How to create RESTful service
This sample explains about the creating the RESTful service to create and updating the resource information available at the sever side. This Restful service will be consumed using client console application.
Step 1: For our example we are suing “EmployeeData” class as Data Access Layer for storing and reading the employee information.
Data Model class:
namespace MyFirstRESTfulService
{
[DataContract]
public class Employee
{
[DataMember]
public int EmpId { get; set; }
[DataMember]
public string Fname { get; set; }
[DataMember]
public string Lname { get; set; }
[DataMember ]
public DateTime JoinDate { get; set; }
[DataMember]
public int Age { get; set; }
[DataMember]
public int Salary { get; set; }
[DataMember]
public string Designation { get; set; }
}
public partial class EmployeeData
{
private static readonly EmployeeData _instance = new EmployeeData();
private EmployeeData() { }
public static EmployeeData Instance
{
get
{
return _instance;
}
}
private List< Employee> empList = new List < Employee>()
{
new Employee() { EmpId = 1, Fname = "Sam", Lname = "kumar", JoinDate=new DateTime(2010,7, 21), Age=30,Salary=10000,Designation="Software Engineer"},
new Employee() { EmpId = 2, Fname = "Ram", Lname = "kumar", JoinDate=new DateTime(2009,6,8), Age=35,Salary=10000,Designation="Senior Software Engineer"},
new Employee() { EmpId = 3, Fname = "Sasi", Lname = "M", JoinDate=new DateTime(2008,3,5), Age=39,Salary=10000,Designation="Projet Manager"},
new Employee() { EmpId = 4, Fname = "Praveen", Lname = "KR", JoinDate=new DateTime(2010, 5,1), Age=56,Salary=10000,Designation="Projet Manager"},
new Employee() { EmpId = 5, Fname = "Sathish", Lname = "V", JoinDate = new DateTime(2006,12,15), Age=72,Salary=10000,Designation="Senior Software Engineer"},
new Employee() { EmpId = 6, Fname = "Rosh", Lname = "A", JoinDate=new DateTime(2009,2,2), Age=25,Salary=10000,Designation="Software Engineer"}
};
public List< Employee> EmployeeList
{
get
{
return empList;
}
}
public void Update(Employee updEmployee)
{
Employee existing = empList.Find(p => p.EmpId == updEmployee.EmpId);
if (existing == null)
throw new KeyNotFoundException("Specified Employee cannot be found");
existing.Fname = updEmployee.Fname;
existing.Lname = updEmployee.Lname;
existing.Age = updEmployee.Age;
}
public void Delete(int empid)
{
Employee existing = empList.Find(p => p.EmpId == empid);
empList.Remove(existing);
}
public void Add(Employee newEmployee)
{
empList.Add(new Employee
{
EmpId = newEmployee.EmpId,
Fname = newEmployee.Fname,
Lname = newEmployee.Lname,
Age = newEmployee.Age,
JoinDate = DateTime.Now,
Designation = newEmployee.Designation,
Salary = newEmployee.Salary
});
}
}
}
Step 2: Let’s start create EmployeeService (simple WCF) with ServiceContract, OperationContract and DataContract as shown below.
Interface and Implementation:
[ServiceContract()]
public interface IEmployeeService
{
[OperationContract]
List< Employee > GetAllEmployeeDetails();
[OperationContract]
Employee GetEmployee(int Id);
[OperationContract]
void AddEmployee(Employee newEmp);
[OperationContract]
void UpdateEmployee(Employee newEmp);
[OperationContract]
void DeleteEmployee(string empId);
}
[AspNetCompatibilityRequirements(RequirementsMode= AspNetCompatibilityRequirementsMode.Allowed )]
public class EmployeeService: IEmployeeService
{
public List < Employee > GetAllEmployeeDetails()
{
return EmployeeData.Instance.EmployeeList;
}
public Employee GetEmployee(int id)
{
IEnumerable< Employee > empList = EmployeeData.Instance.EmployeeList.Where(x => x.EmpId == id);
if (empList != null)
return empList.First< Employee >();
else
return null;
}
public void AddEmployee(Employee newEmp)
{
EmployeeData.Instance.Add(newEmp);
}
public void UpdateEmployee( Employee newEmp)
{
EmployeeData.Instance.Update(newEmp);
}
public void DeleteEmployee(string empId)
{
EmployeeData.Instance.Delete(System.Convert .ToInt32 (empId));
}
}
Step2: This service can be hosted as normal WCF service by creating the ServiceHost object and adding endpoint with different binding. This is already explained in “ConsoledHosted WCF Service”.
As it is mention in introduction section of RESTful service, all the resource located in server side can be accessed using url. Method exposed at the server side can be call using url, to do that we need to decorate the service method with “WebGet” or “WebInvoke” attribute as mention below
[ServiceContract()]
public interface IEmployeeService
{
[WebGet(UriTemplate = "Employee")]
[OperationContract]
List< Employee > GetAllEmployeeDetails();
[WebGet(UriTemplate = "Employee?id={id}")]
[OperationContract]
Employee GetEmployee(int Id);
[WebInvoke(Method = "POST", UriTemplate = "EmployeePOST")]
[OperationContract]
void AddEmployee(Employee newEmp);
[WebInvoke(Method = "PUT", UriTemplate = "EmployeePUT")]
[OperationContract]
void UpdateEmployee(Employee newEmp);
[WebInvoke(Method = "DELETE", UriTemplate = "Employee/{empId}")]
[OperationContract]
void DeleteEmployee(string empId);
}
Step4: In the above interface declaration, you can find that we have added UriTemplate”, it is nothing but a relative path for accessing the service method using url. These methods can be called from client application or browser by typing url as “WCf Service url” + “Relative Path” E.g: http://localhost:8090/MyService/EmployeeService/Employee
Step 5: “Method” is another option we can add to the WebInvoke attribute to specify the mode of transfer like “PUT”, “POST”, or “DELETE”
Step 6: Now we have completed with service implementation project. Let’s start with Hosting the RESTful service. For this example we are using console application for hosting service. WCF framework has provided new class to host the RESTful service i.e WebServiceHost. By hosting the restful service with WebServiceHost host class will automatically set the binding and other configuration setting. In the below code you can see that I have only mention url for the hosting.
Uri httpUrl = new Uri("http://localhost:8090/MyService/EmployeeService");
WebServiceHost host = new WebServiceHost(typeof(MyFirstRESTfulService.EmployeeService), httpUrl);
host.Open();
foreach (ServiceEndpoint se in host.Description.Endpoints)
Console.WriteLine("Service is host with endpoint " + se.Address);
//Console.WriteLine("ASP.Net : " + ServiceHostingEnvironment.AspNetCompatibilityEnabled);
Console.WriteLine("Host is running... Press < Enter > key to stop");
Console.ReadLine();
Step 7: We can access the RESTful service using browser. Just type the url in the web browser to read all the employee details
If we need to get specific employee details, pass the employee as query parameter as we mention in UriTemplate of the service.
Step 8:Now we can start with client application. For this example we can create a console application to read the employee information and add new employee to the server resource. Below code first read the employee details from the server and add new employee and once again it read the employee details to confirm the added resource.
WebChannelFactory < IEmployeeService > cf =
new WebChannelFactory< IEmployeeService >(
new Uri("http://localhost:8090/MyService/EmployeeService"));
IEmployeeService client = cf.CreateChannel();
var d = client.GetEmployee(1);
//Load all the Employee from the server and display
foreach (Employee e in client.GetAllEmployeeDetails() )
{
Console.WriteLine(string.Format("EmpID:{0}, Name:{1} {2}",e.EmpId ,e.Fname ,e.Lname ));
}
//Add new user
client.AddEmployee(new Employee() { EmpId = 11, Fname = "John", Lname = "J", JoinDate = new DateTime(2010, 7, 24), Age = 34, Salary = 10000, Designation = "Software Engineer" });
Console.WriteLine("******************After adding new user ****************");
//Load all the Employee from the server and display
foreach (Employee e in client.GetAllEmployeeDetails() )
{
Console.WriteLine(string.Format("EmpID:{0}, Name:{1} {2}",e.EmpId ,e.Fname ,e.Lname ));
}
Console.ReadLine();
}
Step 9: Run the application to view the output as shown below
Tips!
- Always create the service with Interface->Implementation format, mention the contract in Interface.
- Define the service in Class library and refer the class library in Host project. Don’t use service class in host project.
- Change the instance mode to per call as default.
- Always catch exception using try/catch block and throw exception using FaultException < T >.
- Logging and Include exception should be enable while compiling the project in debug mode. While in production deployment disable the logging and Include exception details.