// Open the SISS catalog on the server
        Catalog catalog = integrationServices.Catalogs[catalogName];
        if (catalog == null)
        {
            Console.WriteLine("Unable to open the SSIS catalog : " + catalogName
                + ", it does not exist on the server");
            return (int)ExitCode.Failure;
        }

        // Open the folder in the catalog
        CatalogFolder folder = catalog.Folders[folderName];
        if (folder == null)
        {
            Console.WriteLine("Unable to open the folder : " + folderName
                + ", it does not exist on the server");
            return (int)ExitCode.Failure;
        }

        // Open the project in the folder
        ProjectInfo projectInfo = folder.Projects[projectName];
        if (projectInfo == null)
        {
            Console.WriteLine("Unable to open the project : " + projectName
                + ", it does not exist on the server");
            return (int)ExitCode.Failure;
        }

        // Check if the package exists
        if (!projectInfo.Packages.Contains(packageName))
        {
            Console.WriteLine("Unable to open the package : " + packageName
                + ", it does not exist on the server");
            return (int)ExitCode.Failure;
        }

private T Extract(string itemType, string itemName, Func<T> itemExtractor) where T : class
{
    var res = itemExtractor();
    if (res == null)
    {
         Console.WriteLine("Unable to open the {0}: {1}", itemType, itemName);
         return null;
    }
    return res;
}

Catalog catalog = Extract("catalog", catalogName, () => integrationServices.Catalogs[catalogName]);
if (catalog == null) return (int)ExitCode.Failure;
CatalogFolder folder =  Extract("folder", folderName, () => catalog.Folders[folderName]);
if (folder == null) return (int)ExitCode.Failure;
ProjectInfo projectInfo = Extract("project", projectName, () => folder.Projects[projectName]);
if (projectInfo == null) return (int)ExitCode.Failure;
string package = Extract("package", packageName, () => projectInfo.Packages.Contains(packageName) ? packageName : null);
if (package == null) return (int)ExitCode.Failure;

private T Extract(string itemType, string itemName, Func<T> itemExtractor) where T : class
{
    var res = itemExtractor();
    if (res == null)
    {
         throw new ItemNotFoundException(string.Format("Unable to open the {0}: {1}", itemType, itemName));
    }
    return res;
}

try
{
    Catalog catalog = Extract("catalog", catalogName, () => integrationServices.Catalogs[catalogName]);
    CatalogFolder folder =  Extract("folder", folderName, () => catalog.Folders[folderName]);
    ProjectInfo projectInfo = Extract("project", projectName, () => folder.Projects[projectName]);
    string package = Extract("package", packageName, () => projectInfo.Packages.Contains(packageName) ? packageName : null);
}
catch (ItemNotFoundException ex)
{
    Console.WriteLine(ex.Message);
    return (int)ExitCode.Failure;
}

private class CatalogException : Exception
{
    public CatalogException(string catalogName) :
        base(String.Format(@"
        Unable to open the SSIS catalog : {0}, it does not exist on the server", catalogName))
    {
    }
}

private class FolderException : Exception
{
    public FolderException(string folderName) :
        base(String.Format(@"
        Unable to open the folder : {0}, it does not exist on the server", folderName))
    {
    }
}

private class ProjectException : Exception
{
    public ProjectException(string projectName) :
        base(String.Format(@"
        Unable to open the project: {0}, it does not exist on the server", projectName))
    {
    }
}

private class PackageException : Exception
{
    public PackageException(string packageName) :
        base(String.Format(@"
        Unable to open the package: {0}, it does not exist on the server", packageName))
    {
    }
}


private int doit()
{
    try
    {
        // Open the SISS catalog on the server
        Catalog catalog = integrationServices.Catalogs[catalogName];
        if (catalog == null)
            throw new CatalogException(catalogName);

        // Open the folder in the catalog
        CatalogFolder folder = catalog.Folders[folderName];
        if (folder == null)
            throw new FolderException(folderName);

        // Open the project in the folder
        ProjectInfo projectInfo = folder.Projects[projectName];
        if (projectInfo == null)
            throw new ProjectException(projectName);

        // Check if the package exists
        if (!projectInfo.Packages.Contains(packageName))
            throw new PackageException(packageName);

        return (int)ExitCode.Sucess;
    }
    catch (Exception e)
    {
        Console.WriteLine(e.Message);
        return (int)ExitCode.Failure;
    }
}

try
{
    // Open the SISS catalog on the server
    var catalog = integrationServices.Catalogs[catalogName];
    if (catalog == null)
    {
        throw new System.Exception("Unable to open the SSIS catalog : " + catalogName + ", it does not exist on the server");
    }
    /*...*/
    return (int)ExitCode.Success;
}
catch (System.Exception x)
{
    System.Console.WriteLine(x.Message);
    return (int)ExitCode.Failure;
}

try
{
    // Open the project in the catalog
    var catalog = integrationServices.Catalogs[catalogName];
    var folder = catalog.Folders[folderName];
    var projectInfo = folder.Projects[projectName];

    // Check if the package exists
    if (!projectInfo.Packages.Contains(packageName))
    {
        throw new System.Exception("Unable to open the package : " + packageName
            + ", it does not exist on the server");
    }
    /*...*/
    return (int)ExitCode.Success;
}
catch
{
    return (int)ExitCode.Failure;
}

public int ExecuteSSISPackage()
{
    string whatFailed = null;
    if (integrationServices.Catalogs.Contains(catalogName))
    {
        var catalog = integrationServices.Catalogs[catalogName];
        if (catalog.Folders.Contains(folderName))
        {
            var folder = catalog.Folders[folderName];
            if (folder.Projects.Contains(projectName))
            {
                var project = folder.Projects[projectName];
                if (project.Packages.Contains(packageName))
                {
                    var package = project.Packages[packageName];

                    //... Execute package?

                } else whatFailed = String.Format("package: {0}", packageName);
            } else whatFailed = String.Format("project: {0}", projectName);
        } else whatFailed = String.Format("folder: {0}", folderName);
    } else whatFailed = String.Format("SSIS catalog: {0}", catalogName);

    if (whatFailed != null)
    {
        Console.WriteLine("Unable to open the {0}, it does not exist on the server", whatFailed);
        return (int)ExitCode.Failure;
    }
    else
        return (int)ExitCode.Success;

Catalog catalog = integrationServices.Catalogs[catalogName];
    if (catalog == null)
    {
        Console.WriteLine("Unable to open the SSIS catalog : " + catalogName
            + ", it does not exist on the server");
        return (int)ExitCode.Failure;
    }

public Catalog this[string key]
    {
        get
        {
            Catalog catalog;

            if(_dictionary.TryGetValue(key, out catalog))
                return catalog;

            return null;
        }
    }

public Catalog this[string catalogName]
    {
        get
        {
            Catalog catalog;

            if(_dictionary.TryGetValue(key, out catalog))
                return catalog;

            throw new Exception("Unable to open the SSIS catalog : " + catalogName +
                ", it does not exist on the server";
        }
    }

public Catalog GetCatalog(string catalogName)
    {
        Catalog catalog;

        if(_dictionary.TryGetValue(key, out catalog))
            return catalog;

        throw new Exception("Unable to open the SSIS catalog : " + catalogName +
            ", it does not exist on the server";
    }

try
{
    // Open the SISS catalog on the server
    Catalog catalog = integrationServices.GetCatalog(catalogName);

    // Open the folder in the catalog
    CatalogFolder folder = catalog.GetFolder(folderName);

    // Open the project in the folder
    ProjectInfo projectInfo = folder.GetProject(projectName);

    // Check if the package exists
    var package = projectInfo.GetPackage(packageName);

    return package;  // or do whatever it is you need the package for
}
catch (Exception ex)
{
    Console.WriteLine(ex.Message);
    //return (int)ExitCode.Failure;
    throw;
}