JsonCommandServlet (Groovy Documentation)

com.cedarsoftware.servlet.JsonCommandServlet

This class will accept JSON REST requests, find the named Spring Bean, find the method, and then invoke the method. Once complete, it will convert the return object to JSON and then send that back to the client. The requests are typically made from a Javascript client, although they could easily be made from Python, Java, or Objective C. The request comes in with http://yoursite.com/json/controllerName/methodName. The "json" part can be whatever name you map to this servlet in web.xml. The arguments are sent as the HTTP POST body, or they can be sent via query params like this: http://yoursite.com/json/Controller/methodName?json=[arg1, arg2,...] When calling the JsonServlet, it will always return an object in the form: {"data":v,"status":false|true|null} where the value 'v' is the return value of the Controller method called. The status is 'true' if the method call properly succeeded. Use the return value 'v' when status === true. If status === false then the communications reach the server, however, there was an exception. A Controller method threw an exception, invalid JSON was passed in, the name of the controller targeted was wrong, the controller targeted was not a BaseController, or the method on the controller was not found. The value 'v' when the the status === false will indicate the error. If the status === null then the call() method within the browser never reached the server. The value 'v' is a message indicating a network communications issue. The returned JSON is gzip compressed if the caller indicates that it accepts Content-Encoding of gzip AND the return message is greater than 512 bytes. The return stream from methods that return large arrays and/or object graphs compresses especially well.
Authors:
John DeRegnaucourt ([email protected])
Copyright (c) Cedar Software LLC

Licensed under the Apache License, Version 2.0 (the "License") you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

Field Summary

Fields
Modifiers	Name	Description
`static java.lang.String`	`ATTRIBUTE_FAIL_MESSAGE`
`static java.lang.String`	`ATTRIBUTE_STATUS`
`private static org.apache.logging.log4j.Logger`	`LOG`
`private NCubeConfigurationProvider`	`nCubeCfgProvider`
`static java.lang.ThreadLocal<javax.servlet.http.HttpServletRequest>`	`servletRequest`
`static java.lang.ThreadLocal<javax.servlet.http.HttpServletResponse>`	`servletResponse`
`private SpringConfigurationProvider`	`springCfgProvider`

Constructor Summary

Constructors
Constructor and description
`JsonCommandServlet ()`

Methods Summary

Methods
Type	Name and description
`private static java.lang.String`	`buildResponse(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response, Envelope envelope)` Build the response envelope as a String to be returned to the client.
`protected void`	`doGet(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response)` Handle JSON GET style request.
`protected void`	`doPost(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response)` Process JSON POST style where the controller, method, and arguments are passed in as the POST data.
`static java.lang.Throwable`	`getDeepestException(java.lang.Throwable e)` Get the deepest (original cause) of the exception chain.
`private java.lang.Object`	`getProvider(javax.servlet.http.HttpServletRequest request, java.lang.String json)` @param request HttpServletRequest passed to the command servlet.
`private void`	`handleRequestAndResponse(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response, java.lang.String json)` This is the main driver of the command servlet.
`void`	`init()`
`private static void`	`removeThreadLocals()` Remove ThreadLocals containing HttpServletRequest and response so that when thread is returned to threadpool there are no lingering references to these values.
`void`	`route(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response)` If using UrlRewrite from tuckey.org, then route HTTP Json commands via this 'route' method and list it in the urlrewrite.xml.
`private static void`	`sendJsonResponse(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response, Envelope envelope)` Build and send the response Envelope to the client.
`private static void`	`writeResponse(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response, java.lang.String json)` Write the response Envelope to the client

Inherited Methods Summary

Inherited Methods
Methods inherited from class	Name
`class javax.servlet.http.HttpServlet`	javax.servlet.http.HttpServlet#service(javax.servlet.ServletRequest, javax.servlet.ServletResponse), javax.servlet.http.HttpServlet#log(java.lang.String, java.lang.Throwable), javax.servlet.http.HttpServlet#log(java.lang.String), javax.servlet.http.HttpServlet#init(javax.servlet.ServletConfig), javax.servlet.http.HttpServlet#init(), javax.servlet.http.HttpServlet#destroy(), javax.servlet.http.HttpServlet#getServletConfig(), javax.servlet.http.HttpServlet#getServletInfo(), javax.servlet.http.HttpServlet#getServletName(), javax.servlet.http.HttpServlet#getServletContext(), javax.servlet.http.HttpServlet#getInitParameter(java.lang.String), javax.servlet.http.HttpServlet#getInitParameterNames(), javax.servlet.http.HttpServlet#wait(long, int), javax.servlet.http.HttpServlet#wait(long), javax.servlet.http.HttpServlet#wait(), javax.servlet.http.HttpServlet#equals(java.lang.Object), javax.servlet.http.HttpServlet#toString(), javax.servlet.http.HttpServlet#hashCode(), javax.servlet.http.HttpServlet#getClass(), javax.servlet.http.HttpServlet#notify(), javax.servlet.http.HttpServlet#notifyAll()
`class javax.servlet.GenericServlet`	javax.servlet.GenericServlet#log(java.lang.String, java.lang.Throwable), javax.servlet.GenericServlet#log(java.lang.String), javax.servlet.GenericServlet#init(javax.servlet.ServletConfig), javax.servlet.GenericServlet#init(), javax.servlet.GenericServlet#destroy(), javax.servlet.GenericServlet#service(javax.servlet.ServletRequest, javax.servlet.ServletResponse), javax.servlet.GenericServlet#getServletConfig(), javax.servlet.GenericServlet#getServletInfo(), javax.servlet.GenericServlet#getServletName(), javax.servlet.GenericServlet#getServletContext(), javax.servlet.GenericServlet#getInitParameter(java.lang.String), javax.servlet.GenericServlet#getInitParameterNames(), javax.servlet.GenericServlet#wait(long, int), javax.servlet.GenericServlet#wait(long), javax.servlet.GenericServlet#wait(), javax.servlet.GenericServlet#equals(java.lang.Object), javax.servlet.GenericServlet#toString(), javax.servlet.GenericServlet#hashCode(), javax.servlet.GenericServlet#getClass(), javax.servlet.GenericServlet#notify(), javax.servlet.GenericServlet#notifyAll()

- Field Detail
  - public static final java.lang.String ATTRIBUTE_FAIL_MESSAGE
  - public static final java.lang.String ATTRIBUTE_STATUS
  - private static final org.apache.logging.log4j.Logger LOG
  - private NCubeConfigurationProvider nCubeCfgProvider
  - public static final java.lang.ThreadLocal<javax.servlet.http.HttpServletRequest> servletRequest
  - public static final java.lang.ThreadLocal<javax.servlet.http.HttpServletResponse> servletResponse
  - private SpringConfigurationProvider springCfgProvider
- Constructor Detail
  - JsonCommandServlet()
- Method Detail
  - private static java.lang.String buildResponse(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response, Envelope envelope)
    
    Build the response envelope as a String to be returned to the client.
    Returns:
    String (JSON format) of envelope to be return to client.
    Parameters:
    request - original servlet request
    response - original servlet response
    envelope - data and status to be written
  - protected void doGet(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response)
    
    Handle JSON GET style request. In this case, 'controller', 'method', and 'json' are specified as URL parameters. Example: http://cedarsoftware.com/coolApp/CoolController/coolMethod?json=[args...]
  - protected void doPost(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response)
    
    Process JSON POST style where the controller, method, and arguments are passed in as the POST data. Example: http://cedarsoftware.com/coolApp/CoolController/coolMethod Post body contains the arguments in JSON format.
  - static java.lang.Throwable getDeepestException(java.lang.Throwable e)
    
    Get the deepest (original cause) of the exception chain.
    Returns:
    Throwable original (causal) exception
    Parameters:
    e - Throwable exception that occurred.
  - private java.lang.Object getProvider(javax.servlet.http.HttpServletRequest request, java.lang.String json)
    
    Returns:
    Either a JsonCommandServlet ConfigurationProvider or an Envelope instance, if unable to obtain the configuration provider. The URL must contain /controller/method, and then if the controller name can be found in the n-cube provider, then the ncubeCfgProvider is returned, otherwise the springCfgProvider is checked. If the controller name can be found there, then the springCfgProvider is returned. If the controller cannot be located by name from either provider, and Envelope is returned, indicating this error.
    Parameters:
    request - HttpServletRequest passed to the command servlet.
  - private void handleRequestAndResponse(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response, java.lang.String json)
    
    This is the main driver of the command servlet. This code obtains the appropriate provider, calls the appropriate method on the provider, and then optionally writes the return response, if the called method did not write to the HTTP response.
    Parameters:
    request - HttpServletRequest passed to the command servlet.
    response - HttpServletResponse passed to the command servlet.
    json - String arguments that were passed in JSON format.
  - void init()
  - private static void removeThreadLocals()
    
    Remove ThreadLocals containing HttpServletRequest and response so that when thread is returned to threadpool there are no lingering references to these values.
  - void route(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response)
    
    If using UrlRewrite from tuckey.org, then route HTTP Json commands via this 'route' method and list it in the urlrewrite.xml.
  - private static void sendJsonResponse(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response, Envelope envelope)
    
    Build and send the response Envelope to the client.
    Parameters:
    request - original servlet request
    response - original servlet response
    envelope - data and status to be written
  - private static void writeResponse(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response, java.lang.String json)
    
    Write the response Envelope to the client
    throws:
    IOException
    
    Parameters:
    request - original servlet request
    response - original servlet response
    json - String response to write

Summary:
Field
Constructor
Method

| Detail:
Field
Constructor
Method

Groovy Documentation

[Groovy] Class JsonCommandServlet

Field Summary

Constructor Summary

Methods Summary

Inherited Methods Summary

Field Detail

public static final java.lang.String ATTRIBUTE_FAIL_MESSAGE

public static final java.lang.String ATTRIBUTE_STATUS

private static final org.apache.logging.log4j.Logger LOG

private NCubeConfigurationProvider nCubeCfgProvider

public static final java.lang.ThreadLocal<javax.servlet.http.HttpServletRequest> servletRequest

public static final java.lang.ThreadLocal<javax.servlet.http.HttpServletResponse> servletResponse

private SpringConfigurationProvider springCfgProvider

Constructor Detail

JsonCommandServlet()

Method Detail

private static java.lang.String buildResponse(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response, Envelope envelope)

protected void doGet(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response)

protected void doPost(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response)

static java.lang.Throwable getDeepestException(java.lang.Throwable e)

private java.lang.Object getProvider(javax.servlet.http.HttpServletRequest request, java.lang.String json)

private void handleRequestAndResponse(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response, java.lang.String json)

void init()

private static void removeThreadLocals()

void route(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response)

private static void sendJsonResponse(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response, Envelope envelope)

private static void writeResponse(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response, java.lang.String json)