Question

I need to use a WCF API to save data into a DB. Ordinarily, I’d use chaining, like the example below:

    IClientBroker clientBroker = UIContext.CreateWcfInterface<IClientBroker>("Data/ClientBroker.svc");
    clientBroker.BeginSetClientBusinessName(_client.ID, businessName, (result) =>
        {
            _client = ((IClientBroker)result.AsyncState).EndSetClientBusinessName(result);

                    clientBroker.BeginSetClientAddress(_client.ID, addressObservableCollection, postcodeZip, (result2) =>
                {
                    _client = ((IClientBroker)result2.AsyncState).EndSetClientAddress(result2);

                            clientBroker.BeginSetClientTelephone(_client.ID, telephone, (result3) =>
                        {
                            _client = ((IClientBroker)result3.AsyncState).EndSetClientTelephone(result3);

                                    clientBroker.BeginSetClientFax(_client.ID, fax, (result4) =>
                                {
                                            _client = ((IClientBroker)result4.AsyncState).EndSetClientFax(result4);

                                            if (customFields.Save(validationSummaryBridge))
                                            {
                                                CloseWindow(true, "ClientID=" + _client.ID.ToString());
                                            }
                                            else
                                            {
                                                validationSummary.Errors.Add(new ValidationSummaryItem("Failed to save Custom Fields"));
                                            }
                                }, clientBroker);
                        }, clientBroker);
                }, clientBroker);
        }, clientBroker);
}

This gives me faux-synchronous behaviour which I need so exceptions are thrown in a timely fashion and I can react on validation events.

This doesn’t map well, however, when I have a loop of fields to save. For example, what pattern would be best to save the following list of “Custom Fields”, where each Custom Field must be saved using a single WCF call?

    ICustomFieldsBroker customFieldsBroker = UIContext.CreateWcfInterface<ICustomFieldsBroker>("Data/CustomFieldsBroker.svc");
    foreach (CustomField customField in _customFields)
    {   
        string newValue=_customFieldControlDictionary[customField].CustomField.Value;
                customFieldsBroker.BeginSetCustomFieldValueForItem(DataTypeID, DataItemID, customField.Key, newValue, (result) =>
            {
                        ((ICustomFieldsBroker)result.AsyncState).EndSetCustomFieldValueForItem(result);
            }, customFieldsBroker);
    }

In the above example, this would just set off, say, 5 requests to the WCF API/threads which would potentially return AFTER the form has closed. I need them to “line up”, so I can list their status and return to the form.

Thanks very much.

Don’t let the WCF distract you, but if you have any comments, do let me know. 🙂

Answer 1

This is the answer I was looking for:

http://www.netfxharmonics.com/2008/11/Understanding-WCF-Services-in-Silverlight-2#WCFSilverlightThreadWaiting