Network Error Handling
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is possible that network errors can occur that cause a TCP connection to drop. When a TCP connection is dropped, requests and sockettimeoutexception responses between nodes participating in a distributed transaction are
Ioexception
not received. Network errors are detected by the keep-alive protocol described in the section called “Detecting failed nodes” and handled by the distributed transaction protocol.Network connectivity failures are caused by:A non-response keep alive timeout occurring.TCP retry timers expiring.Lost routes to remote machines.These errors are usually caused by network cables being disconnected, router crashes, or machine interfaces being disabled.As discussed in the section called “Local and distributed transactions”, all distributed transactions have a transaction initiator that acts as the transaction coordinator. The transaction initiator can detect network failures when sending a request, or reading a response from a remote node. When the transaction initiator detects a network failure, the transaction is rolled back. Other nodes in a distributed transaction can also detect network failures. When this happens, rollback is returned to the transaction initiator, and again the transaction initiator rolls back the transaction. This is shown in Figure 6.4, “Connection failure handling”.Figure 6.4. Connection failure handlingWhen the transaction initiator performs a rollback because of a connection failure - either detected by the initiator or another node in the distributed transaction, the rollback is sent to all known nodes. Known nodes are those that were located using location discovery (see the section called “Location discovery”). This must be done because the initiator does not know which nodes are participating in the distributed transaction. Notice that a rol
Sign in Pricing Blog Support Search GitHub This repository Watch 1,151 Star 16,301 Fork 3,369 square/retrofit Code Issues 42 Pull requests 6 Projects 0 Wiki Pulse Graphs New issue Asynchronous Error Handling on Network in retrofit v2 beta 2 #1260 Closed phirumtan opened this Issue Nov 5, 2015 · 10 comments Projects None yet Labels None https://docs.tibco.com/pub/ast/2.5.5/doc/html/architectsguide/ch06s08.html yet Milestone No milestone Assignees No one assigned 8 participants phirumtan commented Nov 5, 2015 Please help to fix it out, how to handle network error in asynchronous? @Override public void onFailure(Throwable t) { Toast.makeText(MainActivity.this, t.getMessage(), Toast.LENGTH_SHORT).show(); } when request timeout t.getMessage() is null. i https://github.com/square/retrofit/issues/1260 want catch exception on onFailure(Throwable t) to show like : 1. no internet connection 2. request timeout 3. internal error! 4. Invalid credentials please help to write detail because i'm a beginner android. sorry for my bad english. Thank you phirumtan changed the title from Asynchronous Error Handling in Network in retrofit v2 beta 2 to Asynchronous Error Handling on Network in retrofit v2 beta 2 Nov 5, 2015 tomkoptel commented Nov 8, 2015 Hello @phirumtan! You can process errors "no internet connection"(IOException), "request timeout"(SocketTimeoutException) inside onFailure(Throwable). new Callback
Sign in Pricing Blog Support Search GitHub This repository Watch 257 Star 10,698 Fork 679 github/fetch Code Issues 9 Pull requests https://github.com/github/fetch/issues/257 7 Projects 0 Pulse Graphs New issue Handling HTTP error statuses #257 Closed richardscarrott opened this Issue Jan 9, 2016 · 5 comments Projects None yet Labels https://www.tjvantoll.com/2015/09/13/fetch-and-errors/ None yet Milestone No milestone Assignees No one assigned 2 participants richardscarrott commented Jan 9, 2016 The docs recommend handling HTTP error statuses by throwing an network error error so the consumer can handle them within Promise.prototype.catch() -- https://github.com/github/fetch/tree/v0.10.1#handling-http-error-statuses Whilst this is more familiar to people experienced with jQuery.ajax I'm not sure it's the best approach as, unlike jQuery.ajax, window.fetch uses es6 promises meaning runtime errors in the success handler will result in the catch handler being called. e.g. window.fetch('https://api.github.com/users/richardscarrott/repos') .then(checkStatus) // throws if status network error handling is outside 200-299 .then(parseJSON) .then(function success(data) { console.log('request succeeded with JSON response', data); data.foo.bar; // throws as foo is undefined }).catch(function error(error) { console.log('request failed', error); // error could either be a network or a runtime error }); I'm struggling to see how es6 promises can be used to express the semantics between a network error and a runtime error... GitHub member dgraham commented Jan 9, 2016 That section of the documentation is less of a recommendation and more of an acknowledgement that many, probably most, people beginning to use fetch are switching from jQuery. The pattern described there is what we've used at GitHub to transition our legacy jQuery usage over to fetch. Most fetch calls don't need to distinguish between a network failure and an error code from the server. For those that do, we use something like this: fetch('/').then(checkStatus).then(function(response) { // Success handler. }).catch(function(error) { // Treat network errors without responses as 500s. const status = error.response ? error.response.status : 500 if (status ===
fetch() API do? fetch("http://httpstat.us/500") .then(function() { console.log("ok"); }).catch(function() { console.log("error"); }); If you’re like me, you might assume this code logs “error” when run—but it actually logs “ok”. This expectation probably comes from years of jQuery development, as jQuery’s ajax() method invokes its fail handler when the response contains a failed HTTP status code. For example, the code below logs “error” when run: $.ajax("http://httpstat.us/500") .done(function() { console.log("ok"); }).fail(function() { console.log("error"); }); Why does fetch() work this way? Per MDN, the fetch() API only rejects a promise when a “network error is encountered, although this usually means permissions issues or similar.” Basically fetch() will only reject a promise if the user is offline, or some unlikely networking error occurs, such a DNS lookup failure. The good is news is fetch provides a simple ok flag that indicates whether an HTTP response’s status code is in the successful range or not. For instance the following code logs “Error: Internal Server Error(…)”: fetch("http://httpstat.us/500") .then(function(response) { if (!response.ok) { throw Error(response.statusText); } return response; }).then(function(response) { console.log("ok"); }).catch(function(error) { console.log(error); }); To keep this code DRY and reusable, you probably want to create a generic error handling function you can use for all of your fetch() calls. The following code refactors the error handling into a handleErrors() function: function handleErrors(response) { if (!response.ok) { throw Error(response.statusText); } return response; } fetch("http://httpstat.us/500") .then(handleErrors) .then(function(response) { console.log("ok"); }).catch(function(error) { console.log(error); }); For added fun you can use ES6 arrow functions to make the callback formatting a little less verbose: function handleErrors(response) { if (!response.ok) { throw Error(response.statusText); } return response; } fetch("http://httpstat.us/500") .then(handleErrors) .then(response => console.log("ok") ) .catch(error => consol