Introduction
I have a SAP HANA Cloud Platform account. I have also deployed a Java application to the account and created a test servlet, which returns dummy data.
On the other side i have a SAP UI5 application which i develop on the WebIDE. I created also two destinations:
Destination "virtualTEST" is connected to a SAP Backend System (HANA Cloud Connector)
Destination "javaTEST" is connected to my Java servlet application
The neo-app.json is well configured and can obtain data from the test servlet (the dummy data) and data from the SAP Backend System (OData Gateway).
The problem
Now i want to pass variables to the SAP Backend System (virtualTEST) destination, which should not be visible in the frontend to avoid javascript manipulation.
My first thought
My first thought was that i create a new servlet which acts as proxy. In the SAPUI5 i call the servlet from javaTEST destination and pass the "hidden variables" like /testServlet?targetUrl=https://webide-xxx.hana.ondemand.com/sap/opu/odata/TEST_SRV/TEST?$filter=Var eq '{{MYVAR}}' and the Java application replaces {{MYVAR}} with my real variable. Then the target will be loaded (this is also a destination url to my SAPUI5 application). This does not work, i do not know why, but i think the proxy can not obtain data from the destination of an application.
Also, i think this is not the best solution. How can this be solved? Any ideas or best practices? Can destinations be used in Java application? :)
It is not really clear to me what you want to achieve. Of cause you can call destinations from Java.
<resource-ref>
<res-ref-name>myBackend</res-ref-name>
<res-type>com.sap.core.connectivity.api.http.HttpDestination</res-type>
</resource-ref>
import javax.naming.Context;
import javax.naming.InitialContext;
import com.sap.core.connectivity.api.http.HttpDestination;
...
// coding to lookup the destination "myBackend"
Context ctx = new InitialContext();
HttpDestination destination = (HttpDestination)
ctx.lookup("java:comp/env/myBackend");
// coding to call service "myService" on the system configured in the given destination
HttpClient createHttpClient = destination.createHttpClient();
HttpGet get = new HttpGet("myService");
HttpResponse resp = createHttpClient.execute(get);
from the official documentation. in the HttpGet you could set Params if you like.
In my opion your Backend should be so save you don't have to worry about Javascript manipulations, especially not for exposed OData services
Regards
Mathias
Goodday Folks,
I have implemented a get or read operation using an AngularJS application to invoke a Isis service via an $http call. And displaying the collection on the screen using Angular ng-repeat. My next task is to do a create and update on the same entity using AngularJS. I am aware i have to send some parameters in the endpoint URL. Please, I need both Isis guidance and also importantly AngularJS hints or references or code.
I think i should get some sort of acknowledgment to confirm the create or update is succesful.
Below, is an extract from my code for the getList operation, just for starters.
Your logic might be totally different from this.
Thanks a lot.
sampleApp.controller('CrateUpdateController', function($scope, $http) {
$http({ method:'GET',
url: 'http://localhost:8080/xxx-webapp-1.0-SNAPSHOT/restful/services',
headers: {'Accept': 'application/json'}
}).
success(
function (data) {
//code to process outcome and acknowledgement etc
}
);
});
You might be best doing some Angular tutorials to learn the principles of that library. Then, (as I've mentioned before) take a look at using the Spiro library as the main interface to the RO server (Isis or RO.Net).
You should not mix so much different topics. A good practice is to distinguish the server side interface exposed by your HTTP server (Apache Isis) from the client side code accessing it.
This question should be break down to the following:
How to expose create and delete verbs for an existing resource in Isis
How to use create and delete verbs with Angular
The two topics are very different and it does not make so much sense to ask them together. The main point about having Isis exposing an HTTP interface is exactly to abstract from the client side logic.
As a side note, when accessing restful resources with Angular, try to use $resource instead of $http
I communicate with OData services by using Breeze.js and wanna be able to get and save data.
So there are two endpoints which should be used to get and save resources:
1. https://domain.com/smth/getdata
2. https://domain.com/smth/postdata
I created a manager which purpose is to get data, and send them back to server if needed:
var smthManager = new EntityManager(http://domain.com/smth/getdata);
After changing entities in smthManager I have to save them (by using endpoind 2). Investigating documentation I have found the next statement:
you can re-target a "save" to a custom server endpoint such as an
arbitrarily named action method on a separate
So here is the code to "re-target a save":
var so = new SaveOptions({ resourceName: "postdata" }); // also tried with resourceName: 'http://domain.com/smth/postdata'
myEntityManager.SaveChanges(null, so );
But after all these manipulations what can I see that request was sent to https://domain.com/smth/getdata/$batch
Breeze with a WebApi or WebApi2 service supports multiple server endpoints. Breeze with an OData service does not because the OData spec itself only supports a single $batch save for a service.
See http://www.odata.org/documentation/odata-v2-documentation/batch-processing/
Note that any Breeze WebApi or WebApi2 service is a superset of what can be provided directly from an OData service and is in general just as easy to expose your model from ( as long as you have a .NET server).
I'm quite new to JayData, so this may sound like a stupid question.
I've read the OData server tutorial here: http://jaydata.org/blog/install-your-own-odata-server-with-nodejs-and-mongodb - it is very impressive that one can set up an OData provider just like that. However the tutorial did not go into details about how to customize the provider.
I'd be interested in seeing how I can set it up with a custom database and how I can add a layer of authentication/authorization to the OData server. What I mean is, not every user may have permissions to every entity and not every user has the permission to add new entities.
How would I handle such use cases with JayData?
Thanks in advance for your answers!
UPDATE:
Here are two posts that will get you started:
How to use the odata-server npm module
How to set up authentication/authorization
The $data.createODataServer method frequently used in the posts is a convenience method that hides the connect/express pipleline from you. To interact with the pipeline examine the method body of $data.createODataServer function found in node_modules/odata-server folder.
Disregard text below
Authentication must be solved with the connect pipeline there are planty of middleware for that.
For authorization EntityContext constructor accepts an authorization function that must be promise aware.
The all-allow authorizator looks like this.
function checkPerm(access, user, entitysets, callback) {
var pHandler = new $data.PromiseHandler();
var clbWrapper = pHandler.createCallback(callback);
var pHandlerResult = pHandler.getPromise();
clbWrapper.success(true); // this grants a joker rw permission to everyone
//consult user, entitySet and acces to decide on success/error
//since you return a promise you can call async stuff (will not be fast though)
return pHandlerResult;
}
I have to consult with one of the team members on the syntax that let you pass this into the build up process - but I can confirm this is doable and is supported. I'll get back with the answer ASAP.
Having authenticated the user you can also use EntityContext Level Events to intercept Read/Update/Create/Delete operations.
$data.EntityContext.extend({
MySet: { type: $data.EntitySet, elementType: Foobar,
beforeDelete: function(items) {
//if delete was in batch you'll get multiple items
//check items here,access this.request.user
return false // deny access
}
});
And there is a declarative way, you can annotate Role names with permissions on entity sets, this requirest that your user object actually has a roles field with an array of role names.
I too have been researching oData recently and as we develop our platform in both node and C# naturally looked at JayStorm. From my understanding of the technical details of JayStorm the whole capability of Connect and Express are available to make this topic possible. We use Restify to provide the private API of our platform and there we have written numerous middleware modules for exactly this case.
We are using JayData for our OData Service layer also, and i have implemnment a very simple basic authentication with it.
Since the JayData is using Express, so we can leverage Express' features. For Basic Auth, the simplest way is:
app.use(c.session({ secret: 'session key' }));
// Authenticator
app.use(c.basicAuth('admin', 'admin'));
app.use("/odata.svc", $data.JayService.OData.Utils.simpleBodyReader());
you also can refer to this article for more detail for authentication with Express: http://blog.modulus.io/nodejs-and-express-basic-authentication
Thanks.
I wrote that blogpost, I work for JayData.
What do you mean by custom database?
We have written a middleware for authentication and authorization but it is not open source. We might release it later.
We have a service called JayStorm, it has a free version, maybe that is good for you.
We probably will release an appliance version of it.
I need users to be able to post data from a single page browser application (SPA) to me, but I can't put server-side code on the host.
Is there a web service that I can use for this? I looked at Amazon SQS (simple queue service) but I can't call their REST APIs from within the browser due to cross origin policy.
I favour ease of development over robustness right now, so even just receiving an email would be fine. I'm not sure that the site is even going to catch on. If it does, then I'll develop a server-side component and move hosts.
Not only there are Web Services, but nowadays there are robust systems that provide a way to server-side some logic on your applications. They are called BaaS or Backend as a Service providers, usually to provide some backbone to your front end applications.
Although they have multiple uses, I'm going to list the most common in my opinion:
For mobile applications - Instead of having to learn an API for each device you code to, you can use an standard platform to store logic and data for your application.
For prototyping - If you want to create a slick application, but you don't want to code all the backend logic for the data -less dealing with all the operations and system administration that represents-, through a BaaS provider you only need good Front End skills to code the simplest CRUD applications you can imagine. Some BaaS even allow you to bind some Reduce algorithms to calls your perform to their API.
For web applications - When PaaS (Platform as a Service) came to town to ease the job for Backend End developers in order to avoid the hassle of System Administration and Operations, it was just logic that the same was going to happen to the Backend. There are many clones that showcase the real power of this strategy.
All of this is amazing, but I have yet to mention any of them. I'm going to list the ones that I know the most and have actually used in projects. There are probably many, but as far as I know, this one have satisfied most of my news, whether it's any of the previously ones mentioned.
Parse.com
Parse's most outstanding features target mobile devices; however, nowadays Parse contains an incredible amount of API's that allows you to use it as full feature backend service for Javascript, Android and even Windows 8 applications (Windows 8 SDK was introduced a few months ago this year).
How does a Parse code looks in Javascript?
Parse works through classes and objects (ain't that beautiful?), so you first create a specific class (can be done through Javascript, REST or even the Data Browser manager) and then you add objects to specific classes.
First, add up Parse as a script tag in javascript:
<script type="text/javascript" src="http://www.parsecdn.com/js/parse-1.1.15.min.js"></script>
Then, through a given Application ID and a Javascript Key, initialize Parse.
Parse.initialize("APPLICATION_ID", "JAVASCRIPT_KEY");
From there, it's all object manipulation
var Person = Parse.Object.extend("Person"); //Person is a class *cof* uppercase *cof*
var personObject = new Person();
personObject.save({name: "John"}, {
success: function(object) {
console.log("The object with the data "+ JSON.stringify(object) + " was saved successfully.");
},
error: function(model, error) {
console.log("There was an error! The following model and error object were provided by the Server");
console.log(model);
console.log(error);
}
});
What about authentication and security?
Parse has a User based authentication system, which pretty much allows you to store a base of users that can manipulate the data. If map the data with User information, you can ensure that only a given user can manipulate specific data. Plus, in the settings of your Parse application, you can specify that no clients are allowed to create classes, to ensure innecesary calls are performed.
Did you REALLY used in a web application?
Yes, it was my tool of choice for a medium fidelity prototype.
Firebase.com
Firebase's main feature is the ability to provide Real Time to your application without all the hassle. You don't need a MeteorJS server in order to bring Push Notifications to your software. If you know Javascript, you are half way through to bring Real Time magic to your users.
How does a Firebase looks in Javascript?
Firebase works in a REST fashion, and I think they do an amazing job structuring the Glory of REST. As a good example, look at the following Resource structure in Firebase:
https://SampleChat.firebaseIO-demo.com/users/fred/name/first
You don't need to be a rocket scientist to know that you are retrieve the first name of the user "Fred", giving there's at least one -usually there should be a UUID instead of a name, but hey, it's an example, give me a break-.
In order to start using Firebase, as with Parse, add up their CDN Javascript
<script type='text/javascript' src='https://cdn.firebase.com/v0/firebase.js'></script>
Now, create a reference object that will allow you to consume the Firebase API
var myRootRef = new Firebase('https://myprojectname.firebaseIO-demo.com/');
From there, you can create a bunch of neat applications.
var USERS_LOCATION = 'https://SampleChat.firebaseIO-demo.com/users';
var userId = "Fred"; // Username
var usersRef = new Firebase(USERS_LOCATION);
usersRef.child(userId).once('value', function(snapshot) {
var exists = (snapshot.val() !== null);
if (exists) {
console.log("Username "+userId+" is part of our database");
} else {
console.log("We have no register of the username "+userId);
}
});
What about authentication and security?
You are in luck! Firebase released their Security API about two weeks ago! I have yet to explore it, but I'm sure it fills most of the gaps that allowed random people to use your reference to their own purpose.
Did you REALLY used in a web application?
Eeehm... ok, no. I used it in a Chrome Extension! It's still in process but it's going to be a Real Time chat inside a Chrome Extension. Ain't that cool? Fine. I find it cool. Anyway, you can browse more awesome examples for Firebase in their examples page.
What's the magic of these services? If you read your Dependency Injection and Mock Object Testing, at some point you can completely replace all of those services for your own through a REST Web Service provider.
Since these services were created to be used inside any application, they are CORS ready. As stated before, I have successfully used both of them from multiple domains without any issue (I'm even trying to use Firebase in a Chrome Extension, and I'm sure I will succeed soon).
Both Parse and Firebase have Data Browser managers, which means that you can see the data you are manipulating through a simple web browser. As a final disclaimer, I have no relationship with any of those services other than the face that James Taplin (Firebase Co-founder) was amazing enough to lend me some Beta access to Firebase.
You actually CAN use SQS from the browser, even without CORS, as long as you only need the browser to send messages, not receive them. Warning: this is a kludge that would make my CS professors cry.
When you perform a GET request via javascript, the browser will always perform the request, however, you'll only get access to the response if it was from the same origin (protocol, host, port). This is your ticket to ride, since messages can be posted to an SQS queue with just a GET, and who really cares about the response anyways?
Assuming you're using jquery, your queue is https://sqs.us-east-1.amazonaws.com/71717171/myqueue, and allows anyone to post a message, the following will post a message with the body "HITHERE" to the queue:
$.ajax({
url: 'https://sqs.us-east-1.amazonaws.com/71717171/myqueue' +
'?Action=SendMessage' +
'&Version=2012-11-05' +
'&MessageBody=HITHERE'
})
The'll be an error in the console saying that the request failed, but the message will show up in the queue anyways.
Have you considered JSONP? That is one way of calling cross-domain scripts from javascript without running into the same origin policy. You're going to have to set up some script somewhere to send you the data, though. Javascript just isn't up to the task.
Depending in what kind of data you want to send, and what you're going to do with it, one way of solving it would be to post the data to a Google Spreadsheet using Ajax. It's a bit tricky to accomplish though.Here is another stackoverflow question about it.
If presentation isn't that important you can just have an embedded Google Spreadsheet Form.
What about mailto:youremail#goeshere.com ? ihihi
Meantime, you can turn on some free hostings like Altervista or Heroku or somenthing else like them .. so you can connect to their server , if i remember these free services allows servers p2p, so you can create a sort of personal web services and push ajax requests as well, obviously their servers are slow for free accounts, but i think it's enought if you do not have so much users traffic, else you should turn on some better VPS or Hosting or Cloud solution.
Maybe CouchDB can provide what you're after. IrisCouch provides free CouchDB instances. Lock it down so that users can't view documents and have a sensible validation function and you've got yourself an easy RESTful place to stick your data in.