Information Technology Reference
In-Depth Information
Now, a series of problems are exposed with the extensively developed and further
used in cloud computing, of which the most outstanding one is how to reduce cost and
meanwhile keep or improve the QoS, at last maximize the revenues. Workflow tech-
nology can support business process management and business process automation,
and enhance flexibility of business process system and the ability of fitting for
change. Therefore, it can be used to solve such problems. Generally speaking, by
using workflow technology, the business process can be resolved to some manageable
small events, and individually model and control the procedural semantics which
describe constraint relation between activities. A workflow application can be de-
scribed by a directed acyclic graph, the nodes denote tasks and the edges denote the
internal dependency between activities. Single workflow always contains a series of
tasks, and each task may communicate with other task because of the dependency.
A workflow management system (WfMS) can manage the definition and execution
control of business processes. Workflow engine is the key component of a WfMS to
manage workflow's execution, which can be used to perform workflow scheduling,
data transmission and fault tolerance management. The aim of workflow scheduling is
to assign appropriate task to the right resource at appropriate time. Data transmission
is used for the communication between data resources, and fault tolerance manage-
ment works when the execution of some task goes wrong. Workflow scheduling is the
most critical for a WfMS, because an appropriate scheduling plan has a significant
impact on performance of WfMS.
This paper focuses on the typical cloud workflow scheduling algorithms and typi-
cal tools for its research. The rest of the paper is organized as follows. Section 2 brief-
ly introduces the state-of-art of workflow technology and its technical features in
cloud. Section 3 analyzes various existing workflow scheduling algorithms and classi-
fied them into three categories. Section 4 evaluates typical research tools such as
CloudSim, WorkflowSim and SwinFlow-Cloud. Section 5 analyzes the problems of
current workflow scheduling algorithms in the cloud and proposes the improvement
direction. Section 6 concludes the paper.
2
Workflow Technology in Cloud Environment
The promising cloud computing environment brings new challenges to the traditional
workflow technology. The research on cloud workflow aims at deploying the business
process specified by user automatically in cloud, so that can reduce computational
expense and improve the quality of cloud services. It integrates the technical advan-
tages of cloud computing and the workflow system, so regarded as one of optimiza-
tion solutions for cloud computing, it has been obtained more and more attention and
study.
Using workflow technology in the cloud can take advantage of various cloud ser-
vices which facilitate execution of workflow greatly. Unlike other computing envi-
ronments, the resource in cloud is shared and offered to user on demand, meanwhile,
also can use the resource dynamically according to the estimated requirements of
execution. It makes workflow system satisfy the request of applications more easily.
