essential api facade patterns: synchronous to asynchronous conversion (episode 4)
TRANSCRIPT
Apigee@apigee
Santanu Dey@Santanu_Dey
Essential API Facade Patterns
Episode 4 – Synchronous to Asynchronous Conversion
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@Santanu_DeySantanu Dey
Episode 1Composition
Episode 2Session Management
Episode 3One Phase to Two Phase Conversion
Episode 4Synchronous to Asynchronous Conversion
Webcast Series: API Facade Patterns
Problem
Solution
Benefits
Considerations
Episode 4 : Synchronous to Asynchronous ConversionConversion
Conversion of asynchronous style APIs to synchronous
To enable API teams and app developers to implement and improve their API designs and apps
Problem
Example of a Synchronous API
Client waitsfor the response
API Provider
1. Request
2. Response
Example of a Synchronous API
POST http://example.com/smsmessaging/outbound/tel%3A%2B12345678/requests
{"outboundSMSMessageRequest":{ "address":["tel:+13500000991”],
"senderAddress":"tel:12345678", "outboundSMSTextMessage":
{"message":"Hello World”},
"senderName":"ACME Inc.”}
}
Example of a Synchronous API
Response:
HTTP/1.1 200
{"deliveryInfo": {
"address":"tel:+1350000991", "deliveryStatus":"DeliveredToNetwork”
}}
}
What are the Constructs of an Asynchronous API?
Example of an Asynchronous API
Client does not wait for the completion of the process
API Provider
1. RequestClient
Example of an Asynchronous API
Client does not wait for the completion of the process
API Provider
1. Request
Server calls back
2. Asynch Response
Client
Example of an Asynchronous API
POST http://example.com/smsmessaging/outbound/tel%3A%2B12345678/requests{"outboundSMSMessageRequest":
{ "address":["tel:+13500000991”],
"senderAddress":"tel:12345678", "outboundSMSTextMessage":
{"message":"Hello World”},
"senderName":"ACME Inc.”}"receiptRequest": {
"notifyURL":"http://…/notifications/", "callbackData":”12345"},
}
Example of an Asynchronous API
Immediate Response:
HTTP/1.1 201
{"deliveryInfo": {
"address":"tel:+1350000991", "deliveryStatus":"MessageWaiting”
}}
"receiptRequest": {
"notifyURL":"http://…/notifications/", "callbackData":”12345"},
}
Example of an Asynchronous API
Asynch Call-back Response (A new request):
POST http://Client-app.example.com/notifications/{"deliveryInfoNotification": {
"callbackData": "12345”,"deliveryInfo":
{ "address":"tel:+1350000991", "deliveryStatus":"DeliveredToNetwork"
}}}
The end-user facing application use-case may require synchronous behavior
Having a call back URL from a client-application is not feasible
Solution
The solution is to introduce an API Façade in the middle which can handle the conversion
Synch to Asynch
Asynch. ProviderAsynch Synch
Warning! UML Ahead
When the Target Does not Provide a Call Back
Client does not wait for the completion of the process API
Provider
1. Request
Client checks for the status later
2. Check Status
Example of the API Façade
Backend Server
API Façade
Existing Capabilities
API Exposure &
Mgmt.
App relies on REST
Benefits
The API Façade provides a secure & reliable call back host
Robust callback processing options in the API Façade
This pattern can be applied to mediate REST APIs to asynchronous messaging transports such as JMS
Other Considerations
What is a good timeout for asynch to synch conversion?
Do not abandon the Asynchronous APIs• High throughput• Lower response-time
If you really need a synch API -
Have a synchronous variation of the same API alongside an asynchronous variation
Provide Choice to Developers when Possible
Questions?
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