Getting Started
Developer Documentation

The first step is to install the WRENCH library, following the instructions on the installation page.

Running a First Example

Typing make in the top-level directory will compile the examples, and make install will put the examples binaries in the /usr/local/bin folder (for MacOS and most Linux distributions).

WRENCH provides a simple example in the examples/simple-example directory, which generates two executables: a cloud-based example wrench-simple-example-cloud, and a batch-system-based (e.g., SLURM) example wrench-simple-example-batch. To run the examples, simply use one of the following commands:

# Runs the cloud-based implementation
wrench-simple-example-cloud \
<PATH-TO-WRENCH-FOLDER>/examples/simple-example/platform_files/cloud_hosts.xml \
# Runs the batch-based implementation
wrench-simple-example-batch \
<PATH-TO-WRENCH-FOLDER>/examples/simple-example/platform_files/batch_hosts.xml \

Understanding the Simple Example

Both versions of the example (cloud of batch) require two command-line arguments: (1) a SimGrid virtual platform description file; and (2) a WRENCH workflow file.

  • SimGrid simulated platform description file: A SimGrid simulation must be provided with the description of the platform on which an application execution is to be simulated. This is done via a platform description file, in XML, that includes definitions of compute hosts, clusters of hosts, storage resources, network links, routes between hosts, etc. A detailed description on how to create a platform description file can be found here.
  • WRENCH workflow file: WRENCH provides native parsers for DAX (DAG in XML) and JSON workflow description file formats. Refer to their respective Web sites for detailed documentation.

The source file for the cloud-based simulator is at examples/simple-example/SimulatorCloud.cpp and at examples/simple-example/SimulatorBatch.cpp for the batch-based example. These source files, which are heavily commented, and perform the following:

  • The first step is to read and parse the workflow and the platform files, and to create a simulation object (wrench::Simulation).
  • A storage service (wrench::SimpleStorageService) is created and deployed on a host.
  • A cloud (wrench::CloudComputeService) or a batch (wrench::BatchComputeService) service is created and deployed on a host. Both services are seen by the simulation as compute services (wrench::ComputeService) – jobs can then be submitted to these services.
  • A Workflow Management System (wrench::WMS) is instantiated (in this case the SimpleWMS) with a reference to a workflow object (wrench::Workflow) and a scheduler (wrench::Scheduler). The scheduler implements the decision-making algorithms inside the WMS. These algorithms are modularized (so that the same WMS implementation can be iniated with various decision-making algorithms in different simulations). The source codes for the schedulers, which is of interest to "Developers" (i.e., those users who use the WRENCH Developer API), is in directory examples/scheduler.
  • A file registry (wrench::FileRegistryService), a.k.a. a file replica catalog, which keeps track of files stored in different storage services, is deployed on a host.
  • Workflow input files are staged on the storage service
  • The simulation is launched, executes, and completes.
  • Timestamps can be retrieved to analyze the simulated execution.

This simple example can be used as a blueprint for starting a large WRENCH-based simulation project. The next section provides further details about this process.

WRENCH Initialization Tool

The wrench-init tool is a project generator built with WRENCH, which creates a simple project structure with example class files, as follows:

├── CMakeLists.txt
├── src/
│ ├── SimpleSimulator.cpp
│ ├── SimpleStandardJobScheduler.cpp
│ ├── SimpleStandardJobScheduler.h
│ ├── SimpleWMS.cpp
│ └── SimpleWMS.h
├── test/
├── doc/
├── build/
└── data/
├── platform-files/
└── workflow-files/

The SimpleSimulator.cpp source file contains the class representing the simulator (either cloud or batch). SimpleStandardJobScheduler.h and SimpleStandardJobScheduler.cpp contain a simple implementation for a wrench::StandardJobScheduler; SimpleWMS.h and SimpleWMS.cpp denote the implementation of a simple workflow management system. Example platform and workflow files are also generated into the data folder. These files provide the minimum necessary implementation for a WRENCH-enabled simulator.

The wrench-init tool only requires a single argument, the name of the folder where the project skeleton will be generated:

$ wrench-init <PROJECT_FOLDER>

Additional options supported by the tool can be found by using the wrench-init --help command.

Preparing the Environment

Importing WRENCH

For ease of use, all WRENCH abstractions are accessed via a single include statement:

#include <wrench-dev.h>

Note that wrench-dev.h is the only necessary include statement to use WRENCH. It includes all interfaces and services provided in wrench.h (user API), as well as additional interfaces to develop your own algorithms and services.

Creating Your CMakeLists.txt File

Below is an example of a CMakeLists.txt file that can be used as a starting template for developing a WRENCH application compiled using cmake:

cmake_minimum_required(VERSION 3.2)
add_definitions("-Wall -Wno-unused-variable -Wno-unused-private-field")
# include directories for dependencies and WRENCH libraries
include_directories(src/ /usr/local/include /usr/local/include/wrench)
# source files
# test files
# wrench library and dependencies
find_library(WRENCH_LIBRARY NAMES wrench)
find_library(SIMGRID_LIBRARY NAMES simgrid)
find_library(PUGIXML_LIBRARY NAMES pugixml)
find_library(LEMON_LIBRARY NAMES emon)
find_library(GTEST_LIBRARY NAMES gtest)
# generating the executable
add_executable(my-executable ${SOURCE_FILES})
install(TARGETS my-executable DESTINATION bin)
# generating unit tests
add_executable(unit_tests EXCLUDE_FROM_ALL
${GTEST_LIBRARY} wrench -lpthread -lm