private bool CheckIn()
{
    TreeProvider tree = new TreeProvider(CMSContext.CurrentUser);

    // Prepare parameters
    string siteName = CMSContext.CurrentSiteName;
    string aliasPath = "/API-Example";
    string culture = "en-us";
    bool combineWithDefaultCulture = false;
    string classNames = TreeProvider.ALL_CLASSNAMES;
    string where = null;
    string orderBy = null;
    int maxRelativeLevel = -1;
    bool selectOnlyPublished = false;
    string columns = null;

    // Get the document
    TreeNode node = DocumentHelper.GetDocument(siteName, aliasPath, culture, combineWithDefaultCulture, classNames, where, orderBy, maxRelativeLevel, selectOnlyPublished, columns, tree);

    if (node != null)
    {
        WorkflowManager workflowmanager = WorkflowManager.GetInstance(tree);

        // Make sure the document uses workflow
        WorkflowInfo workflow = workflowmanager.GetNodeWorkflow(node);

        if (workflow != null)
        {
            if (node.IsCheckedOut)
            {
                VersionManager versionmanager = VersionManager.GetInstance(tree);

                // Check in the document
                versionmanager.CheckIn(node, null, null);

                return true;
            }
            else
            {
                apiCheckIn.ErrorMessage = "The document hasn't been checked out.";
            }
        }
        else
        {
            apiCheckIn.ErrorMessage = "The document doesn't use workflow.";
        }
    }

    return false;
}

private bool PublishDocument()
{
    TreeProvider tree = new TreeProvider(CMSContext.CurrentUser);

    // Prepare parameters
    string siteName = CMSContext.CurrentSiteName;
    string aliasPath = "/API-Example";
    string culture = "en-us";
    bool combineWithDefaultCulture = false;
    string classNames = TreeProvider.ALL_CLASSNAMES;
    string where = null;
    string orderBy = null;
    int maxRelativeLevel = -1;
    bool selectOnlyPublished = false;
    string columns = null;

    // Get the document
    TreeNode node = DocumentHelper.GetDocument(siteName, aliasPath, culture, combineWithDefaultCulture, classNames, where, orderBy, maxRelativeLevel, selectOnlyPublished, columns, tree);

    if (node != null)
    {
        WorkflowManager workflowManager = WorkflowManager.GetInstance(tree);

        WorkflowInfo workflow = workflowManager.GetNodeWorkflow(node);

        // Check if the document uses workflow
        if (workflow != null)
        {
            // Publish the document
            workflowManager.PublishDocument(node, null);

            return true;
        }
        else
        {
            apiArchiveDocument.ErrorMessage = "The document doesn't use workflow.";
        }
    }

    return false;
}