Interoperability between Java and SharePoint 2013 on Premises

http://ctp-ms.blogspot.com/2012/12/interoperability-between-java-and.html

 

Introduction

One of the main possibilities that provider hosted apps in SharePoint 2013 disclose is the possibility of seamless integration between SharePoint and external systems implemented in non-Microsoft technologies.

In this post are explored the basics of the integration between SharePoint on premises and a Java web application. The RESTfull web service API of SharePoint leverages the communication with the Java web application. TheSharePoint chrome control allows the Java web application to have the same styling of the hosted web site.

The TokenHelper.cs source file provides the token service authentication for provided hosted .Net applications. At the moment, it wasn’t found a Java implementation equivalent to the TokenHelper.cs for SharePoint on premises. Thus, it will be used NTLM authentication for the web service calls from the Java web application to SharePoint. This topic shall be revisited.

Find below an extract of the critical parts of the solution source code.

The Communication Layer with SharePoint

The Java web application reads and writes to a list of cars in the hosted web. The hosted web is called Interop1 and the list with data is called Cars. The list Cars has the columns: Brand, Model and Price.

The Java web application will be called Cars App.

The following are the dependencies of the Cars App in its Java implementation:

json-lib 2.4 helper classes to manipulate Json objects

resteasy-jaxrs 2.2.1.GA RESTEasy was used to access the RESTfull SharePoint API

commons-httpclient 3.1 dependency of RESTEasy

httpclient 4.1.1 dependency of RESTEasy

spring-web 2.5.6

spring-core 2.5.6

spring-webmvc 2.5.6

commons-logging 1.1.1

The payload class where the data about a car is stored could be as follows (file Car.java):

public class Car {

private String brand;

private String name;

private long price;

public String getBrand() {

return brand;

}

public void setBrand(String brand) {

this.brand = brand;

}

public String getName() {

return name;

}

public void setName(String name) {

this.name = name;

}

public long getPrice() {

return price;

}

public void setPrice(long price) {

this.price = price;

}

}

It has been defined the Car service in order to read and write into the Cars list. It has the declaration (file CarService.java):

public interface CarService {

public List<Car> getCars() throws CarException, HttpException, IOException ;

public long insertCar(Car car) throws CarException;

}

The Cars service implementation has the member variables (file CarServiceImpl.java). These member variables define the authentication parameters, the URIs for the web service endpoints in SharePoint and the field names of the Cars list.

String user = "YOUR-USER";

String pass = "YOUR-PASSWORD";

String urlList =

"http://SHAREPOINT-SERVER/sites/Interop1/_api/web/lists/getbytitle('Cars')/items";

String urlDigest = "http://SHAREPOINT-SERVER/sites/Interop1/_api/contextinfo";

// These tags are the ones that SharePoint uses to identify the columns in the

// list. They can be retrieved by making a HTTP Get to the server and

// checking the returning field names.

String brandTag = "x3aj";

String modelTag = "Title";

String priceTag = "Price";

The Cars service implements the following helper methods.

The helper method callRestEasyService reads data by performing a HTTP GET against the RESTfull API of SharePoint. The URI provided in the req parameter defines exactly what is being retrieved; it follows the OData protocol syntax. In our case it would be the items of the list Cars.

The result is returned in JSON format, as stated in “application/json; odata=verbose”. Also, it would be possible to return the result as XML by setting the format as “application/atom+xml”.

public String callRestEasyService(String req, String user, String pass) {

String output = "nothing";

try {

// For Kerberos authentication:

// Credentials credentials =

// new UsernamePasswordCredentials(user, pass);

NTCredentials credentials =

new NTCredentials(user, pass, "JAVA-MACHINE-NAME", "DOMAIN");

HttpClient httpClient = new HttpClient();

httpClient.getState().setCredentials(AuthScope.ANY, credentials);

httpClient.getParams().setAuthenticationPreemptive(true);

ClientExecutor clientExecutor =

new ApacheHttpClientExecutor(httpClient);

java.net.URI uri = new java.net.URI(req);

ClientRequestFactory fac =

new ClientRequestFactory(clientExecutor, uri);

ClientRequest request = fac.createRequest(req);

request.accept("application/json;odata=verbose");

ClientResponse<String> response = request.get(String.class);

if (response.getStatus() != 200) {

throw new RuntimeException("Failed : HTTP error code : " +

response.getStatus());

}

BufferedReader br = new BufferedReader(new InputStreamReader(

new ByteArrayInputStream(response.getEntity().getBytes())));

System.out.println("Output from Server .... \n");

while ((output = br.readLine()) != null) {

return output;

}

} catch (ClientProtocolException e) {

e.printStackTrace();

return e.getMessage();

} catch (IOException e) {

e.printStackTrace();

return e.getMessage();

} catch (Exception e) {

e.printStackTrace();

return e.getMessage();

}

return null;

}

In order to create objects in SharePoint through the RESTfull API (i.e., items in the Cars list), it’s needed to provide in the call a Form Digest. The Form Digest can be obtained through a POST to the hosted web endpoint “/_api/contextinfo”. The helper addRestEasyRetrieveDigest performs this POST and reads the Form Digest. The exact URI is defined in the variable urlDigest, already declared above.

Note the methods callRestEasyService and addRestEasyRetrieveDigest are practically the same, just the first does GET and the second POST.

public String callRestEasyRetrieveDigest (String req, String user, String pass) {

String output = "nothing";

try {

NTCredentials credentials =

new NTCredentials(user, pass, "JAVA-MACHINE-NAME", "DOMAIN");

HttpClient httpClient = new HttpClient();

httpClient.getState().setCredentials(AuthScope.ANY, credentials);

httpClient.getParams().setAuthenticationPreemptive(true);

ClientExecutor clientExecutor =

new ApacheHttpClientExecutor(httpClient);

java.net.URI uri = new java.net.URI(req);

ClientRequestFactory fac =

new ClientRequestFactory(clientExecutor, uri);

ClientRequest request = fac.createRequest(req);

request.accept("application/json;odata=verbose");

ClientResponse<String> response = request.post(String.class);

if (response.getStatus() != 200) {

throw new RuntimeException("Failed : HTTP error code : " +

response.getStatus());

}

BufferedReader br = new BufferedReader(new InputStreamReader(

new ByteArrayInputStream(response.getEntity().getBytes())));

System.out.println("Output from Server .... \n");

while ((output = br.readLine()) != null) {

return output;

}

} catch (ClientProtocolException e) {

e.printStackTrace();

return e.getMessage();

} catch (IOException e) {

e.printStackTrace();

return e.getMessage();

} catch (Exception e) {

e.printStackTrace();

return e.getMessage();

}

return null;

}

The helper addRestEasyPost allows the creation of objects in SharePoint through POSTs as stated in the OData protocol. This method is used to add cars to the list Cars.

The parameter req has the URI where to create the object. Here, it would be the URI of the Cars list.

Another detail regarding objects creation, it’s the need to state its type. In the Cars list, the list items are of type SP.Data.CarsListItem. The type naming convention is as follows:

SP.Data.<ListName>ListItem

In case of doubts, it’s possible to confirm the object type by performing a HTTP GET for the list items and checking their type.

public String addRestEasyPost(String req, String user, String pass, String digestValue, Car car) {

String output = "nothing";

try {

// For Kerberos authentication:

// Credentials credentials =

// new UsernamePasswordCredentials(user, pass);

NTCredentials credentials =

new NTCredentials(user, pass, "JAVA-MACHINE-NAME", "DOMAIN");

HttpClient httpClient = new HttpClient();

httpClient.getState().setCredentials(AuthScope.ANY, credentials);

httpClient.getParams().setAuthenticationPreemptive(true);

ClientExecutor clientExecutor =

new ApacheHttpClientExecutor(httpClient);

java.net.URI uri = new java.net.URI(req);

ClientRequestFactory fac =

new ClientRequestFactory(clientExecutor, uri);

ClientRequest request = fac.createRequest(req);

request.accept("application/json;odata=verbose");

request.header("content-type", "application/json;odata=verbose");

request.header("X-RequestDigest", digestValue);

JSONObject innerObject = new JSONObject();

innerObject.put("type", "SP.Data.CarsListItem");

JSONObject body = new JSONObject();

body.put("__metadata", innerObject);

body.put(brandTag, car.getBrand());

body.put(modelTag, car.getName());

body.put(priceTag, car.getPrice());

request.body("application/json", body.toString());

// This attribute was not needed (despite the documentation):

// request.header("content-length",

// request.getBody().toString().length());

ClientResponse<String> response = request.post(String.class);

if (response.getStatus() != 201) {

throw new RuntimeException("Failed : HTTP error code : " +

response.getStatus());

}

BufferedReader br = new BufferedReader(new InputStreamReader(

new ByteArrayInputStream(response.getEntity().getBytes())));

System.out.println("Output from Server .... \n");

while ((output = br.readLine()) != null) {

return output;

}

} catch (ClientProtocolException e) {

e.printStackTrace();

return e.getMessage();

} catch (IOException e) {

e.printStackTrace();

return e.getMessage();

} catch (Exception e) {

e.printStackTrace();

return e.getMessage();

}

return null;

}

The helper method parseJsonDigestValue parses the JSON response from the endpoint “/_api/contextinfo” retrieving the form digest.

public static String parseJsonDigestValue(String json) {

JSONObject jsonObject = (JSONObject) JSONSerializer.toJSON(json);

jsonObject = (JSONObject) jsonObject.get("d");

jsonObject = (JSONObject) jsonObject.get("GetContextWebInformation");

return jsonObject.getString("FormDigestValue");

}

The following helper, parseJson, translates the JSON response to the Car payload class, returning a list of cars.

public List<Car> parseJson(String json) {

List<Car> spCars = new ArrayList<Car>();

JSONObject jsonObject = (JSONObject) JSONSerializer.toJSON(json);

jsonObject = (JSONObject) jsonObject.get("d");

JSONArray array = (JSONArray) jsonObject.get("results");

Car car;

for (int i = 0; i < array.size(); i++) {

car = new Car();

jsonObject = (JSONObject) array.get(i);

car.setBrand(jsonObject.getString(brandTag));

car.setName(jsonObject.getString(modelTag));

car.setPrice(jsonObject.getLong(priceTag));

spCars.add(car);

}

return spCars;

}

To read items, the Cars service defines the method getCars. The implementation is as follows:

public List<Car> getCars() throws CarException, HttpException, IOException {

String jsonString = callRestEasyService(urlList, user, pass);

return parseJson(jsonString);

}

To write items, the Cars service defines the method insertCar. The implementation uses the helper method as follows:

public long insertCar(Car car) throws CarException {

cars.add(car);

String digestValue =

parseJsonDigestValue(callRestEasyRetrieveDigest(urlDigest, user, pass));

addRestEasyPost(urlList, user, pass, digestValue, car);

return 0;

}

User Experience (UX) for Apps in SharePoint 2013

The App user experience can be designed on top of the three possibilities within SharePoint:

1. Full page user experience
2. App Part user experience
3. Custom Actions

The full page UX means the App will have the whole browser page for its user interface. In the full page UX, the App can make use of the SharePoint chrome control to render the same styling as of the hosted web and, optionally, render a header like SharePoint pages do.

In the App Part UX the App surfaces its UI on a page in the hosted web. A special kind of web part known as App Part takes care of embedding the App's page into the hosted page. The App Part accomplished this by rendering an iFrame where the source is the App's page. The App page can have the same styling of the hosted web by importing the hosted site's CSS files through JavaScript.

Custom Actions allow the placement of links to App’s pages in the Ribbon or in the Edi Control Block of the hosted web. This option has not been explored in this post.

Implementing the User Interface

The code below implements the App page named Car.jsp; it displays the list of cars. The page can be rendered as in the full page UX or in the App Part UX. The URL parameter inAppPart defines which way the page will be rendered (inAppPart=true, then as in the App Part UX; if none or false, then as in the full page UX).

First add a few declarations to the JSP page (file Car.jsp):

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"

pageEncoding="ISO-8859-1"%>

<%@ taglib prefix="fmt" uri="http://java.sun.com/jsp/jstl/fmt"%>

<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>

<%@ taglib prefix="spring" uri="http://www.springframework.org/tags"%>

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN""http://www.w3.org/TR/html4/loose.dtd">

<html>

<head>

<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">

<title><spring:message code="welcome.title" /></title>

The code in the following boxes should be added to the HEAD element of the page.

Add the references to the libraries in the JSP page (file Car.jsp):

<script src="http://ajax.aspnetcdn.com/ajax/4.0/1/MicrosoftAjax.js"

type="text/javascript">

</script>

<script type="text/javascript"

src="http://ajax.aspnetcdn.com/ajax/jQuery/jquery-1.7.2.min.js">

</script>

Initialise the JavaScript block and a few variables from the URL query string:

<script type="text/javascript">

"use strict";

// define a namespace for the JavaScript objects: Interop

window.Interop = window.Interop || {};

$(document).ready(function() {

// initialisations

Interop.CarsApp.init();

Interop.Styling.init();

});

Interop.CarsApp = {

// load URL parameters

inAppPart: "false",

hostUrl: '',

init: function() {

// if the App page is in an App Part,

// the developer could set a URL parameter to inform that.

// Here: inAppPart=true

this.inAppPart =

Interop.CarsApp.getQueryStringParameter("inAppPart");

// the hosted web URL

this.hostUrl = decodeURIComponent(

Interop.CarsApp.getQueryStringParameter("SPHostUrl"));

},

// Function to retrieve a query string value.

// For production purposes you may want to use

// a library to handle the query string.

getQueryStringParameter: function (paramToRetrieve) {

var params = document.URL.split("?")[1].split("&");

var strParams = "";

for ( var i = 0; i < params.length; i = i + 1) {

var singleParam = params[i].split("=");

if (singleParam[0].toLowerCase() ==

paramToRetrieve.toLowerCase())

return singleParam[1];

}

return "";

}

};

The following script loads the CSS or the chrome control from SharePoint into the page:

Interop.Styling = {

// Load the SharePoint styling

init: function () {

var inAppPart = Interop.CarsApp.inAppPart,

hostUrl = Interop.CarsApp.hostUrl, scriptURI, linkMarkup;

// if the App page will be displayed as in full page or

// in an App Part, distinct styling initialisations are done

if(inAppPart === "true") {

// When loading the App page in an App Part

// (i.e., embedded in the hosted page)

// hide a few elements which are just meant for the

// full page user experience

$('.displayJustInFullPage').hide();

// load the hosted web styling

if (hostUrl !== "") {

linkMarkup = "<link rel='stylesheet' href='" + hostUrl +

"/_layouts/15/defaultcss.ashx' />";

} else {

// if no host web URL is available, load the default styling

linkMarkup = "<link rel='stylesheet' " +

"href='/_layouts/15/1033/styles/themable/corev15.css' />";

}

$('head').append(linkMarkup);

} else {

// When loading the App page as in full page user experience

// Load the js file SP.UI.Controls.js,

// afterwards set the Chrome Control and styling

scriptURI = hostUrl + "/_layouts/15/SP.UI.Controls.js";

$.getScript(scriptURI, Interop.Styling.setChromeControl);

}

},

setChromeControl: function () {

// Set the Chrome control and styling

// (used when the App is displayed in the full page user experience)

var hostUrl = Interop.CarsApp.hostUrl,

options = {},

nav;

options.siteTitle ="Cars";

options.siteUrl = hostUrl;

options.appHelpPageUrl = "cars.html?" + document.URL.split("?")[1];

options.appIconUrl = hostUrl + "/Shared Documents/car.png";

options.appTitle = "Cars App";

options.settingsLinks = [

{

"linkUrl" : "car.html?" + document.URL.split("?")[1],

"displayName" : "Car List"

},

{

"linkUrl" : "carForm.html?" + document.URL.split("?")[1],

"displayName" : "Add a Car"

}

];

nav = new SP.UI.Controls.Navigation("chromeControlContainer", options);

nav.setVisible(true);

}

};

</script>

</head>

The following piece of HTML defines the BODY of the page. The elements which should be seen just in the full page user experience are marked with the CSS class displayJustInFullPage. This allows the JavaScript part to hide or display them as seen above.

<body>

<div id='content'>

<div class='displayJustInFullPage'>

<!-- Chrome control placeholder -->

<div id="chromeControlContainer"></div>

<h1>Cars List</h1>

</div>

<table>

<tr class="ms-viewheadertr ms-vhltr">

<th class="ms-vh2">Brand</th>

<th class="ms-vh2">Model</th>

<th class="ms-vh2">Price</th>

</tr>

<c:forEach items="${cars}" var="car">

<tr>

<td class="ms-vb2">${car.brand}</td>

<td class="ms-vb2">${car.name}</td>

<td class="ms-vb2">${car.price}</td>

<tr>

</c:forEach>

</table>

</div>

</body>

</html>

The declarations above should be applied on every page that should look like the hosted web.

The Provider Hosted App

A SharePoint provider hosted app should be created following the instructions:

How to: Create high-trust apps for SharePoint 2013 using the server-to-server protocol (advanced topic)

Once created, edit the AppManifest.xml, setting the URL to a page in your Java web application. That could be the entry page of your application for the full page user experience:

<Properties>

<Title>YOUR-APP-TITLE</Title>

<StartPage>http://JAVA-WEB-APPLICATION-URL/car.html?{StandardTokens}</StartPage>

</Properties>

The App Part

For the App Part user experience, first add an App Part (known as well as Client Web Part) to your SharePoint project. After that, in the Elements.xml of the App Part, set the URL to the Java web application:

<Content Type="html" Src="http://JAVA-WEB-APPLICATION-URL/car.html?{StandardTokens}&amp;inAppPart=true" />

It is important to set there "inAppPart=true" to ensure the App Part user experience.

For instructions about how to create an App Part with Visual Studio 2012, refer to:

How to: Create app parts to deploy with apps for SharePoint

Conclusion

Provider hosted apps unleash great possibilities of integration between SharePoint and systems developed in other platforms as Java. Here, we have seen how to perform basic read/write operations on SharePoint lists. Also, it was shown how to integrate the App at user interface level with the full page and App Part user experiences.