RES Service for Go
Synchronize Your Clients

---

Go package used to create REST, real time, and RPC APIs, where all your reactive web clients are synchronized seamlessly through Resgate.

Visit Resgate.io for more information.

Installation

go get github.com/jirenius/go-res

As easy as

package main

import res "github.com/jirenius/go-res"

func main() {
   s := res.NewService("example")
   s.Handle("model",
      res.Access(res.AccessGranted),
      res.GetModel(func(r res.ModelRequest) {
         r.Model(struct {
            Message string `json:"message"`
         }{"Hello, World!"})
      }),
   )
   s.ListenAndServe("nats://localhost:4222")
}

Prerequisite

Install NATS Server and Resgate. Can be done with 3 docker commands:

docker network create res
docker run -d --name nats -p 4222:4222 --net res nats
docker run --name resgate -p 8080:8080 --net res resgateio/resgate --nats nats://nats:4222

Examples

Example	Description
Hello World	Smallest of services serving a static message.
Edit Text	Single text field that is updated in real time.
Book Collection	List of book titles & authors that can be edited by many.
Book Collection Store	Book Collection example persisting changes using BadgerBD store.
Search Query	Make live queries against a large customer database.

Note

Above examples are complete with both service and client.

Usage

Create a new service

s := res.NewService("myservice")

Add handlers for a model resource

mymodel := map[string]interface{}{"name": "foo", "value": 42}
s.Handle("mymodel",
   res.Access(res.AccessGranted),
   res.GetModel(func(r res.ModelRequest) {
      r.Model(mymodel)
   }),
)

Add handlers for a collection resource

mycollection := []string{"first", "second", "third"}
s.Handle("mycollection",
   res.Access(res.AccessGranted),
   res.GetCollection(func(r res.CollectionRequest) {
      r.Collection(mycollection)
   }),
)

Add handlers for parameterized resources

s.Handle("article.$id",
   res.Access(res.AccessGranted),
   res.GetModel(func(r res.ModelRequest) {
      article := getArticle(r.PathParam("id"))
      if article == nil {
         r.NotFound()
      } else {
         r.Model(article)
      }
   }),
)

Add handlers for method calls

s.Handle("math",
   res.Access(res.AccessGranted),
   res.Call("double", func(r res.CallRequest) {
      var p struct {
         Value int `json:"value"`
      }
      r.ParseParams(&p)
      r.OK(p.Value * 2)
   }),
)

Send change event on model update

A change event will update the model on all subscribing clients.

s.With("myservice.mymodel", func(r res.Resource) {
   mymodel["name"] = "bar"
   r.ChangeEvent(map[string]interface{}{"name": "bar"})
})

Send add event on collection update:

An add event will update the collection on all subscribing clients.

s.With("myservice.mycollection", func(r res.Resource) {
   mycollection = append(mycollection, "fourth")
   r.AddEvent("fourth", len(mycollection)-1)
})

Add handlers for authentication

s.Handle("myauth",
   res.Auth("login", func(r res.AuthRequest) {
      var p struct {
         Password string `json:"password"`
      }
      r.ParseParams(&p)
      if p.Password != "mysecret" {
         r.InvalidParams("Wrong password")
      } else {
         r.TokenEvent(map[string]string{"user": "admin"})
         r.OK(nil)
      }
   }),
)

Add handlers for access control

s.Handle("mymodel",
   res.Access(func(r res.AccessRequest) {
      var t struct {
         User string `json:"user"`
      }
      r.ParseToken(&t)
      if t.User == "admin" {
         r.AccessGranted()
      } else {
         r.AccessDenied()
      }
   }),
   res.GetModel(func(r res.ModelRequest) {
      r.Model(mymodel)
   }),
)

Using routes

s.Route("v2", func(m *res.Mux) {
   m.Handle("mymodel",
      /* ... */
   )
})

Start service

s.ListenAndServe("nats://localhost:4222")

Testing

The restest subpackage is used for testing services and validate responses.

Inter-service communication

The resprot subpackage provides low level structs and methods for communicating with other services over NATS server.

Storage

The store subpackage contains handlers and interfaces for working with database storage.

Name	Description	Documentation
mockstore	Mock store implementation for testing
badgerstore	BadgerDB store implementation

Credits

Inspiration on the go-res API has been taken from github.com/go-chi/chi, a great package when writing ordinary HTTP services, and will continue to do so when it is time to implement Middleware, sub-handlers, and mounting.

Contributing

The go-res package is still under development, but the API is mostly settled. Any feedback on the package API or its implementation is highly appreciated!

Once the API is fully settled, the package will be moved to the resgateio GitHub organization.

If you find any issues, feel free to report them as an issue.