alk About the Challenges

One of the main tasks in Uber service is to match the rider with cabs which means we need two different services in our architecture i.e.

Supply Service (for cabs)

Demand Service (for riders)

Uber has a Dispatch system (Dispatch optimization/DISCO) in its architecture to match supply with demands. This dispatch system uses mobile phones and it takes the responsibility to match the drivers with riders (supply to demand).

2. How Dispatch System Work?

DISCO must have these goals…

Reduce extra driving.

Minimum waiting time

Minimum overall ETA

The dispatch system completely works on maps and location data/GPS, so the first thing which is important is to model our maps and location data.

Earth has a spherical shape so it’s difficult to do summarization and approximation by using latitude and longitude. To solve this problem Uber uses the Google S2 library. This library divides the map data into tiny cells (for example 3km) and gives the unique ID to each cell. This is an easy way to spread data in the distributed system and store it easily.

S2 library gives coverage for any given shape easily. Suppose you want to figure out all the supplies available within a 3km radius of a city. Using the S2 libraries you can draw a circle of 3km radius and it will filter out all the cells with IDs that lie in that particular circle. This way you can easily match the rider to the driver and you can easily find out the number of cars(supply) available in a particular region.

3. Supply Service And How it Works?

In our case cabs are the supply services and they will be tracked by geolocation (latitude and longitude). All the active cabs keep on sending the location to the server once every 4 seconds through a web application firewall and load balancer. The accurate GPS location is sent to the data center through Kafka’s Rest APIs once it passes through the load balancer. Here we use Apache Kafka as the data hub.

Once the latest location is updated by Kafka it slowly passes through the respective worker notes’ main memory.

Also, a copy of the location (state machine/latest location of cabs) will be sent to the database and to the dispatch optimization to keep the latest location updated.

We also need to track a few more things such as the number of seats, presence of a car seat for children, type of vehicle, can a wheelchair be fit, and allocation ( for example, a cab may have four seats but two of those are occupied.)  

https://www.geeksforgeeks.org/system-design-of-uber-app-uber-system-architecture/