Take the 2-minute tour ×
Salesforce Stack Exchange is a question and answer site for Salesforce administrators, implementation experts, developers and anybody in-between. It's 100% free, no registration required.

I have a trigger on the Custom Object that calls a class. That class makes an HTTP GET request to a Web Service.

However I get the following error:

Callout from triggers are currently not supported.

How can I get data to an external Web Service using Apex code?

However i can use @future method but it can only be support void and this method cannot return results, i need to be able to send data to external ervice and receive acknowlegements from it.

share|improve this question
3  
You seem to be aware of the limitations that exist. I suggest you acknowledge whatever needs acknowledging in the @future method and update the triggered object thereafter, you could have statuses on the object like "Reason for Callout", "Pending", "Success"/"Fail" allowing you to build logic around the current state of an object. –  Martin Peters Dec 20 '12 at 10:43
    
@MartinPeters : can you please elaborate your thought? –  Axaykumar Varu Dec 20 '12 at 11:13
2  
I don't know enough about your use case to give a detailed suggestion on what you should do. But basically, when you're firing the @future from a trigger you did id because some criteria on the object was met. You can at the same time set that the object is "pending" the result of the callout. The callout, once complete can query the object it originated and update it with appropriate success/failure based on what the endpoint answered. –  Martin Peters Dec 20 '12 at 11:17

2 Answers 2

up vote 21 down vote accepted

Callouts cannot be made from triggers as that would hold up the database transaction until the callout completed, which can be up to 120 seconds from a limits perspective. This could obviously cause significant contention with other transactions and impact performance.

The only way that you can execute a callout from a trigger is to schedule it to run asynchronously, for example by executing a method with the @future method as you have found. The key word here is asynchronously - you can't wait for a response from the callout as that would require the transaction to stall until it completes, which is the reason that synchronous callouts aren't allowed.

The way that I've handled this kind of thing in the past is to have a field on the object that captures the response. I pass the id(s) of the record(s) that I am processing to the @future method. Then when the callout completes, the @future method can retrieve the record(s) from the database and update the field(s).

If you are trying to return a response to the user (as part of a visualforce page maybe) you can still utilise this mechanism, you just have to poll the controller to check the object to see if a response has been received - I've used an actionpoller for this and provided the user with a 'checking' spinner to keep them (hopefully) interested.

share|improve this answer
2  
To add to Bob's response, if you are worried about validating the response, you can also write the id of the object to a custom log table object, have a trigger on that custom object call the @future method, and then update the fields you need to on the object tabel and also the log tabel with success/fail, and maybe alert the user if the update failed with any errors you got back from the web service/sf –  BritishBoyinDC Dec 21 '12 at 19:09

try using @future(callout=true) http://www.salesforce.com/us/developer/docs/apexcode/Content/apex_classes_annotation_future.htm

The following snippet shows how to specify that a method executes a callout:

  @future (callout=true)
  public static void doCalloutFromFuture() {
   //Add code to perform callout 

}

You can specify (callout=false) to prevent a method from making callouts.

When the callout is done you can get a status 200 code or some response body reponse and make sure the handshake was complete !!! If you want to give the user an idea of the handshake I would suggest create a child object and create a field like " Status of transcation" and insert the response body/ response status code in the field.

To get something from the other end spin up a Rest Endpoint with a httppost method and provide the endpoint to the other vendor so that he can send the data back to you once the transaction is complete at his end.

This way you do not have to wait for the transaction to complete and use future for making callouts!!!

Hope this helps!!

share|improve this answer

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.