CAP or RAP which model to choose?

[former_member128103]

Hi Experts,

I am new to BTP developments but well experienced with ABAP/OData/ Fiori developments. If I have to build a custom application in UI5 where I need to get/push data via REST APIs to non-sap systems. Which programing model should I use ( CAP or RAP ).

What I understood from little reading that I did on this topic

CAP development needs knowledge on Node.js where as ABAP knowledge is enough to get started with RAP. Being an experienced ABAPer I would naturally choose RAP for the ease of coding and not being pushed to learn an entirely new language. But I have also understood that RAP application development needs subscription to ABAP environment service on BTP which is quite costly and CAP apps do not need this. Are there any other advantages of choosing CAP over RAP? what is the best practice (or) guideline from SAP on which model to choose when developing an application on BTP? This are the usual questions that we get from customers when we implement BTP for them

andre.fischer dj.adams.sap dj.adams thomas.jung , your opinion is highly appreciated

[TMNielsen]

I'm no expert, but here's my 2 cents

Your experience push you against RAP.

You say you need to work with non-sap systems. I don't know if this push you agains CAP, but it for sure does not particularly push you against RAP.

Then there is the question of cost. I agree that if you have subscribe to a stand alone BTP ABAP environment, it is costly - I wouldn't say "quit costly", I would say extremely costly. BUT as you mention that you are experienced with ABAP/ODATA/Fiori, I guess you are working at a company that already have some licences that include all or parts of the servers, services etc- that is needed.

In this blog Robert Eijpe argues why to chose CAP, and the blog contains a lot of good points, but if I was in your place (I am in similar place) and if I already had systems including some kind of Steampunk (i don't remember the official name), then I would for sure go with RAP.

[TMNielsen]

PS. from a technical point of view SAP has for 20 years had a fight with itself.
One part of the company want to change from ABAP to java (or javascript) and they regularly introduce fantastic new functionality. The other part of the company strike back and also regularly introduce fantastic new ABAP based functionality. In resent years other movements have been added so now the battle have many parties and new functionality is added extremely often.
My point with this is that from a technical point of view, one of the tools RAP/CAP may today be superior, but tomorrow the situation may have switched and in 6 month it may switch back again.

[former_member128103]

Thanks Thomas for sharing your thoughts. It is just that I don't want to be on side which looses eventually 🙂 when webdynpro was introduced it was avaialble in java and ABAP flavours. At the end ABAP versions prevailed.

[gregorw]

I'm pretty sure here both sides survive. RAP in ABAP Cloud / On Premise S/4HANA and CAP for Cloud development that is more external facing.

[gregorw]

I would suggest you start by some more research:

CAP vs. RAP

[former_member128103]

Thanks Gregor for taking time and responding to the question