What are the good choice for API error code response pattern?
Instead of using different codes indicating different type of error
100001 // username not provided
100002 // password not provided
100003 // password too short
...
I see some other use patterns like the following (non-sequential) ...
20000
20001
20004
20015
Are there any other recommendations?
In my experience developing and using web services, I have found that a strategy of using a combination of top-level HTTP status codes and lower level API error codes work reasonably well. Note that the lower level API error codes don't need to be integers, but can be any enumeration. For a well-known public example, AWS Simple Email Service (SES) uses this strategy of using both HTTP status codes and API level error codes. You can see a sample error code response for SES here. Note that although SES uses XML response error payloads, this strategy works equally well for JSON response payloads.
In my experience, there are a few things that you need to keep in mind when using this strategy:
Strive to return the correct HTTP response code: HTTP is a ubiquitous protocol and is no doubt understood by your web container. Its response codes fit naturally into REST web services. As such, leverage it! If your web service encounters an error condition, you should do your best to return the correct HTTP status code in whose context, the API error code has meaning. One my biggest headaches in debugging issues with web services occur when developers just unconditionally throw arbitrary (usually runtime) exceptions back up the stack. The result is that everything gets returned back to the caller as an HTTP 500 (Internal Server Error) status code even when that's not the case (e.g. the client sends garbage data and the server just can't process it. Some common HTTP status codes you might want to design for include:
400 Bad Request: There is an issue with the client's request. Note this error isn't just used for things like broken JSON syntax in a POST request, but it is also a legitimate response code for semantic issues as well (i.e. the JSON request payload conformed to the prescribed schema, but there was an issue with the data in the payload, such as a number being negative when it is supposed to be only positive).
401 Unauthorized: The caller's credentials were invalid (i.e. authorization error).
403 Forbidden: The caller's credentials were valid, but their access level isn't sufficient to access the resource (i.e. authentication error).
404 Not Found: The resource of the URL doesn't exist.
500 Internal Server Error: Something bad happened inside the server itself, this error could be anything.
502 Bad Gateway: An error occurred when calling downstream service.
503 Service Unavailable: A useful response code for when you get hammered with a ton of "happy" customers who are inadvertently DDOS'ing your service.
504 Gateway Timeout: Like the 502 status code, but indicates a timeout instead of an actual error with the downstream service, per se.
HTTP response codes are the top-level codes, and API error codes only have meaning within that context: By this, I mean that your API error codes are only meaningful for certain HTTP response codes. For example, in the table of SES error codes, each error code is only tied to a single HTTP(S) response code. The error codes ConfigurationSetDoesNotExist and InvalidParameterValue only make sense when a 400 Bad Request is returned by SES - it wouldn't make sense to return these status codes when a 500 Internal Server Error is returned. Similarly, if you were writing a web service that called downstream services and databases, you might have a FooDownstreamServiceTimedOut error code that you would return with a 504 Gateway Timeout HTTP status code when a downstream web service call timed out to the "Foo" web service. You might also have a MyDatabaseError error code that you would return with a 500 Internal Server Error HTTP status code when your query to the internal DB fails.
Have a uniform error code schema irrespective of status codes: Your clients need to be able to process your error content programmatically. As such, it needs to conform to a certain schema. Ideally, your API error code schema should include the error code (i.e. name or ID, etc.). You also probably want to include a natural language description of the error code and the ID/GUID of the request that you are responding to. For an example of an error schema, see this sample AWS SES response and schema. Additionally, you might also want to consider returning a client ID in the response. This is as much for your own benefit as the client's since it can help you drill down into the data to see if one particular client is getting a glut of particular errors vs. your other clients.
Consider returning natural language descriptions of the error codes in the response: To make things easier on your clients, you might want to consider not just returning the error code in the error payload, but a natural language description as well. This kind of behavior can immediately help confused and busy engineers who really don't care that much about your service quickly diagnose what's happening so that they can resolve the issue ASAP. btw, enabling engineers to quickly diagnose issues with your service increases the all-important "uptime" metric that your customers and managers will no doubt care about.
Don't feel obliged to use integers, use enumerations instead: The notion of "error codes" conjures up images of outdated technologies and codebooks where you had to look up what an error meant. It arose from the programming dark ages when engineers needed to fit all possible errors into a byte of space, or a nibble or whatever. Those days are gone, and your error code can be a string, likely without any meaningful impact on performance. You might as well take advantage and make the error code meaningful, as a means of keeping things simple.
Return info to clients that they might need to debug, but be mindful of security: If possible, return whatever debug info your clients may need. However, if your service potentially deals with sensitive information such as credit card numbers and the like, you probably don't want to pass that info around for obvious reasons.
Hope that helps.
A recommendation by the IETF (internet standards body) is using the application/problem+json mediatype.
Notable is that they don't use random numbers, they use strings (specifically uris) to identify errors.
This is a subjective question, but even if you don't use their format, I'd argue that username-not-provided is better in almost every way to 100001.
I would say this heavily depends on what kind of API you're providing.
I were to always include a field called ack or something similar in every response that has three states: failure, warning, success. Success obviously being everything went well. On warning, the request went through and the JSON will contain the expected output, but it will also include a warning string, or even better in case multiple warnings could occur an array called errors which consists of multiple objects containg code, string and type. This array will also be returned in case of failure, and nothing else but this array.
The array contains one object per error or warning, having a code (I would suggest going with your initial idea of 10001, 10002, ...) and a string explaining the error in a very short phrase (e.g. Username contains invalid characters). The type is either error or warning, which is useful in case of a failure ack that contains not only errors but also warnings.
This makes it easy to look up errors by their code (I would provide a page, also with an API, that contains all the error codes in a table along with their short and long description plus common causes/fixes/etc. - All this information should also be available via an API where they can be accessed by providing the error code) while still having a quick short text response so the user can tell what's wrong in most cases without having to look up the error.
This also allows for easy output of warnings and errors to the end user, not just the developers. Using my idea with the API call to get informations about an error, developers using your API could easily provide full information about errors to end-users when needed (including causes/fixes/whatever you see fit).
Instead of writing your own API standard from scratch adopt one of the already available, for example the JSON API standard:
If you’ve ever argued with your team about the way your JSON responses should be formatted, JSON API can be your anti-bikeshedding tool.
By following shared conventions, you can increase productivity, take advantage of generalized tooling, and focus on what matters: your application.
Clients built around JSON API are able to take advantage of its features around efficiently caching responses, sometimes eliminating network requests entirely.
If you decide to go with JSON API it has a section dedicated to errors and a few error examples.
For many years, many developent companies have created things like bitmask for errors, so they can encode multiple variables inside the error:
000 - all ok
001 - something failed with X
010 - something failed with Y
011 - something failed with X and Y
100 - something failed with Z
101 - something failed with X and Z
The limitation is that that limits the error space into however many bytes you decide on the encoding, like 16 or 32 possible combinations, it may be enough for you, or not.
You see this being common in COM+
https://learn.microsoft.com/en-us/windows/desktop/com/com-error-codes-1
I hope this helps.
I am writing a web service in node, and testing it with Postman. I spent a long timing looking for an error. When I finally found it, it turned out to be a simple error formatting the response body, which is json.
If I leave off the final brace in the response body, Postman waits for two minutes, and then reports that it received everything, just fine.
If I leave off the closing quote in the last value in the json, Postman says the server didn't respond, perhaps I should check my security certificates.
I would much rather Postman said "Hey, Buddy, you left off a quote!"
If there some validation service I can talk to? Or a plugin in Postman?
Here there are some validation javascript libraries, you can use:
Validator provides a declarative way of validating javascript objects.
Express-validator acts as an express.js middleware for node-validator.
Meanwhile, Postman got API testing and Collection Runner that can help you through this; which you can write some pre-request script as well as test script for each request.
Also, they got Newman which is a command-line collection runner. It allows you to effortlessly run and test a Postman collection directly from the command-line. It is built with extensibility in mind so that you can easily integrate it with your continuous integration servers and build systems.
I found that Paw worked (https://paw.cloud/). And so far I haven't paid for it.
Where Postman said "check your security certificates," Paw said "we were expecting 376 bytes but you only sent us 312."
Cuts down my time solving the problem a lot!
I use Fiddler for this. It is very good at identifying (with an error message that pops up) problems and bad implementations of the HTTP protocol. Browse the web with it running, and within a few minutes you'll undoubtedly hit a poorly implemented server.
Postman won't be able to handle these cases since it's insulated from poor behavior by the browser's framework.
That's not your problem though.
When I finally found it, it turned out to be a simple error formatting the response body, which is json.
That has absolutely nothing to do with HTTP. HTTP doesn't know or care what your request/response bodies are.
The problem you face is that your API endpoint could be returning whatever it wants. You need a custom solution to your problem, as there is no standard API server in this case.
Most folks will run unit tests that hit common endpoints of your service to ensure they're alive and well.
I should also point out that it should be all but impossible for you to break the JSON response if you're doing it correctly. Sounds like you're serializing JSON manually... never do that, we have JSON serializers for this purpose. Send in an object and let it worry about building the JSON output for you. Otherwise, you'll waste a lot of time on problems like these.
So I am using Amazons Product Advertising API and getting SignatureDoesNotMatchThe everywhere I turn.
The problem is not with my code because I have started using this scratchpad < http://associates-amazon.s3.amazonaws.com/scratchpad/index.html >
What gives? I have created a credential in AWS like all others - what else do I need to do or why is this just failing?
The full error is as follows:
<?xml version="1.0"?>
<ItemLookupErrorResponse xmlns="http://ecs.amazonaws.com/doc/2011-08-01/"><Error>
<Code>SignatureDoesNotMatch</Code>
<Message>The request signature we calculated does not match the signature you provided. Check your AWS Secret Access Key and signing method. Consult the service documentation for details.</Message>
</Error>
<RequestId>a89715b8-8e81-4d33-ad94-b85c92fb0631</RequestId></ItemLookupErrorResponse>
I found signing requests to be painful. I finally got it to work by reading the documentation carefully and using the Signed Requests Helper tool.
The documentation
https://docs.aws.amazon.com/AWSECommerceService/latest/DG/prod-adv-api-dg.pdf
outlines the steps starting on page 55. My problem was getting the url encoding right. Also, as vinayr mentioned, the parameters do have to be in a specific order (byte order, I think).
HOWEVER, the available library makes everything waaaaay easier. I've been using it for weeks now. It converts the XLM responses into an object that holds all the data and is easy to use.
I recently answered the question here:
https://stackoverflow.com/a/33617604/5543992
We have an assignment to check the compatibility of Quick connect project for Foursquare against the REST/JSON 1.1.
When I am testing the process, while invoking Rest API for query Check-in, the process is throwing an error – “OAuth token invalid or revoked”. Can you kindly help to fix this issue.
Access_token for this was generated by registering a sample app with Foursuare.com, having www.google.com as welcome page and redirect URL. Please let me know if this is causing the issue.
Also, let me know is there is any standard method to generate the access_token for this.
Thanks in advance.
Regards,
Shree.
It sounds like you're not following Foursquare's instructions on connecting properly, or need to reconnect to get a new access_token. Keep in mind that the access_token isn't the code that comes back in the redirect, the code needs to be used to exchange for the access_token.
I accessed the following url last night for the first time and saw the JSON data there without a problem: http://mlb.mlb.com/ws/search/MediaSearchService?team_id=111&start=0&site=mlb&hitsPerPage=12&hitsPerSite=10&type=json&c_id=&src=vpp&sort=desc&sort_type=custom
This morning, I get the following message: "Please contact Search administrator as request is coming from invalid host/domain "
I am also unable to get a response in Yahoo Pipes.
Is there a way around what appears to be a block? Not sure what else could have happened.
Are you sure that isn't an internal API which got exposed accidentally? If it is, they have the full right to block everyone out (just tested, I get the very same message) or if it's meant for 3rd party developers but through managed API key storage, you have to obtain an API key somehow.
If there's a block, there's a reason.
I'd be very leery of circumventing this particular block - Major League Baseball has proven very litigious in the past. You don't want to get sued for a DMCA violation - they can afford much, much more expensive lawyers than you can.
Your JSON is being served over http. Since your URL worked before and is not working now, the server is most likely checking for an authentication cookie. which has probably expired. You should check to see if there is an API/way to authenticate your call with their service, otherwise even if you find a workaround there is not guarantee that it will continue to work.