jsondiscoverer.web

Class AbstractJsonDiscoverer

java.lang.Object

javax.servlet.GenericServlet

javax.servlet.http.HttpServlet

jsondiscoverer.web.AbstractJsonDiscoverer

All Implemented Interfaces:

java.io.Serializable, javax.servlet.Servlet, javax.servlet.ServletConfig

Direct Known Subclasses:

FeedbackServlet, JsonAdvancedDiscovererServlet, JsonComposerServlet, JsonInjectorServlet, JsonSimpleDiscovererServlet, ProxyServlet, StatusServlet, VersionServlet

public abstract class AbstractJsonDiscoverer
extends javax.servlet.http.HttpServlet

Abstract class to factor some common behavior among the JSON discoverers.

In particular, this class helps to:

• Draw models. Generates a picture (stored in a file) which is the renderization of a list of EObjects (see drawModel(List, String) and drawModel(List, String, GVFigureDescription)
• Encode files to String. Generates the Base64 representation of files (see encodeToString(File), encodeToString(EPackage, String) and encodeToString(List, String)

Author:

Javier Canovas (me@jlcanovas.es)

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
static java.lang.String	dotExePath The path to the Graphviz DOT execitable (needed for generating the pictures)
(package private) static java.lang.String	jsonParam The jsonParam used for discovery (where the json code is stored)
(package private) java.util.Properties	properties
private static long	serialVersionUID
(package private) static java.lang.String	serverURL Server for the CORS
static java.lang.String	version Version of the app
static java.io.File	workingDir The main path to the working dir (needed for generating the pictures)

Constructor Summary

Constructors

Constructor and Description
AbstractJsonDiscoverer()

Method Summary

Modifier and Type	Method and Description
protected void	addResponseOptions(javax.servlet.http.HttpServletResponse response) Generic method to aoid CORS problems.
protected java.lang.String	digestExceptionMessage(java.lang.String message) Digest an exception message to remove the name of the exception and take the real message
protected void	doOptions(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) Overrides the method to add the CORS headers.
(package private) java.io.File	drawModel(java.util.List<org.eclipse.emf.ecore.EObject> elements, java.lang.String uniqueId) Draws a model into a picture following the standard graphical style.
(package private) java.io.File	drawModel(java.util.List<org.eclipse.emf.ecore.EObject> elements, java.lang.String uniqueId, org.emftools.emf2gv.graphdesc.GVFigureDescription graphDesc) Draws a model into a picture, stored a file.
(package private) java.io.File	drawObjectModel(java.util.List<org.eclipse.emf.ecore.EObject> elements, org.eclipse.emf.ecore.EPackage ePackage, java.lang.String uniqueId) Draws a model into a picture with a UML-like graphical style.
(package private) java.lang.String	encodeToString(org.eclipse.emf.ecore.EPackage ePackage, java.lang.String uniqueId) Saves the EPackage into a XMI and then read it to return it as String in Base64.
(package private) java.lang.String	encodeToString(java.io.File path) Encodes a file into BASE64 format.
(package private) java.lang.String	encodeToString(java.util.List<org.eclipse.emf.ecore.EObject> elements, java.lang.String uniqueId) Saves a list of EObjects into a XMI and then read it to return it as String in Base64.
void	init() Initilizes the servlet class.

Methods inherited from class javax.servlet.http.HttpServlet

doDelete, doGet, doHead, doPost, doPut, doTrace, getLastModified, service, service

Methods inherited from class javax.servlet.GenericServlet

destroy, getInitParameter, getInitParameterNames, getServletConfig, getServletContext, getServletInfo, getServletName, init, log, log

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

serialVersionUID

private static final long serialVersionUID

See Also:

Constant Field Values

workingDir

public static java.io.File workingDir

The main path to the working dir (needed for generating the pictures)

dotExePath

public static java.lang.String dotExePath

The path to the Graphviz DOT execitable (needed for generating the pictures)

version

public static java.lang.String version

Version of the app

jsonParam

static java.lang.String jsonParam

The jsonParam used for discovery (where the json code is stored)

serverURL

static java.lang.String serverURL

Server for the CORS

properties

java.util.Properties properties

Constructor Detail

AbstractJsonDiscoverer

public AbstractJsonDiscoverer()

Method Detail

init

public void init()
          throws javax.servlet.ServletException

Initilizes the servlet class. THis implementation is used in any JSON discoverer servlet.

It performs the following steps:

• Registers the ecore and xmi extensions in EMF to enable the model management
• Reads the properties file (called config.properties and located at WEB-INF folder)

Overrides:

init in class javax.servlet.GenericServlet

Throws:

javax.servlet.ServletException

See Also:

GenericServlet.init()

encodeToString

java.lang.String encodeToString(java.io.File path)
                         throws java.io.IOException

Encodes a file into BASE64 format.

In the context of the tool, this method is used to encode generated pictures (usually with @link drawModel(List, String)) into BASE64 format, which is easy to exchange with the web client.

Parameters:

path - The path to the file to encode

Returns:

A String in BASE64

Throws:

java.io.IOException - Thrown when the file cannot be written

encodeToString

java.lang.String encodeToString(org.eclipse.emf.ecore.EPackage ePackage,
                                java.lang.String uniqueId)
                         throws javax.servlet.ServletException

Saves the EPackage into a XMI and then read it to return it as String in Base64.

The workflow followed is:

• Creates a temp file where the metamodel (as EPackage) will be stored
• Saves the metamodel in the temp file
• Reads the file and encodes it as base64
• Returns the String encoded as Base64

Metamodels are saved in a directory that is configred by providing a value to the corresponding property in the config.properties file. The key to retrieve the property is provided in the para uniqueId.

Parameters:

ePackage - The metamodel (as EPackage

uniqueId - The key to retrieve the property in the config.properties file setting the folder where the metamodel will be saved

Returns:

A String encoded in Base64 representing the metamodel

Throws:

javax.servlet.ServletException - Something went wrong (usually IO-related problem)

encodeToString

java.lang.String encodeToString(java.util.List<org.eclipse.emf.ecore.EObject> elements,
                                java.lang.String uniqueId)
                         throws javax.servlet.ServletException

Saves a list of EObjects into a XMI and then read it to return it as String in Base64. Similar to encodeToString(EPackage, String)

The workflow followed is:

• Creates a temp file where the list of EObjects will be stored
• Saves the list of EObjects in the temp file
• Reads the file and encodes it as base64
• Returns the String encoded as Base64

The list of EObjects are saved in a directory that is configred by providing a value to the corresponding property in the config.properties file. The key to retrieve the property is provided in the para uniqueId.

Parameters:

elements - The list of EObjects

uniqueId - The key to retrieve the property in the config.properties file setting the folder where the list of EObjects will be saved

Returns:

A String encoded in Base64 representing the list of EObjects

Throws:

javax.servlet.ServletException - Something went wrong (usually IO-related problem)

drawModel

java.io.File drawModel(java.util.List<org.eclipse.emf.ecore.EObject> elements,
                       java.lang.String uniqueId,
                       org.emftools.emf2gv.graphdesc.GVFigureDescription graphDesc)
                throws javax.servlet.ServletException

Draws a model into a picture, stored a file.

The process follows these steps:

• First the name of the folder is retrieved from the properties file
• A temp file is created
• Then the model is rendered into a picture and stored in the temp file

Files are stored in a folder configured in the config properties file. The name of the property is set by the uniqueId param.

The generation of the picture is delegated to the method StandaloneProcessor.process(EObject, GVFigureDescription, File, String, org.emftools.emf2gv.processor.core.IProcessorCallback, org.emftools.emf2gv.processor.core.IEObjectIconProvider, String, boolean, boolean, String, List, org.emftools.emf2gv.processor.core.ILogger, org.eclipse.core.runtime.IProgressMonitor)

A graphical style has to be provided. See the documentation of EMF2GV to know how to create it.

Parameters:

elements - List of elements (as EObjects) to be drawn

uniqueId - Id used to retrieve the folder name from the config properties file to store the file

graphDesc - Graphical description according to EMF2GV format

Returns:

The picture file

Throws:

javax.servlet.ServletException - If any problem appears (usually IO-related problems)

drawModel

java.io.File drawModel(java.util.List<org.eclipse.emf.ecore.EObject> elements,
                       java.lang.String uniqueId)
                throws javax.servlet.ServletException

Draws a model into a picture following the standard graphical style.

This method relies on drawModel(List, String, GVFigureDescription)

Default graphical style will be used. The style is provided by EMF2GV library, please refer to its documentation for further details.

Parameters:

elements - List of elements (as EObjects) to be drawn

uniqueId - Id used to retrieve the folder name from the config properties file to store the file

Returns:

The picture file

Throws:

javax.servlet.ServletException - If any problem appears (usually IO-related problems)

drawObjectModel

java.io.File drawObjectModel(java.util.List<org.eclipse.emf.ecore.EObject> elements,
                             org.eclipse.emf.ecore.EPackage ePackage,
                             java.lang.String uniqueId)
                      throws javax.servlet.ServletException

Draws a model into a picture with a UML-like graphical style.

This method relies on drawModel(List, String, GVFigureDescription)

Parameters:

elements - List of elements (as EObjects) to be drawn

ePackage - The metamodel (as EPackage) which the element conform to

uniqueId - Id used to retrieve the folder name from the config properties file to store the file

Returns:

The picture file

Throws:

javax.servlet.ServletException - If any problem appears (usually IO-related problems)

addResponseOptions

protected void addResponseOptions(javax.servlet.http.HttpServletResponse response)

Generic method to aoid CORS problems.

Adds the CORS headers related to access-control-allow settings

The value for the header Access-Control-Allow-Origin is parameterized with the value given in the config.properties with the key serverURL

Parameters:

response - The response where the headers will be added

doOptions

protected void doOptions(javax.servlet.http.HttpServletRequest request,
                         javax.servlet.http.HttpServletResponse response)
                  throws javax.servlet.ServletException,
                         java.io.IOException

Overrides the method to add the CORS headers.

This method relies on addResponseOptions(HttpServletResponse)

Overrides:

doOptions in class javax.servlet.http.HttpServlet

Throws:

javax.servlet.ServletException

java.io.IOException

See Also:

HttpServlet.doOptions(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)

digestExceptionMessage

protected java.lang.String digestExceptionMessage(java.lang.String message)

Digest an exception message to remove the name of the exception and take the real message

Parameters:

message - The undigested exception message

Returns:

The digested exception message