ObjC: Start with helloworld, then the web page

10 years ago · 1f5d62b454
parent 738220d998
commit 1f5d62b454
4 changed files with 7 additions and 547 deletions
--- a/examples/README.md
+++ b/examples/README.md
@ -18,7 +18,7 @@ You can find quick start guides for each language, including installation instru
 * [Android Java](https://github.com/grpc/grpc-java/tree/master/examples/android)
 * [Python](python/helloworld)
 * [C#](csharp)
-* [Objective-C](objective-c/route_guide)
+* [Objective-C](objective-c/helloworld)
 * [PHP](php)
 ## What's in this repository?
--- a/examples/objective-c/auth_sample/README.md
+++ b/examples/objective-c/auth_sample/README.md
@ -1,189 +1,3 @@
 #OAuth2 on gRPC: Objective-C
-This example application demostrates how to use OAuth2 on gRPC to make authenticated API calls on
+This is the supporting code for the tutorial "[OAuth2 on gRPC: Objective-C](http://www.grpc.io/docs/tutorials/auth/oauth2-objective-c.html)."
 behalf of a user. By walking through it you'll learn how to use the Objective-C gRPC API to:
 - Initialize and configure a remote call object before the RPC is started.
 - Set request metadata elements on a call, which are semantically equivalent to HTTP request
 headers.
 - Read response metadata from a call, which is equivalent to HTTP response headers and trailers.
 It assumes you know the basics on how to make gRPC API calls using the Objective-C client library,
 as shown in the [Hello World](../helloworld)
 or [Route Guide](../route_guide) tutorials,
 and are familiar with OAuth2 concepts like _access token_.
 - [Example code and setup](#setup)
 - [Try it out!](#try)
 - [Create an RPC object and start it later](#rpc-object)
 - [Set request metadata of a call: Authorization header with an access token](#request-metadata)
 - [Get response metadata of a call: Auth challenge header](#response-metadata)
 <a name="setup"></a>
 ## Example code and setup
 The example code for our tutorial is in [examples/objective-c/auth_sample](.).
 To download the example, clone this repository by running the following command:
 ```shell
 $ git clone https://github.com/grpc/grpc.git
 ```
 Then change your current directory to `examples/objective-c/auth_sample`:
 ```shell
 $ cd examples/objective-c/auth_sample
 ```
 Our example is a simple application with two views. The first one lets a user sign in and out using
 the OAuth2 flow of Google's [iOS SignIn library](https://developers.google.com/identity/sign-in/ios/).
 (Google's library is used in this example because the test gRPC service we are going to call expects
 Google account credentials, but neither gRPC nor the Objective-C client library is tied to any
 specific OAuth2 provider). The second view makes a gRPC request to the test server, using the
 access token obtained by the first view.
 Note: OAuth2 libraries need the application to register and obtain an ID from the identity provider
 (in the case of this example app, Google). The app's XCode project is configured using that ID, so
 you shouldn't copy this project "as is" for your own app: it would result in your app being
 identified in the consent screen as "gRPC-AuthSample", and not having access to real Google
 services. Instead, configure your own XCode project following the [instructions here](https://developers.google.com/identity/sign-in/ios/).
 As with the other examples, you also should have [Cocoapods](https://cocoapods.org/#install)
 installed, as well as the relevant tools to generate the client library code. You can obtain the
 latter by following [these setup instructions](https://github.com/grpc/homebrew-grpc).
 <a name="try"></a>
 ## Try it out!
 To try the sample app, first have Cocoapods generate and install the client library for our .proto
 files:
 ```shell
 $ pod install
 ```
 (This might have to compile OpenSSL, which takes around 15 minutes if Cocoapods doesn't have it yet
 on your computer's cache).
 Finally, open the XCode workspace created by Cocoapods, and run the app.
 The first view, `SelectUserViewController.h/m`, asks you to sign in with your Google account, and to
 give the "gRPC-AuthSample" app the following permissions:
 - View your email address.
 - View your basic profile info.
 - "Test scope for access to the Zoo service".
 This last permission, corresponding to the scope `https://www.googleapis.com/auth/xapi.zoo` doesn't
 grant any real capability: it's only used for testing. You can log out at any time.
 The second view, `MakeRPCViewController.h/m`, makes a gRPC request to a test server at
 https://grpc-test.sandbox.google.com, sending the access token along with the request. The test
 service simply validates the token and writes in its response which user it belongs to, and which
 scopes it gives access to. (The client application already knows those two values; it's a way to
 verify that everything went as expected).
 The next sections guide you step-by-step through how the gRPC call in `MakeRPCViewController` is
 performed.
 <a name="rpc-object"></a>
 ## Create an RPC object and start it later
 The other basic tutorials show how to invoke an RPC by calling an asynchronous method in a generated
 client object. This shows how to initialize an object that represents the RPC, and configure it
 before starting the network request.
 Assume you have a proto service definition like this:
 ```protobuf
 option objc_class_prefix = "AUTH";
 service TestService {
  rpc UnaryCall(Request) returns (Response);
 }
 ```
 A `unaryCallWithRequest:handler:` method, with which you're already familiar, is generated for the
 `AUTHTestService` class:
 ```objective-c
 [client unaryCallWithRequest:request handler:^(AUTHResponse *response, NSError *error) {
  ...
 }];
 ```
 In addition, an `RPCToUnaryCallWithRequest:handler:` method is generated, which returns a
 not-yet-started RPC object:
 ```objective-c
 #import <ProtoRPC/ProtoRPC.h>
 ProtoRPC *call =
    [client RPCToUnaryCallWithRequest:request handler:^(AUTHResponse *response, NSError *error) {
      ...
    }];
 ```
 The RPC represented by this object can be started at any later time like this:
 ```objective-c
 [call start];
 ```
 <a name="request-metadata"></a>
 ## Set request metadata of a call: Authorization header with an access token
 The `ProtoRPC` class has a `requestMetadata` property (inherited from `GRPCCall`) defined like this:
 ```objective-c
 - (NSMutableDictionary *)requestMetadata; // nonatomic
 - (void)setRequestMetadata:(NSDictionary *)requestMetadata; // nonatomic, copy
 ```
 Setting it to a dictionary of metadata keys and values will have them sent on the wire when the call
 is started. gRPC metadata are pieces of information about the call sent by the client to the server
 (and vice versa). They take the form of key-value pairs and are essentially opaque to gRPC itself.
 ```objective-c
 call.requestMetadata = @{@"My-Header": @"Value for this header",
                         @"Another-Header": @"Its value"};
 ```
 For convenience, the property is initialized with an empty `NSMutableDictionary`, so that request
 metadata elements can be set like this:
 ```objective-c
 call.requestMetadata[@"My-Header"] = @"Value for this header";
 ```
 If you have an access token, OAuth2 specifies it is to be sent in this format:
 ```objective-c
 call.requestMetadata[@"Authorization"] = [@"Bearer " stringByAppendingString:accessToken];
 ```
 <a name="response-metadata"></a>
 ## Get response metadata of a call: Auth challenge header
 The `ProtoRPC` class also inherits a `responseMetadata` property, analogous to the request metadata
 we just looked at. It's defined like this:
 ```objective-c
@property(atomic, readonly) NSDictionary *responseMetadata;
 ```
 To access OAuth2's authentication challenge header you write:
 ```objective-c
 call.responseMetadata[@"www-authenticate"]
 ```
 Note that, as gRPC metadata elements are mapped to HTTP/2 headers (or trailers), the keys of the
 response metadata are always ASCII strings in lowercase.
 Many uses cases of response metadata are getting more details about an RPC error. For convenience,
 when a `NSError` instance is passed to an RPC handler block, the response metadata dictionary can
 also be accessed this way:
 ```objective-c
 error.userInfo[kGRPCStatusMetadataKey]
 ```
--- a/examples/objective-c/helloworld/README.md
+++ b/examples/objective-c/helloworld/README.md
@ -12,11 +12,13 @@ Here's how to build and run the Objective-C implementation of the [Hello World](
 example used in [Getting started](https://github.com/grpc/grpc/tree/master/examples).
 The example code for this and our other examples lives in the `examples` directory. Clone
-this repository to your local machine by running the following command:
+this repository to your local machine by running the following commands:
 ```sh
 $ git clone https://github.com/grpc/grpc.git
 $ cd grpc
 $ git submodule update --init
 ```
 Change your current directory to `examples/objective-c/helloworld`
@ -53,4 +55,4 @@ responds with a `HLWHelloResponse`, which contains a string that is then output
 ## Tutorial
-You can find a more detailed tutorial in [gRPC Basics: Objective-C](../route_guide/README.md).
+You can find a more detailed tutorial in [gRPC Basics: Objective-C](http://www.grpc.io/docs/tutorials/basic/objective-c.html).
--- a/examples/objective-c/route_guide/README.md
+++ b/examples/objective-c/route_guide/README.md
@ -1,360 +1,4 @@
 #gRPC Basics: Objective-C
-This tutorial provides a basic Objective-C programmer's introduction to working with gRPC. By
+This is the supporting code for the tutorial "[gRPC Basics: Objective-C](http://www.grpc.io/docs/tutorials/basic/objective-c.html)."
 walking through this example you'll learn how to:
 - Define a service in a .proto file.
 - Generate client code using the protocol buffer compiler.
 - Use the Objective-C gRPC API to write a simple client for your service.
 It assumes a passing familiarity with [protocol buffers](https://developers.google.com/protocol-buffers/docs/overview).
 Note that the example in this tutorial uses the proto3 version of the protocol buffers language,
 which is currently in alpha release: you can find out more in the [proto3 language guide](https://developers.google.com/protocol-buffers/docs/proto3)
 and see the [release notes](https://github.com/google/protobuf/releases) for the new version in the
 protocol buffers Github repository.
 This isn't a comprehensive guide to using gRPC in Objective-C: more reference documentation is
 coming soon.
 - [Why use gRPC?](#why-grpc)
 - [Example code and setup](#setup)
 - [Try it out!](#try)
 - [Defining the service](#proto)
 - [Generating client code](#protoc)
 - [Creating the client](#client)
 <a name="why-grpc"></a>
 ## Why use gRPC?
 With gRPC you can define your service once in a .proto file and implement clients and servers in any
 of gRPC's supported languages, which in turn can be run in environments ranging from servers inside
 Google to your own tablet - all the complexity of communication between different languages and
 environments is handled for you by gRPC. You also get all the advantages of working with protocol
 buffers, including efficient serialization, a simple IDL, and easy interface updating.
 gRPC and proto3 are specially suited for mobile clients: gRPC is implemented on top of HTTP/2, which
 results in network bandwidth savings over using HTTP/1.1. Serialization and parsing of the proto
 binary format is more efficient than the equivalent JSON, resulting in CPU and battery savings. And
 proto3 uses a runtime that has been optimized over the years at Google to keep code size to a
 minimum. The latter is important in Objective-C, because the ability of the compiler to strip unused
 code is limited by the dynamic nature of the language.
 <a name="setup"></a>
 ## Example code and setup
 The example code for our tutorial is in [examples/objective-c/route_guide](.).
 To download the example, clone this repository by running the following command:
 ```shell
 $ git clone https://github.com/grpc/grpc.git
 ```
 Then change your current directory to `examples/objective-c/route_guide`:
 ```shell
 $ cd examples/objective-c/route_guide
 ```
 Our example is a simple route mapping application that lets clients get information about features
 on their route, create a summary of their route, and exchange route information such as traffic
 updates with the server and other clients.
 You also should have [Cocoapods](https://cocoapods.org/#install) installed, as well as the relevant
 tools to generate the client library code (and a server in another language, for testing). You can
 obtain the latter by following [these setup instructions](https://github.com/grpc/homebrew-grpc).
 <a name="try"></a>
 ## Try it out!
 To try the sample app, we need a gRPC server running locally. Let's compile and run, for example,
 the C++ server in this repository:
 ```shell
 $ pushd ../../cpp/route_guide
 $ make
 $ ./route_guide_server &
 $ popd
 ```
 Now have Cocoapods generate and install the client library for our .proto files:
 ```shell
 $ pod install
 ```
 (This might have to compile OpenSSL, which takes around 15 minutes if Cocoapods doesn't have it yet
 on your computer's cache).
 Finally, open the XCode workspace created by Cocoapods, and run the app. You can check the calling
 code in `ViewControllers.m` and see the results in XCode's log console.
 The next sections guide you step-by-step through how this proto service is defined, how to generate
 a client library from it, and how to create an app that uses that library.
 <a name="proto"></a>
 ## Defining the service
 First let's look at how the service we're using is defined. A gRPC *service* and its method
 *request* and *response* types using [protocol buffers](https://developers.google.com/protocol-buffers/docs/overview).
 You can see the complete .proto file for our example in [`examples/protos/route_guide.proto`](../../protos/route_guide.proto).
 To define a service, you specify a named `service` in your .proto file:
 ```protobuf
 service RouteGuide {
   ...
 }
 ```
 Then you define `rpc` methods inside your service definition, specifying their request and response
 types. Protocol buffers let you define four kinds of service method, all of which are used in the
 `RouteGuide` service:
 - A *simple RPC* where the client sends a request to the server and receives a response later, just
 like a normal remote procedure call.
 ```protobuf
   // Obtains the feature at a given position.
   rpc GetFeature(Point) returns (Feature) {}
 ```
 - A *response-streaming RPC* where the client sends a request to the server and gets back a stream
 of response messages. You specify a response-streaming method by placing the `stream` keyword before
 the *response* type.
 ```protobuf
  // Obtains the Features available within the given Rectangle.  Results are
  // streamed rather than returned at once (e.g. in a response message with a
  // repeated field), as the rectangle may cover a large area and contain a
  // huge number of features.
  rpc ListFeatures(Rectangle) returns (stream Feature) {}
 ```
 - A *request-streaming RPC* where the client sends a sequence of messages to the server. Once the
 client has finished writing the messages, it waits for the server to read them all and return its
 response. You specify a request-streaming method by placing the `stream` keyword before the
 *request* type.
 ```protobuf
  // Accepts a stream of Points on a route being traversed, returning a
  // RouteSummary when traversal is completed.
  rpc RecordRoute(stream Point) returns (RouteSummary) {}
 ```
 - A *bidirectional streaming RPC* where both sides send a sequence of messages to the other. The two
 streams operate independently, so clients and servers can read and write in whatever order they
 like: for example, the server could wait to receive all the client messages before writing its
 responses, or it could alternately read a message then write a message, or some other combination of
 reads and writes. The order of messages in each stream is preserved. You specify this type of method
 by placing the `stream` keyword before both the request and the response.
 ```protobuf
  // Accepts a stream of RouteNotes sent while a route is being traversed,
  // while receiving other RouteNotes (e.g. from other users).
  rpc RouteChat(stream RouteNote) returns (stream RouteNote) {}
 ```
 Our .proto file also contains protocol buffer message type definitions for all the request and
 response types used in our service methods - for example, here's the `Point` message type:
 ```protobuf
 // Points are represented as latitude-longitude pairs in the E7 representation
 // (degrees multiplied by 10**7 and rounded to the nearest integer).
 // Latitudes should be in the range +/- 90 degrees and longitude should be in
 // the range +/- 180 degrees (inclusive).
 message Point {
  int32 latitude = 1;
  int32 longitude = 2;
 }
 ```
 You can specify a prefix to be used for your generated classes by adding the `objc_class_prefix`
 option at the top of the file. For example:
 ```protobuf
 option objc_class_prefix = "RTG";
 ```
 <a name="protoc"></a>
 ## Generating client code
 Next we need to generate the gRPC client interfaces from our .proto service definition. We do this
 using the protocol buffer compiler (`protoc`) with a special gRPC Objective-C plugin.
 For simplicity, we've provided a [Podspec file](RouteGuide.podspec)
 that runs `protoc` for you with the appropriate plugin, input, and output, and describes how to
 compile the generated files. You just need to run in this directory (`examples/objective-c/route_guide`):
 ```shell
 $ pod install
 ```
 which, before installing the generated library in the XCode project of this sample, runs:
 ```shell
 $ protoc -I ../../protos --objc_out=Pods/RouteGuide --objcgrpc_out=Pods/RouteGuide ../../protos/route_guide.proto
 ```
 Running this command generates the following files under `Pods/RouteGuide/`:
 - `RouteGuide.pbobjc.h`, the header which declares your generated message classes.
 - `RouteGuide.pbobjc.m`, which contains the implementation of your message classes.
 - `RouteGuide.pbrpc.h`, the header which declares your generated service classes.
 - `RouteGuide.pbrpc.m`, which contains the implementation of your service classes.
 These contain:
 - All the protocol buffer code to populate, serialize, and retrieve our request and response message
 types.
 - A class called `RTGRouteGuide` that lets clients call the methods defined in the `RouteGuide`
 service.
 You can also use the provided Podspec file to generate client code from any other proto service
 definition; just replace the name (matching the file name), version, and other metadata.
 <a name="client"></a>
 ## Creating the client
 In this section, we'll look at creating an Objective-C client for our `RouteGuide` service. You can
 see our complete example client code in [ViewControllers.m](ViewControllers.m).
 (Note: In your apps, for maintainability and readability reasons, you shouldn't put all of your view
 controllers in a single file; it's done here only to simplify the learning process).
 ### Constructing a client object
 To call service methods, we first need to create a client object, an instance of the generated
 `RTGRouteGuide` class. The designated initializer of the class expects a `NSString *` with the
 server address and port we want to connect to:
 ```objective-c
 #import <RouteGuide/RouteGuide.pbrpc.h>
 static NSString * const kHostAddress = @"http://localhost:50051";
 ...
 RTGRouteGuide *client = [[RTGRouteGuide alloc] initWithHost:kHostAddress];
 ```
 Notice that we've specified the HTTP scheme in the host address. This is because the server we will
 be using to test our client doesn't use [TLS](http://en.wikipedia.org/wiki/Transport_Layer_Security).
 This is fine because it will be running locally on our development machine. The most common case,
 though, is connecting with a gRPC server on the internet, running gRPC over TLS. For that case, the
 HTTPS scheme can be specified (or no scheme at all, as HTTPS is the default value). The default
 value of the port is that of the scheme selected: 443 for HTTPS and 80 for HTTP.
 ### Calling service methods
 Now let's look at how we call our service methods. As you will see, all these methods are
 asynchronous, so you can call them from the main thread of your app without worrying about freezing
 your UI or the OS killing your app.
 #### Simple RPC
 Calling the simple RPC `GetFeature` is nearly as straightforward as calling any other asynchronous
 method on Cocoa.
 ```objective-c
 RTGPoint *point = [RTGPoint message];
 point.latitude = 40E7;
 point.longitude = -74E7;
 [client getFeatureWithRequest:point handler:^(RTGFeature *response, NSError *error) {
  if (response) {
    // Successful response received
  } else {
    // RPC error
  }
 }];
 ```
 As you can see, we create and populate a request protocol buffer object (in our case `RTGPoint`).
 Then, we call the method on the client object, passing it the request, and a block to handle the
 response (or any RPC error). If the RPC finishes successfully, the handler block is called with a
 `nil` error argument, and we can read the response information from the server from the response
 argument. If, instead, some RPC error happens, the handler block is called with a `nil` response
 argument, and we can read the details of the problem from the error argument.
 ```objective-c
 NSLog(@"Found feature called %@ at %@.", response.name, response.location);
 ```
 #### Streaming RPCs
 Now let's look at our streaming methods. Here's where we call the response-streaming method
 `ListFeatures`, which results in our client receiving a stream of geographical `RTGFeature`s:
 ```objective-c
 [client listFeaturesWithRequest:rectangle
                   eventHandler:^(BOOL done, RTGFeature *response, NSError *error) {
  if (response) {
    // Element of the stream of responses received
  } else if (error) {
    // RPC error; the stream is over.
  }
  if (done) {
    // The stream is over (all the responses were received, or an error occured). Do any cleanup.
  }
 }];
 ```
 Notice how the signature of the `eventHandler` block now includes a `BOOL done` parameter. The
 `eventHandler` block can be called any number of times; only on the last call is the `done` argument
 value set to `YES`. If an error occurs, the RPC finishes and the block is called with the arguments
 `(YES, nil, error)`.
 The request-streaming method `RecordRoute` expects a stream of `RTGPoint`s from the cient. This
 stream is passed to the method as an object of class `GRXWriter`. The simplest way to create one is
 to initialize one from a `NSArray` object:
 ```objective-c
 #import <RxLibrary/GRXWriter+Immediate.h>
 ...
 RTGPoint *point1 = [RTGPoint message];
 point.latitude = 40E7;
 point.longitude = -74E7;
 RTGPoint *point2 = [RTGPoint message];
 point.latitude = 40E7;
 point.longitude = -74E7;
 GRXWriter *locationsWriter = [GRXWriter writerWithContainer:@[point1, point2]];
 [client recordRouteWithRequestsWriter:locationsWriter
                              handler:^(RTGRouteSummary *response, NSError *error) {
  if (response) {
    NSLog(@"Finished trip with %i points", response.pointCount);
    NSLog(@"Passed %i features", response.featureCount);
    NSLog(@"Travelled %i meters", response.distance);
    NSLog(@"It took %i seconds", response.elapsedTime);
  } else {
    NSLog(@"RPC error: %@", error);
  }
 }];
 ```
 The `GRXWriter` class is generic enough to allow for asynchronous streams, streams of future values,
 or even infinite streams.
 Finally, let's look at our bidirectional streaming RPC `RouteChat()`. The way to call a
 bidirectional streaming RPC is just a combination of how to call request-streaming RPCs and
 response-streaming RPCs.
 ```objective-c
 [client routeChatWithRequestsWriter:notesWriter
                       eventHandler:^(BOOL done, RTGRouteNote *note, NSError *error) {
  if (note) {
    NSLog(@"Got message %@ at %@", note.message, note.location);
  } else if (error) {
    NSLog(@"RPC error: %@", error);
  }
  if (done) {
    NSLog(@"Chat ended.");
  }
 }];
 ```
 The semantics for the handler block and the `GRXWriter` argument here are exactly the same as for
 our request-streaming and response-streaming methods. Although both client and server will always
 get the other's messages in the order they were written, the two streams operate completely
 independently.