asp.net mvc - Handling concurrency exceptions with external API calls -

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i have following post edit action method, perform 2 update actions:-

  1. edit object on external system suing api calls.

  2. edit object on our system database.

    [httppost] public actionresult create(rackjoin rj, formcollection formvalues) {string controllername = routedata.values["controller"].tostring(); if (modelstate.isvalid) {  var message = "";                 var status = "";                 long assetid = new long();                 xmldocument doc = new xmldocument();                 using (var client = new webclient())                 {                     var query = httputility.parsequerystring(string.empty);                     foreach (string key in formvalues)                     {                         query[key] = this.request.form[key];                     }  query["username"] =  system.web.configuration.webconfigurationmanager.appsettings["apiusername"]; query["password"] =  system.web.configuration.webconfigurationmanager.appsettings["apipassword"]; string apiurl = system.web.configuration.webconfigurationmanager.appsettings["apiurl"]; var url = new uribuilder(apiurl); url.query = query.tostring(); try { string xml = client.downloadstring(url.tostring());                          doc.loadxml(xml);  status = doc.selectsinglenode("/operation/operationstatus").innertext;                         message = doc.selectsinglenode("/operation/message").innertext; }                     catch (webexception ex)                     {                         modelstate.addmodelerror(string.empty, "error occurred:" + ex.innerexception);                     }                 }                  if (status.toupper() == "success")             {                 repository.insertorupdaterack(rj.rack, user.identity.name, rj.resource.resourceid);                 repository.save();                 return redirecttoaction("index");             }             else             {                 modelstate.addmodelerror(string.empty, message.tostring());              }         }     }     catch (dbupdateconcurrencyexception ex)     {

as shown in above code not repository.save() update object on our system, unless api return “success”. facing following problem:- if api return “success” concurrency exception occurred, api update object on external system, object not updated on our system? there way handle situation?

there's no easy way solve situation. 1 way handle ask designers of external api expose method allowing commit transaction done in previous call. first call make modifications external system boolean flag indicating changes still pending. update system , in case of success call external api flag data pending valid.

if have no control on external api , makes changes data first call irreversible, afraid not have choices left. might remember state of object modifying on external system before calling api , in case of exception on system, revert previous state calling api previous values.


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