javascript – Front-end connection between two site collections

I have two site collections on the same server farm (SP 2016 site), but different domains (company. * And projects. *). I have full control over both sites. And yet, I can not access one to the other. I have tried ExecutorRequest

var executor = new SP.RequestExecutor (appweburl);

var service = appweburl + "/_api/SP.AppContextSite(@target)/web/lists/getbytitle('Release')/items?$select=Id,Title,ProjectDeliveryId&$orderby=Title&$top= 1000 & @ target = "" + hostweburl + "& # 39;"
executor.executeAsync (
{
url: service, // appweburl + "/ Projects / _api / web / lists / getbytitle (& # 39;) & items; $ select = Id, Title, ProjectDeliveryId & $ orderby = Title & $ top = 1000 & @ target = " + hostweburl + "& # 39;",
method: "GET",
headers: {"Accept": "application / json; odata = verbose",
"Origin": "https://business.test2016.zaba.hr",
"Access-Control-Allow-Origin": "https://business.test2016.zaba.hr/ICT/Gate2"
}
success: fillReleases,
error: onQueryFailed
}
)

403 PROHIBITED – The server has understood your request, but refuses to execute it.

Even with JSOM

var ctx = new SP.ClientContext (appweburl);
var factory = new SP.ProxyWebRequestExecutorFactory (
appweburl
)
ctx.set_webRequestExecutorFactory (factory);
var appContextSite = new SP.AppContextSite (ctx, hostweburl);
console.log (appweburl, factory, ctx, appContextSite, hostweburl);
list = appContextSite.get_web (). get_lists (). getByTitle ("Publication");
var camlQuery = new SP.CamlQuery ();
camlQuery.set_viewXml ("ten");
var collListItem = list.getItems (camlQuery);
ctx.load (collListItem, Include (Id, Title) & # 39;);
ctx.executeQueryAsync (function () {console.log ("success", list); fillReleases ();} function (jqXHR, textStatus, errorThrown) {console.log ("failure"); onQueryFailed (jqXHR, textStatus, errorThrown );});

I have tried with and without Origin and Access-Control headers. The Trust and Allow-Origin collections are mutually defined. Detailed logs indicate that the IFrame is created, but the final message comes because there is no AppContext context in which to execute the request.

I've also tried DataView, access to pages by javascript query, page viewer and other obvious solutions.

I have full control of the farm and both collections, so you can try what you offer. I would like to avoid server-side programming – I know I can create an HTTP handler, a web service, and so on.