Here I am exposing a sap table as odata using gateway service builder.TCODE is segw.
1.Go to TCODE SEGW.Then click on create icon
Fill Details Project name ,Description and choose package click tick button.A new project will be created.
2.Expand the Node Select Data Model node and right click select import–>DDIC structure
3.Enter name of the entity(give any reasonable name) and select abap structure.Here i have selected a custom table created by me
4.Select which all fields to be exposed.Tick mark needed fields and click next button
5.Select the Key fields in the table and Click finish button
6.Now click on Generate button to generate model provider classes and data provider class.This will be generated automatically by the system.
7.Click tick button.
8.Expand Service Maintenance node and click register button.
9.Select system alias.Here iam selecting LOCAL.Click tick mark button.
10.If you want to change service name you can do it here.Iam not gonna change it.Select local object and press OK button.Now press maintain button
11.Already Now you can view your service in the browser or gateway client.
12.Wow See the result in gateway client.Note that http status is 200 ok.If you get other than 200 You have done something wrong.