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Nuclos proxy business object: proxy BO, implement interface, external data, web service, CollectiveProcessingProxy, write proxy BO, subform. |
Language: Deutsch · English
Proxy business object
Show and write external data like a BO – proxy interface, collective processing and write proxy BO.
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| colour | Blue |
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| title | Application developer |
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| colour | Green |
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| title | Updated: Jul 2026 |
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| colour | Grey |
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| title | applies to Nuclos 4.2026.x |
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What is a proxy BO?
A proxy business object is used when data does not come from the Nuclos database but is read or written via Java code from external sources – e.g. third-party systems, web services or the file system.
Nuclos generates an interface for this, which is implemented in a rule. This implementation handles reading, writing and deleting.
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Proxy BOs can only be used as a subform (a reference field to the parent BO is required). A reference field to a proxy BO is not possible. |
How-to: create a proxy BO
- Create a BO (Configuration → Business object) and enable the proxy business object option – a Java interface is generated.
- Define attributes (ID, name, reference to the parent object …).
- Implement the interface (full package path, e.g.
org.nuclet.businessentity.RechnungProxy). - Register the implementation fully qualified.
- Use the proxy BO as a subform in the layout.
Example: reading/writing proxy BO
The methods define how Nuclos interacts with the external data (getByKunde, getAll, getById, insert, update, delete, commit/rollback):
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package org.nuclet.businessentity;
import java.util.*;
import org.nuclos.api.exception.*;
import org.nuclos.api.rule.*;
public class RechnungProxyImpl implements org.nuclet.businessentity.RechnungProxy {
private User user;
public List<Rechnung> getByKunde(Long id) {
List<Rechnung> rlist = new ArrayList<>();
// Get Rechnungen for Kunde with "id" from another source
// ...
// rlist.add(...)
//
return rlist;
}
public List<Rechnung> getAll() {
// Get Data from another source
}
public List<Long> getAllIds() {
// Get Data from another source
}
public Rechnung getById(Long id) {
// Get Data from another source
}
public void insert(Rechnung rechnung) throws BusinessException {
// Write Data to another source
}
public void update(Rechnung rechnung) throws BusinessException {
// Write Data to another source
}
public void delete(Long id) throws BusinessException {
// Delete Data within another source
}
public void commit() {
}
public void rollback() {
}
public void setUser(User user) {
this.user = user;
}
} |
Collective processing (CollectiveProcessingProxy, from 4.16)
For better performance when loading dependent data, the BO additionally implements CollectiveProcessingProxy. getForCollectiveProcessing is called first; only if it returns null does the standard method (e.g. getByKunde) run per id.
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package org.nuclet.businessentity;
import java.util.*;
import org.nuclos.api.businessobject.attribute.*;
import org.nuclos.api.exception.*;
import org.nuclos.api.rule.*;
import org.nuclos.api.*;
public class RechnungProxyImpl implements org.nuclet.businessentity.RechnungProxy, CollectiveProcessingProxy {
private User user;
public <PK> List getForCollectiveProcessing(ForeignKeyAttribute<PK> attribute, Collection<PK> ids) {
if (attribute == Rechnung.KundeId) {
List ret = new ArrayList<>();
// Fetch Rechnungen für several Kunden (ids) at once
// ret.add(...);
//
return ret;
}
return null; // When null is returned, the standard proxy methods (like getByKunde()) will be called
}
public List<Rechnung> getByKunde(Long id) {
// Rest is the same as before
// ... |
Write proxy BO
Write proxy BOs are a variant of virtual BOs: reading is done via the underlying database view (referenceable also outside subforms), writing via the interface methods – e.g. through a web service:
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package example.rest;
public class ArtikelProxyImpl implements example.rest.ArtikelProxy{
private User user;
public Object insert(Artikel artikel) throws org.nuclos.api.exception.BusinessException{
// Call Webservice
WS myWS =...
WSArtikel artikel=myWS.createArtikel(...);
return artikel.getId();
}
public void update(Artikel artikel) throws org.nuclos.api.exception.BusinessException{
// Call Webservice
WS myWS =...
myWS.updateArtikel(...);
}
public void commit() {
}
public void rollback() {
}
public void setUser(User user) {
this.user = user;
}
public void delete(java.lang.Long id) throws org.nuclos.api.exception.BusinessException{}
} |
Related pages
Virtual business objects
Virtual BOs.
Open →
Creating a view with documents
Practical example.
Open →
