This document discusses using the Bite language to compose RESTful web services and collaborative workflows in a lightweight manner. Bite allows combining RESTful services, human interactions, collaboration services, and backend services. It uses a simple process model and scripting approach to describe control and data flows. Bite activities include basic HTTP primitives, utilities, and controls. Flows can expose entry points as services and define multiple receive activities. The language is extensible and supports UI integration via URLs and HTML rendering.

1. Composing RESTful Services and
Collaborative Workflows
A Light Weight Approach
Author(s): Rosenberg, F (Rosenberg, Florian); Curbera, F (Curbera, Francisco);
Duftler, MJ (Duftler, Matthew J.); Khalaf, R (Khalaf, Rania)
Source: IEEE INTERNET COMPUTING Volume: 12 Issue: 5 Pages: 24-31
DOI: 10.1109/MIC.2008.98
Published: SEP-OCT 2008
Web of Science Categories: Computer Science, Software Engineering
Research Areas: Computer Science
Times Cited: 20 (from Web of Science)
Cited References: 7

2. Abstract
• The use of RESTful Web services (based on
HTTP) can integrate easily into applications
like mashups
• In order to compose RESTful services into
Web-scale workflows, using Bite as a light
composition language to accomplish the task
by describing both the control and data flow

3. Introduction
• Increasing adoption of SOA paradigm
• Limits of Web services model consists of two
contention points:
– The complexity
– Lack of alignment with the Web’s accepted
architectural principles
• The Representational State Transfer (REST)
model is introduced

4. Introduction
• In REST, the main architectural concept is the
information resource, and the principal
interaction mode lets clients retrieve
representations of those resources
• The article addresses the complementary
problem:
– How the service paradigm and SOA’s service
composition model can benefit mainstream Web
applications

5. Introduction
• Explore the potential benefits of process-
oriented composition for Web scenarios
• Focus on design principles and applications of
the process-oriented composition model of
Bite language, derived by aligning SOA process
composition principles with REST architectural
requirements

6. Bite Overview
• Allow web applications can seamlessly
combine:
– RESTful services
– Simple human interaction
– Collaboration services
– Back-end services

7. The Bite Approach
• Requirements and Design Goals:
– Atom life-cycle model
– Light weight process model
– Scripting approach
– Language extensibility
– Web and human integration

8. The Bite Approach
• Basic Model and Language:
– Comprise a flat graph containing actions and links
between them
– Use while activity to allow containing of other
activities
– Encodes graph execution logic in conditional
transition links between activities and supports
error handling via special error links to an error-
handling activity

9. The Bite Approach
• Basic Model and Language:
– Bite’s core activities consist of:
• Basic HTTP communication primitives
• Utility activities
• Control helpers
– A Bite flow both uses external services in its flow
logic and exposes itself as a service
– Each flow instance can define multiple receive
activities corresponding to multiple entry points.

10. The Bite Approach
• Flow Example

11. The Bite Approach
• Bite Extensibility
– Creating Bite extension activities and registering
them with Bite engine
– Creating an extension activity lets developers
implement the core extension logic with minimal
overhead for reading and evaluating the
extension’s syntax

12. The Bite Approach
• Executing Scripts
– Executing script code in the flow facilitates certain
tasks (for example, calculation or accessing some
back-end system)

13. The Bite Approach
• UI Integration and Rendering Capabilities
– Enables a user interface (UI) integration because
all entry points in a flow are accessible via URLs.
– Provides HTML rendering capabilities using
various template languages to render HTTP replies
or emails from a flow

14. Collaborative Flows in Bite