BEA Liquid Data

The morning session of the day introduced me to this product from BEA called Liquid Data. The name fascinated me and as my colleague introduced the product to me, I started drawing parallels between the idea behind Liquid Data and the virtual directory.

For the uninitiated, Liquid Data is a product that BEA ships with WebLogic Server. Here is how BEA describes this product.

BEA Liquid Data for WebLogic is a key element in establishing a service-oriented architecture because it allows all information to be viewed, accessed, and acted upon as if it came from a single, comprehensive, global source. Using its 'Enterprise Data Services Layer,' IT can hide the complexity of accessing multiple, heterogeneous data sources, while presenting a simple, standards-based interface to all business users simultaneously.

Interestingly, the above introduction can also be used to describe virtual directory products that try to provide unified LDAP view of heterogeneous data stores.

So I tried to spot out visible differences between Liquid Data and a typical virtual directory server. Here are some the salient points of difference that I could find out.

Liquid Data	Virtual Directory
Liquid Data uses XML as its language for describing relationships between data, and uses XQuery as a query language	Every Virtual directory has its own mechanism and constructs for definining data relationships. LDAP is the default query language. Now many VD vendors are also supporting usage of DSML .
Liquid Data utilizes WebLogicServer's security, scaling, clustering, and database connection pooling features.	Virtual directory servers have to handle all these aspects by themselves.
At present, Liquid Data seems to offer connectivity only to databases, XML files, Web Services and structured data. The enterprise directory server is visibly missing from the list of data sources it can connect to.	A virtual directory offers more connectivity options. (E.g. Lotus Notes, Windows Domain Users, NIS Systems.)

So Virtual Directory also seems to be a good candidate for embedding inside an application server.