Replace json schema with go validation

[antho1404]

Remove the json schema to replace it with a validation in go with https://github.com/go-playground/validator

It will be easier to plug some specific validation if we want too and it remove some extra complexity.

[krhubert]

Should we only allow ascii in fields like description?

UTF will be better, but I can't find validator for this, we need to create custom validator for utf

[krhubert]

As @ilgooz pointed out in #782

require at least one of the events or tasks sections

[antho1404]

require at least one of the events or tasks sections

Is it really necessary, I agree that it would be almost required but it's not something totally useless to have services without any tasks/event. We could have a service that basically just have one or multiple dependencies like a docker-compose. Maybe we can keep it simple for now, I'm open to both solutions

[krhubert]

The question is - if someone will need a service without event or task? what will be usecase for service which you can't communicate with? If user has such use case then we even must allow both events and tasks to be empty. If there is no use case then importer should validate it and in the future we can take off this restriction if we find usecase for service without events or tasks.

[antho1404]

I just worked on an IPFS this weekend that runs in a MESG service but that actually didn't expose anything except the dependency port to the IPFS node. I agree that this is not the best use of MESG (and I'm actually trying to merge it in the core directly) but this is a use case, just accessing a server from a dependency.

But again both are fine to me

[krhubert]

If there is a use-case (event as you describe not the best) then we should allow such configuration 💪

[krhubert]

Also it will close #695

[krhubert]

I will replace gopkg.in/go-playground/validator.v9 with github.com/asaskevich/govalidator

motiviationŁ

• there is one big issue with validator.v9 - it dosen't export functions to validate so we can only use it inside structs. On the other side govalidator exposes all functions and we are using it in commands/provider and we might want use this in the future.

EDIT:
As I look on both packages - validtor.v9 has better validation options (although it doesn't export any method for validation) and it's developed. As I removed govalidator.

[ilgooz]

@NicolasMahe have you tested each rule manually? Or I need to do that because we don't have full test cov. Code seems fine.

[NicolasMahe]

@NicolasMahe have you tested each rule manually? Or I need to do that because we don't have tests. Code seems fine.

I tested a lot manually.

[ilgooz]

@NicolasMahe have you tested each rule manually? Or I need to do that because we don't have tests. Code seems fine.

I tested a lot manually.

Ok, let me do one more in case if we miss something and then I'll merge.

[ilgooz]

@NicolasMahe I cannot merge because some commits are not signed.

[NicolasMahe]

i fixed the optional SID and added some test

please review

[antho1404]

finished my tests and everything is fine :)