Itemscript, a specification for RESTful JSON integration

Itemscript A declarative language based on JSON

Vision Simple schema data store application markup Applications from components De-couple technical details Lean development Business agility

Itemscript is Declarative Separates design ( what ) from construction ( how ) Simple API Lends itself to iterative development Technical details are hidden Controls are exposed Swap components without breaking the API

Itemscript Philosophy Applications are multi-layered Core is compiled code Wrapped around that are configuration files Wrapped around that are user settings Compiled settings are the hardest to change Configuration files help, but only offer limited access User settings are usually very limited Applications should expose all useful settings Core Configuration User settings

Itemscript is JSON JSON is simple JSON has widespread support JSON is an ideal data-interchange language

JSON easily maps to native objects JSON Objects Native objects & packages Nested object graphs Maps/hashes/dictionaries Databases Key-value stores Cloud databases JSON Arrays Lists/arrays/sets Query results

Extending JSON Deal with more data than fits in memory Databases Queries Handle references Manage local and remote data Handle identifiers Support schemas Manage persistence Handle events

Semantics Itemscript Schema JSON Schema language Itemscript JAM JSON Application Markup

Itemscript schema Dog Type "com.example.petstore.SCHEMA" : { "Dog" : { "ID name" : "", "weight" : 0, "REQUIRED owner" : "", "breed" : "", "isFixed" : true, } } item of type Dog: "com.example.petstore.dogs.Bella" : { "TYPE" : "com.example.petstore.SCHEMA.Dog", "name" : "Bella", "weight" : 9.2, "owner" : "Vera", "breed" : "Cavalier King Charles", "isFixed" : true } http://itemscript.org/ItemscriptSchema.html

Itemscript JAM { "widget" : "GWT.Image", "title" : "Itemscript Logo", "width" : "100px", "height" : "100px", "url" : "./itemscript-logo.jpg" }

Business agility Lean development using declarations Developer & user iterate together Discover needs as you develop solutions Iterate applications as requirements develop Add elements & event handlers as you need them Trade up as better options arrive

Proof of Concept Item Lens ( JAM animator ) rich web UI based on Google GWT Item Store ( Column store ) persistence based on Apache Derby Item Hash (Model application) item tracker built using Itemscript JAM

Itemscript execution Itemscript Item Lens Item Store Schema JAM Item Store Protocol SQL MQ Cache XML

Itemscript Applications “ Small pieces loosely joined” a collection of Lego bricks Compiled objects are managed in libraries, by type All "wiring-up" is done using JSON declarations No sharp distinction between application-building, configuration, or user settings http://www. smallpieces .com

How we built it Build objects that can be configured using JSON. Use semantics that describe the domain widget, handler, page ticket, priority, status white For each object type, build a factory that trades JSON for an object instance. For each class of object ( e.g. widget ), combine the factories into a foundry. Factor out common code.

Itemscript System Each system has one "root" JSON object Acts as shared in-memory database for your application. Application configuration Application state You can load additional Items - hold as long as needed, natively-garbage-collected. Load system and initial configuration Load Item from remote datastore Copy part of Item to current application state Discard Item

The Item The smallest unit of transferrable data. Guaranteed to be transmitted as a whole. Guaranteed to be fully navigable locally/synchronously. Consists of a JSON Object, including nested other objects. Metadata and data live together in the JSON Object. _ prefix denotes metadata . _CONNECTION key tells you where this Item came from. _ID key gives you the GUID key for an Item. _PARENT_ID key gives you the GUID key for a parent

Item Lens applications Application a set of nested Widgets. usually includes a PagePanel. PagePanel shows the Pages that have been defined. Each Page is a set of nested Widgets. Popups are also a set of nested Widgets. Dialog boxes Error boxes

Item Lens bootstrap Item Lens starts an application: loads modules (using GWT module system), modules register Foundries containing Factories, or register additional Factories in existing Foundries. e.g. WidgetFoundry Item Lens loads and stores the script file. Reads script file for more definitions - widgets, pages, popups stores them in the corresponding Foundry. Item Lens reads script file to build the application.

Item Store The Item Store is a key-value store of Items. Any Item can be the root of another key-value store. May map to: database-table-row. Or to: database-table-row-subTable-rowset. Easily replaced with SQL tables, key/value stores Maps Item Store namespace locations to connect to remote locations and services.

Item Store Item Store RPC Simple data store Get Put Remove Simple proxy for the service provider Connect services when your application is ready Swap out services without changing applications

Developing Itemscript applications Client side Wrap widgets and components in Itemscript Wire up components to build interfaces Server side Declare Itemscript data types Assign types to locations Connect locations to services

Item Hash Building the model application item hash use case item hash design process pulldown list example date picker example event example adding a new field adding a new event handler

Editing the Form { "widget" : "GWT.VerticalPanel", "contents" : [ { "widget" : "GWT.Html", "html" : "<small>Priority</small>" "id" : "Priority" }, { "widget" : "GWT.ListBox", "width" : "200px", "height" : "20px" "data" : "ItemHash.db/priorities" } ] }

Item Lens "Can I set the date picker to tomorrow?"

Changing the Date Picker What would the JSON look like? { "widget" : "ItemLens.DatePickerTextBox" "width" : "200px", "height" : "25px", "date" : "tomorrow" }

Changing the Date Picker When the "date" declaration says "tomorrow", what logic do we need to add? if (params.hasOptionalString( "date" )) { String dateStr = params.getString( "date" ); if (dateStr.equalsIgnoreCase( "tomorrow" )) { Date tomorrow = new Date( new Date().getTime()+ DAY_AS_MILLISECONDS ); box.setValue(tomorrow); } }

Event Handling "Let's make the login box pop up."

Event Handling What would the JSON look like? { "widget" : "GWT.Html" "cellHorizontalAlignment" : "right" "html" : "<small><b>login</b></small>" "clickHandlers" : { "clickHandler" : "ItemLens.PopupPanelShowClickHandler", "popup" : "loginPrompt" } }

Event Handling Implementing a "clickHandler" Register a factory to create an action. Animating "popup" : "loginPrompt" Read the "loginPrompt" object in "popups" section. Parse loginPrompt for the parameter needed. Build a popup widget.

Event Handling "popups": { "loginPrompt" : { "widget" : "GWT.DialogBox", "id" : "Login", "title" : "user login", "showRelativeTo" : "searchbox", "width" : "100px", "cellHorizontalAlignment" : "center", "cellVerticalAlignment" : "bottom", "html" : "<strong>User Login</strong>", "autohide" : false, "contents" : { "widget" : "GWT.VerticalPanel", "cellSpacing" : 5 "contents" : [ ...

Adding Widget Libraries GChart { "widget" : "GChart.Chart" , "canvas" : true , "chartHeight" : 200, "chartWidth" : 300, "chartTitle" : "<h3>2008 Sales by Pie Flavor<br>(Puny Pies, Inc.) </h3>" , "legendVisible" : false , "initialPieSliceOrientation" : 0.425, "curves" : [ { "symbol" : "pieSliceOptimalShading" , "modelWidth" : 6, "backgroundColor" : "green" , "borderColor" : "white" , "height" : 0, "fillSpacing" : 0, "fillThickness" : 3, "hoverText" : "Apple, 65%" , "pieSliceSize" : 0.65, "points" : [ { "point" : "5,5" , "annotationText" : "Apple" , "annotationLocation" : "outsidePieArc" } ... Designers learn a few new declarations, not a new API Full demo at http://tinyurl.com/gchartdemo

Downloads Item Lens AJAX using Google GWT Components from Google Maps, Gchart, GWT Widget library Itemscript Core Libraries Convenient JSON library for Java & GWT applications

What's Next? Item Store Itemscript schema validator Declarative security model Hosted Service Application exchange

Working with Itemscript Project pages http://itemscript.org http://code.google.com/p/itemscript/ Twitter updates http://twitter.com/itemscript FAQ http://code.google.com/p/itemscript/wiki/itemscriptfaq

Itemscript, a specification for RESTful JSON integration

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Itemscript, a specification for RESTful JSON integration