UWS API Gateway

We will not add load balancing features in this initial release to control complexity.

Stack

• Rust
• Rocket

Prerequisites

• Rust (We recommend using rustup installer)

Installation & Development

To install the gateway you need to run the following command in your terminal to build project:

 cargo build

Run tests:

cargo test

Then run the server:

cargo run

Auto reload

To trigger certain helpful actions when you update the code (like auto-restarting the server), install cargo-watch

cargo install cargo-watch

Then run the following command to start a server that re-runs with every code change

cargo watch -x run

You can also re-run tests with every code change

cargo watch -x test

Development using Docker

Build containers

docker compose -f docker-compose.dev.yml build

Run the builder to build the project

docker compose -f docker-compose.dev.yml run --rm builder

Run the server

docker compose -f docker-compose.dev.yml run --rm runner

The server auto-reloads if you run the builder and a new debug executable was created.

Concept

In this document, I will assume a basic level of Software Engineering and basic knowledge about the Software as a Service (SaaS) model.

UWS Software as a Service (SaaS) API Gateway is a system that does the following:

1. Receives web requests from consumers.
2. Authenticates and routes the requests to destination services.
3. Charges customers according to their pricing plans.

Structure

High-level structures

We will not add load balancing features in this initial release to control complexity.

The system is comprised of the following structures:

• Server: authenticates & processes incoming requests.
• Data Layer: accesses, queries and persists data.
• Router: routes requests to their correct destination inside a private network using a configurable map.
• Authenticator: controls access of request consumers based on their credentials.
• Biller: Handles quota operations & subscriptions.
• Logger: collects traffic data and stores it in either files or databases.
• Scheduler: controls the flow of inbound and outbound requests.

Quality Attributes

The gateway will do its job successfully if the following conditions are met:

1. The system functions well without errors according to spec.
2. The system fulfills quality attributes.

The following quality attributes should be always taken into consideration while building the system:

1. Performance: Speed is critical because the gateway will intercept each and every request passing through the system.
2. Interoperability: Provided services should be discoverable and easy to communicate with.
3. Maintainability: The code base should be clean, agile and well-tested. The system should be able to self-diagnose and handle common errors.
4. Security: Stored customer data should be secured well. The system should always follow the basics of security.

Considering quality attributes is essential to deliver the desired customer and business value.

Entities

Request

The request is the main artifact. A successful incoming request lifecycle is as follows:

1. Server intercepts incoming request.
2. Authenticator checks request for consumer login credentials & logs it.
3. Biller checks subscriber quota.
4. Router sends request to relevant service & responds to consumer.
5. Biller adds transaction to the subscriber account.

In the case of internal errors or malformed responses from the service, information will be logged and quota will not be deducted.

Subscriber

The subscriber is representation of a customer or a partner business. A subscriber can have many Consumers. Consumers have access to the APIs and can consumer them once authenticated.

Subscribers can choose between different monthly or annual subscription packages, each package contains a monthly quota of tokens. Consuming services depletes this token quota.

Example: As a subscriber you have 10 token in your quota. Service A costs 2 tokens per request. Once you successfully hit Service A your quota will decrease to 8 token.

Consumer

Consumers are the Subscribers' servers or machines. Usually operated by developers consumers will communicate with gateway using HTTP/HTTPS.

All requests from consumers should contain credentials that allows the system to detect and authenticate them.

Consumer history and activity are logged intensively in order to:

1. Resolve conflicts
2. Debug errors
3. Finding patterns to help us improve the system.

Product

The product is an abstract group of services. A product's role in the system is to add structure. In later versions this abstraction will contribute in the functionality of load balancing.

Service

A service is a program hosted on an instance somewhere in our private network. Consumer can access this service using a URL.

Requests to certain services cost a different amount of tokens. AI processes for example cost more than simple graph API calls.

The gateway uses an updated map of all the services and how to reach them to process requests and respond to Consumers accordingly.

Each service has a version. Users can access different version of services using the following url scheme:

protocol://[product.slug].uws.io/[service.slug]/[service.version]/*