ODATA V2 support not working HANA-XSA Project

[saket-sahi]

I am trying to add ODATA V2 support in my HANA -XSA project. I have completed the changes to the package.json and loaded npm odata-v2-proxy on CDS bootstrap. Below is the code. host:port/odata/v4/catalogservice is working but host:port/odata/v2/catalogservice is not working. Error:Cannot GET /odata/v2/catalogservice

var https = require("https"); var port = process.env.PORT || 4000; var express = require("express"); let app = express(); const server = require("https").createServer(app); const cds = require("@sap/cds"); const xsenv = require("@sap/xsenv"); const xsHDBConn = require("@sap/hdbext"); const xssec = require("@sap/xssec"); const passport = require("passport"); var routerData = require('./router/index'); const proxy = require('@sap/cds-odata-v2-adapter-proxy');

xsenv.loadEnv(); https.globalAgent.options.ca = xsenv.loadCertificates(); global.base = dirname + "/"; global.__uaa = process.env.UAA_SERVICE_NAME; passport.use("JWT", new xssec.JWTStrategy(xsenv.getServices({ uaa: { tag: "xsuaa" } }).uaa)); app.use(passport.initialize()); let hanaOptions = xsenv.getServices({hana:{tag:"hana"}}); hanaOptions.hana.pooling = true; app.use( xsHDBConn.middleware(hanaOptions.hana)

); var options = { kind: "hana", logLevel: "error"

};

cds.connect(options); cds.on('bootstrap',(app)=> app.use(proxy()); var odataURL = "/odata/v4/CatalogService/"; cds.serve("gen/csn.json", { crashOnError: false }) .at(odataURL) .with(require("./lib/handlers/cat")) .in(app) .catch((err) => { console.log(err); process.exit(1);
}); app.use('/node',routerData);
app.get("/", (req, res) => { res.redirect(odataURL); }); app.get("/node", (req, res) => { res.redirect(odataURL); });

app.listen(port);

[jung-thomas]

By default the generated proxy URL path isn't going to be /odata/v2/*. It is just normally just /v2. You can see the proxy rewrite in the logs when you do a cds run:

If you want to configure the url path for the proxy you can do that as well. In my sample I configure it to /odata/v2 by adding this to the package.json: https://github.com/SAP-samples/hana-opensap-cloud-2020/blob/main/package.json#L129

[saket-sahi]

proxy created -> http://localhost:50051 proxy rewrite rule created :"^v2" host:51003:/catalogservice-> works fine host:51002:/v2/catalogservice-> internal server error

[jung-thomas]

Did you add the configuration in the package.json I pointed to? This is also necessary to configure a non-standard V4 source. From your code you are setting a non-standard V4 URL path as well so you need to let the v2 proxy know about that

[saket-sahi]

I have added the configuration from beginning. It is still not working.I have couple of questions. I am running the service on HANA on-prem. Why it shows localhost proxy created -> http://localhost:50051 instead of the actual host. Do i need to add specific changes just for on-prem systems Also why the services are not working if i remove cds.serve().to().in(app). shouldn't this code be used only to generate multiple service endpoint for the same service.

[jung-thomas]

Because it's connecting internally within the same Node.js service instance. Therefore localhost. No I don't know of any specific changes for on premise. I've used this on HANA Express without any changes. Not sure what exactly is failing or what this is in the context of the overall application.

[saket-sahi]

Just one last thing. We can run XSA services without server.js. It is just for custom bootstrapping. What changes do i need in package.json to run the services without server.js.

[jung-thomas]

If you want OData V2 you must have a server.js so that you can enhance the boostrapping. See the documentation here: https://cap.cloud.sap/docs/advanced/odata#odata-v2-support

[saket-sahi]

If i do not want odata v2 then i should not be having server.js. My odata v4 services should run with out server.js. but they are still not running without server.js. package,json in srv folder has "start":"node server.js". What if i just want to have ODATA V4 only. Do i need to add anything in package,.json . Its just anaylsis purpose. That will give me a better insight and probably i will be able to fix V2 issue as well

[jung-thomas]

If you don't want OData V2 support then, no, you don't need a server.js. cds run command should start your service with just a package.json and a cds model file somewhere. The server.js is only if you want to customize the startup process.

[saket-sahi]

It give error. As start command expects start: node server.js . What changes are required in package.json to run it without server.js?

[jung-thomas]

What does your package.json scripts section look like? Specifically the start script. If its cds run then I don't see why it would require a server.js.

[saket-sahi]

in srv package.json scripts:{ "start":"cds run" } Error SPAWN CDS EACCES ealrier with server,js it node server.js

[jung-thomas]

Error SPAWN CDS EACCES - that's the complete error log? Are you sure you don't still have it running in another terminal session and the port is already in use?

[saket-sahi]

7/20/21 6:25:25.502 PM [APP/3-0] ERR events.js:174 7/20/21 6:25:25.503 PM [APP/3-0] ERR throw er; // Unhandled 'error' event 7/20/21 6:25:25.503 PM [APP/3-0] ERR ^ 7/20/21 6:25:25.503 PM [APP/3-0] ERR 7/20/21 6:25:25.503 PM [APP/3-0] ERR Error: spawn cds EACCES 7/20/21 6:25:25.503 PM [APP/3-0] ERR at Process.ChildProcess._handle.onexit (internal/child_process.js:240:19) 7/20/21 6:25:25.503 PM [APP/3-0] ERR at onErrorNT (internal/child_process.js:415:16) 7/20/21 6:25:25.503 PM [APP/3-0] ERR at process._tickCallback (internal/process/next_tick.js:63:19) 7/20/21 6:25:25.503 PM [APP/3-0] ERR Emitted 'error' event at: 7/20/21 6:25:25.503 PM [APP/3-0] ERR at Process.ChildProcess._handle.onexit (internal/child_process.js:246:12) 7/20/21 6:25:25.503 PM [APP/3-0] ERR at onErrorNT (internal/child_process.js:415:16) 7/20/21 6:25:25.503 PM [APP/3-0] ERR at process._tickCallback (internal/process/next_tick.js:63:19)

[saket-sahi]

This is the error on start:cds run script

[saket-sahi]

I think it is the version issue. I have successfully implemented a model on Trial BTP. On BTP Trial I was using proxy version ^1.6 and it was generating ODATA V2 metadata. I changed the proxy version to 1.4.13 which is current proxy version of my XSA server and I started getting error for ODATA V2. "Cannot GET /odata/v2/POService/"

[jung-thomas]

If you configure your Web IDE in XSA with an upstream link then you can also fetch module versions from public npm and not be limited to what's delivered in the internal npm cache. https://help.sap.com/viewer/1a8e7ab05a2e4119b02b702f211422f5/2.0.01/en-US/5fd9473b7e994e2aa66092da5a10c75a.html

[saket-sahi]

Client has barred the access to the internet on the XSA server. BASIS needs to download the latest version to web ide cache.

[saket-sahi]

When a specific npm package is uploaded the cache, is it the specific version of the package that is getting loaded or all the versions for the package gets available as well? I thought I was restricted by the package version showing in the XSA server. I changed the package version from the XSA server version to the latest one available in npm and the code started working.