I want to implement REST service in gwt .But I don't know how to go about it. I read some documents where they have implemented it using RestyGwt and jercy. But I have one app which is deployed on tomcat. Then situation is that my client side app is calling the methods on the application present on tomcat.
I have to implement it using REST so that my client side call will first go to Proxy service on client then it make REST call to the application on tomcat and fetch result and return. How can I do this in gwt. ?
As mentioned, you can only communicate with REST service.
Anyway, maybe take a look on dispatch concept in GWTPlatform and their way of implementing it. (https://github.com/ArcBees/GWTP/wiki/Rest-Dispatch).
Idea is easy, you have an action on client side which is registered to deal with rest url. You can define action interface with some additional annotations to tell what is excepected to be send and received. They are using piriti library for json serialization.
It is up to you if you need only client side implementation or you would like to use server side service creation too.
You can NOT implement a REST service in gwt, since gwt is thought as a client-side solution.
What the GWT kit provides for server side are a few utilities to facilitate the comunication between client-side and server-side when both are written in java (RPC, RF).
So you can consume a REST service from gwt (RequestBuilder, gwtquery-ajax, etc), but if you want to provide REST services you need a 3party solution for your server side like Jersey, CXF, etc.
There are, though, 3party solutions which provides the server side and client simultaneously like restygwt, errai-jax, etc.
If you are looking for a simple and reliable solution to query rest services from the client, in this question you have a client implementation done with gwtquery (ajax, databinding, promises)
Related
I am working with a CRM System that provides two types of APIs: servlet API & REST API, both of which are over HTTP.
I used to integrate with REST API from my ASP.NET MVC web application by calling the REST URL and manipulating the returned JSON or XML. But I cannot figure out what is meant by a servlet API and can these APIs be called over the web from my ASP.NET MVC application or these APIs should be called inside a Java application?
Sorry if my question seems trivial to someone.
The Java Servlet API refers to a set of classes used to implement server side programs. The main player is the Servlet:
A servlet is a small Java program that runs within a Web server. Servlets receive and respond to requests from Web clients, usually across HTTP, the HyperText Transfer Protocol.
If you want a very simplistic analogy, the Servlet is Java's version of CGI (Common Gateway Interface).
A REST API is a way to build applications by fully using the architecture of the web. Leaving all details of REST aside and grossly simplifying, it's basically a HTTP API.
If you want to build a HTTP API, you can use Servlets. So you can also use servlets to build a REST API although there are better alternatives to that (e.g. JAX-RS) because servlets are a "low level" component and nothing shields you from all the boiler plate code you need to write.
You can of course call a Java application build on top of the Servlet API from other clients (e.g. from ASP.NET MVC). That's what it was built for. For this reason I don't really understand what exactly your CRM system means by a Servlet API and (a separate!?) REST API... so maybe ask the CRM provider?
EDIT : Based on what I've read about the ManageEngine Service deskPlus APIs, I'm thinking that this is just an unfortunate name chosen by the provider.
As I mentioned in my comments, when you say REST API you already provide some information from the beginning. Most people, when told about REST understand that you have some abstract resources, that these resources can have multiple representations (JSON, XML, whatever), that each resource is identified by a URI, that /customers is referring to a list of customers resources, that /customers/1 is a customer and that /customers/2 is another one, that you use GET /customers/1 to find out details about the customer and DELETE /customers/1 to delete it etc.
REST is one way to interact with an application, another one is to expose operations that can be called by clients, for example like what SOAP is doing. Before REST became the new kid in town people were doing stuff with SOAP. Unlike accessing resources, SOAP is focused on accessing operations. When you mention SOAP to someone she knows that it's a protocol that can use HTTP's POST to transmit messages around, that each message has an XML payload that contains the operation name to invoke and the parameters needed for the call etc.
But even before SOAP and REST becoming widely known, people realized that they can use a form submit to sneak in RPC calls through HTTP. The HTTP form based submission is one of the methods of the API in ManageEngine Service deskPlus. But the form based submission method (as far as I know) doesn't have a cool name like SOAP or REST... so maybe that's why it was named after the Servlet API?! (I'm once again emphasizing that this is just the server implementation which is not important in the context of the HTTP protocol).
So to conclude: Yes, you CAN call the ManageEngine Service deskPlus Servlet API from ASP.NET, even a web browser or any kind of HTTP capable client.
I have my restful CXF service producing JSON with default JSON provider. I want to know if we can use GWT to build client which will user the restful service. Will it work ? If not, what would be a simple work around for this type ?
Thank you.
regards
It will work. See this. Here's a quote:
GWT does not limit you to this one RPC mechanism or server side development environment. You are free to integrate with other RPC mechanisms, such as JSON using the GWT supplied RequestBuilder class, JSNI methods or a third party library.
Is it possible to write a server side of GWT application in other languages then Java if yes how to use GWT-RPC mechanism, an sample code please
Thanks
Please read the GWT documentation Communication with the Server:
If you can run Java on the backend and are creating an interface for your application's server-side business logic, GWT RPC is probably your best choice. [...]
If your application talks to a server that cannot host Java servlets, or one that already uses another data format like JSON or XML, you can make HTTP requests to retrieve the data.
You can write your server in any language you choose, GWT is just JavaScript to be run in your users' browsers.
If you decide to go that route, you should look into using RequestFactory to communicate with your server instead of GWT-RPC, which is Java-specific. RequestFactory uses standard JSON, which any language can read/write.
Dont waist your time with GWT-RPC. It's bad. Use RequestFactory. I am surprised people are promoting GWT-RPC. It's a broken toy.
Is there a way to implement RESTful WebService using Spring 3 (or not) that does not use any web container?
Thank you !
I assume that the RESTful request will arrive over HTTP? So something needs to listen on the appropriate port and dispatch requests off to the service code. Obviously you can write such code, but you are likely to end up with something not very different from a Web Server.
If your objective is to embed this capability in some context then a lighweight container such as Jetty (as proposed by skaffman) seems like an answer - I'd be reluctant to write my own code instead
Using a framework such as JAX-RS makes writing REST services very easy, so if the actual objective is develop RESTful services quickly then I'd be prepared to live with a container that does the work for me.
In theory, yes - the various Spring-WS components are decoupled from the Servlet API. So you could, in theory, use the webserver built in to the Sun Java6 JRE.
In practice, this would be a lot of extra work. You'd have to bridge the Sun Web Server API to the Spring-WS API.
As an alternative to traditional Servlet containers, I can highly recommend Embedded Jetty, where your app can start up a lightweight servlet container within itself, and serve Spring-WS from that.
Is there any way how I can access a web service from GWT using its WSDL? Previously I was trying to use the generated classes from ws-import.... but then someone pointed out to me that GWT cannot handle all Java, just a subset of it, hence it won't understand the ws-import classes.
Thanks and regards,
Krt_Malta
GWT can access web services using a RequestBuilder, which makes HTTP calls to a service and then gets access to its response.
Since your web service is using SOAP, the response you get in your RequestBuilder's callback will be XML. Parse that XML to find the information you're interested in, and you're good to go.
In our project we were using Axis Client to make SOAP Web Service Call(WSDL Driven). We had use the inbuild plug tool provided by the WTP/ AXIS Webservice in Spring Source Tool to create the client using provided WSDL. We had use the same client code to incorporate with GWT and everything works fine.