Installation Requirements Getting started
Setup your project environment
Sample API model Supported API Model Attributes API Types Tips Generate API model from C header files Known caveats
Language Binding Notes Java Language Binding
Notes for Writing Language Bindings Schema/Architecture Overview Informal Summary Semantic Attributes Language-Specific Implementation Attributes
Ownership and License Hints to Contributors This Document
## Overviewzproject is a community project, like most ZeroMQ projects, built using the C4.1 process, and licensed under MPL v2. It solves the Makefile problem really well. It is unashamedly for C, and more pointedly, for that modern C dialect we call CLASS. CLASS is the Minecraft of C: fun, easy, playful, mind-opening, and social. Read more about it hintjens#79.
zproject grew out of the work that has been done to automatically generate the build environment in CZMQ. It allows to share these automations with other projects like zyre, malamute or hydra and at the same time keep everything in sync.
### Scope and Goalszproject has these primary goals:
- generate files for cross-platform build environments.
- generate CLASS (ZeroMQ RFC/21) compliant header and source skeletons for new classes.
- generate a public header file for your library so it can be easily included by others.
- generate stubs for man page documentation which uses the comment based approach from CZMQ.
All you need is a project.xml file in the project's root directory which is your
One file to rule them all
At least the following build environments are currently supported:
- Autotools
- CMake
- Mingw32
- Android
- Visual Studio
Thanks to the ZeroMQ community, you can do all the heavy lifting in C and then easily generate bindings in the following languages:
- Java (JNI)
- Python
- QML
- Qt
- Ruby
The language bindings are minimal, meant to be wrapped in a handwritten idiomatic layer later.
## Demo on PLAYTermThere is a short Demo on PLAYTerm that shows how easy it is to get started with zproject: ZeroMQ - Create new zproject
## Installation ### Requirementszproject uses the universal code generator called GSL to process its XML inputs and create its outputs. Before you start you'll need to install GSL (https://github.com/imatix/gsl) on your system.
git clone https://github.com/imatix/gsl.git
cd gsl/src
make
make installGSL must be able to find the zproject resources on your system. Therefore you'll need to install them.
The following will install the zproject files to /usr/local/bin.
git clone https://github.com/zeromq/zproject.git
cd zproject
autogen.sh
configure
make
make installNB: You may need to use the sudo command when running make install to elevate your privileges, e.g.
sudo make installNB: If you don't have superuser rights on a system you'll have to make sure zproject's gsl scripts can be found on your PATH.
## Setup your project environmentThe easiest way to start is to create a minimal project.xml.
<project script = "zproject.gsl">
<use project = "czmq" />
<main name = "hello" private = "1" />
</project>Once you're done you can create your project's build environment and start compiling:
gsl project.xml
autogen.sh
configure.sh
makeNB: To get a more comprehensive example copy zproject's project.xml. It contains all possible configurations and according documentation.
Licensing your project is important thus you'll need a license file. Here's an overview that might help you decide to choose a license. zproject allows you to add an appropriate disclaimer of your license as a xml file, e.g. license.xml:
<license>
Your license disclaimer goes here!
</license>This disclaimer can be included in your project.xml and is used whenever zproject is generating new files e.g. CLASS skeletons or bindings.
<include filename = "license.xml" />zproject's project.xml contains an extensive description of the available configuration: The following snippet is taken from the project.xml:
<!--
The project.xml generates build environments for:
autotools GNU build system (default)
cmake CMake build system (default)
android Native shared library for Android
cygwin Cygwin build system
debian packaging for Debian
docker packaging for Docker
java Java JNI binding
java-msvc MSVC builds for Java JNI binding
mingw32 Mingw32 build system
nuget Packaging for NuGet
python Python binding
qml QML binding
qt Qt binding
redhat Packaging for RedHat
ruby Ruby binding
travis Travis CI scripts
vs2008 Microsoft Visual Studio 2008
vs2010 Microsoft Visual Studio 2010
vs2012 Microsoft Visual Studio 2012
vs2013 Microsoft Visual Studio 2013
vs2015 Microsoft Visual Studio 2015
Classes are automatically added to all build environments. Further as you
add new classes to your project you can generate skeleton header and source
files according to http://rfc.zeromq.org/spec:21.
script := The gsl script to generate all the stuff !!! DO NOT CHANGE !!!
name := The name of your project (optional)
description := A short description for your project (optional)
email := The email address where to reach you (optional)
repository := git repository holding project (optional)
-->
<project script = "zproject.gsl" name = "myproject">
<!--
Includes are processed first, so XML in included files will be
part of the XML tree
-->
<include filename = "license.xml" />
<!--
Current version of your project.
This will be used to package your distribution
-->
<version major = "1" minor = "0" patch = "0" />
<!--
Specify which other projects this depends on.
These projects must be known by zproject, and the list of
known projects is maintained in the zproject_known_projects.xml model.
You need not specify subdependencies if they are implied.
<use project = "zyre" min_major= "1" min_minor = "1" min_patch = "0" />
<use project = "uuid" optional= "1" implied = "1" />
-->
<!-- Header Files
name := The name the header file to include without file ending
<header name = "myproject_prelude" />
-->
<!--
Classes, if the class header or source file doesn't exist, this will
generate a skeletons for them.
use private = "1" for internal classes
<class name = "myclass">Public class description</class>
<class name = "someother" private = "1">Private class description</class>
-->
<!--
Actors, are built using the simple actor framework from czmq. If the
actors class header or source file doesn't exist, this will generate a
skeleton for them. The generated test method of the actor will teach
you how to use them. Also have a look at the CZMQ docs to learn more
about actors.
<actor name = "myactor">Public actor description</actor>
<actor name = "someactor" private = "1">Private actor description</actor>
-->
<!--
Main programs built by the project
use private = "1" for internal tools
<main name = "progname">Exported public tool</main>
<main name = "progname" private = "1">Internal tool</main>
<main name = "progname" service = "1">Installed as system service</main>
-->
<!--
Benchmark programs built by the project
<bench name = "benchname">Benchmark for class/function...</main>
-->
<!--
Models that we build using GSL.
This will generate a 'make code' target to build the models.
<model name = "sockopts" />
<model name = "zgossip" />
<model name = "zgossip_msg" />
If a model should be generated using a specific gsl script,
this can be set through the script attribute:
<model name = "hydra_msg" script = "zproto_codec_java.gsl" />
Additional parameters to the script can be set via nested
param elements:
<model name = "hydra_msg" script = "zproto_codec_java.gsl">
<param name = "root_path" value = "../main" />
</model>
-->
<!-- Other source files that we need to package
<extra name = "some_resource" />
-->
<!-- Specify targets to build; autotools and cmake are
built in all cases.
<target name = "cmake" />
<target name = "autotools" />
-->
<!-- In order loaded by zproject.gsl -->
<bin name = "zproject.gsl" />
<bin name = "zproject_projects.gsl" />
<bin name = "zproject_class_api.gsl" />
<!-- Mainline generation code -->
<bin name = "zproject_skeletons.gsl" />
<bin name = "zproject_bench.gsl" />
<bin name = "zproject_class.gsl" />
<bin name = "zproject_git.gsl" />
<bin name = "zproject_valgrind.gsl" />
<!-- Targets -->
<bin name = "zproject_android.gsl" />
<bin name = "zproject_autotools.gsl" />
<bin name = "zproject_cmake.gsl" />
<bin name = "zproject_cygwin.gsl" />
<bin name = "zproject_debian.gsl" />
<bin name = "zproject_docker.gsl" />
<bin name = "zproject_gyp.gsl" />
<bin name = "zproject_java.gsl" />
<bin name = "zproject_java_msvc.gsl" />
<bin name = "zproject_mingw32.gsl" />
<bin name = "zproject_nuget.gsl" />
<bin name = "zproject_python.gsl" />
<bin name = "zproject_python_cffi.gsl" />
<bin name = "zproject_qml.gsl" />
<bin name = "zproject_qt.gsl" />
<bin name = "zproject_redhat.gsl" />
<bin name = "zproject_ruby.gsl" />
<bin name = "zproject_travis.gsl" />
<bin name = "zproject_vs2008.gsl" />
<bin name = "zproject_vs20xx.gsl" />
<bin name = "zproject_vs20xx_props.gsl" />
<bin name = "zproject_known_projects.xml" />
<bin name = "mkapi.py" />
<bin name = "fake_cpp" />
</project>The zproject scripts can also optionally generate the @interface in your class headers from an API model, in addition to a host of language bindings. To opt-in to this behavior, just make a model to the api directory of your project. For example, if your project.xml contains <class name = "myclass"/>, you could create the following api/myclass.api file:
<!--
This model defines a public API for binding.
It shows a language binding developer what to expect from the API XML
files.
-->
<class name = "myclass" >
My Feature-Rich Class
<include filename = "license.xml" />
<constant name = "default port" value = "8080">registered with IANA</constant>
<enum name = "mode">
Enumeration defining different work modes. Constants are mandatory.
<constant name="normal" constant = "1">
<constant name="fast" constant = "2">
<constant name="safe" constant = "3">
</enum>
<!-- Constructor is optional; default one has no arguments -->
<constructor>
Create a new myclass with the given name.
<argument name = "name" type = "string" />
</constructor>
<!-- Destructor is optional; default one follows standard style -->
<destructor>
Destructors implicitely get a new argument prepended, which:
* is called `self_p`
* is of this class' type
* is passed by reference
* is marked as the self pointer for the destructor (`destructor_self = "1"`)
</destructor>
<!-- This models an CZMQ actor. By default the actor method equals the
class name.
-->
<actor>
To work with my_actor, use the CZMQ zactor API:
Create new my_actor instance.
zactor_t *actor = zactor_new (my_actor, NULL);
Destroy my_actor instance
zactor_destroy (&actor);
Enable verbose logging of commands and activity:
zstr_send (actor, "VERBOSE");
</actor>
<!-- This models a method with no return value -->
<method name = "sleep">
Put the myclass to sleep for the given number of milliseconds.
No messages will be processed by it during this time.
<argument name = "duration" type = "integer" />
</method>
<!-- This models an accessor method -->
<method name = "has feature">
Return true if the myclass has the given feature.
<argument name = "feature" type = "string" />
<return type = "boolean" />
</method>
<method name = "send strings">
This does something with a series of strings (until NULL). The strings
won't be touched.
Because the next method has the same name with a prepended "v", it's
recognized as this method's `va_list` sibling (in GSL:
`method.has_va_list_sibling = "1"`). This information might be used by
the various language bindings.
<argument name = "string" type = "string" variadic = "1" />
<return type = "boolean" />
</method>
<method name = "vsend strings">
This does something with a series of strings (until NULL). The strings
won't be touched (they're declared immutable by default).
<argument name = "string" type = "string" variadic = "1" />
<return type = "boolean" />
</method>
<!-- Callback typedefs can be declared like methods -->
<callback_type name = "handler_fn">
<argument name = "self" type = "myclass" />
<argument name = "action" type = "string" />
<return type = "boolean" />
</callback_type>
<!-- Callback types can be used as method arguments -->
<method name = "add handler">
Store the given callback function for later
<argument name = "handler" type = "my_class_handler_fn" callback = "1" />
</method>
<!-- If singleton = "1", no class struct pointer is required. -->
<method name = "test" singleton = "1">
Self test of this class
<argument name = "verbose" type = "boolean" />
</method>
<method name = "new thing" singleton = "1" >
Creates a new myclass. The caller is responsible for destroying it when
finished with it.
<return type = "myclass" fresh = "1" />
</method>
<method name = "free" singleton = "1">
Frees a provided string, and nullify the parent pointer. Setting
`mutable = "1"` is not needed here, because transfering ownership from
the caller to the function using `by_reference = "1"` implies that it's
mutable.
<argument name = "string pointer" type = "string" by_reference = "1" />
</method>
<method name = "rotate" singleton = "1">
Rotates the characters in `data` in-place. This means that all
characters are shifted to the left by one, removing the left-most
character and appending it to the end.
<argument name = "data" type = "string" mutable = "1" />
</method>
<!-- These are the types we support
Not all of these are supported in all language bindings;
see each language binding's file for supported types in that
language, and add more types as needed where appropriate.
Also, see zproject_class_api.gsl to see how they're handled exactly.
-->
<method name = "tutorial">
<argument name = "void pointer" type = "anything" />
<argument name = "standard int" type = "integer" />
<argument name = "standard float" type = "real" />
<argument name = "standard bool" type = "boolean" />
<argument name = "fixed size unsigned integer" type = "number" size = "4">
Supported sizes are 1, 2, 4, and 8.
</argument>
<argument name = "a byte" type = "byte" />
<argument name = "conversion mode" type = "enum:myclass.mode">
The container for this argument will get the following attributes:
* `is_enum = 1"
* `enum_class = "myclass"`
* `enum_name = "mode"`
* `c_type = "my_class_mode_t"`
</argument>
<argument name = "char pointer to C string" type = "string" />
<argument name = "byte pointer to buffer" type = "buffer" />
<argument name = "buffer size" type = "size" />
<argument name = "file handle" type = "FILE" />
<argument name = "file size" type = "file_size" />
<argument name = "time" type = "time" />
<argument name = "format" type = "format">
This makes the function is variadic (will cause a new argument to be
added to represent the variadic arguments).
</argument>
<argument name = "variadic list argument" type = "va_list" />
<argument name = "custom pointer" type = "my custom class">
Any other type is valid, as long as there is a corresponding C
type, in this case `my_custom_class_t`.
</argument>
<return type = "nothing">void method</return>
</method>
<method name = "set foo" polymorphic = "1">
Set attribute foo to a new value. Note that this method takes a
polymorphic reference (`void *`) as its first argument, which could point
to structs of different types.
This also means that high-level bindings might give you the choice to
call this method directly on an instance, or with an explicit receiver.
<argument name = "new value" type="integer" />
</method>
<method name = "set bar">
This method takes an argument type of the (descriptive) type `foo`, but
resolving it to a corresponding C type will be skipped because it's
overridden to `foobarbaz_t` by the `c_type` attribute.
<argument name = "new foo" type="foo" c_type="foobarbaz_t" />
</method>
</class>This would cause the following @interface to be generated inside of include/myclass.h. Note that if include/myclass.h has other handwritten content outside of the @interface this content will be retained.
// @warning THE FOLLOWING @INTERFACE BLOCK IS AUTO-GENERATED BY ZPROJECT!
// @warning Please edit the model at "api/myclass.api" to make changes.
// @interface
// Create a new myclass with the given name.
MYPROJECT_EXPORT myclass_t *
myclass_new (const char *name);
// Destroy the myclass.
MYPROJECT_EXPORT void
myclass_destroy (myclass_t **self_p);
// Return true if the myclass has the given feature.
MYPROJECT_EXPORT bool
myclass_has_feature (myclass_t *self, const char *feature);
// Put the myclass to sleep for the given number of milliseconds.
// No messages will be processed by the actor during this time.
MYPROJECT_EXPORT void
myclass_sleep (myclass_t *self, int duration);
// Self test of this class
MYPROJECT_EXPORT void
myclass_test (bool verbose);
// @endThe following attributes are supported for methods:
name- the name of the method (mandatory).singleton = "1"- the method is not invoked within the context of a specific instance of an object. Use this if your method does not need to be passed aselfpointer as the first argument as normal. Implicit for allconstructors anddestructors and for the implicittestmethod.
The following attributes are supported for arguments and return values:
type- the conceptual type or class name of the argument or return value (default:"nothing", which translates tovoidin C).mutable = "1"- the argument or the return value can be modified. All string, format, and buffer arguments are immutable by default.by_reference = "1"- ownership of the argument (and responsibility for freeing it) is transferred from the caller to the function - in practice, the implementation code should also nullify the caller's reference, though this is not enforced by the API model. If a string or buffer is passed by reference, it is also mutable by default.fresh = "1"- the return value is freshly allocated, and the caller receives ownership of the object and the responsibility for destroying it. Implies mutable = "1".variadic = "1"- used for representing variadic arguments.
This is an incomplete list of API types:
-
"nothing" -- for return only, means "void" in C.
-
"anything" -- means "void *" in C.
-
"size" -- long size (64 bits), "size_t" in C.
-
"time" -- long time (64 bits), "time_t" in C.
-
"file_size" -- long file size (64 bits).
-
"boolean" -- Boolean.
-
"byte" -- single octet.
-
"char" -- single character (possibly multibyte, do we care?)
-
"integer" -- 32-bit signed integer.
-
"number" -- unsigned number, with 'size = "1|2|4|8"'.
-
"real" -- single-precision floating point. [TODO: single? why not double?]
-
"buffer" -- byte array. To return a byte array, you should specify 'size' attribute that defines size. This can be a constant, 'size = "ZUUID_LEN"', or a dot followed by method name in the same class, e.g. 'size = ".size"'.
-
"string" -- character array.
-
"format" -- printf format, followed by zero or more arguments.
-
"FILE", "va_list", "zmq_pollitem", "socket" -- literally that, in C. (Not sure if it is wise to use raw C types.)
-
enumerations - to be reviewed as these have a specific syntax that crams multiple properties into one attribute, not our usual way of working.
-
callbacks - tbd.
-
Names of classes, e.g. zmsg.
At any time, you can examine a resolved model as an XML string with all of its children and attributes using the appropriate GSL functions:
# if the `method` variable is a <method/> entity:
echo method.string() # will print the model as an XML string.
method.save(filename) # will save the model as an XML string to the given file.
You can save a snapshot of the entire resolved project model using this syntax:
gsl -save:1 project.xml
Writing API model for bigger project with a lot of classes can be tedious job. There mkapi.py, which automates most of the task.
In order to use it, you must install zproject itself and then pycparser. For most of real world code, you must have fake_libc_includes available too.
virtualenv/venv mkapi
source mkapi/bin/activate
pip install pycparser
git clone https://github.com/eliben/pycparser.gitThen from root directory of your project (for example czmq), type following
mkapi.py -I /path/to/your/pycparser/utils/fake_libc_include include/czmq.hNote you must use top-level include as pycparser fails if it does not know any definition.
The tool might expect -DWITH_DRAFTS parameter if the class is not marked as a stable.
The tool can't distinguish methods which allocates new object. It does print a comment about adding fresh = "1" attribute to each method, which return non const pointer. However the final assigment must be done manually.
## Language Binding Notes ### Java Language Binding-
Skips methods that it cannot handle properly.
-
To build, you need gradle (or equivalent). Run 'gradle build jar' in the bindings/jni directory.
-
To install, run 'gradle install'. This puts the files into $HOME/.m2/repository.
zproject lets you mark classes and methods as 'draft' so that they are not installed by default in stable builds. This lets you deliver draft APIs to your users, and change them later.
By default all classes and methods are draft, unless you specify otherwise. To mark the state of a class or method, specify in the project.xml:
<class name = "classname" state = "stable" />
Or in the class API XML file:
<class name = "classname" state = "stable">
...
<method name = "methodname" state = "stable">
...
</method>
</class>
The method will inherit the class state unless it has its own 'state' attribute.
The allowed states are:
- draft - the class or method is not built/installed in stable releases.
- stable - the class or method is always built and installed. A method may not be changed once marked as stable.
- legacy - the class or method is always built and installed. It may carry a warning that support can be withdrawn at any time.
Using autotools or CMake, you can specify --with-drafts to enable draft APIs, and --without-drafts to disable them. By default, drafts are built and installed when you work in a git repository (if the directory ".git" is present), and otherwise they are not. That means, if you build from a tarball, drafts are disabled by default.
## TargetsEach target produces scripts and code for a specific build system, platform, or language binding.
To see a list of available targets:
gsl -target:? project.xml
To build a specific target:
gsl -target:android project.xml
To run zproject without building any targets:
gsl -target:- project.xml
To request specific targets in your project.xml file (autotools and cmake are automatic):
<target name = "android" />
<target name = "java" />
To request all targets in your project.xml file:
<target name = "*" />
make uninstall- All
classes SHALL be in the project model (project.xml). - Each
classMAY have a corresponding API model (api/{class name}.api). - A binding generator SHOULD consider only
classes with an API model (where defined (class.api)). - Each API model SHALL consist of both explicit information (written in the XML file) and implicit information (inferred by the
zproject_class_apiscript). Both kinds of information will already be resolved (and indistinguishable) when each language binding generator is invoked. - Each API model SHALL have exactly one
classentity at the top level. - Each
classSHALL have anameattribute. - Each
classMAY have one or moremethodentities. - Each
classMAY have one or moreconstructorentities. - Each
classMAY have one or moredestructorentities. - Each
method,constructor, anddestructorMAY have one or moreargumententities. - Each
method,constructor, anddestructorSHALL at least onereturnentity, and if more than onereturnentity exist, only the first SHOULD be considered. Thereturnentity MAY be ignored if it hastype = "nothing"(the default when notypeis given). - Each entity SHALL have its semantic attributes fully resolved before reaching the language binding generators.
- Each language binding generator SHALL NOT modify values of semantic attributes of entities.
- Each language binding generator MAY assign values to language-specific implementation attributes of entities.
- Each language binding generator SHOULD use a unique prefix for names of language-specific implementation attributes of entities.
A class is always the top-level entity in an API model, and it will be merged with the corresponding class entity defined in the project model. A class contains methods, constructors, and destructors (collectively, "method"s), and methods contain arguments and returns (collectively, "container"s). Each entity will contain both semantic attributes and language-specific implementation attributes.
Semantic attributes describe something intrinsic about the container.
For example, arguments may be described as passed by_reference to indicate that ownership is transferred from the caller. Similarly, return values may be described as fresh to indicate that ownership is transferred to the caller, which must destroy the object when it is finished with it. It's important to remember that these attributes are primarily meant to be an abstraction that describes conceptual information, leaving the details of how code generators interpret (or ignore) each attribute up to the authors.
Semantic attributes may be implicit (not given a value in the written model). In this case, it is up to the zproject_class_api script to fully resolve default values for all attributes. Downstream code generators should never resolve or alter semantic attributes, as this could change the behavior of any code generator that is run after the errant code generator.
These are the semantic attributes for each kind of entity that will be resolved before language bindings generators are invoked:
class.name # string (as given in the API model)
class.description # string (comment in the API model, or empty string)
method.name # string (as given in the API model, or a default value)
method.description # string (comment in the API model, or a default value)
method.singleton # 0/1 (default: 0, but 1 for constructors/destructors)
method.is_constructor # 0/1 (default: 0, but 1 for constructors)
method.is_destructor # 0/1 (default: 0, but 1 for destructors)
method.has_va_list_sibling # 0/1 (default: 0)
container.name # string (as given in the API model, or "_")
container.type # string (as given, or "nothing")
container.mutable # 0/1 (default: 0)
container.by_reference # 0/1 (default: 0)
container.callback # 0/1 (default: 0)
container.fresh # 0/1 (default: 0)
container.is_enum # 0/1 (default: 0)
container.enum_name # string if is_enum, otherwise undefined
container.enum_class # string if is_enum, otherwise undefined
container.variadic # 0/1 (default: 0)
container.va_start # string - that holds the argment name for va_start ()
Language-specific implementation attributes hold information that is not intrinsic to the concept of the container, but to the binding implementation.
In practice, language-specific attributes may contain any information that is useful to store as part of the container model to facilitate generation, according to any schema that is useful, but it may be helpful to try to follow patterns observed in other code generator scripts.
However, because the container is shared between all generators, which are run in an unspecified order, it's important that generators not rely on information resolved in generators. The one exceptions is that many generators will rely directly on information from the C implementation to which they bind.
It is also important that language-specific implementation attributes use a naming convention that avoids collisions. The easiest way to avoid collisions is to prefix all language-specific attributes with the name of the language, though in principle, any collision-free convention would be acceptable.
## Ownership and LicenseThe contributors are listed in AUTHORS. This project uses the MPL v2 license, see LICENSE.
zproject uses the C4.1 (Collective Code Construction Contract) process for contributions.
To report an issue, use the zproject issue tracker at github.com.
### Hints to ContributorsMake sure that the project model hides all details of backend scripts. For example don't make a user enter a header file because autoconf needs it.
Do read your code after you write it and ask, "Can I make this simpler?" We do use a nice minimalist and yet readable style. Learn it, adopt it, use it.
Before opening a pull request read our contribution guidelines. Thanks!
### This DocumentThis document is originally at README.txt and is built using gitdown.