Tuesday, April 01, 2008

[Misc] Registry vs. Repository

In present software projects you encounter buzz words, such as SOA, Registry, Repository and many others. Today I took some time to look at the differences between Registry and Repository. From understanding I always had some "question marks" about:
  • Are there any differences between them?
  • Sharing concepts?
  • Is there a relationship between a Registry and a Repository?
  • Why is it necessary for a SOA, or does an SOA also work without an Registry?
Many people use these words as synonym, but there are two different worlds as I found in a blog. On this blog I've found a statement:
"[...] webcast on the topic of registries and repositories, the consensus was that registries hold references to things and repositories hold the things. [...]"
Based on this statement we can say, that Service Registries contains Meta Data about the services available in a repository. A Repository can then be used without an registry, but a registry without repository makes less sense, or does it?
"Design-time data typically reflects artifacts such as code -- and thus typical design-time repositories use standards such as CVS (Concurrent Versions System). Runtime repositories typically store messages and provide query, audit, logging and a variety of archiving capabilities."

RepositoryCode versions
Queriable message store

A RDMBS is a good example for a repository at runtime. You can save your data and query this data by using SQL for example or other query languages. A phone book for example can be seen as a registry.

I hope the difference is clear between them. Some hints from other people about the key differences between a Registry and Repository?

1 comment:

Marco Zapletal said...

The initial blog entry refers to the ebXML Registry Spec, which has this differentiation since its beginning in 2001 (!). In my opinion, the ebXML Reg/Rep would provide means - in opposite to UDDI - to realize the vision of SOA business registry. I am curious how long will the WS world yet keep up with UDDI...