mirror of
https://github.com/openfaas/faas.git
synced 2025-06-10 17:26:47 +00:00
78 lines
3.1 KiB
Markdown
78 lines
3.1 KiB
Markdown
# Guide on Asynchronous processing
|
|
|
|
Asynchronous function calls can be queued up using the following route:
|
|
|
|
```
|
|
$ curl --data "message" http://gateway:8080/async-function/{function_name}
|
|
```
|
|
|
|
Summary of modes for calling functions via API Gateway:
|
|
|
|
| Mode | Method | URL | Body | Headers | Query string
|
|
| -------------|--------|------------------------------------------------|------|--------- |------------------- |
|
|
| Synchronous | POST | http://gateway:8080/function/{function_name} | Yes | Yes | Yes |
|
|
| Synchronous | GET | http://gateway:8080/function/{function_name} | Yes | Yes | Yes |
|
|
| Asynchronous | POST | http://gateway:8080/async-function/{function_name} | Yes | Yes | Yes [#369](https://github.com/openfaas/faas/issues/369) |
|
|
| Asynchronous | GET | Not supported | - | - | - |
|
|
|
|
> Note: This work was originally carried out under [PR #131](https://github.com/openfaas/faas/pull/131).
|
|
|
|
*Logical flow for synchronous functions:*
|
|
|
|
|
|
|
|
## Why use Asynchronous processing?
|
|
|
|
* Enable longer time-outs
|
|
|
|
* Process work whenever resources are available rather than immediately
|
|
|
|
* Consume a large batch of work within a few seconds and let it process at its own pace
|
|
|
|
## How does async work?
|
|
|
|
Here is a conceptual diagram
|
|
|
|
<img width="1440" alt="screen shot 2017-10-26 at 15 55 19" src="https://user-images.githubusercontent.com/6358735/32060206-047eb75c-ba66-11e7-94d3-1343ea1811db.png">
|
|
|
|
You can also use asynchronous calls with a callback URL
|
|
|
|
<img width="1440" alt="screen shot 2017-10-26 at 15 55 06" src="https://user-images.githubusercontent.com/6358735/32060205-04545692-ba66-11e7-9e6d-b800a07b9bf5.png">
|
|
|
|
The reference implementation for asychronous processing uses NATS Streaming, but you are free to extend OpenFaaS and write your own [queue-worker](https://github.com/open-faas/nats-queue-worker).
|
|
|
|
> The asynchronous stack is now built-in by default. Previously it was an optional configuration.
|
|
|
|
## Call a function
|
|
|
|
Functions do not need to be modified to work asynchronously, just use this alternate route:
|
|
|
|
```
|
|
http://gateway:8080/async-function/{function_name}
|
|
```
|
|
|
|
If you want the function to call another function or a different endpoint when it is finished then pass the `X-Callback-Url` header. This is optional.
|
|
|
|
```
|
|
$ curl http://gateway:8080/async-function/{function_name} --data-binary @sample.json -H "X-Callback-Url: http://gateway:8080/function/send2slack"
|
|
```
|
|
|
|
You can also use the following site to setup a public endpoint for testing HTTP callbacks: [requestb.in](https://requestb.in)
|
|
|
|
## Extend function timeouts
|
|
|
|
Functions have three timeouts configurable by environmental variables expressed in seconds:
|
|
|
|
HTTP:
|
|
|
|
* read_timeout
|
|
* write_timeout
|
|
|
|
Hard timeout:
|
|
|
|
* exec_timeout
|
|
|
|
To make use of these just add them to your Dockerfile when needed as ENV variables.
|
|
|
|
> [Function watchdog reference](https://github.com/openfaas/faas/tree/master/watchdog)
|