Posts Tagged ‘json’

JSON Namespacing

Wednesday, September 2nd, 2009

(or “Why JSON Hyper Schema means JSON doesn’t need XML’s namespacing colon cancer”)

I recently posted a proposal for an addition to JSON Schema, called JSON Hyper Schema, for defining the properties of a JSON structure that represent links or references within data structures. This is intended to provide the same linking capabilities of JSON Referencing, but in a much more flexible manner such that schemas can be used to describe link information in existing data structures without requiring a fixed convention. I wanted to exposit one of the further benefits of using this type of schema: satisfying the goals of namespacing in JSON.

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Posted in JavaScript, thoughts | 8 Comments

More Query and Caching Power for Data Stores: ClientFilter, JsonQuery, and JsonQueryRestStore

Thursday, December 18th, 2008

Dojo includes several new modules which open up new querying and caching capabilities for Dojo data stores. dojox.data.ClientFilter is available in Dojo 1.2, and provides the ability to cache queries, update the query results and cached queries based on local modifications, and performs sub-queries and sorting on the client-side. The JsonQuery is a new mixin class for Dojo 1.3 that converts Dojo query objects and sort objects to JSONQuery expressions; JSONQuery can be used for delivering complex queries to the server. JsonQueryRestStore is a new module (for Dojo 1.3) that extends the JsonRestStore and combines the ClientFilter and JSONQuery such that any query can be executed on the client or the server automatically based on what data has been locally cached on the client-side, utilizing dojox.json.query to execute queries on the client-side when appropriate.

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Posted in Dojo, JavaScript, Performance, ajax | 16 Comments

JSON Schema in Dojo

Friday, October 31st, 2008

JSON Schema is a specification for defining the structure of JSON data. JSON Schema provides the definition of contractual type constraints for describing a valid set of values for object style data structures. JSON Schema development is based on the concepts from XML Schema, RelaxNG, and Kwalify, but is a JSON-based format, so it is well suited for JSON-based applications. It is intended to provide validation, documentation, and interaction control. Defining type constraints provides a standardized form of data documentation that can be used for data persistence, form generation, and creating contracts on data used in web services.

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Posted in Dojo, JavaScript, Persevere, ajax, api | 3 Comments

Security in Ajax

Thursday, September 25th, 2008

Security in Ajax web applications is of growing importance. While the client-server model is very useful for architecting web applications, the web security is model is not client-server, but rather a client-deputy-server model. Understanding this security model is important for building secure web applications, and it is becoming even more important as we build mashups and web applications that utilize cross-site resources.

In a client-server model, the client acts on behalf of the user, and the server trusts the client to the degree that a user is authorized. In the client-deputy-server model, the deputy (the browser) acts on behalf of the user, with suspicion of the client (web page/JavaScript), taking responsibility for some aspects of security, limiting client to client interaction. By understanding the mechanisms for the deputy boundaries, servers can appropriately participate in the security model with proper trust for the browser to act on behalf of the user. We will look at how to secure resources from being accessed from the wrong clients and protect clients from malicious server code.

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Posted in DWR, Dojo, ajax | 5 Comments

JSON Referencing in Dojo

Tuesday, June 17th, 2008

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Non-trivial data often has structures that cannot be well-defined with normal linear, acyclic data descriptions. Data that consists of cycles, many-to-one relationships, and non-local references often requires custom strategies for serialization and transfer of the data over JSON. Dojo 1.2 has added support for JSON referencing with the dojox.json.ref module. This module provides support for several forms of referencing including circular, multiple, inter-message, and lazy referencing using id, path, and combined referencing forms.

These references can be automatically generated on serialization and resolved on deserialization. JSON referencing is designed to decouple the topology of data structures from the meaning of the data structures in a way that is consistent with runtime object models of modern OO languages (foremost JavaScript). Separating graph connectedness concerns allows referencing and dereferencing to be handled by dojox.json.ref with minimal or no knowledge of and integration with higher level JSON consumers and producers, and permits more extensive JavaScript serialization capabilities.

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Posted in Dojo, JavaScript, Open Source, ajax | 13 Comments

RESTful JSON + Dojo Data

Friday, June 13th, 2008

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Dojo 1.2 now includes an infrastructure for interacting with JSON REST services and data storage systems. JsonRestStore is a new Dojo Data store for interacting with the RESTful JSON data sources. This new data store allows you to communicate with server side database/persistent data storage using the Dojo Data API with JavaScript and efficiently handles create, read, update, and delete (CRUD) operations. This can greatly simplify client server communication, interacting can be done simply using straightforward JavaScript instead of having to build your communication for CRUD actions. In addition, Dojo data stores can plugin to many Dojo widgets (Dijits).

Complex database driven widgets can be utilized with minimal coding effort. RESTful JSON is an increasingly popular database interface, and in later posts we will look at how JsonRestStore can be used with Amazon S3, CouchDB, Persevere, and Ruby on Rails. The JsonRestStore fully implements the Dojo Data read, write, notification, and identity interfaces. Therefore it can be used with any widget that can utilize these data stores including widgets with editing and live auto-updating features.

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Posted in Dojo, Dojo Grid, Dojo Offline, JavaScript, ajax | 88 Comments