Category: .NET

I love mashups. It’s fun to combine technologies in unexpected ways. So when Wade Wegner of Salesforce asked me to participate in a webinar about the new Salesforce Toolkit for .NET, I decided to think of something unique to demonstrate. So, I showed off how to link Twilio – which in an API-driven service for telephony and SMS – with Salesforce.com data. In this scenario, job applicants can call a phone number, enter their tracking ID and hear the current status of their application. The rest of this blog post walks through what I built.

The Salesforce.com application

In my developer sandbox, I added a new custom object called Job Application that holds data about applicants, which job they applied to, and the status of the application (e.g. Submitted, In Review, Rejected).

I then created a bunch of records for job applicants. Here’s an example of one applicant in my system.

I want to expose a programmatic interface to retrieve “Application Status” that’s an aggregation of multiple objects. To make that happen, I created a custom Apex controller that exposes a REST endpoint. You can see below that I defined a custom class called ApplicationStatus and then a GetStatus operation that inflates and returns that custom object. The RESTful attributes (@RestResource, @HttpGet) make this a service accessible via REST query.

@RestResource(urlMapping='/ApplicationStatus/*')
global class CandidateRestService {

    global class ApplicationStatus {

        String ApplicationId {get; set; }
        String JobName {get; set; }
        String ApplicantName {get; set; }
        String Status {get; set; }
    }

    @HttpGet
    global static ApplicationStatus GetStatus(){

        //get the context of the request
        RestRequest req = RestContext.request;
        //extract the job application value from the URL
        String appId = req.requestURI.substring(req.requestURI.lastIndexOf('/')+1);

        //retrieve the job application
        seroter__Job_Application__c application = [SELECT Id, seroter__Application_Status__c, seroter__Applicant__r.Name, seroter__Job_Opening__r.seroter__Job_Title__c FROM seroter__Job_Application__c WHERE seroter__Application_ID__c = :appId];

        //create the application status object using relationship (__r) values
        ApplicationStatus status = new ApplicationStatus();
        status.ApplicationId = appId;
        status.Status = application.seroter__Application_Status__c;
        status.ApplicantName = application.seroter__Applicant__r.Name;
        status.JobName = application.seroter__Job_Opening__r.seroter__Job_Title__c;

        return status;
    }
}

With this in place – and creating an “application” that gave me a consumer key and secret for remote access – I had everything I needed to consume Salesforce.com data.

The ASP.NET Web API project

How does Twilio know what to say when you call one of their phone numbers? They have a markup language called TwiML that includes the constructs for handling incoming calls. What I needed was a web service that Twilio could reach and return instructions for what to say to the caller.

I created an ASP.NET Web API project for this service. I added NuGet packages for DeveloperForce.Force (to get the Force.com Toolkit for .NET) and Twilio.Mvc, Twilio.TwiML, and Twilio. Before slinging the Web API Controller, I added a custom class that helps the Force Toolkit talk to custom REST APIs. This class, CustomServiceHttpClient, copies the base ServiceHttpClient class and changes a single line.

public async Task<T> HttpGetAsync<T>(string urlSuffix)
        {
            var url = string.Format("{0}/{1}", _instanceUrl, urlSuffix);

            var request = new HttpRequestMessage()
            {
                RequestUri = new Uri(url),
                Method = HttpMethod.Get
            };

Why did I do this? The class that comes with the Toolkit builds up a particular URL that maps to the standard Salesforce.com REST API. However, custom REST services use a different URL pattern. This custom class just takes in the base URL (returned by the authentication query) and appends a suffix that includes the path to my Apex controller operation.

I slightly changed the WebApiConfig.cs to add a “type” to the route template. I’ll use this to create a pair of different URIs for Twilio to use. I want one operation that it calls to get initial instructions (/api/status/init) and another to get the actual status resource (/api/status).

public static class WebApiConfig
    {
        public static void Register(HttpConfiguration config)
        {
            // Web API configuration and services

            // Web API routes
            config.MapHttpAttributeRoutes();

            config.Routes.MapHttpRoute(
                name: "DefaultApi",
                routeTemplate: "api/{controller}/{type}",
                defaults: new { type = RouteParameter.Optional }
            );
        }
    }

Now comes the new StatusController.cs that handles the REST input. The first operation takes in VoiceRequest object that comes from Twilio and I build up a TwiML response. What’s cool is that Twilio can collect data from the caller. See the “Gather” operation where I instruct Twilio to get 6 digits from the caller, and post to another URI. In this case, it’s a version of this endpoint hosted in Windows Azure. Finally, I forced the Web API to return an XML document instead of sending back JSON (regardless of what comes in the inbound Accept header).

The second operation retrieves the Salesforce credentials from my configuration file, gets a token from Salesforce (via the Toolkit), issues the query to the custom REST endpoint, and takes the resulting job application detail and injects it into the TwiML response.

public class StatusController : ApiController
    {
        // GET api/<controller>/init
        public HttpResponseMessage Get(string type, [FromUri]VoiceRequest req)
        {
            //build Twilio response using TwiML generator
            TwilioResponse resp = new TwilioResponse();
            resp.Say("Thanks for calling the status hotline.", new { voice = "woman" });
            //Gather 6 digits and send GET request to endpoint specified in the action
            resp.BeginGather(new { action = "http://twilioforcetoolkit.azurewebsites.net/api/status", method = "GET", numDigits = "6" })
                .Say("Please enter the job application ID", new { voice = "woman" });
            resp.EndGather();

            //be sure to force XML in the response
            return Request.CreateResponse(HttpStatusCode.OK, resp.Element, "text/xml");

        }

        // GET api/<controller>
        public async Task<HttpResponseMessage> Get([FromUri]VoiceRequest req)
        {
            var from = req.From;
            //get the digits the user typed in
            var nums = req.Digits;

            //SFDC lookup
            //grab credentials from configuration file
            string consumerkey = ConfigurationManager.AppSettings["consumerkey"];
            string consumersecret = ConfigurationManager.AppSettings["consumersecret"];
            string username = ConfigurationManager.AppSettings["username"];
            string password = ConfigurationManager.AppSettings["password"];

            //create variables for our auth-returned values
            string url, token, version;
            //authenticate the user using Toolkit operations
            var auth = new AuthenticationClient();

            //authenticate
            await auth.UsernamePasswordAsync(consumerkey, consumersecret, username, password);
            url = auth.InstanceUrl;
            token = auth.AccessToken;
            version = auth.ApiVersion;

            //create custom client that takes custom REST path
            var client = new CustomServiceHttpClient(url, token, new HttpClient());

            //reference the numbers provided by the caller
            string jobId = nums;

            //send GET request to endpoint
            var status = await client.HttpGetAsync<dynamic>("services/apexrest/seroter/ApplicationStatus/" + jobId);
            //get status result
            JObject statusResult = JObject.Parse(System.Convert.ToString(status));

            //create Twilio response
            TwilioResponse resp = new TwilioResponse();
            //tell Twilio what to say to the caller
            resp.Say(string.Format("For job {0}, job status is {1}", statusResult["JobName"], statusResult["Status"]), new { voice = "woman" });

            //be sure to force XML in the response
            return Request.CreateResponse(HttpStatusCode.OK, resp.Element, "text/xml");
        }
     }

My Web API service was now ready to go.

Running the ASP.NET Web API in Windows Azure

As you can imagine, Twilio can only talk to services exposed to the public internet. For simplicity sake, I jammed this into Windows Azure Web Sites from Visual Studio.

Once this service was deployed, I hit the two URLs to make sure that it was returning TwiML that Twilio could use. The first request to /api/status/init returned:

Cool! Let’s see what happens when I call the subsequent service endpoint and provide the application ID in the URL. Notice that the application ID provided returns the corresponding job status.

So far so good. Last step? Add Twilio to the mix.

Setup Twilio Phone Number

First off, I bought a new Twilio number. They make it so damn easy to do!

With the number in place, I just had to tell Twilio what to do when the phone number is called. On the phone number’s settings page, I can set how Twilio should respond to Voice or Messaging input. In both cases, I point to a location that returns a static or dynamic TwiML doc. For this scenario, I pointed to the ASP.NET Web API service and chose the “GET” operation.

So what happens when I call? Hear the audio below:

One of the other great Twilio features is the analytics. After calling the number, I can instantly see usage trends …

… and a log of the call itself. Notice that I see the actual TwiML payload processed for the request. That’s pretty awesome for troubleshooting and auditing.

Summary

In the cloud, it’s often about combining best-of-breed capabilities to deliver innovative solutions that no one technology has. It’s a lot easier to do this when working with such API-friendly systems as Salesforce and Twilio. I’m sure you can imagine all sorts of valuable cases where an SMS or voice call could retrieve (or create) data in a system. Imagine walking a sales rep through a call and collecting all the data from the customer visit and creating an Opportunity record! In this scenario, we saw how to query Salesforce.com (using the Force Toolkit for .NET) from a phone call and return a small bit of data. I hope you enjoyed the walkthrough, and keep an eye out for the recorded webcast where Wade and I explain a host of different scenarios for this Force Toolkit.

Salesforce.com is a juggernaut in the software-as-a-service space and continues to sign up a diverse pool of global customers. While Salesforce relies on its own language (Apex) for coding extensions that run within the platform, developers can use any programming framework to integrate with Salesforce.com from external apps. That said, .NET is one of the largest communities in the Salesforce developer ecosystem and they have content specifically targeted at .NET devs.

A few months back, a Toolkit for .NET was released and I’m participating in a fun webinar next week where we show off a wide range of use cases for it. The Toolkit makes it super easy to interact with the full Force.com platform without having to directly consume the RESTful interface. Wade Wegner – the creator of the Toolkit – will lead the session as we look at why this Toolkit was built, the delivery pipeline for the NuGet package, and a set of examples that show off how to use this in web apps, Windows Store apps, and Windows Phone apps.

Sign up and see how to take full advantage of this Toolkit when building Salesforce.com integrations!

Wade Wegner, a friend of the blog and an evangelist for Salesforce.com, just built a new .NET Toolkit for Salesforce developers. This Toolkit is open source and available on GitHub. Basically, it makes it much simpler to securely interact with the Salesforce.com REST API from .NET code. It takes care of “just working” on multiple Windows platforms (Win 7/8, WinPhone), async processing, and wrapping up all the authentication and HTTP stuff needed to call Salesforce.com endpoints. In this post, I’ll do a basic walkthrough of adding the Toolkit to a project and working with a Salesforce.com resource.

After creating a new .NET project (Console project, in my case) in Visual Studio, all you need to do is reference the NuGet packages that Wade created. Specifically, look for the DeveloperForce.Force package which pulls in the “common” package (that has baseline stuff) as well as the JSON.NET package.

First up, add a handful of using statements to reference the libraries we need to use the Toolkit, grab configuration values, and work with dynamic objects.

using System.Configuration;
using Salesforce.Common;
using Salesforce.Force;
using System.Dynamic;

The Toolkit is written using the async and await model for .NET, so calling this library requires some knowledge of this. To make life simple for this demo, define an operation like this that can be called from the Main entry point.

static void Main(string[] args)
{
        Do().Wait();
}

static async Task Do()
{
     ...
}

Let’s fill out the “Do” operation that uses the Toolkit. First, we need to capture our Force.com credentials. The Toolkit supports a handful of viable authentication flows. Let’s use the “username-password” flow. This means we need OAuth/API credentials from Salesforce.com. In the Salesforce.com Setup screens, go to Create, then Apps and create a new application. For a full walkthrough of getting credentials for REST calls, see my article on the DeveloperForce site.

With the consumer key and consumer secret in hand, we can now authenticate using the Toolkit. In the code below, I yanked the credentials from the app.config accompanying the application.

//get credential values
string consumerkey = ConfigurationManager.AppSettings["consumerkey"];
string consumersecret = ConfigurationManager.AppSettings["consumersecret"];
string username = ConfigurationManager.AppSettings["username"];
string password = ConfigurationManager.AppSettings["password"];

//create auth client to retrieve token
var auth = new AuthenticationClient();

//get back URL and token
await auth.UsernamePassword(consumerkey, consumersecret, username, password);

When you call this, you’ll see that the AuthenticationClient now has populated properties for the instance URL and access token. Pull those values out, as we’re going to use them when interacting the the REST API.

var instanceUrl = auth.InstanceUrl;
var accessToken = auth.AccessToken;
var apiVersion = auth.ApiVersion;

Now we’re ready to query Salesforce.com with the Toolkit. In this first instance, create a class that represents the object we’re querying.

public class Contact
    {
        public string Id { get; set; }
        public string FirstName { get; set; }
        public string LastName { get; set; }
    }

Let’s instantiate the ForceClient object and issue a query. Notice that we pass in a SQL-like syntax when querying the Salesforce.com system. Also, see that the Toolkit handles all the serialization for us!

var client = new ForceClient(instanceUrl, accessToken, apiVersion);

//Toolkit handles all serialization
var contacts = await client.Query<Contact>("SELECT Id, LastName From Contact");

//loop through returned contacts
foreach (Contact c in contacts)
{
      Console.WriteLine("Contact - " + c.LastName);
}

My Salesforce.com app has the following three contacts in the system …

Calling the Toolkit using the code above results in this …

Easy! But does the Toolkit support dynamic objects too? Let’s assume you’re super lazy and don’t want to create classes that represent the Salesforce.com objects. No problem! I can use late binding through the dynamics keyword and get back an object that has whatever fields I requested. See here that I added the “FirstName” to the query and am not passing in a known class type.

var client = new ForceClient(instanceUrl, accessToken, apiVersion);

var contacts = await client.Query<dynamic>("SELECT Id, FirstName, LastName FROM Contact");

foreach (dynamic c in contacts)
{
      Console.WriteLine("Contact - " + c.FirstName + " " + c.LastName);
}

What happens when you run this? You should have all the queried values available as properties.

The Toolkit supports more than just “query” scenarios. It also works great for create/update/delete as well. Like before, these operations worked with strongly typed objects or dynamic ones. First, add the code below to create a contact using our known “contact” type.

Contact c = new Contact() { FirstName = "Golden", LastName = "Tate" };

string recordId = await client.Create("Contact", c);

Console.WriteLine(recordId);

That’s a really simple way to create Salesforce.com records. Want to see another way? You can use the dynamic ExpandoObject to build up an object on the fly and send it in here.

dynamic c = new ExpandoObject();//
c.FirstName = "Marshawn";
c.LastName = "Lynch";
c.Title = "Chief Beast Mode";

string recordId = await client.Create("Contact", c);

Console.WriteLine(recordId);

After running this, we can see this record in our Salesforce.com database.

Summary

This is super useful and a fantastic way to easily interact with Salesforce.com from .NET code. Wade’s looking for feedback and contributions as he builds this out further. Add issues if you encounter bugs, and issue a pull request if you want to add features like error handling or support for other operations.

I’ve been asked to write a few more articles for the DeveloperForce site (the developer-centric destination for Salesforce.com developers) and the first one is now online. This article, entitled “Working with Custom SOAP and REST Services in .NET Applications” takes a look at how to construct custom SOAP and REST services in Force.com, and then consume them from .NET applications.

In this longer-than-expected article, I reviewed WHY you create custom services in a product that already has a robust SOAP/REST API, and show you how to build composite services, transaction-friendly services, and more. Consuming these custom services from .NET (or products like BizTalk Server) is easy and I tried to make it simple to follow along.

Salesforce.com is growing like gangbusters, and the need for qualified integration architects is growing with it. Every time someone stands up a SaaS application, they should be thinking about how to integrate with other cloud or on-premises systems. I’ve been writing all these articles for them because (a) it’s fun, and (b) it’s important to understand all the integration options! Next up, I’ll be looking at mobile notification services (like Windows Azure Notification Hubs) and their Streaming API.