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ImplementingaFormCommandChain
Bungeni Editor selector forms use a flow processor to process submissions. This page details how the flow processor has been implemented
Introduction
Selector forms use the "chain of responsibilty" pattern for submission processing. The command processor has been implemented using Apache chain .
Command Catalogs
The command chain is a series of cataloged commands which can be invoked by the application. This catalog of commands resides in an XML file called commandChain.xml. The editor supports multiple catalog sources, and catalog sources can be set per dialog. The directory of call command catalogs available to the editor is stored in the 'CATALOG_SOURCE' table:
| form name | catalog source |
| org.bungeni.editor.selectors.InitPapers | /org/bungeni/commands/chains/commandChain.xml |
| org.bungeni.editor.selectors.InitDebateRecord | /org/bungeni/commands/chains/commandChain.xml |
| org.bungeni.editor.selectors.InitQAsection | /org/bungeni/commands/chains/commandChain.xml |
The editor loads a specific command chain depending on the dialog invoked.
Command Chains
Command chains are contained within the command catalog. These are named sequences of grouped commands which are invoked by the dialog on clicking submit. The example below shows the command chain for creating the mast head in TEXT_INSERTION mode :
<catalogs>
<catalog name="debaterecord">
<chain name="debateRecordFullInsertMasthead">
<command id="addSectionIntoSectionWithStyling"
className="org.bungeni.commands.addSectionIntoSectionWithStyling"/>
<command id="setSectionMetadataForAction"
className="org.bungeni.commands.setSectionMetadataForAction"/>
<command id="addImageIntoSection"
className="org.bungeni.commands.addImageIntoSection"/>
<command id="addDocumentIntoSection"
className="org.bungeni.commands.addDocumentIntoSection"/>
<command id="setInputFieldValue"
className="org.bungeni.commands.setInputFieldValue"/>
<command id="setInputFieldValue2"
className="org.bungeni.commands.setInputFieldValue"/>
<command id="addDocumentMetadata"
className="org.bungeni.commands.addDocumentMetadata"/>
</chain>
..........
</catalog>
</catalogs>The dialog knows which command chain to invoke based on the metadata set in the 'FORM_COMMAND_CHAIN' table:
| item no | form name | form mode | command catalog | command chain |
| 1 | org.bungeni.editor.selectors.InitDebateRecord | TEXT_INSERTION | debaterecord | debateRecordFullInsertMasthead |
| 2 | org.bungeni.editor.selectors.InitDebateRecord | TEXT_EDIT | debaterecord | debateRecordFullEditMasthead |
| 3 | org.bungeni.editor.selectors.InitDebateRecord | TEXT_SELECTED_INSERT | debaterecord | debateRecordSelectedInsertMasthead |
In the above example, the depicted command chain is represented in item#1.
Commands
Command chains are composed of individual commands. Individual commands in Bungeni Editor are implemented as individual classes. Every class wishing to become a 'Command' must implement the Command interface, for e.g. the following command imports an image into a document section.
public class addImageIntoSection implements Command {
/** Creates a new instance of addImageIntoSection */
public addImageIntoSection() {
}
/**
* Requires: current_section and selected_logo variables to be set in the preInserMap of the caller class
*/
public boolean execute(Context context) throws Exception {
BungeniFormContext formContext = (BungeniFormContext) context;
String currentSection = (String) formContext.getPreInsertMap().get("current_section");
String logoPath = (String) formContext.getPreInsertMap().get("selected_logo");
boolean bAddImage = CommonActions.action_addImageIntoSection(formContext.getOoDocument(),
currentSection,
logoPath );
return false;
}
}
The command must return false to continue processing the next command in the chain. Returning true halts the chain.
Passing parameters
A command usually requires an input parameter. Input parameters are passed using the command chain's context. The context is set using the BungeniFormContext class, which is an extension of the contextBase class provided by Apache Chain.
The BungeniFormContext class acts as a marshaller of variables between the command chain and the dialog invoking the command chain. The dialog, prior to invoking the chain sets all the input variables into a HashMap, using standard names known by the commands as keys.
public class BungeniFormContext extends ContextBase implements IBungeniFormContext{
.....
public HashMap<String, Object> getPreInsertMap() {
return preInsertMap;
}
public void setPreInsertMap(HashMap<String, Object> preInsertMap) {
this.preInsertMap = preInsertMap;
}
....
public ArrayList<ooDocMetadataFieldSet> getMetadataFieldSets() {
return metadataFieldSets;
}
public void setMetadataFieldSets(ArrayList<ooDocMetadataFieldSet> metadataFieldSets) {
this.metadataFieldSets = metadataFieldSets;
}
}
This map is then passed into the form context, and used by the individual commands to retrieve their input variables. The get & set methods of the preInsertMap (see above example source) is used to get and set the marshalled variables.
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