Redirect from one WebAPI to an another WebAPI and getting the response

Question

User411771660 posted

I want to create lets say a master/core api.Want to check for a certain parameter value and redirect to a an external api hosted in the same server.I have an api with uri http://hello.test.com/auth which takes two auth params Username and Password.Now i add a third parameter lets say Area.

{
"Username":"jason",
"Password":"bourne",
"Area":"mars"
}

Now coming to the master api, if with this uri for example http://master.test.com/v1/mster and i pass Username, Password and Area,and if the Area has value of lets say "mars" it should call the external mars api having uri http://mars.test.com/auth ,do the auth the process and return the response in the master api.is this possible?

With my /auth api i have this controller returning the response :

 [HttpPost]
        [Route(ApiEndpoint.AUTH)]
        public HttpResponseMessage Auth(Login authBDTO)
        {
            if (!ModelState.IsValid)
                return Request.CreateResponse(HttpStatusCode.BadRequest, ModelState);

            using (AccountBusinessService accountService = new AccountBusinessService())
            {
                var result = accountService.Auth(authBDTO);
                return Request.CreateResponse(HttpStatusCode.OK, result);
            }
        }

Answer 1

User1120430333 posted

You can use HttpClient() normally using  it in connection of WebAPI client to a WebAPI service, The one WebAPI becomes a client to the other WebAPI. 

https://docs.microsoft.com/en-us/dotnet/api/system.net.http.httpclient?view=netframework-4.8#examples

WebAPI client, which happens to be used in ASP.NET MVC project, is calling methods on an ASP.NET WebAPI service. The DTO is known between the WebAPI client and WebAPI service.

using System;
using System.Collections.Generic;
using System.Net.Http;
using System.Net.Http.Headers;
using System.Text;
using Entities;
using Newtonsoft.Json;
using Newtonsoft.Json.Linq;

namespace ServiceLayer
{
    public class ArticleSvc :IArticleSvc
    {
        public List<DtoArticle> GetAll()
        {
            var dtoarticles = new List<DtoArticle>();

            using (var client = new HttpClient())
            {
                var uri = new Uri("http://localhost/WebAPI/api/article/GetAll");

                var response = client.GetAsync(uri).Result;

                if (!response.IsSuccessStatusCode)
                    throw new Exception(response.ToString());

                var responseContent = response.Content;
                var responseString = responseContent.ReadAsStringAsync().Result;

                dynamic articles = JArray.Parse(responseString) as JArray;

                foreach (var obj in articles)
                {
                    DtoArticle dto = obj.ToObject<DtoArticle>();

                    dtoarticles.Add(dto);
                }
            }

            return dtoarticles;
        }

        public List<DtoArticle> GetArticlesByAuthorId(int id)
        {
            var dtoarticles = new List<DtoArticle>();

            using (var client = new HttpClient())
            {
                var uri = new Uri("http://localhost/WebAPI/api/article/GetArticlesByAuthorId?id=" + id);

                var response = client.GetAsync(uri).Result;

                if (!response.IsSuccessStatusCode)
                    throw new Exception(response.ToString());

                var responseContent = response.Content;
                var responseString = responseContent.ReadAsStringAsync().Result;

                dynamic articles = JArray.Parse(responseString) as JArray;

                foreach (var obj in articles)
                {
                    DtoArticle dto = obj.ToObject<DtoArticle>();

                    dtoarticles.Add(dto);
                }
            }

            return dtoarticles;
        }
        public DtoArticle Find(int id)
        {
            DtoArticle dto;

            using (var client = new HttpClient())
            {
                var uri = new Uri("http://localhost/WebAPI/api/article/Find?id=" + id);
                HttpResponseMessage getResponseMessage = client.GetAsync(uri).Result;

                if (!getResponseMessage.IsSuccessStatusCode)
                    throw new Exception(getResponseMessage.ToString());

                var responsemessage = getResponseMessage.Content.ReadAsStringAsync().Result;

                dynamic article = JsonConvert.DeserializeObject(responsemessage);

                dto = article.ToObject<DtoArticle>();
            }

            return dto;
        }

        public void Add(DtoArticle dto)
        {
            using (var client = new HttpClient { BaseAddress = new Uri("http://localhost") })
            {
                string serailizeddto = JsonConvert.SerializeObject(dto);

                var inputMessage = new HttpRequestMessage
                {
                    Content = new StringContent(serailizeddto, Encoding.UTF8, "application/json")
                };

                inputMessage.Headers.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));

                HttpResponseMessage message =
                    client.PostAsync("WebAPI/api/article/Add", inputMessage.Content).Result;

                if (!message.IsSuccessStatusCode)
                    throw new Exception(message.ToString());
            }
        }

        public void Update(DtoArticle dto)
        {
            using (var client = new HttpClient { BaseAddress = new Uri("http://localhost") })
            {
                string serailizeddto = JsonConvert.SerializeObject(dto);

                var inputMessage = new HttpRequestMessage
                {
                    Content = new StringContent(serailizeddto, Encoding.UTF8, "application/json")
                };

                inputMessage.Headers.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));

                HttpResponseMessage message =
                    client.PostAsync("WebAPI/api/article/Update", inputMessage.Content).Result;

                if (!message.IsSuccessStatusCode)
                    throw new Exception(message.ToString());
            }
        }

        public void Delete(DtoId dto)
        {
            using (var client = new HttpClient { BaseAddress = new Uri("http://localhost") })
            {
                string serailizeddto = JsonConvert.SerializeObject(dto);

                var inputMessage = new HttpRequestMessage
                {
                    Content = new StringContent(serailizeddto, Encoding.UTF8, "application/json")
                };

                inputMessage.Headers.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));

                HttpResponseMessage message =
                    client.PostAsync("WebAPI/api/article/Delete", inputMessage.Content).Result;

                if (!message.IsSuccessStatusCode)
                    throw new Exception(message.ToString());
            }
        }
    }
}

Answer 2

User283571144 posted

Hi tarun02,

Now coming to the master api, if with this uri for example http://master.test.com/v1/mster and i pass Username, Password and Area,and if the Area has value of lets say "mars" it should call the external mars api having uri http://mars.test.com/auth ,do the auth the process and return the response in the master api.is this possible?

It possbile, you could send the http request in web api to another web api by using httpclient library. 

You could write the codes inside the auth method to check the area , then you could use below codes to send the request to another web api. At last, you could generate the response according to another web api returned response.

More details about how to send the request, you could refer to below codes:

var httpWebRequest = (HttpWebRequest)WebRequest.Create("http://url");
httpWebRequest.ContentType = "application/json";
httpWebRequest.Method = "POST";

using (var streamWriter = new StreamWriter(httpWebRequest.GetRequestStream()))
{
    string json = "{\"user\":\"test\"," +
                  "\"password\":\"bla\"}";

    streamWriter.Write(json);
}

var httpResponse = (HttpWebResponse)httpWebRequest.GetResponse();
using (var streamReader = new StreamReader(httpResponse.GetResponseStream()))
{
    var result = streamReader.ReadToEnd();
}

Best Regards,

Brando

Answer 3

User411771660 posted
sir,there are multiple apis for different customers which is consumed by a mobile client.So instead of creating individual app for different customer,i want lets say a dropdown list in the said mobile app with username,password and AREA.area will define the said api in my server.so if the request comes with "mars" value for the area, i want to call the api from mars.test.com/auth and return the response.

Answer 4

User1120430333 posted

sir,there are multiple apis for different customers which is consumed by a mobile client.So instead of creating individual app for different customer,i want lets say a dropdown list in the said mobile app with username,password and AREA.area will define the said api in my server.so if the request comes with "mars" value for the area, i want to call the api from mars.test.com/auth and return the response.

It's called using routing in the WebAPI, like test.com/api/mars/auth.

Here is a VB.NET example using WebAPI 2, but instead of using HttpClient() I am using WebClient(), along with using ActionName attribute. I think  you should be able to understand the concept, even if it's in VB.

https://docs.microsoft.com/en-us/aspnet/web-api/overview/web-api-routing-and-actions/attribute-routing-in-web-api-2

Imports System.Net
Imports Entities
Imports Newtonsoft.Json

Namespace WebApi
    Public Class WebApi
        Implements IWebApi

        #Region "Project"
        public Function  GetProjsByUserIdApi(userid As String) as List(of DtoProject) Implements IWebApi.GetProjsByUserIdApi

            dim dtoprojects = new List(Of DtoProject)

            dim url = "http://localhost/WebApiVB/api/project/GetProjectsByUserId?userid=" & userid

            Using webclient As New WebClient
                dim json  = webclient.DownloadString(url)
                Dim projects = JsonConvert.DeserializeObject(of List(Of DtoProject))(json)
                dtoprojects = projects
            End Using

            Return dtoprojects

        End Function
       
        public Function GetProjByIdApi(id As int32) as DtoProject Implements IWebApi.GetProjByIdApi

            dim dto as DtoProject

            dim url = "http://localhost/WebApiVB/api/project/GetProjectById?id=" & id

            Using webclient As New WebClient
                dim json  = webclient.DownloadString(url)
                Dim project = JsonConvert.DeserializeObject(of DtoProject)(json)
                dto = project
            End Using
           
            Return dto

        End Function

        public sub CreateProjectApi(dto As DtoProject) Implements IWebApi.CreateProjectApi

            Dim reqString As byte()

            Using webclient As New WebClient

                dim url as string = "http://localhost/WebApiVB/api/project/CreateProject"
                webClient.Headers("content-type") = "application/json"
                reqString = Encoding.Default.GetBytes(JsonConvert.SerializeObject(dto, Formatting.Indented))
                webClient.UploadData(url, "post", reqString)

            End Using
            
        End sub
        
        public sub UpdateProjectApi(dto As DtoProject) Implements IWebApi.UpdateProjectApi

            Dim reqString As byte()

            Using webclient As New WebClient

                dim url as string = "http://localhost/WebApiVB/api/project/UpdateProject"
                webClient.Headers("content-type") = "application/json"
                reqString = Encoding.Default.GetBytes(JsonConvert.SerializeObject(dto, Formatting.Indented))
                webClient.UploadData(url, "post", reqString)

            End Using

        End sub

        public sub DeleteProjectApi(dto As DtoId) Implements IWebApi.DeleteProjectApi

            Dim reqString As byte()

            Using webclient As New WebClient

                dim url as string = "http://localhost/WebApiVB/api/project/DeleteProject"
                webClient.Headers("content-type") = "application/json"
                reqString = Encoding.Default.GetBytes(JsonConvert.SerializeObject(dto, Formatting.Indented))
                webClient.UploadData(url, "post", reqString)

            End Using

        End sub
        #End Region

        #Region "Task"

        public function GetTasksByProjIdApi(id as int32) as List(Of DtoTask) Implements IWebApi.GetTasksByProjIdApi

            Dim dtotasks = new List(Of DtoTask)

            dim url = "http://localhost/WebApiVB/api/task/GetTasksByProjectId?id=" & id

            Using webclient As New WebClient
                dim json  = webclient.DownloadString(url)
                Dim tasks = JsonConvert.DeserializeObject(of List(Of DtoTask))(json)
                dtotasks = tasks
            End Using

            Return dtotasks

        End function
        
        public Function  GetTaskByIdApi(id As int32) As DtoTask Implements IWebApi.GetTaskByIdApi

            dim dto as DtoTask

            dim url = "http://localhost/WebApiVB/api/task/GetTaskById?id=" & id

            Using webclient As New WebClient
                dim json  = webclient.DownloadString(url)
                Dim task = JsonConvert.DeserializeObject(of DtoTask)(json)
                dto = task
            End Using

            return dto

        End Function

        public sub CreateTaskApi(dto As DtoTask) Implements IWebApi.CreateTaskApi

            Dim reqString As byte()

            Using webclient As New WebClient

                dim url as string = "http://localhost/WebApiVB/api/task/CreateTask"
                webClient.Headers("content-type") = "application/json"
                reqString = Encoding.Default.GetBytes(JsonConvert.SerializeObject(dto, Formatting.Indented))
                webClient.UploadData(url, "post", reqString)

            End Using
          
        End sub
        
        public sub UpdateTaskApi(dto As DtoTask) Implements IWebApi.UpdateTaskApi

            Dim reqString As byte()

            Using webclient As New WebClient

                dim url as string = "http://localhost/WebApiVB/api/task/UpdateTask"
                webClient.Headers("content-type") = "application/json"
                reqString = Encoding.Default.GetBytes(JsonConvert.SerializeObject(dto, Formatting.Indented))
                webClient.UploadData(url, "post", reqString)

            End Using
            
        End sub
        
        public sub DeleteTaskApi(dto As DtoId) Implements IWebApi.DeleteTaskApi

            Dim reqString As byte()

            Using webclient As New WebClient

                dim url as string = "http://localhost/WebApiVB/api/task/DeleteTask"
                webClient.Headers("content-type") = "application/json"
                reqString = Encoding.Default.GetBytes(JsonConvert.SerializeObject(dto, Formatting.Indented))
                webClient.UploadData(url, "post", reqString)

            End Using

        End sub
        #End Region  
        
        #Region "Cache"

        public Function  GetCacheApi() As DtoCache Implements IWebApi.GetCacheApi

            dim dtocache = new DtoCache()

            dim url = "http://localhost/WebApiVB/api/cache/GetCache"

            Using webclient As New WebClient
                dim json  = webclient.DownloadString(url)
                Dim deserialized = JsonConvert.DeserializeObject(of DtoCacheRoot)(json)

                dtocache.ProjectTypes = deserialized.DtoCache.ProjectTypes
                dtocache.Durations = deserialized.DtoCache.Durations
                dtocache.Statuses = deserialized.DtoCache.Statuses
                dtocache.Resources = deserialized.DtoCache.Resources

            End Using

            return dtocache

        End Function
        #End Region

    End Class
End Namespace

Imports System.Web.Http
Imports DAL
Imports Entities

Namespace Controllers

    <CustomExceptionFilter>
    Public Class ProjectController
        Inherits ApiController

        Private ReadOnly _daoproject As IDaoProject

        public sub New (daoproject As IDaoProject)
            _daoproject = daoproject
        End sub

        <HttpGet>
        <ActionName("GetProjectById")>
        public Function GetProjectById(ByVal id As Int32) As DtoProject
            return _daoproject.GetProjectById(id)
        End Function


        <HttpGet>
        <ActionName("GetProjectsByUserId")>
        public Function GetProjectsByUserId(ByVal userid As String) As List(Of DtoProject)
            return _daoproject.GetProjectsByUserId(userid)
        End Function

        <HttpPost>
        <ActionName("CreateProject")>
        public sub CreateProject(ByVal dto As DtoProject)
            Call _daoproject.CreateProject(dto)
        End sub
        
        <HttpPost>
        <ActionName("UpdateProject")>
        public sub UpdateProject(ByVal dto As DtoProject)
            Call _daoproject.UpdateProject(dto)
        End sub

        <HttpPost>
        <ActionName("DeleteProject")>
        public sub  DeleteProject(ByVal dto As DtoId)
            Call _daoproject.DeleteProject(dto.Id)
        End sub
        
    End Class
End Namespace

Answer 5

User411771660 posted

Hello sir,

How do i pass parameter from the body in here

string json = "{\"user\":\"test\"," +
                  "\"password\":\"bla\"}";

My parameter comes from 

public HttpResponseMessage esp(Login auth) //

Answer 6

User1120430333 posted

Hello sir,

How do i pass parameter from the body in here

string json = "{\"user\":\"test\"," +
                  "\"password\":\"bla\"}";

My parameter comes from 

public HttpResponseMessage esp(Login auth) //

Hello sir,

How do i pass parameter from the body in here

string json = "{\"user\":\"test\"," +
                  "\"password\":\"bla\"}";

My parameter comes from 

public HttpResponseMessage esp

(Login auth) //

So why can't you use a DTO known by the client and the service, Json serialize the DTO and send the DTO, which the code I have presented in C# and VB is Json serializing the DTO or deserializing a DTO sent by the service? You must know what a DTO is as your code seems to be using one. The DTO usage is a example of using Encapsulation.

 https://en.wikipedia.org/wiki/Encapsulation_(computer_programming)

Answer 7

User411771660 posted

I tried this :

        [HttpPost]
        [Route(ApiEndpoint.SAS)]
        public HttpResponseMessage esp(Login auth)
        {
            var httpWebRequest = (HttpWebRequest)WebRequest.Create("http://sastest.test.com");
            httpWebRequest.ContentType = "application/json";
            httpWebRequest.Method = "POST";
            var reqString = Encoding.Default.GetBytes(JsonConvert.SerializeObject(auth, Formatting.Indented));

            using (var streamWriter = new StreamWriter(httpWebRequest.GetRequestStream()))
            {
                string json = "{\"user\":" + auth.UserName +
                              "{\"password\":"+ auth.Password +
                              "\"coop\":" + auth.Coop;


                streamWriter.Write(json);
            }

            var httpResponse = (HttpWebResponse)httpWebRequest.GetResponse();
            using (var streamReader = new StreamReader(httpResponse.GetResponseStream()))
            {
                var result = streamReader.ReadToEnd();
            }
            return null;
        }

Answer 8

User283571144 posted

Hi tarun02,

According to your description, I suggest you could try to use Newtonsoft.Json package to covnert the model to json to make sure the json format is right.

For example, you could refer to below codes:

Create a userclass:

    public class Userclass
    {
        public string user { get; set; }
        public string password { get; set; }
       public string coop { get; set; }

       
    }

Use below codes to convert the class to json.

            Userclass u1 = new Userclass() { user = auth.UserName,  password = auth.Password, coop= auth.Coop };
            string json = JsonConvert.SerializeObject(u1);

Details codes:

        [HttpPost]
        [Route(ApiEndpoint.SAS)]
        public HttpResponseMessage esp(Login auth)
        {
            var httpWebRequest = (HttpWebRequest)WebRequest.Create("http://sastest.test.com");
            httpWebRequest.ContentType = "application/json";
            httpWebRequest.Method = "POST";
            var reqString = Encoding.Default.GetBytes(JsonConvert.SerializeObject(auth, Formatting.Indented));

            using (var streamWriter = new StreamWriter(httpWebRequest.GetRequestStream()))
            {
               Userclass u1 = new Userclass() { user = auth.UserName, password = auth.Password, coop= auth.Coop };
               string json = JsonConvert.SerializeObject(u1);


                streamWriter.Write(json);
            }

            var httpResponse = (HttpWebResponse)httpWebRequest.GetResponse();
            using (var streamReader = new StreamReader(httpResponse.GetResponseStream()))
            {
                var result = streamReader.ReadToEnd();
            }
            return null;
        }

Best Regards,

Brando

Answer 9

User411771660 posted

This worked :

Route(ApiEndpoint.SAS)]
    public IHttpActionResult esp(Login auth)
    {
        if (auth.Coop == "PMC")
        {
            var httpWebRequest = (HttpWebRequest)WebRequest.Create("http://localhost:60069/api/v1/auth");
            httpWebRequest.ContentType = "application/json";
            httpWebRequest.Method = "POST";

            using (var streamWriter = new StreamWriter(httpWebRequest.GetRequestStream()))
            {
                string json = new JavaScriptSerializer().Serialize(new
                {
                    Username = auth.UserName,
                    Password = auth.Password
                });

                streamWriter.Write(json);
            }

            var httpResponse = (HttpWebResponse)httpWebRequest.GetResponse();
            using (var streamReader = new StreamReader(httpResponse.GetResponseStream()))
            {

                var result = streamReader.ReadToEnd();
                dynamic obj = JsonConvert.DeserializeObject<ExpandoObject>(result);
                obj.BaseUrl = "http://localhost:60069/api/v1";

                return Ok(obj);

            }

        }