This Blog attempts to make its audience understand the way to disable the cache content for UI5 Applications using SAP Netweaver Gateway/OData. It should be noted that there are mechanisms to disable the cache in a UI5 development environment but the blog focusses on disabling them using SAP Netweaver Gateway Implementation.

Understanding the Scenario – I’m Curious πŸ˜•

Q: What is the need to disable the CACHE in a UI5 Application that consumes OData Services ?

A: While performing a specific change/functionality in a UI5 application, it is desired that the Application loads fresh data from the backend and does not display stale/unchanged data.

Q: When does this happen ?

A: Specifically, When an OData service is called to perform an UPDATE operation, A Read is not enforced to fetch the updated DATA.

Q: So Why use GATEWAY/OData to disable cache on a service layer, Why not UI5 environment on an application layer ? πŸ˜•

A: UI5 applications are browser specific applications. For some of the browsers: IE, Firefox – The browser engine does not force a cache READ and has its limitations when trying to READ the data after an update is performed.

Q: Is this a restriction on only CRUD Services ?

A: This behaviour is exhibited for CRUD and Function Import/Non CRUD Operations as well.

Q: Is this a common development to adapt for for all the browsers ?

A: IE specifically, Firefox and Chrome are scenario centric.

Feeling contented…. 😐 Read Further … πŸ™‚

~~ How do I do it ?

  • Ok, Let’s get down to some Business. What OData scenario am I looking at ?

          How about a CRUD Operation : Let’s say an Update !

      

  1. Navigate to your DPC Ext Implementation and locate the CORE_SRV_RUNTIME~READ_ENTITYSET Implementation.
  2. Redefine the method by clicking on the icon as shown in the snapshot./wp-content/uploads/2014/05/1_462384.png
  3. Copy the code from below into the redefined method !

 

Code Snippet

data: ls_header type ihttpnvp.

ls_headername = ‘Cache-Control’.

ls_headervalue = ‘no-cache, no-store’.

APPEND ls_header TO ct_headers.

ls_headername = ‘Pragma’.

ls_headervalue = ‘no-cache’.

APPEND ls_header TO ct_headers.

CALL METHOD SUPER->/IWBEP/IF_MGW_CORE_SRV_RUNTIME~READ_ENTITYSET

    EXPORTING

      iv_entity_name                = iv_entity_name

      iv_source_name              = iv_source_name

      is_paging                          = is_paging

      it_order                               = it_order

      it_filter_select_options  = it_filter_select_options

      is_request_details           = is_request_details

    CHANGING

      ct_headers                         = ct_headers

      cr_entityset                       = cr_entityset     .

Looks Simple ? Does it solve my problem…….? πŸ˜•

Wait !! 😐 This is a READ ENTITYSET Implementation.

What if the Data that I’m trying to update is expected from an Entity and not an Entity Set ??  πŸ˜• πŸ˜•    .

As every problem has a solution so does this one !  πŸ™‚ 😎

4. Navigate to your DPC Ext implementation and Locate the CORE_SRV_RUNTIME~READ_ENTITY Implementation.

/wp-content/uploads/2014/05/2_462385.png

5. Redefine the method by clicking on the icon in the first snapshot as shown above.

6. Next, copy the code from below into the redefined method !

Code Snippet

data: ls_header type ihttpnvp.

ls_headername = ‘Cache-Control’.

ls_headervalue = ‘no-cache, no-store’.

APPEND ls_header TO ct_headers.

ls_headername = ‘Pragma’.

ls_headervalue = ‘no-cache’.

APPEND ls_header TO ct_headers.

CALL METHOD SUPER->/IWBEP/IF_MGW_CORE_SRV_RUNTIME~READ_ENTITY

   EXPORTING

     iv_entity_name       = iv_entity_name

     iv_source_name     = iv_source_name

     is_request_details  = is_request_details

   CHANGING

     ct_headers            = ct_headers

     cr_entity               = cr_entity.


Hmmm…..What If I’m calling a Function Import Service to update the Data ? Does the above Read Entity/Read Entity Set implementation takes care of the behaviour as well ? πŸ˜•

Not Really. We need to implement something more now ! 😎

7. Navigate to your DPC Ext implementation and Locate the CORE_SRV_RUNTIME~EXEC_SERVICE_OPERATION Implementation.

/wp-content/uploads/2014/05/3_462422.png

8. Redefine the method by clicking on the icon in the first snapshot as shown above..

9. Copy the code from below into the redefined method !

Code Snippet

data: ls_header type ihttpnvp.

ls_headername = ‘Cache-Control’.

ls_headervalue = ‘no-cache, no-store’.

APPEND ls_header TO ct_headers.

ls_headername = ‘Pragma’.

ls_headervalue = ‘no-cache’.

APPEND ls_header TO ct_headers.

CALL METHOD SUPER->/IWBEP/IF_MGW_CORE_SRV_RUNTIME~EXEC_SERVICE_OPERATION

   EXPORTING

     iv_action_name     = iv_action_name

     iv_return_type     = iv_return_type

     iv_multiplicity    = iv_multiplicity

     is_request_details = is_request_details

   CHANGING

     ct_headers         = ct_headers

     cr_data            = cr_data.

10. Lastly, Remember to activate all the implementations.

That’s it. That’s all you need to implement. πŸ˜†

You can access your UI5 OData application on Internet Explorer without pondering over – Why the Data was not getting updated ? !!! 😎

Thank you for spending time on this space. Glad if it helped you !! πŸ™‚

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15 Comments

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  1. Matt Harding

    Thanks Stefan. Saved me today and very suprised this is not automatically there inside the framework with the option to selectively change (if you do want to do caching) as this causes all sorts of grief when people use IE and you’ve been testing using Chrome because IE is horrible to do UI5 development/testing in.

    Cheers,

    Matt

    (0) 
  2. Wolfgang RΓΆckelein

    Are you sure this is needed for actions besides GET? IMHO a intermediate cache or a browser will not cache POST/PUT/MERGE/DELETE requests, so the header need only to be added to GET_ENTITY and GET_ENTITYSET?

    (0) 
    1. Vivek Vishal Post author

      Thanks,

      The FI READ/GET does work with theΒ EXEC_SERVICE_OPERATION. For all other kinds of operation that does not involve a READ, the browser generally does not cache.

      (0) 

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