Step by step guide to build an OData Service based on RFCs – Part 1Posted by Volker Drees in volker.drees on Oct 26, 2012 11:43:50 AMinShare10

Hello fellow OData Service developers out there.

When it comes to OData Service development with SAP NetWeaver Gateway a very typical use case is to build a service that is based on an RFC module (or a set of RFC modules) – e.g. for a List / Detail application. For such a scenario there are dozens of RFC modules (BAPIs) available in the SAP standard that can be used. And of course you can also build and consume your own (Z-)RFC modules if the existing modules don’t satisfy your needs... For additional information regarding the Service Builder please also see Thomas Meigens Blog:  The new SAP NetWeaver Gateway Service Builder: Build new OData Services in 3 Quick Steps

In this Step-by-step Guide we will build an OData Service that consumes two RFC modules from the EPM (Enterprise Procurement Model) demo content. From this EPM demo content we pick two BAPIs that retrieve the list and detail of Sales Orders / Line Items. The data model is pretty simple. We have one entity for the Sales Order header data, and one entity for the Sales Order Line Item.

The two BAPIs that we will use in our service are: BAPI_EPM_SO_GET_LIST and BAPI_EPM_SO_GET_DETAILThis guide is based on SAP NetWeaver Gateway 2.0 SP5. We will be mainly using the SAP NetWeaver Gateway Service Builder for the service creation. The Service Builder allows us to build our service without writing a single line of code (although you still can do coding – if you want…). In this first part (1) we will build a Meta Model of the service. In the second part (2) we will perform the service implementation. So let’s get started. 1. Create a new project ZGW100_XX_SO  (SO stands for Sales Order). XX is just a placeholder for a group number and GW100 indicates the course number – as the screen shots were taken from the GW100 training course material that I have created.

 

 

2. Create the first entity by importing an RFC interface. For this right-click on Data Model and choose Import -> RFC/BOR Interface

  3. Enter the following values in the wizard and then choose Next:

 Entity Type Name SalesOrder

Target System Local

Data Source Type Remote Function Calls

Data Source Name BAPI_EPM_SO_GET_LIST

  4. Expand the SOHEADERDATA node and select the following fields:SO_ID,  NOTE,  BUYER_ID, BUYER_NAME,  CURRENCY_CODE,  GROSS_AMOUNT, NET_AMOUNT,  TAX_AMOUNT   Note that SOHEADERDATA is not selected. Choose Next.

  5. In the first line, SO_ID, select the field Is Key and choose Finish:

  6. Create the second entity again by importing an RFC interface. Right-click Data Model and choose Import -> RFC/BOR Interface

  7. Enter the following values in the wizard and choose Next:

 Entity Type Name SalesOrderItem

Target System Local

Data Source Type Remote Function Calls

Data Source Name BAPI_EPM_SO_GET_LIST

  8. Expand the SOITEMDATA node and select the following fields:SO_ID,  SO_ITEM_POS,  PRODUCT_ID,  NOTE,  CURRENCY_CODE,  GROSS_AMOUNT,  NET_AMOUNT,  TAX_AMOUNT,  QUANTITY,  QUANTITY_UNITNote that SOITEMDATA is not selected. Choose Next.

  9. In the first and second line, SO_ID,  SO_ITEM_POS, select the field Is Key and choose Finish:

  Now our project has 2 entities – one for the Sales Order and one for the Sales Order Line Item. As a next step we create entity-sets out of these entities.

1. Expand the node Data Model and double-click Entity Sets: 

 

 2. Click the Create button twice to add two new lines to the table:

  3. Enter the following values:

 Name Entity Type Name

SalesOrderCollection SalesOrder

SalesOrderItemCollection SalesOrderItem 4. Choose Save:

   Now the basic definition of the Model is done. As a next step we can generate the necessary runtime artifacts.  1. Choose the Generate pushbutton:

  2. Leave the default values and choose Enter:

Please note the Technical Service Name ZGW100_XX_SO_SRV is equal to the External Service Name required to consume this service later on. 3. Choose Local Object:

  4. Verify that the runtime objects have been generated successfully:

  Now we can Register and Activate the Service. 1. Double-click Service Maintenance:

  2. Select system ZME and choose the Register button. Please note that the entries listed here depend on the System Alias configuration you have done in the SAP NetWeaver Gateway Implementation Guide (IMG). In a local deployed environment (Backend and Hub components deployed on the same box) you might also find “LOCAL” with the RFC destination “NONE” here.

  3. Confirm the warning message displayed in the popup:

  4. Press F4 to select the system alias. Select ERP_EMEA from the input help. Please note that you won’t get any popup if there is only 1 System Alias maintained. As mentioned above, depending on the deployment method and IMG configuration you possibly see an alias “LOCAL” instead of the ones shown in the screen shot:

  5. Confirm the Select System Alias popup:

  6. Leave the default values and enter $tmp as the package and choose Enter:

 The External Service Name is defaulted with the Technical Service Name from the Generation Step. 7. Verify that the service has been registered and activated successfully:

  Now we can run our service the first time. Please note that we’ve only maintained the basic model data so far. As a consequence we can access the metadata of the service, but not yet any business data (that will come in part 2). 1. Open a new window, start transaction /IWFND/GW_CLIENT.

2. Enter URI:  /sap/opu/odata/sap/ZGW100_XX_SO_SRV/$metadata and choose Execute:

 ZGW100_XX_SO_SRV is the External Service Name that was registered before. So we are done – for the moment. We have created a Service Builder Project with two entities and two entity-sets. We have generated the runtime artifacts and registered and activated our OData service. In part 2 we will map the data provider to bring life into our OData service.55220 Views Products: sap_netweaver_gateway Topics: mobile Tags: gateway, odata, netweaver_gateway, service_builderAverage User Rating(20 ratings)My Rating:

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Comments

18   Comments

Syam Babu Nov 15, 2012 10:56 AMHi Drees, Nice Blog. When i am trying to create project through SEGW project is created success but in import menu option i am not getting BAPI/RFC Interface tab. Ref: Using SP04 Thanks,Syam.Like (0)

oVolker Drees Nov 15, 2012 1:11 PM (in response to Syam Babu)Hi Syam,that is correct. The mentioned features are available as of GW2.0 SP5.

 Best Regards,VolkerLike (0)

Syam Babu Nov 15, 2012 1:31 PM (in response to Volker Drees)Hi Drees, Thanks for the information.Like (0)

Matteo Somensi May 12, 2014 9:21 AM (in response to Volker Drees)hi, someone can help me?I followed step by step your guide, but it does not work, the service when I call SalesOrderCollection or SalesOrderItemCollection gives me an error like this:

Like (0)

Nick Archontis Jul 11, 2013 8:35 PMThanks! Very clear and precise. Nick.Like (0)

Phillip Parkinson Jul 24, 2013 4:36 PMExcellent blog, thanks Volker.Maybe worth mentioning the EPM Data Generator transaction is sepm_dg for those that are using a fresh system without data yet. CheersPhillipLike (0)

Akhila M Dec 4, 2013 6:14 AMThanks so much Volker, It is really helpfulLike (0)

Arshad Ansary Jun 11, 2014 10:23 AMHi Volker, Thanks for the blog. This is very helpful for beginners in Gateway.I followed your steps and I registered the service using  /iwfnd/maint_service in LOCAL server. 1 While creating data model for Gateway servcice , I am not able to select the individaul fields w/o selecting the SOITEMDATA and SOHEADERDATA nodes. 2 I am not able to test the service in /IWFND/GW_CLIENT it syas some HTTP error. But I copied the URL and paste it in chrome browser . I am able to get the result but the individual fields in Entity is not shown

 RegardsArshad

Like (0)

oVolker Drees Jun 13, 2014 3:49 PM (in response to Arshad Ansary)Hi Arshad,the reason for not marking SOHEADERDATA was to keep the Entity Type name that you defined on the first page of the wizard. The blog was created based on GW 2.0 SP5. Now with SP8 (and SP9 coming soon) the behavior of SEGW has changed a bit. So it's not a problem if the SOITEMDATA or SOHEADERDATA nodes are marked. You just need to make sure that you get the expected Entity Type name in the end.Also the Entity-Sets you do not need to add manually anymore. This is done using the "Create Default Entity Set" check-box automatically. As per the 2nd error it's more tricky to say what is wrong. I learned that you e.g. need to have the certificates generated in STRUSTSSO2. But there might be more steps necessary. Best Regards,VolkerLike (0)

Martin Maruskin Jan 14, 2015 2:42 PMHi Volker, interesting blog! I have a question whether pagination can be done within your example - BAPI BAPI_EPM_SO_GET_LIST. I see that within the code of the BAPI the pagination related parameter (IS_PAGING_OPTIONS) of method QUERY_BY_HEADER are not passed. So I not think it is supported but maybe you found a way for this... 

In case you agree with me that no pagination supported by the above mentioned BAPI... Are you aware of any other standard SAP BAPI which supports pagination functionality within the result set? thanksm./Like (0)

oVolker Drees Jan 14, 2015 4:04 PM (in response to Martin Maruskin)Hello Martin,the BAPI BAPI_EPM_SO_GET_LIST unfortunately does not expose the parameter IS_PAGING_OPTIONS. Therefore it is not possbile to use it when calling the BAPI. In the generated DPC method (...GET_ENTITYSET) the paging is handled out of the box. But this is done in a generic way - after the BAPI has provided the full list. You can adjust the generated coding to fill the MAX_ROWS parameter based on the paging request. That can improve the performance when calling the BAPI. I'm not aware of any standard BAPI that supports full paging. If you have access to a NW 7.40 system with SAP_GWFND SP8 installed you can check my sample service (/sap/opu/odata/IWBEP/GWSAMPLE_BASIC) which implements the paging by performing a direct database access (SELECT). Best Regards, VolkerLike (2)

Martin Maruskin Jan 14, 2015 7:52 PM (in response to Volker Drees)Thanks for clarifying this, much appreciated!Like (0)

Arshad Ansary Jan 23, 2015 5:07 AM (in response to Volker Drees)Hi Volker, I am in SP10 and I am not able to find your sample service GWSAMPLE_BASIC in /IWFND/MAINT_SERVICE. Can you post the code of pagination handling in select if we can limit the records at the select itself(instead of at the DPC classes),we can hugely improve the performance. Moreover how the pagination should work along with sort is also a question. Because ideally sort should happen first and then top skip pagination should happen next. In our project we are currently getting all records from DB  and then doing sorting and pagination after that which is affecting perfomance RegardsArshadLike (0)

Volker Drees Jan 23, 2015 5:22 PM (in response to Arshad Ansary)Hi Arshad,I assume you are on 7.40? Have you tried to use "Add Service" to add theGWSAMPLE_BASIC service if it is not yet present in the list of registered services? As per the pagination in a SELECT statement, you can only use the "up to x rows" statement to reduce the number of items to be read. As a consequence the efficiency is higher if you are browsing the first pages of your entityset. In my example I first prepare some helper varaibles (all of type i): 

     lv_top  = io_tech_request_context->get_top( ).     lv_skip = io_tech_request_context->get_skip( ).     IF ( lv_top > 0 ).       lv_maxrows = lv_top + lv_skip.     ENDIF. And in the SELECT statement I use the lv_maxrows variable to limit the number of records to be read. sy-dbcnt helps me to skip the records at the beginning (though they still need to be read from the DB). Sorting and filtering takes place along with the SELECT statement.         SELECT          <...some fields...>          INTO (<...some fields...>)          FROM ( <...some joined tables...> )          UP TO lv_maxrows ROWS          WHERE (lv_where_clause)          ORDER BY (lv_orderby_clause).           IF ( sy-dbcnt > lv_skip ).            APPEND ls_entity TO et_entityset.          ENDIF.        ENDSELECT. hthBest Regards, VolkerLike (0)

Archana Bellamkonda Jun 2, 2015 12:23 AMThank you for the blog. It was really helpful to get started. -ArchanaLike (0)

Kavitha Fredrick Jul 14, 2015 7:22 AMHi Volker, This is an excellent document. Thank You. During "Service Maintenance", after I select the system, I see all buttons like "Register,Maintain, Error Log and Gateway Client" are disabled(greyed out). What cloud be the reason? Please help. Is that role assignment issue? Regards,KavithaLike (0)

oVolker Drees Jul 14, 2015 3:33 PM (in response to Kavitha Fredrick)Hi Kavitha,the mentioned buttons are typically greyed out if the project has not been generated. In that case no runtime artifacts exist which can be used for e.g. registration. Can you please try to generate the project and check if the buttons are still disabled? Best Regards, VolkerLike (0)

Kavitha Fredrick Jul 15, 2015 8:00 AM (in response to Volker Drees)Done..

 Thanks