Thanks Aravinth for your reply.

Below is the code which i am calling to update the journal article and start the workflow.
But journal article is getting updated with status as approved instead of Pending.
The use case i am trying to achieve is .. user will updated the web content and submit it for approval.
In this flow new task should get created in pending status and assigned to any reviewer.
Can you please tell me how to achieve this.

journalArticle = JournalArticleLocalServiceUtil.updateJournalArticle(updatedJournalArticle);  

ServiceContext serviceContext = new ServiceContext();
serviceContext.setScopeGroupId(themeDisplay	.getScopeGroupId());
serviceContext.setWorkflowAction(WorkflowConstants.ACTION_SAVE_DRAFT); 
WorkflowHandlerRegistryUtil.startWorkflowInstance(
							journalArticle.getCompanyId(),
							journalArticle.getUserId(),
							JournalArticle.class.getName(),
							journalArticle.getClassPK(), journalArticle,
							serviceContext);