as well as the interactivity that happens between components.

There are three collaborating components that compose the entire system. Each component running as a microservice are the following.

Request GET Parameters

Successfull Response

HTTP Status 202 (Accepted)

Response Headers

Error Responses

HTTP Status 404 (Not Found)

Request GET Parameters

Successfull Response

HTTP Status 200 (OK)

Response Body

Error Responses

HTTP Status 404 (Not Found)

• Fulfilment Of All Required Functionalities such as listings of available currencies symbols and querying latest and historial exchage rates.
• Documentation with clear and useful examples written in such a way that we can get the gist of ​​how it works at a glance and thus see in which it is easier to apply such instructions to avoid wasting time and effort.
• JSON Data Format has been leading the way in terms of data representation formats for APIs for quite some time. One of its benefits is that it can be easily read by humans and it is also easier to implement.
• Examples and Libraries of code in the programming language that we are using or a library that “talks” with the API in the language in question must given by the provider.- Limits And Interactions- Support And Community forum offers by the provider must have a good reputation for solving problems in a timely and relevant manner.
• A free service with a potential to grow rapidly must be designed and implemented with Scalability and High Availability.

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