Add Angular support

[ajguerrer]

My first PR! I hope this PR provides a good first stab in closing #382. It adds a 'framework=angular' option which generates an Angular singleton service. Each method in the Angular service wraps the RPC in a rxjs observable, providing that distinctive Angular flavor and opening up use of a wide range of operators.

Metadata events, from on('status'), are not supported. Doing so requires generating code that, in my opinion, gets rather ugly. I decided to wait for an easier API, which seems to be in flight (looking at #603). I can share my on own thoughts on the API if interested.

An Angular 'echo' example app was added using Angular Material. Testing for the generated code was added the Angular ng test way. Let me know what you think.

[linux-foundation-easycla]

The committers are authorized under a signed CLA.

• ✅ Andrew Guerrero (1c91baf, 9d321e8, 1d8ed07)
• ✅ Stanley Cheung (af46816)

[ajguerrer]

required for @angular/cli to work.

[stanley-cheung]

This is great! Thanks for the contributions. I will definitely take a look at this soon.

[ajguerrer]

@stanley-cheung , Some design decisions here effect the API of the generator. I know such decisions require some foresight, so if something should be changed, I'm happy to do so.

Perhaps the most controversial decision is whether to include Angular here or make another protobuf plugin. Personally, I think moving Angular support to a separate plugin would make it 'second class'. I look forward to your thoughts on this.

[Dasio]

Is it possible to somehow support https://github.com/SafetyCulture/grpc-web-devtools?
I can't access client inside service because it's private.

[smnbbrv]

@Dasio I'm unsure if clients are not private its gonna be more helpful. Problem is you don't know when / whether the services are created.

The whole approach of the extension you pointed to is slightly weird. I filed there an issue SafetyCulture/grpc-web-devtools#54 which, if resolved, allows to have custom intercepters pushing the data in. This would be more helpful, however somebody still needs to add intercepters support on this side...

[kabriel]

Would love to see this merged

[ridewindx]

Would love to see this merged

[smnbbrv]

Check https://github.com/ngx-grpc/ngx-grpc

[ajguerrer]

Nice work @smnbbrv! To be fair, ngx-grpc is probably the more practical solution. Judging by the time this PR has been open, I'm guessing there isn't enough bandwidth to maintain an Angular integration. I get the feeling it falls out of the scope of this project.

Making this PR was a fun way to learn more about grpc-web from the perspective of a hobbyist. If it helped someone then great, but I have no personal intention of seeing this merged unless the maintainers of this project have an interest in it. I thought maybe they did since its in the roadmap.