As I have noted before, I think I share more similarities to Stephen than differences, but on this issue, I am offering an alternate view point.
Because learning objects are invisible to Google [sic] operators of learning content management systems are intended to access these federated searches.
Repository existed not only for objects which are invisible to Google. Back in 1999, while serving EdNA, I have looked at the collaboration issues of "subject gateways" (SG in short hereafter) which are in many ways similar to today's repository.
First of all, we must recognize the value provided by these SGs. Let me use two examples. Stephen's own Edu-RSS is widely subscribed, so is his OLDaily. I am a keen reader of his writings. The greatest value in OLDaily, to me at least, is the "coloured"-view through a man who I trust. I respect his selection, I like to read his comment and would occasionally follow through to the items. Another example: some investors pay good money for the recommendation of some advisors. The information on which such advisor is based should be public knowledge (otherwise, they are liable to the charge of insider trading). But the value to their subscribers is the unique analysis - the coloured view. Subject gateways serve a similar function. These SGs are run and owned by people who have immense interest and "authority" in the subject area. Users trust the recommendation. On 21st Oct, 2004 issue of OLDaily, Stephen pointed to an item "Information Cascades in Online Learning" which describes the chaotic environment which may be created by the information linking. SGs, in a way, can serve as a nice balance to this chaos.
The second thing I did on tackling this SG collaboration issue was to look at the sustainability of the SGs and recognized the competition and collaboration requirements. On one hand, SG owners need to competitively bid for funding, but there are obviously significant duplication in terms of infra-structure and scalability. Referring back to the data model I developed (see Meta Meta Meta Data Draft 0.1, the value the SG owners would protect in order to maintain their survival is "type 2" data. I did not see how they will give up type 2 data without killing themselves. The collaboration model, hence, has to protect the ownership of type 2 data. What we can do, at the time, was to come up with a harmonized type 3 data so that searches can be done to these SG without SG explicitly sharing their type 2 data. We called this "mega" search (instead of the then current term meta search) and it is what is known as "federated search".
Stephen also commended on the efficiency of federated search.
If this process seems odd and cumbersome, it is. In practice, the federated search over even a small number of repositories is significantly slower than Google.
This is a price we pay for the concept of "loose" connectedness. While Stephen is a great promoter of loosely coupled structure for learning services, I don't see any reason why search must be centralized controlled by Google. As our network speed and the interface among SG (or repositories) improves, the performance will improve as well. Peer-to-peer network is based on the same principle. I understand the value of a network is a function of the number of nodes in the network. To really make federated search a viable strategy, repositories need to join together to form a value-network which is comparable to Google and continue to leverage on the network effort to grow the value. If repositories remain to be closed, I agree with Stephen that the doom day is coming.
As I noted, we share more common than difference. The last quote from Stephen will pull us back together.
What Google has, that a federated search system by definition cannot have, is what I call third party metadata and what Google calls PageRank.
All our difference boils down to just terminology. To Stephen, repositories are just data store and hence federated search across multiple stores makes no sense. What I try to say here is that *some* repositories have significant value added and we should also support mechanisms which protect such value. Diversity is great!