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JSON Integration Adapter

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{{Admon/obsolete}} [[category: NexJ Current Past Projects]]
[[category: NexJ Express JSON Message Adapter]]
 
== Project Repository ==
 
https://bitbucket.org/b_lim/nexj-express-json-integration-adapter/overview
 
== Project Goal==
To create an adapter for the NexJ Core similar in methodology and design of existing message adapters (XML, Fixed, CSV etc.) but using the JSON format
===Contributors===
* [[User:Gbatumbya|Grace Batumbya]]
* [[User:Brianlim | Brian Lim]]
 
== Current Status==
* '''Completed''' (February 02, 2012)
 
 
== Project Repository ==
BitBucket : https://bitbucket.org/gbatumbya/nexjexpress-jsonintergrationadapter/
<br/>Deprecated: <del>https://bitbucket.org/b_lim/nexj-express-json-integration-adapter/</del>
 
 
== Definitions ==
 
{| class="wikitable" border="1"
|-
! Term
! Description
|-
| Formatter
| Turns data into JSON
|-
| Parser
| Turns JSON into data
|-
| Message
| The metadata to be used when formatting and parsing a message. The grammar. It is a tree-like structure.
|-
| MessageInstance
| The information to be parsed or formatted
|}
 
Because the Integration layer allows a Model to interact with external applications asynchronously, a description / grammar of the data to be exchanged between the two systems is defined using a Message in the Model.
 
* Formatting is turning internal NexJ representation of a MessageInstance into JSON. The formatter is given a Message (the grammar), MessageInstance (the data), and a pipe. This accomplished by walking the Message tree-like structure while validating the data in the MessageInstance and streaming JSON format to the pipe. If the data in the MessageInstance does not conform to the Message, the formatter throws an exception.
 
* Parsing is turning JSON representation of a MessageInstance into an internal NexJ representation of a MessageInstance. The parser is given a Message (the grammar) and an input stream. First the input stream is parsed for JSON using a JSONParser which returns either an Object or an Array. The formatter walks the Message building the structure of the MessageInstance and adding validated values in the object returned by the JSONParser to the MessageInstance. If the data from the input stream does not match the expected input at any time, the parser throws an exception.
 
 
==== Message Fundamentals ====
Message - Messages can contain values or other messages. The red nodes are messages, the green nodes are values.
Currently at Phase II and beginning Phase III[[File:NexJExpressMessages.gif|NexJ Express Messages]]
==Project Phases==Internally, messages are Transfer Objects. To determine if a node is a message, use instanceof on CompositeMessagePartInstance after retrieving the MessagePart. For example,
JSON Integration Adapter Phases<pre>public void format(TransferObject tobj, Message message, Output out) throws IntegrationException{...CompositeMessagePart root = message.getRoot(); // Gets the root of the message.Iterator it = root.getPartIterator();while (it.hasNext()){ part = (MessagePart)it.next()); if (part instanceof CompositeMessagePartInstance) { // This part is a message } else if (part instanceof PrimitiveMessagePart) { // This part is a value }...}...</pre>
===Phase INOTE: THE MESSAGE PARAMETER DOES NOT CONTAIN THE MESSAGE VALUES. THE MESSAGE PARAMETER CONTAINS THE MESSAGE METADATA. THE TRANSFER OBJECT CONTAINS THE MESSAGE VALUES WHICH MUST BE VALIDATED AGAINST THE MESSAGE TO ENSURE CORRECT FORMAT. Research===
# Complete Fundamentals ; MessagePart:Parts of a message. Messages can contain values or other messages. NexJ Studio tutorial# Complete NexJ Integration tutorial# Install NexJ Studio Express from sourcehas two types of message parts, ''CompositeMessagePart'' and ''PrimitiveMessagePart''.
===Phase II; CompositeMessagePart: implementation is CompositeMessagePartInstance . Planning The relationship between CompositeMessagePartInstance and Approval===PrimitiveMessagePart with the above picture is as follows - CompositeMessagePartInstance are messages (the red nodes) and PrimitiveMessagePart are values (the green nodes). To determine multiplicity of MessageParts, use isCollection() method of MessagePart. Note that multiplicity of the above screenshot are all '''[0..1]''', that is zero or one instance. Possible node multiplicities:; '''[0..1]''' : zero or one instance (i.e. an optional entry); '''[1..1]''' : exactly one instance (i.e. required); '''[1..N]''' : collection of at least one, at most N instances; '''[0..0]''' : collection of zero to infinite instances (displayed as '''[*]'''); '''[1..0]''' : collection of at least one, possibly unlimited instances
# Receive general approval for project# Receive approval for JSON encoding options; XMLJSONMessageMappingLoader# Receive approval : Used by the framework to autoload JSONMessagePartMapping for JSON formatting optionseach of the message parts.
===Phase III; JSONMessagePartMapping: Each node in the above picture ''may'' has a corresponding JSONMessagePartMapping. Each node may have its own mapping, with its own values initialized in XMLJSONMessageMappingLoader. In order to get the mapping, first cast MessagePart to a concrete class such as CompositeMessagePartInstance or PrimitiveMessagePart, then use part.getMapping(). The purpose of the mapping is metadata for each node. Message Formatter===
# Add JSON ; JSONMessageFormatter: Used to .XSD base types# Create sample JSON .message # Parse sample turn messages into JSON format.message with JUnit Test# Create first set of unit tests for Message Formatter# Code Message Formatter first draft# Resolve issues with first set of unit tests# Create second set of unit tests# Resolve issues with second set of unit tests# Refactor and code message formatter ===Phase IV. Message Parser ===
# Discover how ; JSONMessageParser: Used to connect turn JSON RPC parser with Message Parser# Create first set of trivial unit tests for Message Parser# Code Message Parser skeleton# Pass first set of trivial unit tests# Create second set of unit tests (non-trivial) for Message Parser# Code Message Formatter first draft# Resolve issues with second set of unit tests# Refactorinto a message.
===Phase V. Integration and Stress Tests= Algorithm ====
format(TransferObject tobj, Message message, Output out)Algorithm for format method is as follows# Test Message Formatter and Message Parser with integration and stress testsRetrieve the root of the message# Test Iterate through NexJ Studio Express GUI each of the parts of the root## If the part is a CompositeMessagePartInstance, it is a message node## If the part is a PrimitiveMessagePart, it is a value node## Validate the part against the MessagePartMapping. Different types of validation must be done if the part is a Composite versus if it is a Primitive.## If the part is a CompositeMessagePartInstance, recursively call the format method with TransferObject set to the part. Suggested to overload the format method to format(manual testingTransferObject tobj, MessagePart message, Output out)and pass in the part, since retrieving a message root with getRoot() will always get the highest root of the message but what you want is the parent.## If the part is a PrimitiveMessagePart, write the message part to the output.
===Phase VI. Internal Code Review===
# Internally review code at CDOT==Project Phases==
===Phase VII1. OptimizationResearch (DONE)===# Complete Fundamentals of NexJ Studio tutorial# Complete NexJ Integration tutorial# Install NexJ Studio Express from source
===Phase 2. Design Proposal (DONE)===# Find more code optimizations relevant to Enterprise environments Receive general approval for project# Receive approval for JSON encoding options# Receive approval for JSON formatting options# [https://docs.google.com/document/d/1wAjG-xSJi227GBPUZtADAROSydIn3KuimoZarqO7xDQ/edit?hl=en_US Final Project Proposal]
===Phase VIII3. First Code Review at NexJCreate Classes (DONE)===# JSONMessagePartMapping# XMLJSONMessageMappingLoader# JSONMessageFormatter# JSONMessageParser# JSONMessageFormatterTest
===Phase 4. Internal Code Review (DONE)===# Date TBAInternally review code at CDOT
===Phase IX5. Code RewriteReview 1 (DONE)===# August 9, 2011# Code review took place at NexJ with [[User:Gbatumbya|Grace Batumbya]], [[User:Brianlim | Brian Lim]] and Andrew Borzenko (NexJ Developer) in attendance.
===Phase 6. Apply Changes from Code Review 1===# Rewrite code Estimated Duration: 3 Weeks (August 29, 2011)# [[JSON_Integration_Adapter_Code_Review_1_Changes | Changes to make]]'''Summary of [[JSON_Integration_Adapter_Code_Review_1_Changes | changes]]'''# Allowing modes for all Composite message parts, not just the root.# Refactoring methods to conform with NexJ suggestions and standardscheck for != right condition instead of checking for the wrong condition to throw an exception. (whitelist instead of blacklist)# Formatting all primitives before writing or storing them (e.g. timestamps, decimal numbers.)# Creating a RootJSONMessagePartMapping extending JSONMessagePartMapping
===Phase X7. Second Code Review at NexJ2===* Proposed Date: Week of <del>September 23</del> October 15
# Date TBA===Phase 8. Apply Changes from Code Review 2===*[[JSON_Integration_Adapter_Code_Review_2_Changes | Changes to make]]
===Phase XI9. Project CompletionCode Review 3===* Week of November 14
== Project Repository =Phase 10. Apply Changes from Code Review 3===*[[JSON_Integration_Adapter_Code_Review_3_Changes | Changes to make]]
BitBucket : https://bitbucket.org/b_lim/nexj-express-json-integration-adapter/
== Resources ==
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