MidPoint Query Mechanisms

Last modified 22 Apr 2021 17:31 +02:00

MidPoint repository implements an abstraction of an object-oriented data store. The data may be stored in several types of relational databases (with even more possibility for future). Yet, the repository always presents the data in the same form, regardless of the actual storage mechanism.

However, data processing means much more than just a storage of data. One of the most important aspects is how to query the data, how to search for objects. This too has to be done in a way that is independent of the underlying storage mechanism.

As the query is such as important aspect, midPoint has its own query language (or languages), and a dedicated programming interface (API).

Query Languages

MidPoint has two query languages. Axiom query language is a new language, based on concepts of Axiom data modeling. This language is mostly user-friendly. Then there is an older XML-based query language. This goes back to the times when midPoint was completely XML-based. The languages are summarized in the following table:

Language Summary Available since Example

Axiom query language

User-friendly, text-based query language

MidPoint 4.3 (experimental)

name = "jack"

XML-based query language

Pure XML, deep element hierarchy

MidPoint 1.7

<q:equal>
  <q:path>name</q:path>
  <q:value>jack</q:value>
</q:equal>

Axiom query language is a relative new development, introduced in midPoint 4.3. It is expected to be fully supported in midPoint 4.4 LTS, where it should become a recommended option. The Axiom query language should replace the XML-based language as soon as possible. The XML-based language will be still supported for several years, but it will be dropped eventually.

Query API

MidPoint code deals with data queries all the time. Therefore there is a special API designed to represent the queries in native Java form. The API can also be used to construct the queries programmatically.

Please see Query API for details.

The query API is the same, regardless of the query language.