Offline Odata Native App – Easy as a pie with Agentry

Background

Offline Odata Native App, sounds good? If users ask for it, usually it will be positioned to a Fiori/UI5 requirement. There is some posts talking about how to build an offline UI5 app with Kapsel, wrap it up and run it in Fiori Client. But from my experience, it is still not good enough, especially from a UX perspective.

So from the SAP product stack, is there an answer for a robust native offline odata app?

Yes. That is Agentry, which is an already proven offline mobile solution. What if I tell you it can also be build cross-platform? Awesome

So let us get started. If you are new to Agentry, follow this landing page to get some information.

Set up the environment

For Agentry beginners, check these prerequisites:

1. Install SAP Mobile Platform server. See this tutorial.

2. Install Agentry Editor Plugin for eclipse.

3. You can build a simple Agentry app or just easily deploy the work manager app, refer to the tutorial mentioned in step 1.

Then we need to set up our environment to use Apache Olingo Library (our odata client), but before that we need to set up Maven in our eclipse. The steps have been covered in my previous blog.

The reason we use Olingo is that it supports Odata V4 and has a good dev community. Odata4j is another option but currently it only support Odata V2 but it is very easy to set up. Also check this useful blog which describe how to connect odata from Agentry without coding. But for flexibility purpose, using 3rd-party library such as Olingo is highly recommended.

Get Started

Suppose you have everything ready. The idea of this blog is to call the Northwind sample odata service, pull out all the customer entities and make it offline with Agentry.

The major steps are listed below:

1. set up the olingo dependencies in maven. Check my previous blog on how to set up maven for Agentry java project.

2. create the steplet class and pojo class in our eclipse java project.

3. create data model “Customer” with three properties”CustomerID, CompanyName,ContactName” and the collection in Agentry Project.

4. create a fetch for the “Customers” collection and pull out the data from the odata source.

5. deploy and test.

First edit the maven pom.xml to include Olingo libraries in the Maven Project. More information is provided by Apache.

<dependency>
     <groupId>org.apache.olingo</groupId>
     <artifactId>odata-client-api</artifactId>
     <version>4.3.0</version>
</dependency>
<dependency>
     <groupId>org.apache.olingo</groupId>
      <artifactId>odata-client-core</artifactId>
      <version>4.3.0</version>
</dependency>
<dependency>
      <groupId>org.apache.olingo</groupId>
      <artifactId>odata-commons-api</artifactId>
      <version>4.3.0</version>
  </dependency>
  <dependency>
       <groupId>org.apache.olingo</groupId>
       <artifactId>odata-commons-core</artifactId>
       <version>4.3.0</version>
  </dependency>

Then we create the pojo class for the object “ZOdataCustomer”.

package com.syclo.customer.sap.component.odata.object;
import com.syclo.sap.SAPObject;
import com.syclo.sap.SAPObjectI;
import com.syclo.sap.jco.JCO.Table;
public class ZOdataCustomer extends SAPObject implements SAPObjectI {
  public String customerID;
  public String companyName;
  public String contactName;
  public String ID;
  public ZOdataCustomer() {
  }
  public void setCustomerID(String customerid) {
  this.customerID = customerid;
  }
  public String getCustomerID() {
  return this.customerID;
  }
  public void setCompanyName(String companyname) {
  this.companyName = companyname;
  }
  public String getCompanyName() {
  return this.companyName;
  }
  public void setContactName(String contactname) {
  this.contactName = contactname;
  }
  public String getContactName() {
  return this.contactName;
  }
  public void setID(String id) {
  this.ID = id;
  }
  public String getID() {
  return null;
  }
  public void setNotes(Table arg0) throws Exception {
  }
  public void setProperties(Table arg0) throws Exception {
  }
}

Then create the steplet class including the call to the odata service. We are using the sample Northwind Odata service V4. Within the steplet, it is call the odata service API, get the “Customers” entityset data and iterate it into the ZOdataCustomer objects. Jump into the Apache Olingo website for more information about the supported APIs. As this is only a tutorial, I intend to make it simple. It is always good to follow the SAP’s best practice to create the stephandler and so on.

package com.syclo.customer.sap.component.odata.steplet;
import java.net.URI;
import java.util.ArrayList;
import org.apache.olingo.client.api.communication.response.ODataRetrieveResponse;
import org.apache.olingo.client.api.domain.ClientEntity;
import org.apache.olingo.client.api.domain.ClientEntitySet;
import org.apache.olingo.client.api.domain.ClientEntitySetIterator;
import org.apache.olingo.client.api.ODataClient;
import org.apache.olingo.client.core.ODataClientFactory;
import com.syclo.agentry.AgentryException;
import com.syclo.customer.sap.component.odata.object.ZOdataCustomer;
import com.syclo.sap.SAPObject;
import com.syclo.sap.SAPObjectFactory;
import com.syclo.sap.Steplet;
import com.syclo.sap.User;
public class GetOdataCustomerSteplet extends Steplet {
  protected com.syclo.sap.FetchSession _stepletFetchSession = null;
  public GetOdataCustomerSteplet(com.syclo.agentry.FetchSession session)
  throws AgentryException {
  super(session);
  this._stepletFetchSession = ((com.syclo.sap.FetchSession) session);
  this._stepletFetchSession.setSteplet(this);
  }
  @Override
  public boolean execute() throws AgentryException {
  try {
  ZOdataCustomer customer = null;
  ArrayList<SAPObject> recs = new ArrayList<SAPObject>();
  ODataClient client = ODataClientFactory.getClient();
  String serviceRoot = "http://services.odata.org/V4/Northwind/Northwind.svc";
  URI customersUri = client.newURIBuilder(serviceRoot)
  .appendEntitySetSegment("Customers").build();
  ODataRetrieveResponse<ClientEntitySetIterator<ClientEntitySet, ClientEntity>> response = client
  .getRetrieveRequestFactory()
  .getEntitySetIteratorRequest(customersUri).execute();
  ClientEntitySetIterator<ClientEntitySet, ClientEntity> iterator = response
  .getBody();
  while (iterator.hasNext()) {
  ClientEntity oCustomer = iterator.next();
  customer = new ZOdataCustomer();
  customer.setCustomerID(oCustomer.getProperty("CustomerID")
  .getValue().toString());
  customer.setCompanyName(oCustomer.getProperty("CompanyName")
  .getValue().toString());
  customer.setContactName(oCustomer.getProperty("ContactName")
  .getValue().toString());
  recs.add(customer);
  }
  int sz = recs.size();
  if (sz > 0) {
s._returnData = createSAPObjectArray(
  SAPObjectFactory.create(
  "com.syclo.customer.sap.component.odata.object.ZOdataCustomer",
  new Class[] { User.class }, null), recs);
  }
  return true;
  } catch (Throwable e) {
  throwExceptionToClient(e);
  }
  return false;
  }
}

Export the java source to jar file. In here I will use the maven shade plugin so that I can get a single jar file with all the dependencies and deploy it to SMP server. Again refer to my previous bloghttp://scn.sap.com/community/developer-center/mobility-platform/blog/2016/09/27/how-to-set-up-maven-with-agentry-java-project on how to set it up in maven. Once we got the jar file from the target folder, copy it to the java folder of your Agentry app and update the classpath in JavaBE.ini file. Restart SMP server.

Then in Agentry Project, create a new object “ZOdataCustomer” with the following properties. customerID is the key.

Create a collection in MainObject named “ZOdataCustomers”.

Create a Step named “ZGetOdataCustomerSteplet”, pointing to the steplet java class we just created.

Finally create the fetch “ZOdataCustomersFetch”, pointing to the collections “ZOdataCustomers” using the step “ZGetOdataCustomerSteplet”.

OK. Now publish the Agentry project to SMP and we are done. Run the test from the test environment and you can see the odata has been made offline!

Next Step

I will try to read with “$expand” option in the “Customers” entityset in the sample service. This will make the all the orders for the customers offline. Also I will do some CRUD operations. I will also try to consume to a SAP Gateway exposed Odata service. These will be covered in my next post.

Feel free to leave your comments. Happy coding!