Aay to manage large number of APIs in an organization is by creating layers and/or categories. One example is API-led connectivity by MuleSoft that proposes three layers: Experience, Process, and System API.

1. Layers of API
Experience, Process, System, and more APIs

2. 2
MONOLITH vs SOA vs MICROSERVICES

3. MONOLITHs

4. SOA
4
SSS
Online app
SOA
Legacy

5. 5
SOAP
Legacy Operational Data Store
API
Initially Read only
Read/Write
Existing data flow
New data flow
ETL

6. 6
API led connectivity
source: Mulesoft

7. API led connectivity in a Bank
7
Customer API Accounts API Transactions API
GET /customerAccounts API GET /transactionSummary API
GET /home API
Data Store

8. 8
XAPI
PAPI
SAPI
Data base
XAPI
PAPI
SAPI
Data base
XAPI
PAPI
SAPI
Data base
XAPI
PAPI
SAPI
Data base
XAPI
PAPI
SAPI
Data base

9. DOMAIN DRIVEN DESIGN
MONOLITH
Tightly coupled
MICROSERVICES
Loosely coupled sub-domains

10. 10

11. Dom Ser 1 Dom Ser 2 Dom Ser 3 Dom Ser 4 Dom Ser n
Home Products Eligibility Offer
Home API
Customer
Products API
Customer
Eligibility API
Offer API
…

13. 13
Backend For Frontend
Source: Sam Newman & Associates

14. 14

15. 15
Experience Service
Source: EBay

16. 16

17. 17
API Gateway

18. 18

19. 19
DATA ACCESS APIs
PRESENTATION APIs
BUSINESS FUNCTION APIs
Layers