Schedule/batch for large number of webservice callouts? - web-services

Question

I'am new to Apex and I have to call a webservice for every account (for some thousands of accounts).
Usualy a single webservice request takes 500 to 5000 ms.
As far as I know schedulable and batchable classes are required for this task.
My idea was to group the accounts by country codes (Europe only) and start a batch for every group.
First batch is started by the schedulable class, next ones start in batch finish method:
global class AccValidator implements Database.Batchable<sObject>, Database.AllowsCallouts {
private List<String> countryCodes;
private countryIndex;
global AccValidator(List<String> countryCodes, Integer countryIndex) {
this.countryCodes = countryCodes;
this.countryIndex = countryIndex;
...
}
// Get Accounts for current country code
global Database.QueryLocator start(Database.BatchableContext bc) {...}
global void execute(Database.BatchableContext bc, list<Account> myAccounts) {
for (Integer i = 0; i < this.AccAccounts.size(); i++) {
// Callout for every Account
HttpRequest request ...
Http http = new Http();
HttpResponse response = http.send(request);
...
}
}
global void finish(Database.BatchableContext BC) {
if (this.countryIndex < this.countryCodes.size() - 1) {
// start next batch
Database.executeBatch(new AccValidator(this.countryCodes, this.countryIndex + 1), 200);
}
}
global static List<String> getCountryCodes() {...}
}
And my schedule class:
global class AccValidatorSchedule implements Schedulable {
global void execute(SchedulableContext sc) {
List<String> countryCodes = AccValidator.getCountryCodes();
Id AccAddressID = Database.executeBatch(new AccValidator(countryCodes, 0), 200);
}
}
Now I'am stuck with Salesforces execution governors and limits:
For nearly all callouts I get the exceptions "Read timed out" or "Exceeded maximum time allotted for callout (120000 ms)".
I also tried asynchronous callouts, but they don't work with batches.
So, is there any way to schedule a large number of callouts?

Answer 1

Have you tried to limit your execute method to 100? Salesforce only allows 100 callout per transaction. I.e.
Id AccAddressID = Database.executeBatch(new AccValidator(countryCodes, 0), 100);
Perhaps this might help you:
https://salesforce.stackexchange.com/questions/131448/fatal-errorsystem-limitexception-too-many-callouts-101