Introduction to the Google APIs .NET client library https://code.google.com/p/google-api-dotnet-client/

1. Introduction to the .NET
client library
https://code.google.com/p/google-api-dotnet-client/
Eyal Peled
peleyal@

2. Agenda
Rest
Http Layer
Client Service
Service Request
Media
OAuth2
PCL
3rd parties
Discovery
Code Generator
https://code.google.com/p/google-api-dotnet-client/

3. Agenda
Rest
Http Layer
Client Service
Service Request
Media
OAuth2
PCL
3rd parties
Discovery
Code Generator
https://code.google.com/p/google-api-dotnet-client/

4. Google APIs .NET REST
●
Representational State Transfer
●
Client and servers
transfer resource representations
●
The set of verbs in a REST API
is typically limited to “CRUD”
●
See Google API Explorer for links
to all Google API Rest services
https://code.google.com/p/google-api-dotnet-client/

5. Agenda
Rest
Http Layer
Client Service
Service Request
Media
OAuth2
PCL
3rd parties
Discovery
Code Generator
https://code.google.com/p/google-api-dotnet-client/

6. Google APIs .NET Http Layer
HttpClient
●A simple programming interface to code against -
SendAsync, GetAsync, etc.
●It uses the new Task based asynchronous methods, which
makes writing responsive and performant UI applications
across all platforms a lot simpler.
●Targets Windows 7 and 8, WP, etc. See PCL
●Part of .NET 4.5 (not PCL) and available for .NET 4.0
developers as a PCL (using NuGet)
https://code.google.com/p/google-api-dotnet-client/

7. https://code.google.com/p/google-api-dotnet-client/
Google APIs .NET Http Layer
HttpClient
●Message handlers as a key architectural component
●Every request is passed through a chain of handlers
(derive from HttpMessageHandler)
●HttpClientHandler uses
●
System.Net.HttpWebRequest
and
●
System.Net.HttpWebResponse
under the cover, and provides a
great abstraction.

8. Google APIs .NET Http Layer
ConfigurableMessageHandler The main HTTP logic
IHttpExecuteInterceptor Interceptor before request is made
IHttpUnsuccessfulResponseHandler Handler for abnormal HTTP response
IHttpExceptionHandler Handler for an exception during a request
https://code.google.com/p/google-api-dotnet-client/

9. Google APIs .NET Http Layer
ws
https://code.google.com/p/google-api-dotnet-client/
ConfigurableHttpClient
●
Inherits from HttpClient
●
Contains the handler

10. Google APIs .NET Http Layer
https://code.google.com/p/google-api-dotnet-client/
HttpClientFactory
• Constructs a new HttpClient
• Great for mocking using
CreateHandler
(By default creates HttpClientHandler)

11. Google APIs .NET Http Layer
https://code.google.com/p/google-api-dotnet-client/
BackOffHandler
●
Implements exception and unsuccessful
response handlers
●
Contains a BackOff logic

12. Agenda
Rest
Http Layer
Client Service
Service Request
Media
OAuth2
PCL
3rd parties
Discovery
Code Generator
https://code.google.com/p/google-api-dotnet-client/

13. Google APIs .NET Client Service
https://code.google.com/p/google-api-dotnet-client/
IClientService
●
Serialization
●
GZip support
●
Authenticator
(Will be removed after a new Auth library will
be created)

14. Google APIs .NET Client Service
https://code.google.com/p/google-api-dotnet-client/
BaseClientService
●
Thread-safe uses Initializer
●
Expoenential back-off policy
●
Api Key
●
GZip Enabled
●
Client Factory

15. Google APIs .NET Client Service
Generated services inherit from BaseClientSerivce
●
They implement resource related properties
• They contain resources and methods based on Discovery
Follow DriveService implementation in the next slide...
https://code.google.com/p/google-api-dotnet-client/

16. Google APIs .NET Client Service
public class DriveService : Google.Apis.Services.BaseClientService
{
public DriveService(Google.Apis.Services.BaseClientService.Initializer initializer)
: base(initializer)
{
about = new AboutResource(this);
files = new FilesResource(this);
...
}
public override string Name { get { return "drive"; } }
public override string BaseUri { get { return "https://www.googleapis.com/drive/v2/"; } }
public override string BasePath { get { return "drive/v2/"; } }
public enum Scopes
{
/// <summary>View and manage the files and documents in your Google Drive</summary>
[Google.Apis.Util.StringValueAttribute("https://www.googleapis.com/auth/drive")]
Drive,
/// <summary>View and manage its own configuration data in your Google Drive</summary>
[Google.Apis.Util.StringValueAttribute("https://www.googleapis.com/auth/drive.appdata")]
DriveAppdata,/// <summary>View your Google Drive apps</summary>
…
}
https://code.google.com/p/google-api-dotnet-client/

17. Agenda
Rest
Http Layer
Client Service
Service Request
Media
OAuth2
PCL
3rd parties
Discovery
Code Generator
https://code.google.com/p/google-api-dotnet-client/

18. Google APIs .NET Service Request
https://code.google.com/p/google-api-dotnet-client/
ClientServiceRequest
●
ETag support
●
based TPL
Execute ExecuteAsync
ExecuteAsStream
ExecuteAsStreamAsync

19. Google APIs .NET Service Request
Generated requests inherit from ClientServiceRequest
● They Implement the concrete HttpMethod, RestPath, etc.
● They are executed by calling to Execute (or ExecuteAsync)
Follow GetRequest (File) implementation in the next slide...
https://code.google.com/p/google-api-dotnet-client/

20. Google APIs .NET Service Request
public class GetRequest : DriveBaseServiceRequest<Google.Apis.Drive.v2.Data.File>
{
public GetRequest(Google.Apis.Services.IClientService service, string fileId)
: base(service)
{
FileId = fileId;
InitParameters();
}
[Google.Apis.Util.RequestParameterAttribute("fileId", Google.Apis.Util.RequestParameterType.Path)]
public virtual string FileId { get; private set; }
[Google.Apis.Util.RequestParameterAttribute("projection",
Google.Apis.Util.RequestParameterType.Query)]
public virtual System.Nullable<ProjectionEnum> Projection { get; set; }
public override string MethodName { get { return "get"; } }
public override string HttpMethod { get { return "GET"; } }
public override string RestPath { get { return "files/{fileId}"; } }
…
}
https://code.google.com/p/google-api-dotnet-client/

21. Agenda
Rest
Http Layer
Client Service
Service Request
Media
OAuth2
PCL
3rd parties
Discovery
Code Generator
https://code.google.com/p/google-api-dotnet-client/

22. Google APIs .NET Media
Resumable Media Upload
https://code.google.com/p/google-api-dotnet-client/
The protocol
●
Recovery server errors
●
Chunk size
●
Progress changed event
●
Upload
●
UploadAsync

23. Google APIs .NET Media
Media Downloader
https://code.google.com/p/google-api-dotnet-client/
●
Chunk size
●
ProgressChanged event
●
Download
●
DownloadAsync

24. Agenda
Rest
Http Layer
Client Service
Service Request
Media
OAuth2
PCL
3rd parties
Discovery
Code Generator
https://code.google.com/p/google-api-dotnet-client/

25. Google APIs .NET OAuth2
https://code.google.com/p/google-api-dotnet-client/

26. Google APIs .NET OAuth2
https://code.google.com/p/google-api-dotnet-client/
Google OAuth2 documentation
Google API Console
Support installed and web applications
Support service account
Current implementation
●IAuthenticator to apply authorization header to a request
●Usage of DotNetOpenAuth
●Implementation is in Google.Apis.Authentication.OAuth2

27. Google APIs .NET OAuth2
https://code.google.com/p/google-api-dotnet-client/
Roadmap
●
Remove DotNetOpenAuth
●
Create a Google.Apis.Auth PCL
●
Create concrete implementation for

Google.Apis.Auth.DotNet4 (installed applications)

Google.Apis.Auth.Mvc4 (web applications)

Google.Apis.Auth.WP (Windows Phone)

Google.Apis.Auth.WinRT (Windows 8 applications)
The main reason for creating a specific assembly for a
platform is based on the way we read the authorization code.

28. Agenda
Rest
Http Layer
Client Service
Service Request
Media
OAuth2
PCL
3rd parties
Discovery
Code Generator
https://code.google.com/p/google-api-dotnet-client/

29. Google APIs .NET PCL
Portable Class Library
Current status
●
Google.Apis is PCL
●
The generated APIs are PCLs as well
Roadmap
●
Create a Google.Apis.Auth PCL library (see OAuth slides)
https://code.google.com/p/google-api-dotnet-client/

30. Agenda
Rest
Http Layer
Client Service
Service Request
Media
OAuth2
PCL
3rd parties
Discovery
Code Generator
https://code.google.com/p/google-api-dotnet-client/

31. Google APIs .NET 3rd parties
NuGet packages:
•
Newtonsoft.Json 5.0.5
Json is the client's default data format
•
Microsoft.Net.Http 2.1.10
We use HttpClient as our transport layer.
•
Microsoft.Bcl.Async 1.10.16
Although we target .NET 4.0 we use async-await
•
Zlib.Portable 1.9.2
While GZip is enabled, we use this library to encode messages
•
log4net
The library's logging framework
https://code.google.com/p/google-api-dotnet-client/

32. Agenda
Rest
Http Layer
Client Service
Service Request
Media
OAuth2
PCL
3rd parties
Discovery
Code Generator
https://code.google.com/p/google-api-dotnet-client/

33. Google APIs .NET Discovery
●
Each Google API service exposes a discovery doc using the
json format (e.g.
https://www.googleapis.com/discovery/v1/apis/drive/v2/rest)
●
The service generator generates a service, resources,
models and requests by this doc
●
Similar to wsdl
●
Read more about Discovery API here
https://code.google.com/p/google-api-dotnet-client/

34. Agenda
Rest
Http Layer
Client Service
Service Request
Media
OAuth2
PCL
3rd parties
Discovery
Code Generator
https://code.google.com/p/google-api-dotnet-client/

35. Google APIs .NET Code Generator
https://code.google.com/p/google-api-dotnet-client/
●
From 1.5.0-beta we use Google APIs client generator (which
is available here)
●
The .NET specific templates for 1.5.0-beta are available
here.
●
The decision to move to Google APIs client generator was
based on the following:

Share logic with other Google APIs client libraries

It is easier to use Django templates

It reduces library code significantly

One step forward supporting End Points

36. Resources
•
code.google.com - WIKI
•
Google API .NET Announcements blog
•
StackOverflow google-api-dotnet-client tag
•
Google Group
•
Google API Explorer
•
Google API Console
https://code.google.com/p/google-api-dotnet-client/

37. Questions?
https://code.google.com/p/google-api-dotnet-client/