Basically all methods of the deprecated WSS RPC Protocol (MSDN) can be invoked via the SPWeb’s ProcessBatchData method. Since there’s small to no documentation regarding most of the RPC methods as to their treatment directly with ProcessBatchData we can suspect that their support may be dropped in the new SharePoint 2010 (we still have to see how much of the CAML will be thrown out of it, and we’re talking about some really ancient stuff which’s been around since the times of the SharePoint Team Services). Most of the RPC methods were designed to serve point tasks in the ancient STS but with the rising of the SharePoint object model most of these may possibly now be much simpler carried out with the latter. But … the thing is that even now in SharePoint 2007 the RPC methods are left intact and the ProcessBatchData is advertised as a quicker method for inserting, updating and deleting (at least for that, but this may be right for other usages as well) of multiple list items than the standard SPListItem object model implementation.

So, let’s have a look at the Show method. A sample XML for calling it may look like this:

The SetList element contains the SPList ID, the Cmd SetVar – the method’s name. The XMLDATA SetVar parameter is really mandatory but even if its value is FALSE the productivity of the method will be in XML format, not an HTML presentation of the list data. The View SetVar parameter is not mandatory – if it is not present, the defaulting view of the list will be used, but the GUID format is vital here – it should be with curly braces and uppercase. The result XML from the ProcessBatchData method will look something like this:

The XML machinate of the result (the part within the corresponding Result element) is really identical to the XML machinate of the result of the GetListItems method of the standard Lists web service (even if the former is generated in the COM owssvr.dll library and the latter in the Microsoft.SharePoint.dll assembly with managed code – in the getter of the SPListItemCollection.Xml property). The result XML contains the data of all fields in the specified view plus several system fields and the returned items are sorted and filtered in accordance with the view’s query settings.

Several additional SetVar parameters can be used for simple filtering and sorting of the returned result set – basically these are the same that appear as query parameters when you sort or filter list views in the SharePoint UI – e.g. SortField, SortDir, FilterField1, FilterValue1, FilterField2, FilterValue2, RootFolder:

If you use the RootFolder parameter with * as value you will get all items in the list recursively.

There is yet another discretionary SetVar parameter that can be used with the Show method – the Query parameter. Despite its name, you cannot specify a view CAML query in it, but just a list of field names, separated with spaces – basically with it you can specify the view fields that will appear in the result (the superfluous system fields will appear too). An unpleasant side effect of by it is that it effectively overrides the specified view’s query settings – so you end up with an unfiltered and unsorted result set – the effect of the SortField, FilterField1, etc SetVar-s (if present) is not affected even if. A sample treatment of the Query parameter (the asterisk – * – value can be used here as well):

So, the conclusion about the Show ProcessBatchData method is that it is yet another way to retrieve SharePoint list item data, even if it is not as flexible as the other mechanisms for list item data fetching – at least in respect to the query options that can be used for filtering and sorting the result set. One advantage even if may be that like the other ProcessBatchData methods it can be executed in batches – so with one call of the ProcessBatchData method you will be able to retrieve the data from several lists.

Check it out:Stefan Stanev’s SharePoint blog