Prism

Prism is a data representation layer. Prism is responsible for parsing the data from data representation formats such as XML, JSON or YAML. Prism makes the data available to Java application in an abstract, format-independent way.

Prism can read and write the data in any of the common data formats (XML, JSON or YAML). The data are made available to the application in a common form, regardless of which representation format was used. Prism can then write the data to any data format as well. The users may use any data format of their choice when working with the Prism-based application.

The data are usually available to the application through several facets. One of the facets makes the data available in a form of generated code (Java beans). This makes the use of the data very easy, it also allows the compiler to catch basic programming errors. The other facet allows to iterate over the data, inspect the data structures and values in a way that is similar to working with hashmaps. This method allows to access all the details about data (and metadata). It provides access to data structures in a programmatic way, which allows the application to work with custom schema extensions.

Prism is a completely schema-based system. Prism knows the definition of every data item in every data structure. It knows data item names, data types, multiplicity and all the details of data model. Prism is designed to work with dynamic schemas, schemas that are available only in runtime.

Tip

Why "Prism"? An optical prism is a multi-faceted optical element that breaks the light to its constituent spectral colors. Similarly to optical prism, the Prism framework has many facets and its "breaks" data to its constituent elements. The data can be accessed by many ways (facets, or spectral colors). It allows to inspect even a miniscule detail of the data or meta data. Prism can also represent the data in many ways, such as XML, JSON or YAML.

Data Representation Formats

Prism can work with the data in several data formats. The following representations describe the same user data structure in XML, JSON and YAML:

XML

<user>
    <name>alice</name>
    <fullName>Alice Anderson</fullName>
    <activation>
        <administrativeStatus>enabled</administrativeStatus>
    </activation>
</user>

JSON

{
    "@root" : "user",
    "name" : "alice",
    "fullName" : "Alice Anderson",
    "activation" : {
        "administrativeStatus" : "enabled"
    }
}

YAML

"@root": "user"
name: "alice"
fullName: "Alice Anderson"
activation:
    administrativeStatus: "enabled"

All the three files will result in the same Prism data structures when they are parsed. Prism data can be stored in any of these formats.

Prism Java API

Prism is a Java framework, designed to be used in Java applications. Prism data are represented as Java data structures. There are two ways how data can be accessed.

The native Prism way is to use the concepts of items and values. This method is similar to working with hashmaps and lists. The following pseudo-code illustrates the way how to access full name of a user data structure:

user.findProperty("fullName").getRealValue()

Then there is another way to access the data. This method relies on a code generated from the schema at build time:

user.getFullName()

Migration from 4.3

Before version 4.3 Prism was part of midPoint project. As of version 4.4 Prism is separate project and this resulted in Maven group IDs change.

If you were using any of following artifacts in your maven dependencies, please update group ID based on following table. (Note: packages names are still same, in order to ease migration and provide stable API compatiblity).

Artifact ID	New Group ID	Old Group ID (before 4.4)
axiom	com.evolveum.axiom	com.evolveum.axiom
concepts	com.evolveum.commons	com.evolveum.midpoint.infra
util	com.evolveum.commons	com.evolveum.midpoint.tools
test-ng	com.evolveum.commons	com.evolveum.midpoint.infra
prism-api	com.evolveum.prism	com.evolveum.midpoint.infra
prism-impl	com.evolveum.prism	com.evolveum.midpoint.infra
prism-maven-plugin	com.evolveum.prism	com.evolveum.midpoint.infra
schema-dist-maven-plugin	com.evolveum.prism.tools	com.evolveum.midpoint.tools
xjc-plugin	com.evolveum.prism.tools	com.evolveum.midpoint.tools