Developer's Guide: .NET

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The Google Health Data API allows client applications to view and update Health content in the form of Google Data API feeds. Your client application can request a user's profile as a CCR document, retrieve a list of notices sent to their account, or send a notice to a user.

In addition to providing some background on the capabilities of the Health Data API, this document provides examples for interacting with the API using the .NET client library. This document provides .NET specifics for performing the general actions described in the developer's guide overview page.

Contents

Audience

This document is intended for programmers who want to write client applications using the Google Data API .NET client library that can interact with Google Health.

Getting started

To use the .NET client library, you'll need the .NET 1.2.x runtime, and you should also be current on all patches. After downloading the client library, you'll find the DLLs you need to get started in the lib/Release subdirectory of the distribution.

There are some ASP samples available for download to demonstrate basic usage of the Health API.

To compile the examples in this document into your own code, you'll need to import the following namespaces:

<%@ Import Namespace="System.Net" %>
<%@ Import Namespace="System.Text.RegularExpressions" %>
<%@ Import Namespace="System.IO" %>
<%@ Import Namespace="System.Xml" %>
<%@ Import Namespace="Google.GData.Client" %>
<%@ Import Namespace="Google.GData.Health" %>
<%@ Import Namespace="Google.GData.Extensions" %>

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Authenticating to the Health service

Before you can interact with Google Health, you must register your application with Google. Register your domains by reviewing and fill-out the API Terms of Service.

Multiple-user web application client authentication

The AuthSub login protocol allows your web-based application to have a user authenticate through Google's servers. This article covers the basics of how to use AuthSub in the .NET client library.

The following code generates an AuthSub URL for Google Health.

String authSubLink = AuthSubUtil.getRequestUrl("https", "www.google.com",
  "/health/authsub", "http://localhost/test/Health.aspx",
  "https://www.google.com/health/feeds/", false, true);

Here we are using another version of getRequestUrl that allows us to specify the Google Health AuthSub server. You also need to specify the service name for Google Health, health, as seen here:

GAuthSubRequestFactory authFactory = new GAuthSubRequestFactory("health", "Health-Profile-Tester");

ClientLogin username/password authentication

Use ClientLogin authentication if your client is a standalone, single-user "installed" client (such as a desktop application). Set the credentials of your service object as follows:

HealthService service = new HealthService("exampleCo-exampleApp-1");
service.setUserCredentials("email", "password");

In the snippet above, we pass a single argument to the HealthService constructor. The parameter should be set to a string identifying your application and be of the form companyName-applicationName-versionID.

For more information about ClientLogin authentication, including sample requests and responses, see the Authentication for Installed Applications documentation.

Note: Use the same token for all requests in a given session; don't acquire a new token for each Health request.

Note: As described in the ClientLogin documentation, the authentication request may fail and request a CAPTCHA challenge. If you want Google to issue and handle the CAPTCHA challenge, then send the user to https://www.google.com/accounts/DisplayUnlockCaptcha?service=health (rather than to the CAPTCHA-handling URL given in the ClientLogin documentation).

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Get a user's profile

The profile feed allows you to retrieve a CCR document describing a user's health information stored with Google. Each profile is encapsulated inside of an Atom entry. The .NET client library can be used to extract the CCR information and print it to the page:

HealthQuery profileQuery = new HealthQuery("https://www.google.com/health/feeds/profile/default");
profileQuery.Digest = true;

try
{
  HealthFeed feed = service.Query(profileQuery);

  foreach (HealthEntry entry in feed.Entries)
  {
    XmlNode ccr = entry.CCR;
    if (ccr != null)
    {
      Response.Write("<pre>");
      StringWriter sw = new StringWriter();
      XmlTextWriter xw = new XmlTextWriter(sw);
      xw.Formatting = Formatting.Indented;
      ccr.WriteTo(xw);
      Response.Write(HttpUtility.HtmlEncode(sw.ToString()));
      Response.Write("</pre>");
    }
  }
}
catch (GDataRequestException e)
{
  ...
}

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Interacting with the register feed

Notices are the primary means by which your application can communicate and interact with the user. They allow you to send informational messages and CCR profile data to a user. Currently, the only thing you can do using AuthSub is post new notices; you can't update or delete notices using AuthSub. ClientLogin allows for reading existing notices, posting new notices, and updating or deleting notices.

Get a list of notices

Note: This feature is available only with ClientLogin.

You can retrieve notices that your application has access to view using the register feed in conjunction with a profile ID: register/ui/profileID. Note that you can use standard Google Data API query parameters to narrow down the results of this query.

The following code retrieves all of the notices associated with the given profile. It also prints out any attached CCR data appended to a notice.

FeedQuery query = new FeedQuery();

query.Uri = new Uri("https://www.google.com/health/feeds/register/ui/profileID");

AtomFeed healthFeed = service.Query(query);
foreach (AtomEntry entry in healthFeed.Entries)
{
  Response.Write("<div>");
  Response.Write("From: " + entry.Authors[0].Name + "<br/>");
  Response.Write("Date: " + entry.Published + "<br/>");
  Response.Write("Subject: " + entry.Title.Text + "<br/>");
  Response.Write("Message: " + entry.Content.Content + "<br/>");

  foreach (XmlElement element in entry.ExtensionElements)
  {
    if (element.Name == "ContinuityOfCareRecord")
    {
      Response.Write("Contains CCR data: <br/>");
      Response.Write("<pre>");
      StringWriter sw = new System.IO.StringWriter();
      XmlTextWriter xw = new XmlTextWriter(sw);
      xw.Formatting = Formatting.Indented;
      element.WriteTo(xw);
      Response.Write(HttpUtility.HtmlEncode(sw.ToString()));
      Response.Write("</pre>");
    }
  }

  Response.Write("</div><br/>");
}

The above also prints out any attached CCR data appended to a notice.

Send a notice

Creating a new notice is accomplished by constructing an Atom entry and sending an HTTP POST to the register feed.

CCR data can be included with your notice. The below code shows adding a CCR fragment from a string variable called ccrXmlString.

AtomEntry newNotice = new AtomEntry();

newNotice.Title.Text = "A test message";

newNotice.Content.Content = "This is a test message.";

// Set the content type if you're using HTML in your message body
//newNotice.Content.Type = "html";

XmlDocument ccrDoc = new XmlDocument();
ccrDoc.LoadXml(ccrXmlString);
newNotice.ExtensionElements.Add(ccrDoc.DocumentElement);

service.Insert(new Uri("https://www.google.com/health/feeds/register/default"), newNotice);

...

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