...
I know that under strict ReSTful architecture, there should be no hint of the service being provided in the URI naming (in other words avoid rpc style naming conventions), to this end I have mapped eah URI to one and only one HTTP command.
Under the hood
Let's exam the following service entry points
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@GET @POST |
Essentially I have created two entry points to the same service __createUser() on the same interface class UserRestService. I am going to repeat this pattern for all the other services I want to expose. This is a simple case of refactoring the interfaces methods.
The __createUser() method looks like this
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private Response __createUser( User usr )
{
Response resp;
try
{
DBConnector connector = DBConnector.getConnector();
connector.loadAndConnect();
UserHandler.getLoader().addUser(connector.getConnection(), usr);
resp = Response.status(200).entity(usr).build();
} catch (IOException ex)
{
resp = Response.status(500).entity(new SimpleErrorMessage("CANNOT ADD USER - SERVER PROBLEM")).build();
Logger.getLogger(UserRestServices.class.getName()).log(Level.SEVERE, null, ex);
} catch (ResponseException ex)
{
Logger.getLogger(UserRestServices.class.getName()).log(Level.SEVERE, null, ex);
resp = Response.status(500).entity(ex.getResponse()).build();
} catch (SQLException ex)
{
resp = Response.status(409).entity(new SimpleErrorMessage(usr.getUserID() + " CANNOT BE ADDED - ALREADY EXIST")).build();
Logger.getLogger(UserRestServices.class.getName()).log(Level.SEVERE, null, ex);
}
return resp;
} |
I didn't use Java 8 exception multi catch statements as I wanted to report different messages back to the client.
The call at line 6 is to a singleton. We could have used non singleton implementation and this would have worked to, but backend implementation works in a non webservice context too, such as with JSPs.
Notice the error codes that I am returning in the reponse, see http://www.restapitutorial.com/httpstatuscodes.html for valid codes
Client Code
Here we present several examples of client side code
| Code Block | ||||||
|---|---|---|---|---|---|---|
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package com.celestial.jaxrs.client;
import com.celestial.dbankbusinessobjects.User;
import com.sun.jersey.api.client.Client;
import com.sun.jersey.api.client.ClientResponse;
import com.sun.jersey.api.client.WebResource;
import com.sun.jersey.api.client.config.ClientConfig;
import com.sun.jersey.api.client.config.DefaultClientConfig;
import com.sun.jersey.api.json.JSONConfiguration;
/**
*
* @author Selvyn
*/
public class TestServices
{
public static void main(String[] args)
{
try
{
User usr = new User("David", "PP-WW-QQ");
ClientConfig clientConfig = new DefaultClientConfig();
clientConfig.getFeatures().put(
JSONConfiguration.FEATURE_POJO_MAPPING, Boolean.TRUE);
Client client = Client.create(clientConfig);
WebResource webResource = client
.resource("http://localhost:8084/dbwstier/dbrest/user/fu");
ClientResponse response = webResource.accept("application/json")
.type("application/json").post(ClientResponse.class, usr);
if (response.getStatus() != 201)
{
throw new RuntimeException("Failed : HTTP error code : "
+ response.getStatus());
}
String output = response.getEntity(String.class);
System.out.println("Server response .... \n");
System.out.println(output);
} catch (Exception e)
{
e.printStackTrace();
}
}
}
|
The next examples only show the body changed code
| Code Block | ||||||||
|---|---|---|---|---|---|---|---|---|
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User us = new User("penny", "leonard");
ClientConfig clientConfig = new DefaultClientConfig();
clientConfig.getFeatures().put(
JSONConfiguration.FEATURE_POJO_MAPPING, Boolean.TRUE);
Client client = Client.create(clientConfig);
WebResource webResource = client
.resource("http://localhost:8084/dbwstier/dbrest/user/du");
ClientResponse response = webResource.accept("application/json")
.type("application/json").delete(ClientResponse.class, us);
if (response.getStatus() != 200)
{
throw new RuntimeException("Failed : HTTP error code : "
+ response.getStatus());
}
String output = response.getEntity(String.class);
System.out.println("Server response .... \n");
System.out.println(output); |
| Code Block | ||||||
|---|---|---|---|---|---|---|
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User us = new User("David", "");
ClientConfig clientConfig = new DefaultClientConfig();
clientConfig.getFeatures().put(
JSONConfiguration.FEATURE_POJO_MAPPING, Boolean.TRUE);
Client client = Client.create(clientConfig);
WebResource webResource = client
.resource("http://localhost:8084/dbwstier/dbrest/user/cu");
ClientResponse response = webResource.accept("application/json")
.type("application/json").post(ClientResponse.class, us);
if (response.getStatus() != 201)
{
throw new RuntimeException("Failed : HTTP error code : "
+ response.getStatus());
}
String output = response.getEntity(String.class);
System.out.println("Server response .... \n");
System.out.println(output); |
To update a record we are going to use HTTP PUT command
| Code Block | ||||||||
|---|---|---|---|---|---|---|---|---|
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User oldUser = new User("David", "ppp");
User newUser = new User("David", "PP-XX-YY");
UserMap umap = new UserMap( oldUser, newUser );
ClientConfig clientConfig = new DefaultClientConfig();
clientConfig.getFeatures().put(
JSONConfiguration.FEATURE_POJO_MAPPING, Boolean.TRUE);
Client client = Client.create(clientConfig);
WebResource webResource = client
.resource("http://localhost:8084/dbwstier/dbrest/user/uu");
ClientResponse response = webResource.accept("application/json")
.type("application/json").put(ClientResponse.class, umap);
if (response.getStatus() != 200)
{
throw new RuntimeException("Failed : HTTP error code : "
+ response.getStatus());
}
String output = response.getEntity(String.class);
System.out.println("Server response .... \n");
System.out.println(output);
|
Notice the new class UserMap at line 28
| Code Block | ||||
|---|---|---|---|---|
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public class UserMap
{
public User oldUser;
public User newUser;
public UserMap(){}
public UserMap( User oldU, User newU )
{
oldUser = oldU;
newUser = newU;
}
} |
This will be a carrier object, holding two objects of type User.
Let's see the full server side service interface
| Code Block | ||||||||
|---|---|---|---|---|---|---|---|---|
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package dbk.webservices;
/**
*
* @author Selvyn
*/
import com.celestial.dbankbusinessobjects.User;
import com.celestial.dbankbusinessobjects.UserMap;
import com.celestial.util.objects.SimpleErrorMessage;
import dbk.dbutils.DBConnector;
import dbk.dbutils.ResponseException;
import dbk.dbutils.UserHandler;
import java.io.IOException;
import java.sql.SQLException;
import java.util.Random;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.ws.rs.Consumes;
import javax.ws.rs.DELETE;
import javax.ws.rs.GET;
import javax.ws.rs.POST;
import javax.ws.rs.PUT;
import javax.ws.rs.Path;
import javax.ws.rs.PathParam;
import javax.ws.rs.Produces;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Response;
@Path("/user")
public class UserRestServices
{
private String genPassword()
{
String result = "";
Random gen = new Random();
for (int x = 0; x < 8; x++)
{
result += (char) (gen.nextInt(26) + 'A');
}
return result;
}
@GET
@Path("/sayhello")
@Produces(MediaType.TEXT_HTML)
public String sayHtmlHelloTest()
{
return "<html> " + "<title>" + "Hello World" + "</title>"
+ "<body><h1>" + "Hello from the Deutsche Bank DB Tier" + "</h1></body>" + "</html> ";
}
@GET
@Path("/cu/{user}")
@Produces(MediaType.APPLICATION_JSON)
public Response createUser(@PathParam("user") String userId)
{
User usr = new User(userId, genPassword());
return __createUser(usr);
}
@POST
@Path("/cu")
@Consumes(MediaType.APPLICATION_JSON)
public Response createUserFromObject(User usr)
{
usr.setUserPwd(genPassword());
return __createUser(usr);
}
private Response __createUser( User usr )
{
Response resp;
try
{
DBConnector connector = DBConnector.getConnector();
connector.loadAndConnect();
UserHandler.getLoader().addUser(connector.getConnection(), usr);
resp = Response.status(201).entity(usr).build();
} catch (IOException ex)
{
resp = Response.status(500).entity(new SimpleErrorMessage("CANNOT ADD USER - SERVER PROBLEM")).build();
Logger.getLogger(UserRestServices.class.getName()).log(Level.SEVERE, null, ex);
} catch (ResponseException ex)
{
Logger.getLogger(UserRestServices.class.getName()).log(Level.SEVERE, null, ex);
resp = Response.status(500).entity(ex.getResponse()).build();
} catch (SQLException ex)
{
resp = Response.status(409).entity(new SimpleErrorMessage(usr.getUserID() + " CANNOT BE ADDED - ALREADY EXIST")).build();
Logger.getLogger(UserRestServices.class.getName()).log(Level.SEVERE, null, ex);
}
return resp;
}
@DELETE
@Path("/du")
@Consumes(MediaType.APPLICATION_JSON)
public Response deleteUser(User usr)
{
Response resp;
try
{
DBConnector connector = DBConnector.getConnector();
connector.loadAndConnect();
UserHandler.getLoader().deleteUser(connector.getConnection(), usr);
resp = Response.status(200).entity( usr ).build();
} catch (IOException ex)
{
resp = Response.status(500).entity(new SimpleErrorMessage("CANNOT DELETE USER - SERVER PROBLEM")).build();
Logger.getLogger(UserRestServices.class.getName()).log(Level.SEVERE, null, ex);
} catch (ResponseException ex)
{
Logger.getLogger(UserRestServices.class.getName()).log(Level.SEVERE, null, ex);
resp = Response.status(200).entity(ex.getResponse()).build();
} catch (SQLException ex)
{
resp = Response.status(409).entity(new SimpleErrorMessage(usr.getUserID() + " CANNOT BE DELETD - USER DOES NOT EXIST")).build();
Logger.getLogger(UserRestServices.class.getName()).log(Level.SEVERE, null, ex);
}
return resp;
}
@PUT
@Path("/uu")
@Consumes(MediaType.APPLICATION_JSON)
public Response updateUserFromObject(UserMap umap)
{
return __updateUser( umap );
}
@GET
@Path("/uu/{oldid}/{oldpwd}/{newid}/{newpwd}")
@Produces(MediaType.APPLICATION_JSON)
public Response updateUser( @PathParam("oldid") String oldId,
@PathParam("oldpwd") String oldpwd,
@PathParam("newid") String newId,
@PathParam("newpwd") String newpwd)
{
User oldUser = new User( oldId, oldpwd );
User newUser = new User( newId, newpwd );
UserMap umap = new UserMap( oldUser, newUser );
return __updateUser( umap );
}
private Response __updateUser( UserMap umap )
{
Response resp;
try
{
DBConnector connector = DBConnector.getConnector();
connector.loadAndConnect();
UserHandler.getLoader().updateUser(connector.getConnection(), umap.oldUser, umap.newUser);
resp = Response.status(200).entity( umap ).build();
} catch (IOException ex)
{
resp = Response.status(500).entity(new SimpleErrorMessage("CANNOT UPDATE USER - SERVER PROBLEM")).build();
Logger.getLogger(UserRestServices.class.getName()).log(Level.SEVERE, null, ex);
} catch (ResponseException ex)
{
Logger.getLogger(UserRestServices.class.getName()).log(Level.SEVERE, null, ex);
resp = Response.status(200).entity(ex.getResponse()).build();
} catch (SQLException ex)
{
resp = Response.status(409).entity(new SimpleErrorMessage(umap.oldUser.getUserID() + " CANNOT BE CHANGED - USER DOES NOT EXIST")).build();
Logger.getLogger(UserRestServices.class.getName()).log(Level.SEVERE, null, ex);
}
return resp;
}
@POST
@Path("/fu")
@Consumes(MediaType.APPLICATION_JSON)
@Produces(MediaType.APPLICATION_JSON)
public Response findUser( User usr )
{
return __findUser( usr );
}
@GET
@Path("/fu/{user}/{pwd}")
@Produces(MediaType.APPLICATION_JSON)
public Response findUser(@PathParam("user") String userId, @PathParam("pwd") String pwd)
{
User usr = new User( userId, pwd );
return __findUser( usr );
}
private Response __findUser( User requsr )
{
User usr = null;
try
{
DBConnector connector = DBConnector.getConnector();
connector.loadAndConnect();
usr = UserHandler.getLoader().loadFromDB(connector.getConnection(), requsr.getUserID(), requsr.getUserPwd());
if (usr != null)
{
return Response.status(200).entity(usr).build();
} else
{
SimpleErrorMessage msg = new SimpleErrorMessage("USER NOT FOUND");
return Response.status(200).entity(msg).build();
}
} catch (IOException ex)
{
Logger.getLogger(UserRestServices.class.getName()).log(Level.SEVERE, null, ex);
} catch (ResponseException ex)
{
Logger.getLogger(UserRestServices.class.getName()).log(Level.SEVERE, null, ex);
return Response.status(200).entity(ex.getResponse()).build();
}
SimpleErrorMessage msg = new SimpleErrorMessage("ERROR IN DB TIER");
return Response.status(200).entity(msg).build();
}
} |