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Difference between revisions of "EclipseLink/FAQ/SDO"
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== What is SDO? == | == What is SDO? == | ||
| − | + | SDO is designed to be a unified view of data, much like the POJO is in Java EE. There are several programming languages (of which Java is one) that support the SDO specification. | |
| + | |||
| + | === SDO as a Dynamic Object Model === | ||
| + | |||
| + | SDO metadata is represented as Type and Property objects. A Type is comparable to a Java class, and a property to a Java field. This metadata is defined at runtime either programmatically or from an XML schema. | ||
| + | <source lang="java"> | ||
| + | Type customerType = TypeHelper.INSTANCE.getType(“urn:example”, “customer”); | ||
| + | Property firstNameProperty = customerType.getProperty(“first-name”); | ||
| + | |||
| + | Type addressType = TypeHelper.INSTANCE.getType(“urn:example”, “address”); | ||
| + | </source> | ||
| + | Data is represented as instances of Types called DataObjects, these correspond to objects in Java. DataObjects have many generic accessors that can be used to manipulate the data. | ||
| + | <source lang="java"> | ||
| + | DataObject customerDO = DataFactory.INSTANCE.create(customerType); | ||
| + | customerDO.setString(firstNameProperty, “Jane”); | ||
| + | |||
| + | DataObject addressDO = DataFactory.INSTANCE.create(“urn:example”, address); | ||
| + | addressDO.set(“street”, “123 Any Street”); | ||
| + | </source> | ||
| + | |||
| + | === SDO as a Typed Object Model === | ||
| + | |||
| + | SDO as dynamic object models is useful in certain frameworks (dynamic models allow metadata to be added without requiring a redeployment of the application), but in other situations a strongly typed model is required (typed models allow for code completion in an IDE). A code generation step can be performed to produce typed interfaces complete with bean style accessors. | ||
| + | <source lang="java"> | ||
| + | Customer customerDO = (Customer) DataFactory.INSTANCE.create(customerType); | ||
| + | CustomerDO.setFirstName(“Jane”); | ||
| + | </source> | ||
| + | |||
| + | === SDO as an XML Representation === | ||
| + | |||
| + | SDO has built in support for handling XML. The SDO metadata can be introspected to determine what the corresponding XML representation is. | ||
| + | <source lang="java"> | ||
| + | XSDHelper.INSTANCE.isMixed(customerType); | ||
| + | XSDHelper.INSTANCE.isElement(firstNameProperty); | ||
| + | </source> | ||
| + | The DataObjects themselves can then be converted to from/XML | ||
| + | <source lang="java"> | ||
| + | XMLHelper.INSTANCE.save(customerDO, “urn:example”, “customer”, System.out); | ||
| + | </source> | ||
| + | |||
| + | === SDO as a Disconnected Object === | ||
| + | |||
| + | SDO was designed to represent disconnected data in a SCA (Service Component Architecture) environment. The main mechanism for accomplishing this goal is the ChangeSummary which tracks changes made to data objects over time (for DataObjects that have a ChangeSummary property). | ||
| + | <source lang="java"> | ||
| + | List changed = customerDO.getChangeSummary().getChangedDataObjects(); | ||
| + | </source> | ||
| + | |||
| + | === Summary === | ||
| + | EclipseLink is focussed on separating data from its messaging or persisted representations. Now with SDO support this data can be a POJO or a DataObject. This allows you to work with data in both Java EE and SCA environments. | ||
== How do I use SDO? == | == How do I use SDO? == | ||
The following examples demonstrate how to use EclipseLink SDO: | The following examples demonstrate how to use EclipseLink SDO: | ||
* [[EclipseLink/Examples/SDO | SDO Examples]] | * [[EclipseLink/Examples/SDO | SDO Examples]] | ||
| + | |||
| + | == How do I use SDO to Interact with a Relational Database? == | ||
| + | EclipseLink provides an integration point between SDO and JPA. For more informations see: | ||
| + | * [[EclipseLink/Examples/SDO/JPA | Accessing Relational Data as SDO DataObjects using JPA]] | ||
[[Category:EclipseLink FAQ|SDO]] | [[Category:EclipseLink FAQ|SDO]] | ||
Latest revision as of 20:35, 3 August 2009
Contents
What is SDO?
SDO is designed to be a unified view of data, much like the POJO is in Java EE. There are several programming languages (of which Java is one) that support the SDO specification.
SDO as a Dynamic Object Model
SDO metadata is represented as Type and Property objects. A Type is comparable to a Java class, and a property to a Java field. This metadata is defined at runtime either programmatically or from an XML schema.
Type customerType = TypeHelper.INSTANCE.getType(“urn:example”, “customer”); Property firstNameProperty = customerType.getProperty(“first-name”); Type addressType = TypeHelper.INSTANCE.getType(“urn:example”, “address”);
Data is represented as instances of Types called DataObjects, these correspond to objects in Java. DataObjects have many generic accessors that can be used to manipulate the data.
DataObject customerDO = DataFactory.INSTANCE.create(customerType); customerDO.setString(firstNameProperty, “Jane”); DataObject addressDO = DataFactory.INSTANCE.create(“urn:example”, address); addressDO.set(“street”, “123 Any Street”);
SDO as a Typed Object Model
SDO as dynamic object models is useful in certain frameworks (dynamic models allow metadata to be added without requiring a redeployment of the application), but in other situations a strongly typed model is required (typed models allow for code completion in an IDE). A code generation step can be performed to produce typed interfaces complete with bean style accessors.
Customer customerDO = (Customer) DataFactory.INSTANCE.create(customerType); CustomerDO.setFirstName(“Jane”);
SDO as an XML Representation
SDO has built in support for handling XML. The SDO metadata can be introspected to determine what the corresponding XML representation is.
XSDHelper.INSTANCE.isMixed(customerType); XSDHelper.INSTANCE.isElement(firstNameProperty);
The DataObjects themselves can then be converted to from/XML
XMLHelper.INSTANCE.save(customerDO, “urn:example”, “customer”, System.out);
SDO as a Disconnected Object
SDO was designed to represent disconnected data in a SCA (Service Component Architecture) environment. The main mechanism for accomplishing this goal is the ChangeSummary which tracks changes made to data objects over time (for DataObjects that have a ChangeSummary property).
List changed = customerDO.getChangeSummary().getChangedDataObjects();
Summary
EclipseLink is focussed on separating data from its messaging or persisted representations. Now with SDO support this data can be a POJO or a DataObject. This allows you to work with data in both Java EE and SCA environments.
How do I use SDO?
The following examples demonstrate how to use EclipseLink SDO:
How do I use SDO to Interact with a Relational Database?
EclipseLink provides an integration point between SDO and JPA. For more informations see: