Standard Promises #71
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melnikovi
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| Another way that was proposed to execute service contracts in an asynchronous manner was to use async web API, but there | ||
| are number of problems with that approach: | ||
| * Async web API allows execution of the same operation with different sets of arguments, but not different operations | ||
| * Async web API was meant for execution big number of operations at the same time (thouthands) which is not the case |
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Actually, it's not only an import operation - place orders, shipments creation, invoicing, shipping rates retrieving.
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| and to let client code to chain, pass and properly receive promises of results of operations. | ||
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| #### How will it look? | ||
| There are to ways we can go about using promises for asynchronous execution of service contracts: |
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| ```php | ||
| interface SomeRepositoryInterface | ||
| { | ||
| public function save(DTOInterface $dto): void; |
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What about existing repositories which returns DTOInterface entity on save method?
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They can, that's just an example meant to show that 2nd approach does not require a particular return type
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| $saveOperation->then(function ($result) use (&$updated) { $updated = $result; }); | ||
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| //Waiting for all | ||
| $saveOperation->wait(); |
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Should we call wait for both async and sync approaches?
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you would call 'wait' to wait for an operation to complete if it's required, you can just provide a callback to 'then' method if you don't need waiting
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| ### Why? | |||
| Service contracts in the future will often be executed in an asynchronous manner | |||
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Please elaborate more on the purpose and provide examples where it can be used now. As I understand, the purpose is to allow call APIs in parallel when we need to call multiple APIs consequentially and as a result improve performance? Where promises will be used, do you propose public API to return promises?
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public API methods don't have to return promise since we'll be calling them via HTTP. If you mean that when a service contract implementation will actually be calling web API on another server then yes, if we go with the 1st route they'd have to return a promise
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| ### Implementation | ||
| A wrapper around [Guzzle Promises](https://github.com/guzzle/promises) will be created to implement the APIs above. Guzzle Promises fit | ||
| most important criteria - they allow synchronous execution as well as asynchronous. It's a mature |
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What are the benefits of the interface that would allow us to call something both ways?
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if a promise would only allow 'then' and 'otherwise' callback then all the client code using would have to be returning promises as well because there would be no way to actually wait for an async operation to finish
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| ### Using promises for existing code | ||
| We have a standard HTTP client - Magento\Framework\HTTP\ClientInterface, it can benefit from allowing async requests |
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Does it mean that we will have to change the interface? This might be backwards incompatible.
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we would have to add methods or add an interface that will extend the existing one
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| #### How will it look? | ||
| There are to ways we can go about using promises for asynchronous execution of service contracts: | ||
| * Service interfaces themselves returning promises for client code to use |
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How will this work in the existing system? In web API for instance?
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web API controllers would just have to updated to expect promises, calling wait on them and then rendering results
AlexMaxHorkun
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Decided that futures serve us better |
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@AlexMaxHorkun could you add async http interface description? @melnikovi , @akaplya do you have any comments/objections? |
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Page described how to work with DeferredInterface introduced in magento/architecture#71
Standard promises to be used with asynchronous operations in Magento. Operations like calling a remote service or just sending an HTTP request asynchronously.