feature/go-support

.gitignore

@@ -36,3 +36,4 @@ target-sbt
 node_modules
 .idea/
 .nyc_output
+go-support/shoppingcart/cmd/shoppingcart/tck_shoppingcart

.travis.yml

@@ -25,28 +25,35 @@ jobs:
     script:
     - cd node-support && npm test && cd -
     - cd samples/js-shopping-cart && npm test && cd -
-  
+
   - name: sbt tests
     before_script: sbt update
     script: sbt 'set concurrentRestrictions in Global += Tags.limitAll(1)' test
-
+
+  - name: go tests
+    before_script:
+      - ./go-support/build/prebuild_go-support_in_docker.sh
+    script:
+      - cd go-support && ./build/run_go_test_in_docker.sh && cd -
+
   - name: docs tests
     before_script:
     - cd node-support && npm install && cd -
     - cd docs/src/test/js && npm install && cd -
     script:
     - sbt 'set concurrentRestrictions in Global += Tags.limitAll(1)' docs/paradox docs/test
     - cd docs/src/test/js && npm test && cd -
-  
+
   - stage: TCK
     name: Run TCK against reference implementation
     before_script:
     - sbt update
     - cd node-support && npm install && cd -
     - cd samples/js-shopping-cart && npm install && cd -
+    - sbt go-support/compile
     script:
     - sbt 'set concurrentRestrictions in Global += Tags.limitAll(1)' tck/it:test
-  
+
   - stage: Deploy
     name: Deploy documentation to cloudstate.io
     if: branch = master AND type = push
@@ -64,13 +71,13 @@ jobs:
       name: CloudState Deployment Bot
       on:
         branch: master
-  
+
   - name: Publish docker images
     if: tag =~ /^v*/
     script:
     - echo "$DOCKER_PASSWORD" | docker login -u cloudstatebot --password-stdin
     - sbt "set concurrentRestrictions in Global += Tags.limitAll(1)" "dockerBuildAllNonNative publish" operator/docker:publish
-  
+
   - name: Upload CloudState descriptor
     if: tag =~ /^v*/
     script: sbt operator/compileK8sDescriptor

build.sbt

@@ -4,6 +4,7 @@ import java.util.Date
 import com.typesafe.sbt.packager.docker.DockerChmodType
 import sbt.Keys.{developers, scmInfo}
 import sbt.url
+import scala.sys.process._
 
 inThisBuild(
   Seq(
@@ -128,7 +129,9 @@ lazy val docs = (project in file("docs"))
         "extref.jsdoc.base_url" -> ".../user/lang/javascript/api/module-cloudstate.%s",
         "cloudstate.version" -> "0.4.3", // hardcode, otherwise we'll end up with the wrong version in the docs
         "cloudstate.java-support.version" -> "0.4.3",
-        "cloudstate.node-support.version" -> "0.0.1"
+        "cloudstate.node-support.version" -> "0.0.1",
+        "cloudstate.go-support.version" -> "0.0.1",
+        "cloudstate.go.version" -> "1.13"
       ),
     paradoxNavigationDepth := 3,
     inConfig(Test)(
@@ -658,6 +661,31 @@ lazy val `java-shopping-cart` = (project in file("samples/java-shopping-cart"))
     }
   )
 
+lazy val `go-support` = (project in file("go-support"))
+  .settings(
+    name := "go-support",
+    (compile in Compile) := {
+      // FIXME only recompile if any of the files in the project has changed
+      import scala.util.Properties.{isLinux, isMac, isWin}
+      val (os_arch, cmd) =
+        if (isLinux) ("linux on amd64", "./go-support/build/run_tck_shopping_cart_build.sh linux amd64")
+        else if (isMac) ("darwin on amd64", "./go-support/build/run_tck_shopping_cart_build.sh darwin amd64")
+        else if (isWin)
+          ("windows on amd64", "& .\\go-support\\build\\run_tck_shopping_cart_build.ps1 windows amd64") // FIXME IMPLEMENT
+        else throw new IllegalStateException("Running on an unsupported OS/ARCH combination: " + sys.props("os.name"))
+
+      val SuccessMessage = "go-support compiled successfully: " + os_arch + "\n"
+
+      (cmd !) match {
+        case 0 =>
+          streams.value.log.success(SuccessMessage)
+          (compile in Compile).value // TODO should we produce our own compilation result instead perhaps?
+        case err =>
+          throw new IllegalStateException("go-support compilation failed: " + err)
+      }
+    }
+  )
+
 lazy val `akka-client` = (project in file("samples/akka-client"))
   .enablePlugins(AkkaGrpcPlugin)
   .settings(
@@ -719,7 +747,7 @@ lazy val `tck` = (project in file("tck"))
     fork in test := true,
     parallelExecution in IntegrationTest := false,
     executeTests in IntegrationTest := (executeTests in IntegrationTest)
-        .dependsOn(`proxy-core` / assembly, `java-shopping-cart` / assembly)
+        .dependsOn(`proxy-core` / assembly, `java-shopping-cart` / assembly, `go-support` / Compile / compile)
         .value
   )
 

docs/src/main/paradox/developer/language-support/index.md

@@ -7,6 +7,7 @@ This is achieved by having a gRPC based protocol between the Proxy and the User
 
 * Java
 * JavaScript
+* Go
 
 ## Creating language support libraries
 

docs/src/main/paradox/user/lang/go/api.md

@@ -0,0 +1,4 @@
+# Go API docs
+
+The Go API docs can be found [here](https://godoc.org/?q=cloudstate.io%2Fgosupport). 
+(TODO: supply it by godoc.org, but that needs a public available repo)

docs/src/main/paradox/user/lang/go/crdt.md

@@ -0,0 +1,6 @@
+# Conflict-free Replicated Data Types
+
+* Explain how to use the CRDT API
+* Explain how to use CrdtFactory and where it comes from
+* Explain how to handle streamed calls
+* Explain the APIs for each different CRDT

docs/src/main/paradox/user/lang/go/effects.md

@@ -0,0 +1,5 @@
+# Forwarding and effects
+
+* Explain the ServiceCallFactory interface
+* Explain how to forward replies to another service.
+* Explain how to emit effects.

docs/src/main/paradox/user/lang/go/eventsourced.md

@@ -0,0 +1,117 @@
+# Event sourcing
+
+This page documents how to implement CloudState event sourced entities in Go. For information on what CloudState event sourced entities are, please read the general @ref[Event sourcing](../../features/eventsourced.md) documentation first.
+
+An event sourced entity can be created by embedding the `cloudstate.EventEmitter` type and also implementing the `cloudstate.EntityInitializer` interface. **(TODO: link to godoc)**
+
+@@snip [shoppingcart.go](/docs/src/test/go/docs/user/eventsourced/shoppingcart.go) { #entity-type }
+
+Then by composing the CloudState entity with an `cloudstate.EventSourcedEntity` and register it with `cloudState.Register()`, your entity gets configured to be an event sourced entity and handled by the CloudState instance for now on.
+
+@@snip [shoppingcart.go](/docs/src/test/go/docs/user/eventsourced/eventsourced.go) { #event-sourced-entity-type }
+
+The `PersistenceID` is used to namespace events in the journal, useful for when you share the same database between multiple entities. It defaults to the simple name for the entity type (in this case, `ShoppingCart`), it's good practice to select one explicitly, this means your database isn't depend on type names in your code.
+
+The `SnapshotEvery` parameter controls how often snapshots are taken, so that the entity doesn't need to be recovered from the whole journal each time it's loaded. If left unset, it defaults to 100. Setting it to a negative number will result in snapshots never being taken.
+
+## Persistence types and serialization
+
+Event sourced entities persist events and snapshots, and these need to be serialized when persisted. The most straight forward way to persist events and snapshots is to use protobufs. CloudState will automatically detect if an emitted event is a protobuf, and serialize it as such. For other serialization options, including JSON, see @ref:[Serialization](serialization.md).
+
+While protobufs are the recommended format for persisting events, it is recommended that you do not persist your services protobuf messages, rather, you should create new messages, even if they are identical to the services. While this may introduce some overhead in needing to convert from one type to the other, the reason for doing this is that it will allow the services public interface to evolve independently from its data storage format, which should be private.
+
+For our shopping cart example, we'll create a new file called `domain.proto`, the name domain is selected to indicate that these are my applications domain objects:
+
+@@snip [domain.proto](/docs/src/test/proto/domain.proto)
+
+## State
+
+Each entity should store its state locally in a mutable variable, either a mutable field or a multiple structure such as an array type or slice. For our shopping cart, the state is a slice of products, so we'll create a slice of LineItems to contain that:
+
+@@snip [shoppingcart.go](/docs/src/test/go/docs/user/eventsourced/shoppingcart.go) { #entity-state }
+
+## Constructing
+
+The CloudState Go Support Library needs to know how to construct and initialize entities. For this, an entity has to implement the `cloudstate.EntityInitializer` interface.
+
+(TODO: provide: The constructor below shows having the entity id injected)
+
+@@snip [shoppingcart.go](/docs/src/test/go/docs/user/eventsourced/shoppingcart.go) { #constructing }
+
+## Handling commands
+
+Command handlers are declared by implementing the gRPC ShoppingCartServer interface which is generated from the protobuf definitions. The CloudState Go Support library together with the registered ServiceName in the `cloudstate.EventSourcedEntity` is then able to dispatch commands it gets from the CloudState proxy.
+
+The return type of the command handler is by definition of the service interface, the output type for the gRPC service call, this will be sent as the reply.
+
+The following shows the implementation of the `GetCart` command handler. This command handler is a read-only command handler, it doesn't emit any events, it just returns some state:
+
+@@snip [shoppingcart.go](/docs/src/test/go/docs/user/eventsourced/shoppingcart.go) { #get-cart }
+
+### Emitting events
+
+Commands that modify the state may do so by emitting events.
+
+@@@ warning
+The **only** way a command handler may modify its state is by emitting an event. Any modifications made directly to the state from the command handler will not be persisted, and when the entity is passivated and next reloaded, those modifications will not be present.
+@@@
+
+A command handler may emit an event by using the embedded `cloudstate.EventEmitter` and invoking the `Emit` method on it. Calling `Emit` will immediately invoke the associated event handler for that event - this both validates that the event can be applied to the current state, as well as updates the state so that subsequent processing in the command handler can use it.
+
+Here's an example of a command handler that emits an event:
+
+@@snip [shoppingcart.go](/docs/src/test/go/docs/user/eventsourced/shoppingcart.go) { #add-item }
+
+This command handler also validates the command, ensuring the quantity items added is greater than zero. Returning a `error` fails the command and the support library takes care of signaling that back to the requesting proxy as a `Failure` reply.  
+
+## Handling events
+
+Event handlers are invoked at two points, when restoring entities from the journal, before any commands are handled, and each time a new event is emitted. An event handlers responsibility is to update the state of the entity according to the event. Event handlers are the only place where its safe to mutate the state of the entity at all.
+
+Event handlers are declared by either implementing the `cloudstate.EventHandler` interface
+
+@@snip [shoppingcart.go](/docs/src/test/go/docs/user/eventsourced/event.go) { #event-handler }
+
+or implementing an unary method that matches the type of the event to be handled. Event handlers are differentiated by the type of event they handle. By default, the type of event an event handler handles will be determined by looking for a single argument that the event handler takes. If for any reason this needs to be overridden, or if the event handler method doesn't exists at all, the event is handed over to the `cloudstate.EventHandler` `Handle` method when the entity implements that interface. The by implementing the `HandleEvent(event interface{}) (handled bool, err error)` method, a event handler indicates if he handled the event or if any occurred, returns an error. The returned error has precedent and the handled flag would not be considered.  
+
+Here's an example event handler for the `ItemAdded` event.
+
+@@snip [shoppingcart.go](/docs/src/test/go/docs/user/eventsourced/shoppingcart.go) { #item-added }
+
+## Producing and handling snapshots
+
+## Multiple behaviors
+
+Multiple behaviors are not supported yet by the Go support library. 
+
+## Registering the entity
+
+Once you've created your entity, you can register it with the `cloudstate.CloudState` server, by invoking the `Register` method of an CloudState instance. In addition to passing your entity type and service name, you also need to pass any descriptors that you use for persisting events, for example, the `domain.proto` descriptor.
+
+During registration the oprtional ServiceName and the ServiceVersion can be configured as Options.
+
+@@snip [shoppingcart.go](/docs/src/test/go/docs/user/eventsourced/shoppingcart.go) { #register }
+
+```
+// main creates a CloudState instance and registers the ShoppingCart
+// as a event sourced entity.
+func main() {
+	cloudState := cloudstate.NewCloudState(&cloudstate.Options{
+		ServiceName:    "shopping-cart",
+		ServiceVersion: "0.0.1",
+	})
+	err := cloudState.Register(
+		&cloudstate.EventSourcedEntity{
+			Entity:      (*ShoppingCart)(nil),
+			ServiceName: "com.example.shoppingcart.ShoppingCart",
+		},
+		cloudstate.DescriptorConfig{
+			Service: "shoppingcart/shoppingcart.proto",
+		}.AddDomainDescriptor("shoppingcart/persistence/domain.proto"),
+	)
+	if err != nil {
+		log.Fatal(err)
+	}
+	cloudState.Run()
+}
+```

docs/src/main/paradox/user/lang/go/gettingstarted.md

@@ -0,0 +1,78 @@
+# Getting started with stateful services in Go
+
+## Prerequisites
+
+Go version
+: CloudState Go support requires at least Go $cloudstate.go.version$
+
+Build tool
+: CloudState does not require any particular build tool, you can select your own.
+
+protoc
+: Since CloudState is based on gRPC, you need a protoc compiler to compile gRPC protobuf descriptors. While this can be done by downloading, installing and running protoc manually.
+
+docker
+: CloudState runs in Kubernetes with [Docker](https://www.docker.com), hence you will need Docker to build a container that you can deploy to Kubernetes. Most popular build tools have plugins that assist in building Docker images.
+
+In addition to the above, you will need to install the CloudState Go support library by issuing `go get -u cloudstate.io/cloudstate` or with module support let the dependency downloaded by `go [build|run]`. 
+
+By using the Go module support your go.mod file will reference the latest version of the support library or you can define which version you like to use.
+
+go get
+: @@@vars
+```text
+go get -u cloudstate.io/cloudstate
+```
+@@@
+
+import path
+: @@@vars
+```text
+import "cloudstate.io/cloudstate"
+```
+@@@
+
+go.mod
+: @@@vars
+```
+module example.com/yourpackage
+    require (
+        cloudstate.io/cloudstate $cloudstate.go-support.version$
+    )
+go $cloudstate.go.version$
+```
+@@@
+
+## Protobuf files
+
+The CloudState Go Support Library provides no dedicated tool beside the protoc compiler to build your protobuf files. The CloudState protocol protobuf files as well as the shopping cart example application protobuf files are provided by the CloudState Protocol Repository (TODO: whats this?).
+
+In addition to the protoc compiler, the gRPC Go plugin is needed to generate *.pb.go files. Please follow the instructions at the [Go support for Protocol Buffers](https://github.com/golang/protobuf) project page to install the protoc compiler as well as the `protoc-gen-go` plugin which also includes the Google standard protobuf types.
+
+To build the example shopping cart application shown earlier in @ref:[gRPC descriptors](../../features/grpc.md), you could simply paste that protobuf into `protos/shoppingcart.proto`. You may wish to also define the Go package using the `go_package` proto option, to ensure the package name used conforms to Go package naming conventions:
+
+```proto
+option go_package = "example.com/shoppingcart";
+```
+
+Now if you place your protobuf files under protos/ and run `protoc --go_out=. *.proto`, you'll find your generated protobuf files in `TODO`.
+
+## Creating and starting a server
+
+## Creating a main package
+
+Your main package will be responsible for creating the CloudState gRPC server, registering the entities for it to serve, and starting it. To do this, you can use the CloudState server type, for example:
+
+@@snip [shoppingcart.go](/docs/src/test/go/docs/user/eventsourced/shoppingcart.go) { #shopping-cart-main }
+
+We will see more details on registering entities in the coming pages.
+
+## Interfaces to be implemented
+
+CloudState entities in Go work by implementing interfaces and composing types. 
+
+To get support for the CloudState event emission the CloudState entity should embed the `cloudstate.EventEmitter` type. The EventEmitter allows the entity to emit events during the handling of commands.
+
+Second, by implementing the `EntityInitializer` interface with its method `New() interface{}`, a CloudState instance gets to know how to create and initialize an event sourced entity.
+
+@@snip [shoppingcart.go](/docs/src/test/go/docs/user/eventsourced/shoppingcart.go) { #compose-entity }

docs/src/main/paradox/user/lang/go/index.md

@@ -0,0 +1,16 @@
+# Go
+
+CloudState offers an idiomatic, annotation based Go support library for writing stateful services.
+
+@@toc { depth=1 }
+
+@@@ index
+
+* [Getting started](gettingstarted.md)
+* [Event sourcing](eventsourced.md)
+* [Conflict-free Replicated Data Types](crdt.md)
+* [Forwarding and effects](effects.md)
+* [Serialization](serialization.md)
+* [API docs](api.md)
+
+@@@

docs/src/main/paradox/user/lang/go/serialization.md

@@ -0,0 +1,32 @@
+# Serialization
+
+CloudState functions serve gRPC interfaces, and naturally the input messages and output messages are protobuf messages that get serialized to the protobuf wire format. However, in addition to these messages, there are a number of places where CloudState needs to serialize other objects, for persistence and replication. This includes:
+
+* Event sourced @ref[events and snapshots](eventsourced.md#persistence-types-and-serialization).
+* CRDT @ref[map keys and set elements](crdt.md), and @ref[LWWRegister values](crdt.md).
+
+CloudState supports a number of types and serialization options for these values.
+
+## Primitive types
+
+CloudState supports serializing the following primitive types:
+
+| Protobuf type | Go type     |
+|---------------|-------------|
+| string        | string      |
+| bytes         | []byte      |
+| int32         | int32       |
+| int64         | int64       |
+| float         | float32     |
+| double        | float64     |
+| bool          | bool        |
+
+The details of how these are serialized can be found @ref[here](../../../developer/language-support/serialization.md#primitive-values).
+
+## JSON
+
+CloudState uses the package [`encoding/json`](https://golang.org/pkg/encoding/json/) to serialize JSON. Any type that has a field declared with a string literal tag ``json:"fieldname"`` will be serialized to and from JSON using the [Marshaller and Unmarshaller](https://golang.org/pkg/encoding/json/#Marshal) from the Go standard library package `encoding/json`.
+
+The details of how these are serialized can be found @ref[here](../../../developer/language-support/serialization.md#json-values).
+
+Note that if you are using JSON values in CRDT sets or maps, the serialization of these values **must** be stable. This means you must not use maps or sets in your value, and you should define an explicit ordering for the fields in your objects. **(TODO: mention the ordering of fields here by the Go standard library implementation).**