Access and USE list data across site collections

Question

I have two site collections in SharePoint Online environment (Office 365 dedicated).

Site A: https://SharePoint.com/sites/SiteA (Data Source - Read Only Access)

Site B: https://SharePoint.com/sites/SiteB (Data Consumer)

Requirement is for Site B list items linked to Site B list itmes. When an item is created or changed on Site A it creates or changes linked data on Site B. Currently Site A list can be viewed on Site B with a data view consuming a SOAP web service from Site A. This is a live feed but it cannot respond to any changes i.e. start a workflow or highlight what was recently modified. Ideally this would be an external list then workflow could handle the business logic .. I just need to get the data into a list on Site B so it can be acted on using OOTB SharePoint to do the rest.

Environment is running 2010 which will upgrade to 2013 in Q1 2014.

Challenges:

• No access to BCS or Secure Store
• Sandbox does not allow cross-site calls, so no code in the Sandbox
• This will be a business user environment with limited development support

Thoughts:

• SPServices and jQuery - how to create a list item from a web service?
• InfoPath Filler form with code behind - no full trust and no sandbox
• jQuery with JSONp
• Event receiver - how to get around the Sandbox x-site restrictions
• WCF - how to get around the Sandbox x-site restrictions?

Please, any thoughts would be helpful! Lone developer here

Answer 1

When I looked into this last year with Microsoft, I quickly came to the conclusion that the only legitimate way to link SharePoint Online Site collections was via Enterprise Search [which didn’t deliver the functionality we were after], as any bespoke solution would be short-term: Microsoft could collapse the link at any time via a platform upgrade.

So we made the painful architectural decision to keep everything in one site collection to overcome this difficulty. Microsoft explained that this restriction with the online service was due to the GUID security model they had implemented [after all the SharePoint Online service is built on a shared customer service].

Of course moving to an in-house or hosted environment would resolve this cross-access site collection issue.

One thing you will need to keep in mind is the size of your lists. In the online environment you will start to experience problems as they start to grow beyond 5000 items. So careful planning is required. Alex

Answer 2

Research on this has proven out one possible route: WCF service with JSON-P (JSON with padding) - here are some links

Accessing Business Data in SharePoint using jQuery and WCF

How to do external integration in SharePoint Online

Calling a Cross Domain WCF Service from a SharePoint Online Solution

Consuming cross-domain WCF REST services with jQuery

Wictor Wilen Office 365 JSONP

So now I have to get this working. Hopefully I will be able to post results here :)