XML INTEGRATORGoogle Wave Gadget

PURPOSE

Create mapping from one XML schema to another XML schema

Support collaborative creation of that mapping

Export that mapping as a XSLT transformation

WHAT’S A MAPPING? I

Translation of one or many XML elements in the source XML to an element in the destination XML

More precisely, XML is a tree hierarchy of XML elements. This hierarchy structure can be defined using XSD or other ways, ex. DTD. But XSD is mostly used, therefore was chosen as the source of XML structure for this application.

WHAT’S A MAPPING? II

Usually, it’s required to modify the source element, so it can be mapped to a destination element.

Therefore mapping must contain definition of this modification.

MAPPING LIFECYCLE

1) Choose source and destination XSD2) Add mappings3) Create XSLT4) Apply to a XML

EXAMPLE OF A MAPPING

MAPPING DEFINITION

Transformation type Maximal number of inputs (optional) XPath expression (optional) Inputs map Output list

TRANSFORMATIONS

Name Inputs Bounded

XPath XPath enabled

Identity 1 ●

Sorted 2 ●

Condition 2 ●

Sequence 1

Copy-of 1

Value-of 1

Concatenation

1

Longer 2 ●

XPath 1 string(#0)

●

IMPLEMENTATION – DATA STRUCTURES

XML Mapping Model Source schema Destination schema Elements mappings

TYPES OF EDITS

Add mapping Remove mapping Change mapping’s transformation Translate mapping inside editor Add connection between mapping and other

elements Source element, destination element, another

mapping Remove connection

GOOGLE WAVE

Google Wave

Wave Robot

State Server

DBUser

User

User

EDIT DATA STRUCTURE

ID Author Type Other attributes depending on the type of

edit

EDIT LIFECYCLE

User creates an edit Sends it to State server

Servers merges it into model Receives edit ID

This ID is from increasing number sequence Puts edit into Gadget state Receives new Gadget state

Merges all newer edits into local model Newer merges edit with ID higher than last edit

processed by State server to the local instance of the mapping model

GADGET STATE OVERVIEW

User A

User B

User C State Serverand

Wave Robot

Database

Gadget State

User A edits the mapping1) Sends edit to State Server2) State Server processes the edit

(saves merged state to database) and returns edit ID

3) Edit ID and Edit is submit to Gadget state

4) Gadget state is send to each user and robot

GADGET STATE OVERVIEW II

Size limit defined by Google is 100KiB for gadget state

Therefore mapping state is being held on State server

Inside gadget state are some state attributes and especially set of the edits made by users

When the state’s size would be greater than 100KiB, than Robot clear state and forces users to reload mapping state from the State server

PROTOCOL – DATA STRUCTURES

Model ID Version Last edit ID List of edits

Edit ID Edit content

MERGING

Edits are sorted by their ID Each is processed If there would be any conflicts, the last wins,

or will be ignored All edits show in the edit log

CONFLICTS

User wants edit/remove already removed mapping Edit/remove is being ignored

In other cases the last edit wins

BEFORE EXPORT CHECK

Not all mappings are compatible with each other, so there must be check before the export to XSLT

Also there mustn’t be any cycle

LIMITS OF THE GADGET

In source even in destination XSD mustn’t be any recursive structure. Otherwise the model will limit the depth of the recursion to 1.

EXAMPLE XSLT