Difference between revisions of "Rest API"

Revision as of 12:09, 21 September 2009

Introduction

The Email API provides most of the functions of Rackspace's Email and Apps Control Panel through a web-based API (Application Programming Interface). Whether it is adding a new customer account, adding mailboxes, or any other of the supported features the API allows your application to administer the changes regardless of your application's language or nature. The API is a RESTful web service based on the Hypertext Transfer Protocol (HTTP). Actions and data requests are performed by using HTTP-based commands. For more information on RESTful web services refer to the following sites:

http://en.wikipedia.org/wiki/Representational_State_Transfer

http://java.sun.com/developer/technicalArticles/WebServices/restful/

Right now the API is in its beta release and is restricted to resellers only.

Operations

The following pages detail the operations that the API supports. The operations are grouped into sections based on the entity/object types that each operation interacts with.

The examples shown in the operation pages are written in Ruby and extensively use the helper functions shown in the Ruby Examples below.

Accessing the API

Your application will need to make HTTP requests to remote servers. Most programming languages have this function provided in its class library. In addition to the common GET and POST HTTP methods, the library used will also need to support PUT and DELETE. All API calls should be directed to a URL in the following format.

http://api.emailsrvr.com/(version)/(resource)

Example:

http://api.emailsrvr.com/v0/customers/12345678/domains/customerbusiness.com

Versions

The API version number is a component of the URL that is used to access the API. For example, to access the root of the API, the URL is http://api.emailsrvr.com/v0/. Bug fixes and minor non-breaking changes will be made without changing the version number. When major features or breaking changes are introduced, the version number will be incremented. It is not yet determined how many versions are going to be supported at any one time.

Note: Pre-release versions of the API will be located at http://api.emailsrvr.com/v0/.

Authentication

To gain access to the API, your request must include a properly constructed X-Api-Signature HTTP header. Details on what to put in the header are below. To construct the header, you must have the following keys that that are generated from the Control Panel Web interface.

An unsuccessful authentication will result in a 403 HTTP code.

X-Api-Signature Header

Format is as follows:

<User Key>:<Timestamp>:<Signature>

Example: eGbq9/2hcZsRlr1JV1Pi:20010317143725:HKUn0aajpSDx7qqGK3vqzn3FglI=

User Key:
This is the public key issued by the Control Panel interface.

Timestamp:
The format is YYYYMMDDHHmmssff. All values besides year are zero-padded to two spaces. For example, March 17th 2001 at 2:37.25pm would be 20010317143725.

Signature:

A SHA1 (Secure Hash Algorithm) hash must be applied to a string with the following information:

<User Key><User Agent><Timestamp><Secret Key>

Note that the 'User Agent' must be the exact same as what is specified in the User-Agent HTTP Header. Using the above example data, the string before hashing is:
eGbq9/2hcZsRlr1JV1PiRackspace Management Interface20010317143725QHOvchm/40czXhJ1OxfxK7jDHr3t

Resulting base-64 SHA1 Hash:
HKUn0aajpSDx7qqGK3vqzn3FglI=

Be sure to encode the binary hash, not the hex hash, into base-64. The resulting string should be 28 characters long.

Using the API

Requests

HTTP requests should be sent to the server with the correct URL, HTTP Method, HTTP Headers and form data (if needed). The URLs, corresponding HTTP Methods, and necessary form data for the desired operations are detailed in the operation pages.

URL

The URLs are specifies the resource or resource collection. Objects are organized in a tree collection, starting with customers at the top, then domains, then domain objects next (such as mailboxes, contacts, and distribution lists) and so on. The URLs of the resources and collections accessible are found on the operation pages.

HTTP Method

It is the HTTP Method that specifies what operation will be done on the resource. For example, to get the details of a mailbox a HTTP GET will be done on /customers/12345678/domains/example.com/ex/mailboxes/john.smith. If the mailbox does not exist, a HTTP POST to the same URL with the necessary form data will add the mailbox. Then, a HTTP PUT to the same URL will edit mailbox. And to delete the mailbox, an HTTP DELETE would be used.

The types of operations a certain method performs is consistent and is outlined in the table below.

HTTP Headers

All requests to the API must then include HTTP headers with the following information:

Filter/Search

The results of Index actions can be filtered/searched. The index URLs can take either one of the query strings: "?startswith=xx" or "?contains=xx," where "xx" is the key word. If the request specifies more than one of these two query strings, a 400 HTTP error will be returned. Different fields will be searched depending on the resource type, see below.

Note that "0-9" is a reserved key word for query string "startswith." It represents any result starting with numbers.

Reference Number

For the customer object only, the query string "referenceNumber=xx" searches for a customer with an exact reference number. The result if found is the detail page of the customer.

Throttling

The server limits the number of requests allowed per user in a certain period of time. The current limit is 2500 requests over 5 minutes. The number of requests made are logged per minute. Calls that were made correctly with a user's API key, but not completed for any reason, including those exceeding the throttle limit, are included in this count.

If a user is over the throttling limit then a 403 HTTP code will be returned with an "Exceeded request limits" message.

Examples

Example requests:

Index of Exchange Mailboxes:

Hypertext Transfer Protocol
    GET /v0/customers/12345678/domains/example.com/ex/mailboxes?size=100&offset=100 HTTP/1.1
        Request Method: GET
        Request URI: /v0/customers/12345678/domains/example.com/ex/mailboxes?size=100&offset=100
        Request Version: HTTP/1.1
    Host: api.emailsrvr.com
    User-Agent: Rackspace Management Interface
    X-Api-Signature: eGbq9/2hcZsRlr1JV1Pi:20010317143725:HKUn0aajpSDx7qqGK3vqzn3FglI=
    Accept: text/xml

    
Adding New Exchange Mailbox:

Hypertext Transfer Protocol
    POST /v0/customers/12345678/domains/example.com/ex/mailboxes/john.smith HTTP/1.1
        Request Method: POST
        Request URI: /v0/customers/12345678/domains/example.com/ex/mailboxes/john.smith
        Request Version: HTTP/1.1
    Host: api.emailsrvr.com
    User-Agent: Rackspace Management Interface
    X-Api-Signature: eGbq9/2hcZsRlr1JV1Pi:20010317143725:HKUn0aajpSDx7qqGK3vqzn3FglI=
    Accept: text/xml
    Content-Length: 53
        [Content length: 53]
    Content-Type: application/x-www-form-urlencoded
    
Line-based text data: application/x-www-form-urlencoded
    size=2048&displayName=John%20Smith&password=abcABC123
    

Responses

On a successfully executed request, a 200 HTTP Code is returned. Requested data is also returned if the operation was a Show or Index action. If the request is unsuccessful, then an error HTTP Code is returned with a message detailing the error. The errors and their corresponding codes are detailed on the operation pages.

Returned Data

Requests for data (index and show requests) are returned with XML or JSON data based on what your application populates the HTTP Accept Header with.

For XML, populate the header with 'text/xml' (ex: Headers!["Accept"] = "text/xml"). The XML document returned will conform to a published XSD (XML Schema Document). There are many ways to extract data from an XML document, but we have found that the XPath tree-style traversal has served our purposes. In any case, your application will likely need to use a library with the functions necessary for whichever method you choose to use to extract data.

For JSON, populate the header with 'application/json' (ex: Headers!["Accept"] = "application/json"). As with XML, a library will likely be needed to parse the data.

Paging

The results of Index actions are split into pages to lessen potentially high resource usage. The index URLs have a query string with parameters in the format "?size=xx&offset=xx." If a query parameter is omitted, the default value is used.

Examples

Ruby

This examples is written in Ruby. To make the examples shorter, helper methods have been written. These methods are part of a NetMethods module. The contents of the NetMethods module is listed below.

module NetMethods 
  def get(url_string, format)
    url = URI.parse('http://' + server_host + server_port + version + url_string)
    @response = Net::HTTP::start(url.host, url.port)  do |http|
      sign_request
      assign_format(format)
      @request = Net::HTTP::Get.new(url.path, @headers)
     
      http.request(@request)
    end
  end
 
  def post(url_string, format, fields_hash)
    url = URI.parse('http://' + server_host + server_port + version + url_string)

    sign_request
    assign_format(format)
    @request = Net::HTTP::Post.new(url.path, @headers)

    @request.set_form_data(fields_hash)
    @response = Net::HTTP::start(url.host, url.port) do |http|
      http.request(@request)
    end
  end

  def assign_format (format)
    @headers['Accept'] = format
  end
   
  def sign_request
    userAgent = 'Ruby Test Client'
    timestamp = DateTime.now.new_offset.strftime('%Y%m%d%H%M%S00')
    apiKey = 'XXXXXXXXXXXXXXXXXXXX'
    secretKey = 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
   
    data_to_sign = apiKey + userAgent + timestamp + secretKey
   
    signature = Base64.encode64(Digest::SHA1.digest(data_to_sign))
   
    @headers = Hash.new
    @headers['User-Agent'] = userAgent
    @headers['X-Api-Signature'] = apiKey + ":" + timestamp + ":" + signature
  end
 
  def server_host
    'api.emailsrvr.com'
  end
 
  def server_port
    '80'
  end

  def version
    '/v0'
  end
end 

C#

This examples is written in C#.

using System;
using System.Collections.Specialized;
using System.Security.Cryptography;
using System.Text;
using System.Net;

public class WebMethods
{
  private WebClientBase client;
  private string baseUrl;
  private string apiKey;
  private string secretKey;

  public WebMethods(WebClientBase client, string baseUrl, string apiKey, string secretKey)
  {
    this.client = client;
    this.baseUrl = baseUrl;
    this.apiKey = apiKey;
    this.secretKey = secretKey;
  }

  public virtual string Get(string url)
  {
    return MakeRemoteCall((client) =>
      {
        return client.DownloadString(baseUrl + url);
      },
      format);
  }

  public virtual string Post(string url, NameValueCollection data)
  {
    return MakeRemoteCall((client) =>
      {
        var bytes = client.UploadValues(baseUrl + url, data);
        return Encoding.UTF8.GetString(bytes);
      },
      format);
  }

  private void SignMessage()
  {
    var userAgent = "C# Client Library";
    client.Headers["User-Agent"] = userAgent;

    var dateTime = DateTime.UtcNow.ToString("yyyyMMddHHmmssff");

    var dataToSign = apiKey + userAgent + dateTime + secretKey;
    var hash = SHA1.Create();
    var signedBytes = hash.ComputeHash(Encoding.UTF8.GetBytes(dataToSign));
    var signature = Convert.ToBase64String(signedBytes);

    client.Headers["X-Api-Signature"] = apiKey + ":" + dateTime + ":" + signature;
  }

  private void AssignFormat(string format)
  {
    client.Headers["Accept"] = format;
  }

  private string MakeRemoteCall(Func<WebClientBase, string> remoteCall, string format)
  {
    try
    {
      SignMessage();
      AssignFormat(format);
      return remoteCall.Invoke(client);
    }
    catch (WebException e)
    {
      throw new ApiException(e);
    }
  }
}

PHP

The PHP Example can be found here.