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Batch operations in JAX-RS

Context
I am currently working on a JavaEE project with a lot of existing resource based JAX-RS services. For this project we would like to have batch processing to prevent a lot of separate calls and, most importantly, to execute these different methods in a transactional context for rollback purposes with the native MongoDB driver. We want to avoid manually creating new methods for all possible combinations. I could not find any solution to this issue on Stack Overflow so I started analyzing the implementation of RESTEasy and I came up with the following solution.
Below a simplified/pseudo version of my code:
JAX-RS method
#POST
#Consumes(MediaType.APPLICATION_JSON)
#Produces(MediaType.APPLICATION_JSON)
#Path("execute")
public Response executeBatch(BatchRequestWrapper batchRequestWrapper) throws UnsupportedEncodingException
{
// Retrieve information from context
HttpServletRequest httpServletRequest = ResteasyProviderFactory.getContextData(HttpServletRequest.class);
HttpServletResponse httpServletResponse = ResteasyProviderFactory.getContextData(HttpServletResponse.class);
ServletContext servletContext = ResteasyProviderFactory.getContextData(ServletContext.class);
HttpResponse httpResponse = ResteasyProviderFactory.getContextData(HttpResponse.class);
SynchronousDispatcher dispatcher = (SynchronousDispatcher) ResteasyProviderFactory.getContextData(Dispatcher.class);
ResteasyHttpHeaders httpHeaders = (ResteasyHttpHeaders) ResteasyProviderFactory.getContextData(HttpHeaders.class);
ResteasyUriInfo uriInfo = (ResteasyUriInfo) ResteasyProviderFactory.getContextData(UriInfo.class);
// Create Mongo Client Session object and save it in a Singleton which contains a ThreadLocal object so that DAO layer can reuse the client session object for all methods.
// Iterate over all the methods and invoke dispatcher
for (BatchRequest batchRequest : batchRequestWrapper.getBatchRequests())
{
// Update URI based on specific endpoint
uriInfo.setRequestUri(URI.create(batchRequest.getUri()));
// Temporary use mock response for the response
MockHttpResponse response = new MockHttpResponse();
// Create httpservletinput message from RESTEasy lib to pass to the dispatcher. It will automatically resolve all parameters/methods etc.
HttpServletInputMessage request = new HttpServletInputMessage(httpServletRequest, httpServletResponse, servletContext, httpResponse, httpHeaders, uriInfo, batchRequest.getHttpMethod(), dispatcher);
// Set body in input stream if body is specified. This will inject the correct 'body' parameters in the methods. Query and Path parameters are already resolved in the method above.
if(!Strings.isNullOrEmpty(batchRequest.getBody()))
{
InputStream targetStream = new ByteArrayInputStream(batchRequest.getBody().getBytes(StandardCharsets.UTF_8));
request.setInputStream(targetStream);
}
// Actual invoke
dispatcher.invoke(request, response);
// Do something with response object
}
// Clean or abort session based on invoke result
return Response.ok().entity(null).build();
}
Request Object
public class BatchRequestWrapper
{
private List<BatchRequest> batchRequests;
public List<BatchRequest> getBatchRequests()
{
return batchRequests;
}
public void setBatchRequests(List<BatchRequest> batchRequests)
{
this.batchRequests = batchRequests;
}
}
public class BatchRequest
{
private String uri;
private String httpMethod;
private String body;
public String getUri()
{
return uri;
}
public void setUri(String uri)
{
this.uri = uri;
}
public String getHttpMethod()
{
return httpMethod;
}
public void setHttpMethod(String httpMethod)
{
this.httpMethod = httpMethod;
}
public String getBody()
{
return body;
}
public void setBody(String body)
{
this.body = body;
}
}
My solution works with one new REST method and let's me reuse all the existing JAX-RS annotated methods in the project. Before I actually fully implement this and bring it to production, I would like to know if this is the way to actually do this or are there better alternatives? I am not a big fan of the hard dependency on RESTEasy though.

Creating and injecting a per request scoped variable

I would like to have a variable that follows along the full lifecycle of a request in java EE.
For example it could be for a logging function, so that I can filter all log entries by request.
The key part that I want to get at is that it must be relatively easy to implement in an already existing application so if possible some sort of dependency injection that gets the variable related to the specific request.
I've tried injectiong a #RequestScoped variable, but it doesn't work since it is only scoped to the container. I would need to be able to inject the same object to different containers. Is this at all possible?
EDIT: I want something along the lines of this:
#RequestScoped
public class RequestVariables {
public String id;
}
#Stateless
public class Logger {
#Inject
private RequestVariables requestVariables;
public void log(String message) {
System.out.println(requestVariables.id + ":" + message);
}
}
#Stateless
public class Service {
#Inject
private Logger logger;
#Inject
private RequestVariables requestVariables;
public void save(String data) {
logger.log("Save");
session.save(data + requestVariables.id); //Maybe add request parameter to save aswell
}
}
public class API {
#Inject
private Service service;
#Inject
private Logger logger;
#Inject
private RequestVariables requestVariables;
#Path("/1")
#GET
public Response get(#QueryParam("data") String data) {
requestVariables.id = UUID.randomUUID().toString()
service.save(data);
logger.log("Get");
return Response.status(204).build();
}
}
Currently this is what I have experimented with:
#RequestScoped
public class RequestScope {
private int test = 0;
public RequestScope(int test) {
this.test = test;
}
public RequestScope(){}
public int getTest() {
return test;
}
public void setTest(int test) {
this.test = test;
}
}
#Provider
public class RequestScopeFilter implements ContainerRequestFilter {
#Inject
private javax.inject.Provider<RequestScope> requestScopeProvider;
#Context
private HttpServletRequest request;
#Override
public void filter(ContainerRequestContext requestContext) throws IOException {
requestScopeProvider.get().setTest(42);
request.setAttribute("test", "superTest");
}
}
#Stateless
#TransactionManagement(TransactionManagementType.BEAN)
#TransactionAttribute(value=TransactionAttributeType.NOT_SUPPORTED)
public class Service {
#Context
private HttpServletRequest httpServletRequest;
#Inject
private Provider<RequestScope> requestScopeProvider;
public void test() {
RequestScope scope = requestScopeProvider.get();
String test = (String)httpServletRequest.getAttribute("test");
}
}
So when I get the scope from my service then it is a new object with test set to 0, and then it throws an NPE since httpServletRequest is null

option #1
Implement an Interceptor and set the request id as HttpServletRequest attribute:
#AroundInvoke
public Object setRequestId(InvocationContext ic) throws Exception {
HttpServletRequest request = [..] // getHttpServletRequest(ic);
request.setAttribute("request-id", UUID.randomUUID().toString());
return ic.proceed();
}
Then use HttpServletRequest everywhere you need it
#Context
private HttpServletRequest httpRequest;
option #2
If want just to filter your logs by an unique id, you can configure your Logger to print the thread name: [%t]
Example: Log4j PatternLayout
option #3
Use a custom java bean to encapsulate the request data (query param, request id etc.) and pass this bean across your application services.
public class API {
#Inject
private Service service;
#Path("/1")
#GET
public Response get(MyCustomRequestBean data) {
service.doSomejob(data);
return Response.status(204).build();
}
}
Set the request id and query param in ParamConverter:
Jax-RS ParamConverter - ParamConverterProvider method return type mismatch

You can inject a provider in your service:
#Inject
Provider<RequestVariables> vars
And then call get () to get the instance. If you try to get () in a thread outside a request scope context you'll get an exception. I would however try to structure in a way that would not allow this to happen

A solution that I found is to use ThreadLocal variables. It seems rather dirty, but it works since each request is executed on it's own thread(as far as I am aware). So this is what I got:
public class RequestScope {
private static final ThreadLocal<String> id = ThreadLocal.withInitial(() -> UUID.randomUUID().toString());
public static String get() {
return id.get();
}
}
With that I can also easily exchange the ThreadLocal to return something more specific if so desired.
And I can get the variables from pretty much anywhere, assuming that the request is not starting a different thread

How to redirect to external url from service class?

In my current spring project, I am adding several pairs of classes (controller/service) to provide payment option through several payment services. Each one of this classes have a structure like that:
controller
#Controller
#RequestMapping(value = "pagseguro")
public class pagseguroPaymentController extends paymentController<Pagseguro> {
...
#Override
#RequestMapping(value = "comprar", method = RequestMethod.POST)
public void comprar(String payerId, String guid) throws Exception {
this.payment.comprar(payerId, guid);
}
...
}
service
#Service
public class pagseguroPaymentService extends paymentService<Pagseguro> {
...
#Override
public void comprar(String payerId, String guid) throws Exception {
...
String response = checkout.register(null, false);
}
...
}
in the method comprar from service class, I need redirect the application to an URL stored in a String variable (response in the example above).
My initial idea is use the library java.net from Java and create a utilitary class like that:
public class Redirect {
public static String url;
public static void redirect() {
...
}
}
Anyone can give me a hint about how to accomplish that?

To perform a simple redirection, you can inject the HttpServletResponse in your Controller layer:
#RequestMapping(value = "comprar", method = RequestMethod.POST)
public void comprar(String payerId, String guid, HttpServletResponse response) throws Exception {
this.payment.comprar(payerId, guid);
}
And then simply do a redirect using that object:
response.sendRedirect("http://newUrl");
Now - as the Luiggi mentions in the comment - I would not do the redirect itself in the service layer, but rather return a boolean which decides if the redirect needs to be done - and then do it here, in the controller layer.
Hope it helps.

Combining HttpSession with EJb

I'm trying to figure out the best way to handle httpsession in combination with pure EJB web services. I have created a utility class and I have a controller class. Where is the best place to instantiate a utility class inside the controller class? The plan is that each user that visits/calls a webservice i.e. using the website the first time should have a httpsession object assigned to them:
public class Utility {
#Resource
private WebServiceContext wsContext;
public MessageContext mc = wsContext.getMessageContext();
public HttpSession getSession(){
return ((HttpServletRequest)mc.get(MessageContext.SERVLET_CONTEXT)).getSession(true);
}
}
#Path("controller")
#Stateless
public class ControllerEJB {
#POST
public void registerUser(
#QueryParam("fornamn") String fornamn,
#QueryParam("efternamn") String efternamn,
#QueryParam("epost") String epost,
#QueryParam("epost2") String epost2,
#QueryParam("password") String password
){
User user = new User();
user.setEmail(epost);
user.setPassword(password);
user.setFornamn(fornamn);
user.setEfternamn(efternamn);
}
#GET
#Produces(MediaType.APPLICATION_JSON)
public String firstMethod(){
User user = new User();
user.setEmail("sam.gholizadeh");
return "unfisnihedmethod";
}
}
I've followed this tutorial http://docs.oracle.com/cd/E12839_01/web.1111/e13734/stateful.htm but as metioned earlier I'm not sure how and where to implement the logic that keeps track if a visitor has been assigned a session id or not.
Edit: Should the controller class be stateful or stateless?

Since you are using JAX-RS, it's even easier to directly get the HttpServletRequest using JAX-RS:
#Path("controller")
#Stateless
public class ControllerEJB {
#POST
public void registerUser(
#QueryParam("fornamn") String fornamn,
#QueryParam("efternamn") String efternamn,
#QueryParam("epost") String epost,
#QueryParam("epost2") String epost2,
#QueryParam("password") String password,
#Context HttpServletRequest request){
HttpSession session = request.getSession(true);
...
}
}

How to Call java Rest WebService inside a Servlet

I have a java Rest WebService URL http://localhost:8080/WebServiceEx/rest/hello/dgdg
When i execute the URL ,the WebService Method Returns a String
My Requirement is to call the above WebService URL inside a Servlet ,Could any one Help?
ServletCode:
public Class StoreServlet extends HttpServlet{
protected void doPost(HttpServletRequest req, HttpServletResponse resp)
throws IOException, ServletException {
//Invoke WebService and Get Response String Here
}
WebService Code:
public class HelloWorldService {
#Context
private ServletContext context;
#GET
#Path("/{param}")
public Response getMsg(#PathParam("param") String msg) {
return Response.status(200).entity(msg).build();
}
}

Take a look at Apache CXF JAX-RS client:
http://cxf.apache.org/docs/jax-rs-client-api.html
e.g.
BookStore store = JAXRSClientFactory.create("http://bookstore.com", BookStore.class);
// (1) remote GET call to http://bookstore.com/bookstore
Books books = store.getAllBooks();
// (2) no remote call
BookResource subresource = store.getBookSubresource(1);
// {3} remote GET call to http://bookstore.com/bookstore/1
Book b = subresource.getBook();
Or, if you use JAX-RS 2.0, it has a client API
e.g.
Client client = ClientFactory.newClient();
String bal = client.target("http://.../atm/balance")
.queryParam("card", "111122223333")
.queryParam("pin", "9876")
.request("text/plain").get(String.class);
Or you can do it the "core" way using just plain Java: http://www.mkyong.com/webservices/jax-rs/restfull-java-client-with-java-net-url/

One possibility is to generate a webservice client using jaxws(for this purposes - look up for a tutorial on the internet). Thus you get some Java classes you can use as usually inside your servlet.