From 4c63187abaef32037edad63c6b82b31763584bff Mon Sep 17 00:00:00 2001 From: Jeremie Koenig Date: Fri, 8 Apr 2011 13:56:56 +0200 Subject: gsoc2011 (java): Initial import of the proposal --- user/jkoenig/gsoc2011_classes.dia | 2227 +++++++++++++++++++++++++++++++++++ user/jkoenig/gsoc2011_classes.png | Bin 0 -> 59337 bytes user/jkoenig/gsoc2011_proposal.mdwn | 567 +++++++++ 3 files changed, 2794 insertions(+) create mode 100644 user/jkoenig/gsoc2011_classes.dia create mode 100644 user/jkoenig/gsoc2011_classes.png create mode 100644 user/jkoenig/gsoc2011_proposal.mdwn (limited to 'user') diff --git a/user/jkoenig/gsoc2011_classes.dia b/user/jkoenig/gsoc2011_classes.dia new file mode 100644 index 00000000..1aa3ef6c --- /dev/null +++ b/user/jkoenig/gsoc2011_classes.dia @@ -0,0 +1,2227 @@ + + + + + + + + + + + + + #A4# + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + ## + + + #User-defined classes# + + + + + + + + + + + + + + + + + + + + #HelloIo# + + + ## + + + #Implements a file which always contains "Hello, World!\n"# + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + #write# + + + ## + + + #int# + + + + + + ## + + + + + + + + + + + + + + + + + #data# + + + #char[]# + + + ## + + + ## + + + + + + + + #offset# + + + #int# + + + ## + + + ## + + + + + + + + + + #read# + + + ## + + + #char[]# + + + + + + ## + + + + + + + + + + + + + + + + + #offset# + + + #int# + + + ## + + + ## + + + + + + + + #amount# + + + #int# + + + ## + + + ## + + + + + + + + + + #seek# + + + ## + + + #int# + + + + + + ## + + + + + + + + + + + + + + + + + #offset# + + + #int# + + + ## + + + ## + + + + + + + + #whence# + + + #int# + + + ## + + + ## + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + ## + + + #MIG-generated classes# + + + + + + + + + + + + + + + + + + + + #IoServer# + + + ## + + + #Implements a message handler using a given IO object as a backend# + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + #IoServer# + + + ## + + + ## + + + + + + ## + + + + + + + + + + + + + + + + + #back# + + + #Io# + + + ## + + + ## + + + + + + + + + + #handle# + + + ## + + + #Message# + + + + + + ## + + + + + + + + + + + + + + + + + #message# + + + #Message# + + + ## + + + ## + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + #Io# + + + #interface# + + + ## + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + #write# + + + ## + + + #int# + + + + + + ## + + + + + + + + + + + + + + + + + #data# + + + #char[]# + + + ## + + + ## + + + + + + + + #offset# + + + #int# + + + ## + + + ## + + + + + + + + + + #read# + + + ## + + + #char[]# + + + + + + ## + + + + + + + + + + + + + + + + + #offset# + + + #int# + + + ## + + + ## + + + + + + + + #amount# + + + #int# + + + ## + + + ## + + + + + + + + + + #seek# + + + ## + + + #int# + + + + + + ## + + + + + + + + + + + + + + + + + #offset# + + + #int# + + + ## + + + ## + + + + + + + + #whence# + + + #int# + + + ## + + + ## + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + #IoUser# + + + ## + + + #Implements the Io interface by performing RPC# + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + #IoUser# + + + ## + + + ## + + + + + + ## + + + + + + + + + + + + + + + + + #port# + + + #MachPort# + + + ## + + + ## + + + + + + + + + + #write# + + + ## + + + #int# + + + + + + ## + + + + + + + + + + + + + + + + + #data# + + + #char[]# + + + ## + + + ## + + + + + + + + #offset# + + + #int# + + + ## + + + ## + + + + + + + + + + #read# + + + ## + + + #char[]# + + + + + + ## + + + + + + + + + + + + + + + + + #offset# + + + #int# + + + ## + + + ## + + + + + + + + #amount# + + + #int# + + + ## + + + ## + + + + + + + + + + #seek# + + + ## + + + #int# + + + + + + ## + + + + + + + + + + + + + + + + + #offset# + + + #int# + + + ## + + + ## + + + + + + + + #whence# + + + #int# + + + ## + + + ## + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + ## + + + ## + + + + + + + + + ## + + + + + + + + + + + + ## + + + ## + + + + + + + + + ## + + + ## + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + ## + + + ## + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + ## + + + #libports-like library# + + + + + + + + + + + + + + + + + + + + #Server# + + + #interface# + + + ## + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + #handle# + + + ## + + + #Message# + + + + + + ## + + + + + + + + + + + + + + + + + #msg# + + + #Message# + + + ## + + + ## + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + #Demux# + + + ## + + + ## + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + #addServer# + + + ## + + + ## + + + + + + ## + + + + + + + + + + + + + + + + + #s# + + + #Server# + + + ## + + + ## + + + + + + + + + + #handle# + + + ## + + + #Message# + + + + + + ## + + + + + + + + + + + + + + + + + #msg# + + + #Message# + + + ## + + + ## + + + + + + + + + + + + + + + + + ## + + + + + + + + + + + + ## + + + ## + + + + + + + + + ## + + + ## + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + #Plus some kind of port set +support and a way to start +a server thread.# + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + ## + + + ## + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + #io.defs# + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + #mig# + + + ## + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + ## + + + ## + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + ## + + + ## + + + + + + + + diff --git a/user/jkoenig/gsoc2011_classes.png b/user/jkoenig/gsoc2011_classes.png new file mode 100644 index 00000000..7149b813 Binary files /dev/null and b/user/jkoenig/gsoc2011_classes.png differ diff --git a/user/jkoenig/gsoc2011_proposal.mdwn b/user/jkoenig/gsoc2011_proposal.mdwn new file mode 100644 index 00000000..666733c1 --- /dev/null +++ b/user/jkoenig/gsoc2011_proposal.mdwn @@ -0,0 +1,567 @@ + +# Java for Hurd (and vice vera) + +Contact information: + + * Full name: Jérémie Koenig + * Email: jk@jk.fr.eu.org + * IRC: jkoenig on Freenode and OFTC + +## Introductions + +I am a first year M.Sc. student +in Computer Science at University of Strasbourg (France). +My interests include capability-based security, +programming languages and formal methods (in particular, proof-carrying code). + +### Previous involvement + +Although I have known the Hurd for some time, +I did not contribute until last summer, +during which I participated to Google Summer of Code +as a student for the Debian project. +I worked on porting Debian-Installer to Hurd. +This project was mostly a success, +although we still have to use a special mirror for installation +with a few modified packages +and tweaked priorities +to work around some uninstallable packages +with Priority: standard. + +Shortly afterwards, +I rewrote the procfs translator +to fix some issues with memory leaks, +make it more reliable, +and improve comptibility with Linux-based tools +such as `procps` or `htop`. + +Although I have not had as much time +as I would have liked to dedicate to the Hurd +since that time, +I have continued to maintain the mirror in question, +and I have started to work +on implementing POSIX threads signal semantics in glibc. + +### Project-related skills and interests + +I have used Java mostly for university assignements. +This includes non-trivial projects +using threads and distributed programming frameworks +such as Java RMI or CORBA. +I have also used it to experiment with +Google App Engine +(web applications) +and Google Web Toolkit +(a compiler from Java to Javascript which helps with AJAX code), +and I have some limited experience with JNI +(the Java Native Interface, to link Java with C code). + +My knowledge of the Hurd and Debian GNU/Hurd is reasonable, +as the Debian-Installer and procfs projects +gave me the opportunity to fiddle with many parts of the system. + + +## Improve Java support + +### Justification + +Java is a popular language and platform used by many desktop and web +applications (mostly on the server side). As a consequence, competitive Java +support is important for any general-purpose operating system. + +### Current situation + +Java is currently supported on Hurd with the GNU Java suite: + + * GCJ, the GNU Compiler for Java, is part of GCC and can compile Java + source code to Java bytecode, and both source code and bytecode to + native code; + * libgcj is the implementation of the Java runtime which GCJ uses. It is + based on GNU Classpath. It includes a bytecode interpreter which enables + Java applications compiled to native code to dynamically load and execute + Java bytecode from class files. + * The gij command is a wrapper around the above-mentioned virtual machine + functionality of libgcj and can be used as a replacement for the java + command. + +However, GCJ does not work flawlessly on Hurd.r +For instance, some parts of libgcj relies on +the POSIX threads signal semantics, which are not yet implemented. +In particular, this makes ant hang waiting for child processes, +which makes some packages fail to build on Hurd +(“ant” is the “make” of the Java world). + +### Tasks + + * **Finish implementing POSIX thread semantics** in glibc (high priority). + According to POSIX, signal dispositions should be global to a process, + while signal blocking masks should be thread-specific. Signals sent to the + process as a whole are to be delivered to any thread which does not block + them. By contrast, Hurd has per-thread signal dispositions and signals + sent to a process are delivered to the main thread only. I have been + working on refactoring the glibc signal code and implementing the POSIX + semantics as a per-thread option. However, due to lack of time I have not + yet been able to test and debug my code properly. Finishing this work + would be my first task. + * **Fix further problems with GCJ on Hurd** (high priority). While I’m not + aware of any other problems with GCJ at the moment, I suspect some might + turn up as I progress with the other tasks. Fixing these problems would + also be a high-priority task. + * **Port OpenJDK 6** (medium priority). While GCJ is fine, it is not yet + 100% complete. It is also slower than OpenJDK on architectures where a + just-in-time compiler is available. Porting OpenJDK would therefore + improve Java support on Hurd in scope and quality. Besides, it would also + be a good way to test GCJ, which is used for bootstrapping by the Debian + OpenJDK packages. Also note that OpenJDK 6 is now the default Java + Runtime Environment on all released Linux-based Debian architectures; + bringing Hurd in line with this would probably be a good thing. + * **Port Eclipse and other Java applications** (low priority). Eclipse is a + popular, state-of-the-art IDE and tool suite used for Java and other + languages. It is a dependency of the Joe-E verifier (see part 3 of this + proposal). Porting Eclipse would be a good opportunity to test GCJ and + OpenJDK. + + +## Create Java bindings for the Hurd interfaces + +### Justification + +Java is a popular language, used for many applications and often taught to +introduce object-oriented programming. The fact that Java is a +garbage-collected language makes it easier to use, especially for the less +experienced programmers. Besides, the object-oriented nature of Java is a +natural fit for the capability-based design of Hurd. + +Advantages over other garbage-collected, object-oriented languages include +performance, type safety and the possibility to compile a Java translator to +native code and link it statically using GCJ, should anyone want to use a +translator written in Java for booting. Note that Java is being used in this +manner for embedded development. + +Java bindings would lower the bar for newcomers +to begin experimenting with what makes Hurd unique +without being faced right away with the complexity of +low-level systems programming. + +### Approach + +One approach used previously to interface programming languages with the Hurd +has been to create bindings for helper libraries such as libtrivfs. Instead, +for Java I would like to take a lower-level approach by providing access to +Mach primitives and extending MIG to generate Java code from the interface +description files. + +This approach would be initially more involved, and would introduces several +issues related to overcoming the "impedence mismatch" between Java and Mach. +However, once an initial implementation is done it would be easier to maintain +in the long run and we would be able to provide Java bindings for a large +percentage of the Hurd’s interfaces. + +### Design goals + +FIXME: a completer + + * Give maximum flexibility to the Java code while maintaining the memory + safety of Java, and using a minimum amount of C code. + * Provide higher-level interfaces as well, ... + * Hurd objects would map to Java objects. + * Local objects can be accessed directly, + remote objects can be accessed transparently over IPC. + +### Bindings for Mach system calls + +In this low-level approach, my intention is to enable Java code to use Mach +system calls (in particular, mach_msg) more or less directly. This would +ensure full access to the system from Java code, but it raises a number of +issues: + + * the Java code must be able to manipulate Mach-level entities, such as port + rights or page-aligned buffers mapped outside of the garbage-collected + heap (for out-of-line transfers); + * putting together IPC messages requires control of the low-level + representation of data. + +In order to address these concerns, classes would be encapsulating these +low-level entities so that they can be referenced through normal, safe objects +from standard Java code. Bindings for Mach system calls can then be provided +in terms of these classes. Their implementation would use C code through the +Java Native Interface (JNI). + +More specifically, this functionality would be provided by the `org.gnu.mach` +package, which would contain at least the following classes: + + * `MachPort` would encapsulate a `mach_port_t`. (Some of) its constructors + would act as an interface for the `mach_port_allocate()` system call. + `MachPort` objects would also be instanciated from other parts of the JNI + C code to represent port rights received through IPC. The `deallocate()` + mehod would call `mach_port_deallocate()` and replace the encapsulated + port name with `MACH_PORT_DEAD`. We would recommend that users call it + when a port is no longer used, but the finalizer would also deallocate the + port when the `MachPort` object is garbage collected. + * `Buffer` would represent a page-aligned buffer allocated outside of the + Java heap, to be transferred (or having been received) as out-of-line + memory. The JNI code would would provide methods to read and write data at + an arbitrary offset (but within bounds) and would use `vm_allocate()` and + `vm_deallocate()` in the same spirit as for `MachPort` objects. + * `Message` would allow Java code to put together Mach messages. The + constructor would allocate a `byte[]` member array of a given size. + Additional methods would be provided to fill in or query the information + in the message header and additional data items, including `MachPort` and + `Buffer` objects which would be translated to the correponding port names + and out-of-line pointers. + A global map from port names to the corresponding `MachPort` object + would probably be needed to ensure that there is a one-to-one + correspondance. + * `Syscall` would provide static JNI methods for performing system calls not + covered by the above classes, such as `mach_msg()` or + `mach_thread_self()`. These methods would accept or return `MachPort`, + `Buffer` and `Message` objects when appropriate. The associated C code + would access the contents of such objects directly in order to perform the + required unsafe operations, such as constructing `MachPort` and `Buffer` + objects directly from port names and C pointers. + +Note that careful consideration should be given to the interfaces of these +classes to avoid “safety leaks” which would compromise the safety guarantees +provided by Java. Potential problematic scenarios include the following +examples: + + * It must not be possible to write an integer at some position in a + `Message` object, and to read it back as a `MachPort` or `Buffer` object, + since this would allow unsafe access to arbitrary memory addresses and + mach port names. + * Providing the `mach_task_self()` system call would also provide acces to + arbitrary addresses and ports by using the `vm_*` family of RPC operations + with the returned `MachPort` object. This means that the relevant task + operations should be provided by the `Syscall` class instead. + +Finally, access should be provided to the initial ports and file descriptors +in `_hurd_ports` and `FIXME`, for instance through static methods such as +`getCRDir()`, `getCWDir()`, `getProc()`, ... in a dedicated class such as +`org.gnu.hurd.InitPorts`. + +A realistic example of code based on such interfaces would be: + + import org.gnu.mach.MsgType; + import org.gnu.mach.MachPort; + import org.gnu.mach.Buffer; + import org.gnu.mach.Message; + import org.gnu.mach.Syscall; + import org.gnu.hurd.InitPorts; + + public class Hello + { + public static main(String argv[]) + /* Parent class for all Mach-related exceptions */ + throws org.gnu.mach.MachException + { + /* Allocate a reply port */ + MachPort reply = new MachPort(); + + /* Allocate an out-of-line buffer */ + Buffer data = new Buffer(MsgType.CHAR, 13); + data.writeString(0, "Hello, World!"); + + /* Craft an io_write message */ + Message msg = new Message(1024); + msg.setRemotePort(InitPorts.getdport(1)); + msg.setLocalPort(reply, Message.Type.MAKE_SEND_ONCE); + msg.setId(21000); + msg.addBuffer(data); + + /* Make the call, MACH_MSG_SEND | MACH_MSG_RECEIVE */ + Syscall.machMsg(msg, true, true, reply); + + /* Extract the returned value */ + msg.assertId(21100); + int retCode = msg.readInt(0); + int amount = msg.readInt(1); + } + } + +### Generating Java stubs with MIG + +Once the basic machinery is in place to interface with Mach, Java programs +have more or less equal access to the system functionality without resorting +to more JNI code. However, as illustrated above, this access is far from +convenient. + +As a solution I would modify MIG to add the option to output Java code. MIG +would emit a Java interface, a client class able to implement the interface +given a Mach port send right, an a server class which would be able to handle +incoming messages. The class diagram below, although it is by no means +complete or exempt of any problem, illustrates the general idea: + +[[gsoc2011_classes.png]] + +This structure is somewhat reminiscent of Java RMI or similar systems, +which aim to provide more or less transparent access to remote objects. +The exact way the Java code would be generated still needs to be determined, +but basically: + + * An interface, corresponding to the header files generated by MIG, would + enumerate the operations listed in a given .defs files. Method names would + be transformed to adhere to Java conventions (for instance, + `some_random_identifier` would become `someRandomIdentifier`). + * A user class, corresponding to the `*User.c` files, + would implement this interface by doing RPC over a given MachPort object. + * A server class, corresponding to `*Server.c`, would be able to handle + incoming messages using a user-provided implementation of the interface. + (Possibly, a skelton class providing methods which would raise + `NotImplementedException`s would be provided as well. + Users would derive from this class and override the relevant methods. + This would allow them not to implement some operations, + and would avoid pre-existing code from breaking when new operations are + introduced.) + +In order to help with the implementation of servers, some kind of library +would be needed to associate Mach receive rights with server objects and to +handle incoming messages on dedicated threads, in the spirit of libports. +This would probably require support for port sets at the level of the Mach +primitives described in the previous section. + +When possible, operations involving the transmission of send rights +of some kind would be expressed in terms of the MIG-generated interfaces +intead of `MachPort` objects. +Upon reception of a send right, +a `FooUser` object would be created +and associated with the corresponding `MachPort` object. +If the received send right corresponds to a local port +to which a server object has been associated, +this object would be used instead. +This way, +subsequent operations on the received send right +would be handled as direct method calls +instead of going through RPC mechanisms. + +Some issues will still need to be solved regarding how MIG will convert +interface description files to Java interfaces. For instance: + + * `.defs` files are not explicitely associated with a type. For instance in + the example above, MIG would have to somehow infer that io_t corresponds + to `this` in the `Io` interface. + * More generally, a correspondance between MIG and Java types would have + to be determined. Ideally this would be automated and not hardcoded + too much. + * Initially, reply port parameters would be ignored. However they may be + needed for some applications. + +So the details would need to be flushed out during the community bonding +period and as the implementation progresses. However I’m confident that a +satisfactory solution can be designed. + +Using these new features, the example above could be rewritten as: + + import org.gnu.hurd.InitPorts; + import org.gnu.hurd.Io; + import org.gnu.hurd.IoUser; + + class Hello { + static void main(String argv[]) throws ... + { + Io stdout = new IoUser(InitPorts.getdport(1)); + String hello = “Hello, World!\n”; + + int amount = stdout.write(hello.getBytes(), -1); + + /* (A retCode corresponding to an error + would be signalled as an exception.) */ + } + } + +An example of server implementation would be: + + import org.gnu.hurd.Io; + import java.util.Arrays; + + class HelloIo implements Io { + final byte[] contents = “Hello, World!\n”.getBytes(); + + int write(byte[] data, int offset) { + return SOME_ERROR_CODE; + } + + byte[] read(int offset, int amount) { + return Arrays.copyOfRange(contents, offset, + offset + amount - 1); + } + + /* ... */ + } + +A new server object could then be created with `new IoServer(new HelloIo())`, +and associated with some receive right at the level of the ports management +library. + +### Base classes for common types of translators + +Once MIG can target Java code, and a libports equivalent is available, +creating new translators in Java would be greatly facilitated. However, +we would probably want to introduce basic implementations of filesystem +translators in the spirit of libtrivfs or libnetfs. They could take the form +of base classes implementing the relevant MIG-generated interfaces which +would then be derived by users, +or could define a simpler interface +which would then be used by adapter classes +to implement the required ones. + +I would draw inspiration from libtrivfs and libnetfs +to design and implement similar solutions for Java. + +### Packaging and long-term maintenance + +The Java libraries resulting from this work +(including any MIG support classes), +as well as the class files built from the MIG-generated code +for the Mach and Hurd interface definition files, +would be provided as single `hurd-java` package for +Debian GNU/Hurd. +This package would be separate from both Hurd and Mach, +so as not to impose unreasonable build dependencies on them. + +I expect I would be able to act as its maintainer in the forseeable future, +either as an individual or as a part of the Hurd team. +Hopefully, +my code would be claimed by the Hurd project as their own, +and consequently the modifications to MIG +(which would at least conceptually depend on the Mach Java package) +could be integrated upstream. + +Since by design, +the Java code would use only a small number of stable interfaces, +it would not be subject to excessive amounts of bitrot. +Consequenty, +maintenance would primarily consist in +fixing bugs as they are reported, +and adding new features as they are requested. +A large number of such requests +would mean the package is useful, +so I expect that the overall amount of work +would be correlated with the willingness of more people +to help with maintenance +should I become overwhelmed or get hit by a bus. + + +## Timeline + +The dates listed are deadlines for the associated tasks. + + * *Community bonding period.* + Discuss, refine and complete the design of the Java bindings + (in particular the MIG and "libports" parts) + * *May 23.* + Coding starts. + * *May 30.* + Finish implementing pthread signal semantics. + * *June 5.* + Port OpenJDK + * *June 19 (two weeks).* + Fix the remaining problems with GCJ and/or OpenJDK, + possibly port Eclipse or other big Java packages. + * *June 26.* + Create the bindings for Mach. + * *July 3.* + Work on some kind of basic Java libports + to handle receive rights. + * *July 10.* + Test, write some documentation and examples. + * *July 24 (two weeks).* + Add the Java target to MIG. + * *July 31.* + Test, write some documentation and examples. + * *August 7.* + Try to write a basic but non-trivial translator + to evaluate the performance and ease of use of the result, + rectify any rough edges this would uncover. + * *Last two weeks.* + Polish the code, + do the packaging. + + +## Conclusion + + + + +## Appendix: potential applications of object-capability languages + +The work discussed is this last part would have +fewer immediate benefits for the Hurd project +and has more of a research orientation. +It is also unlikely that there would be any time remaining +to work on it at the end of the summer. +(Though it could work as some kind of reward +if I somehow managed to do a prefect job of all the rest +within the allocated time :-) ). +As a consequence, +I don't really consider this a part of my application. + +This being said, +to some extent the project discussed here +will informed the way I design the Java bindings, +since it depends on them +and I intend to work on this at some point in the future. +I also believe it touches on some interesting ideas, +and a Summer of Code application is probably +as good an occasion as any to discuss them. + +### Justification + +The primary advantage of multi-server operating systems is the ability to +break what used to be the kernel into small pieces which can be isolated +from each others. This makes sense from an engineering perspective, as +smaller components can be swapped with different implementations and reduce +the impact of bugs. +A capability-based approach also ensures that the +authority wielded by components is clear and reduced to the minimum required +for them to function. +These properties are crucial to the Hurd's agenda of user freedom, +since in order to allow them to plug their own code into the system +[FIXME: développer] + +However, this flexibility has a cost. In a system where the isolation of +components relies on running them inside different address spaces, +communication between them must be done through IPC calls. +This introduces a trade-off between the size of the modules +and performance as well as practicality, +which imposes a limit to the granularity with which the system +can be decomposed and the principle of least authority applied +(to the code within a given process, a Mach port is ambient authority). + +Another issue is that of the threading structure of the system as a whole. +In systems based on a monolithic kernel, user threads execute the kernel +code themselves, which is then intrinsically concurrent. By contrast, in a +system based on a “client-server” paradigm, each server must be explicitly +multi-threaded if it is to serve requests concurrently. + +### Object-capability languages + +An object-capability language is an object-oriented language which is +restricted enough so that object references are themselves capabilities. + +One such language is Joe-E (FIXME: lien), +which is an object-capability subset of Java: +global state and static methods are mostly forbidden; +careful white-listing of the objects and methods +provided by the Java standard library +ensures that compliant code cannot not access ambient autority. +Ways in which object references can be transferred +are restricted to the most obvious ones +(for instance, exceptions are carefully restricted). + +As a result, untrusted Joe-E code can be executed without any further +isolation and its autority can be controlled by carefully limiting the +object references which are passed to it. +This would allow to load and execute translators written in Joe-E +in a single address space. + +### Bundling translators into a single process + +[mechanisme pour transmettre le code Joe-E +et les port initiaux au serveur] +[émulation des différentes tâches] + +### Challenges and further work + +[proof-carrying code / typed assembly, +resource accounting (passer en revue la conception de Viengoos?)] + -- cgit v1.2.3 From d0c962939e6aba58465265a2202fcbbb992836f9 Mon Sep 17 00:00:00 2001 From: Jeremie Koenig Date: Fri, 8 Apr 2011 14:31:25 +0200 Subject: gsoc2011 (java): add some links --- user/jkoenig/gsoc2011_proposal.mdwn | 28 +++++++++++++++++++++------- 1 file changed, 21 insertions(+), 7 deletions(-) (limited to 'user') diff --git a/user/jkoenig/gsoc2011_proposal.mdwn b/user/jkoenig/gsoc2011_proposal.mdwn index 666733c1..5d40a97f 100644 --- a/user/jkoenig/gsoc2011_proposal.mdwn +++ b/user/jkoenig/gsoc2011_proposal.mdwn @@ -73,11 +73,13 @@ support is important for any general-purpose operating system. Java is currently supported on Hurd with the GNU Java suite: - * GCJ, the GNU Compiler for Java, is part of GCC and can compile Java + * [GCJ](http://gcc.gnu.org/java/), + the GNU Compiler for Java, is part of GCC and can compile Java source code to Java bytecode, and both source code and bytecode to native code; - * libgcj is the implementation of the Java runtime which GCJ uses. It is - based on GNU Classpath. It includes a bytecode interpreter which enables + * libgcj is the implementation of the Java runtime which GCJ uses. + It is based on [GNU Classpath](http://www.gnu.org/software/classpath/). + It includes a bytecode interpreter which enables Java applications compiled to native code to dynamically load and execute Java bytecode from class files. * The gij command is a wrapper around the above-mentioned virtual machine @@ -134,9 +136,13 @@ natural fit for the capability-based design of Hurd. Advantages over other garbage-collected, object-oriented languages include performance, type safety and the possibility to compile a Java translator to -native code and link it statically using GCJ, should anyone want to use a -translator written in Java for booting. Note that Java is being used in this -manner for embedded development. +native code and +[link it statically](http://gcc.gnu.org/wiki/Statically_linking_libgcj) +using GCJ, should anyone want to use a +translator written in Java for booting. Note that Java is +[being](http://oss.readytalk.com/avian/) +[used](http://www.linuxjournal.com/article/8757) +in this manner for embedded development. Java bindings would lower the bar for newcomers to begin experimenting with what makes Hurd unique @@ -278,6 +284,12 @@ A realistic example of code based on such interfaces would be: } } +Should this paradigm prove insufficient, +more ideas could be borrowed from the +[`org.vmmagic`](http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.151.5253&rep=rep1&type=pdf) +package used by [Jikes RVM](http://jikesrvm.org/), +a research Java virtual machine itself written in Java. + ### Generating Java stubs with MIG Once the basic machinery is in place to interface with Mach, Java programs @@ -293,7 +305,9 @@ complete or exempt of any problem, illustrates the general idea: [[gsoc2011_classes.png]] -This structure is somewhat reminiscent of Java RMI or similar systems, +This structure is somewhat reminiscent of +[Java RMI](http://en.wikipedia.org/wiki/Java_remote_method_invocation) +or similar systems, which aim to provide more or less transparent access to remote objects. The exact way the Java code would be generated still needs to be determined, but basically: -- cgit v1.2.3 From f339908d26851950ed204172765fd89e56e79b52 Mon Sep 17 00:00:00 2001 From: Jeremie Koenig Date: Fri, 8 Apr 2011 14:38:26 +0200 Subject: gsoc2011 (java): add a 'draft' comment at the beginning --- user/jkoenig/gsoc2011_proposal.mdwn | 2 ++ 1 file changed, 2 insertions(+) (limited to 'user') diff --git a/user/jkoenig/gsoc2011_proposal.mdwn b/user/jkoenig/gsoc2011_proposal.mdwn index 5d40a97f..620ac95b 100644 --- a/user/jkoenig/gsoc2011_proposal.mdwn +++ b/user/jkoenig/gsoc2011_proposal.mdwn @@ -1,6 +1,8 @@ # Java for Hurd (and vice vera) +*[Draft] I'll finish this later today and send an email to bug-hurd when I'm done* + Contact information: * Full name: Jérémie Koenig -- cgit v1.2.3 From 5876a9f012898f8b1e5e60f53fb8b026c8d351e9 Mon Sep 17 00:00:00 2001 From: Jeremie Koenig Date: Fri, 8 Apr 2011 15:51:55 +0200 Subject: gsoc2011 (java): split the appendix into another page --- user/jkoenig/gsoc2011_proposal.mdwn | 94 ++++--------------------------------- user/jkoenig/objcap.mdwn | 85 +++++++++++++++++++++++++++++++++ 2 files changed, 93 insertions(+), 86 deletions(-) create mode 100644 user/jkoenig/objcap.mdwn (limited to 'user') diff --git a/user/jkoenig/gsoc2011_proposal.mdwn b/user/jkoenig/gsoc2011_proposal.mdwn index 620ac95b..d53c094f 100644 --- a/user/jkoenig/gsoc2011_proposal.mdwn +++ b/user/jkoenig/gsoc2011_proposal.mdwn @@ -62,6 +62,14 @@ My knowledge of the Hurd and Debian GNU/Hurd is reasonable, as the Debian-Installer and procfs projects gave me the opportunity to fiddle with many parts of the system. +Initially, +I started working on this project because I wanted to use Joe-E +(a subset of Java) +to investigate the potential +[[applications of object-capability languages|objcap]] +in a Hurd context. +I also believe that imrpoving Java support on Hurd +would be an important milestone. ## Improve Java support @@ -495,89 +503,3 @@ The dates listed are deadlines for the associated tasks. ## Conclusion - - - -## Appendix: potential applications of object-capability languages - -The work discussed is this last part would have -fewer immediate benefits for the Hurd project -and has more of a research orientation. -It is also unlikely that there would be any time remaining -to work on it at the end of the summer. -(Though it could work as some kind of reward -if I somehow managed to do a prefect job of all the rest -within the allocated time :-) ). -As a consequence, -I don't really consider this a part of my application. - -This being said, -to some extent the project discussed here -will informed the way I design the Java bindings, -since it depends on them -and I intend to work on this at some point in the future. -I also believe it touches on some interesting ideas, -and a Summer of Code application is probably -as good an occasion as any to discuss them. - -### Justification - -The primary advantage of multi-server operating systems is the ability to -break what used to be the kernel into small pieces which can be isolated -from each others. This makes sense from an engineering perspective, as -smaller components can be swapped with different implementations and reduce -the impact of bugs. -A capability-based approach also ensures that the -authority wielded by components is clear and reduced to the minimum required -for them to function. -These properties are crucial to the Hurd's agenda of user freedom, -since in order to allow them to plug their own code into the system -[FIXME: développer] - -However, this flexibility has a cost. In a system where the isolation of -components relies on running them inside different address spaces, -communication between them must be done through IPC calls. -This introduces a trade-off between the size of the modules -and performance as well as practicality, -which imposes a limit to the granularity with which the system -can be decomposed and the principle of least authority applied -(to the code within a given process, a Mach port is ambient authority). - -Another issue is that of the threading structure of the system as a whole. -In systems based on a monolithic kernel, user threads execute the kernel -code themselves, which is then intrinsically concurrent. By contrast, in a -system based on a “client-server” paradigm, each server must be explicitly -multi-threaded if it is to serve requests concurrently. - -### Object-capability languages - -An object-capability language is an object-oriented language which is -restricted enough so that object references are themselves capabilities. - -One such language is Joe-E (FIXME: lien), -which is an object-capability subset of Java: -global state and static methods are mostly forbidden; -careful white-listing of the objects and methods -provided by the Java standard library -ensures that compliant code cannot not access ambient autority. -Ways in which object references can be transferred -are restricted to the most obvious ones -(for instance, exceptions are carefully restricted). - -As a result, untrusted Joe-E code can be executed without any further -isolation and its autority can be controlled by carefully limiting the -object references which are passed to it. -This would allow to load and execute translators written in Joe-E -in a single address space. - -### Bundling translators into a single process - -[mechanisme pour transmettre le code Joe-E -et les port initiaux au serveur] -[émulation des différentes tâches] - -### Challenges and further work - -[proof-carrying code / typed assembly, -resource accounting (passer en revue la conception de Viengoos?)] - diff --git a/user/jkoenig/objcap.mdwn b/user/jkoenig/objcap.mdwn new file mode 100644 index 00000000..e4cd20e8 --- /dev/null +++ b/user/jkoenig/objcap.mdwn @@ -0,0 +1,85 @@ + +# Potential applications of object-capability languages + +The work discussed is this last part would have +fewer immediate benefits for the Hurd project +and has more of a research orientation. +It is also unlikely that there would be any time remaining +to work on it at the end of the summer. +(Though it could work as some kind of reward +if I somehow managed to do a prefect job of all the rest +within the allocated time :-) ). +As a consequence, +I don't really consider this a part of my application. + +This being said, +to some extent the project discussed here +will informed the way I design the Java bindings, +since it depends on them +and I intend to work on this at some point in the future. +I also believe it touches on some interesting ideas, +and a Summer of Code application is probably +as good an occasion as any to discuss them. + +### Justification + +The primary advantage of multi-server operating systems is the ability to +break what used to be the kernel into small pieces which can be isolated +from each others. This makes sense from an engineering perspective, as +smaller components can be swapped with different implementations and reduce +the impact of bugs. +A capability-based approach also ensures that the +authority wielded by components is clear and reduced to the minimum required +for them to function. +These properties are crucial to the Hurd's agenda of user freedom, +since in order to allow them to plug their own code into the system +[FIXME: développer] + +However, this flexibility has a cost. In a system where the isolation of +components relies on running them inside different address spaces, +communication between them must be done through IPC calls. +This introduces a trade-off between the size of the modules +and performance as well as practicality, +which imposes a limit to the granularity with which the system +can be decomposed and the principle of least authority applied +(to the code within a given process, a Mach port is ambient authority). + +Another issue is that of the threading structure of the system as a whole. +In systems based on a monolithic kernel, user threads execute the kernel +code themselves, which is then intrinsically concurrent. By contrast, in a +system based on a “client-server” paradigm, each server must be explicitly +multi-threaded if it is to serve requests concurrently. + +### Object-capability languages + +An object-capability language is an object-oriented language which is +restricted enough so that object references are themselves capabilities. + +One such language is Joe-E (FIXME: lien), +which is an object-capability subset of Java: +global state and static methods are mostly forbidden; +careful white-listing of the objects and methods +provided by the Java standard library +ensures that compliant code cannot not access ambient autority. +Ways in which object references can be transferred +are restricted to the most obvious ones +(for instance, exceptions are carefully restricted). + +As a result, untrusted Joe-E code can be executed without any further +isolation and its autority can be controlled by carefully limiting the +object references which are passed to it. +This would allow to load and execute translators written in Joe-E +in a single address space. + +### Bundling translators into a single process + +[mechanisme pour transmettre le code Joe-E +et les port initiaux au serveur] +[émulation des différentes tâches] + +### Challenges and further work + +[proof-carrying code / typed assembly, +resource accounting (passer en revue la conception de Viengoos?)] + + -- cgit v1.2.3 From 3fd06c9149344aafa928d8db454991a35cd7e875 Mon Sep 17 00:00:00 2001 From: Jeremie Koenig Date: Fri, 8 Apr 2011 16:01:42 +0200 Subject: gsoc2011 (java): add a summary --- user/jkoenig/gsoc2011_proposal.mdwn | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'user') diff --git a/user/jkoenig/gsoc2011_proposal.mdwn b/user/jkoenig/gsoc2011_proposal.mdwn index d53c094f..92bed1b4 100644 --- a/user/jkoenig/gsoc2011_proposal.mdwn +++ b/user/jkoenig/gsoc2011_proposal.mdwn @@ -16,6 +16,15 @@ in Computer Science at University of Strasbourg (France). My interests include capability-based security, programming languages and formal methods (in particular, proof-carrying code). +### Proposal summary + +This project would consist in improving Java support on Hurd. +The first part would consist in +fixing bugs and porting Java-related packages. +The second part would consist in +creating low-level Java bindings for the Hurd interfaces, +as well as libraries to make translator development easier. + ### Previous involvement Although I have known the Hurd for some time, -- cgit v1.2.3 From b02cb9177df853ffef97e73f98a31b4204479747 Mon Sep 17 00:00:00 2001 From: Jeremie Koenig Date: Fri, 8 Apr 2011 16:31:13 +0200 Subject: gsoc2011 (java): miscellaneous fixes --- user/jkoenig/gsoc2011_proposal.mdwn | 18 +++++++++++------- 1 file changed, 11 insertions(+), 7 deletions(-) (limited to 'user') diff --git a/user/jkoenig/gsoc2011_proposal.mdwn b/user/jkoenig/gsoc2011_proposal.mdwn index 92bed1b4..d9617ab5 100644 --- a/user/jkoenig/gsoc2011_proposal.mdwn +++ b/user/jkoenig/gsoc2011_proposal.mdwn @@ -14,7 +14,8 @@ Contact information: I am a first year M.Sc. student in Computer Science at University of Strasbourg (France). My interests include capability-based security, -programming languages and formal methods (in particular, proof-carrying code). +programming languages and formal methods +(in particular, object-capability languages and proof-carrying code). ### Proposal summary @@ -27,8 +28,7 @@ as well as libraries to make translator development easier. ### Previous involvement -Although I have known the Hurd for some time, -I did not contribute until last summer, +I started contributing to Hurd last summer, during which I participated to Google Summer of Code as a student for the Debian project. I worked on porting Debian-Installer to Hurd. @@ -72,14 +72,16 @@ as the Debian-Installer and procfs projects gave me the opportunity to fiddle with many parts of the system. Initially, -I started working on this project because I wanted to use Joe-E +I started working on this project because I wanted to use +[Joe-E](http://code.google.com/p/joe-e/) (a subset of Java) to investigate the potential [[applications of object-capability languages|objcap]] in a Hurd context. -I also believe that imrpoving Java support on Hurd +I also believe that improving Java support on Hurd would be an important milestone. + ## Improve Java support ### Justification @@ -87,6 +89,8 @@ would be an important milestone. Java is a popular language and platform used by many desktop and web applications (mostly on the server side). As a consequence, competitive Java support is important for any general-purpose operating system. +Better Java support would also be a prerequisite +for the second part of my proposal. ### Current situation @@ -442,8 +446,8 @@ to design and implement similar solutions for Java. ### Packaging and long-term maintenance -The Java libraries resulting from this work -(including any MIG support classes), +The Java libraries resulting from this work, +including any MIG support classes as well as the class files built from the MIG-generated code for the Mach and Hurd interface definition files, would be provided as single `hurd-java` package for -- cgit v1.2.3 From cd48e7119c3634550411daa66c3a617082d39630 Mon Sep 17 00:00:00 2001 From: Jeremie Koenig Date: Fri, 8 Apr 2011 16:31:41 +0200 Subject: gsoc2011 (java): improve the structure of the proposal --- user/jkoenig/gsoc2011_proposal.mdwn | 54 ++++++++++++++++++++++++++++--------- 1 file changed, 41 insertions(+), 13 deletions(-) (limited to 'user') diff --git a/user/jkoenig/gsoc2011_proposal.mdwn b/user/jkoenig/gsoc2011_proposal.mdwn index d9617ab5..e8f7679b 100644 --- a/user/jkoenig/gsoc2011_proposal.mdwn +++ b/user/jkoenig/gsoc2011_proposal.mdwn @@ -146,6 +146,14 @@ which makes some packages fail to build on Hurd proposal). Porting Eclipse would be a good opportunity to test GCJ and OpenJDK. +### Deliverables + + * The glibc pthreads patch and any other fixes on the Hurd side + would be submitted upstream + * Patches against Debian source packages + required to make them build on Hurd would be submitted + to the [Debian bug tracking system](http://bugs.debian.org/). + ## Create Java bindings for the Hurd interfaces @@ -172,7 +180,33 @@ to begin experimenting with what makes Hurd unique without being faced right away with the complexity of low-level systems programming. -### Approach +### Tasks summary + + * Implement Java bindings for Mach + * Implement a libports-like library for Java + * Modify MIG to output Java code + * Implement libfoofs-like Java libraries + +### Design principles + +The principles I would use to guide the design +of these Java bindings would be the following ones: + * The system should be hooked into at a low level, + to ensure that Java is a "first class citizen" + as far as the access to the Hurd's interfaces is concerned. + * At the same time, the memory safety of Java should be maintained + and extended to Mach primitives such as port names and + out-of-line memory regions. + * Higher-level interfaces should be provided as well + in order to make translator development + as easy as possible. + * A minimum amount of JNI code (ie. C code) should be used. + Most of the system should be built using Java itself + on top of a few low-level primitives. + * Hurd objects would map to Java objects. + * Using the same interfaces, + objects corresponding to local ports would be accessed directly, + and remote objects would be accessed over IPC. One approach used previously to interface programming languages with the Hurd has been to create bindings for helper libraries such as libtrivfs. Instead, @@ -186,17 +220,6 @@ However, once an initial implementation is done it would be easier to maintain in the long run and we would be able to provide Java bindings for a large percentage of the Hurd’s interfaces. -### Design goals - -FIXME: a completer - - * Give maximum flexibility to the Java code while maintaining the memory - safety of Java, and using a minimum amount of C code. - * Provide higher-level interfaces as well, ... - * Hurd objects would map to Java objects. - * Local objects can be accessed directly, - remote objects can be accessed transparently over IPC. - ### Bindings for Mach system calls In this low-level approach, my intention is to enable Java code to use Mach @@ -444,7 +467,12 @@ to implement the required ones. I would draw inspiration from libtrivfs and libnetfs to design and implement similar solutions for Java. -### Packaging and long-term maintenance +### Deliverables + + * A hurd-java package would contain the Java code developped + in the context of this project. + * Modifications to MIG would be submitted upstream, + or a patched MIG package would be made available. The Java libraries resulting from this work, including any MIG support classes -- cgit v1.2.3 From ba3c75a2496401fc189006db19ea75fede28907d Mon Sep 17 00:00:00 2001 From: Jeremie Koenig Date: Fri, 8 Apr 2011 17:45:01 +0200 Subject: gsoc2011 (java): random improvements --- user/jkoenig/gsoc2011_proposal.mdwn | 27 +++++++++++++++------------ 1 file changed, 15 insertions(+), 12 deletions(-) (limited to 'user') diff --git a/user/jkoenig/gsoc2011_proposal.mdwn b/user/jkoenig/gsoc2011_proposal.mdwn index e8f7679b..7179ff87 100644 --- a/user/jkoenig/gsoc2011_proposal.mdwn +++ b/user/jkoenig/gsoc2011_proposal.mdwn @@ -171,8 +171,8 @@ native code and [link it statically](http://gcc.gnu.org/wiki/Statically_linking_libgcj) using GCJ, should anyone want to use a translator written in Java for booting. Note that Java is -[being](http://oss.readytalk.com/avian/) -[used](http://www.linuxjournal.com/article/8757) +[being](http://www.linuxjournal.com/article/8757) +[used](http://oss.readytalk.com/avian/) in this manner for embedded development. Java bindings would lower the bar for newcomers @@ -471,6 +471,8 @@ to design and implement similar solutions for Java. * A hurd-java package would contain the Java code developped in the context of this project. + * The Java code would be documented using javadoc + and a tutorial for writing translators would be written as well. * Modifications to MIG would be submitted upstream, or a patched MIG package would be made available. @@ -519,27 +521,28 @@ The dates listed are deadlines for the associated tasks. Finish implementing pthread signal semantics. * *June 5.* Port OpenJDK - * *June 19 (two weeks).* + * *June 12.* Fix the remaining problems with GCJ and/or OpenJDK, possibly port Eclipse or other big Java packages. - * *June 26.* + * *June 19.* Create the bindings for Mach. - * *July 3.* + * *June 26.* Work on some kind of basic Java libports to handle receive rights. - * *July 10.* + * *July 3.* Test, write some documentation and examples. - * *July 24 (two weeks).* + * *July 17 (two weeks).* Add the Java target to MIG. - * *July 31.* + * *July 24.* Test, write some documentation and examples. - * *August 7.* + * *August 7 (two weeks).* + Implement a modular libfoofs to help with translator development. Try to write a basic but non-trivial translator to evaluate the performance and ease of use of the result, rectify any rough edges this would uncover. - * *Last two weeks.* - Polish the code, - do the packaging. + * *August 22. (last two weeks)* + Polish the code and packaging, + finish writing the documentation. ## Conclusion -- cgit v1.2.3 From 31044d5cfa4f861f510fc0fe130f5a82fae48b6a Mon Sep 17 00:00:00 2001 From: Jeremie Koenig Date: Fri, 8 Apr 2011 17:45:08 +0200 Subject: gsoc2011 (java): conclusion --- user/jkoenig/gsoc2011_proposal.mdwn | 47 +++++++++++++++++++++++++++++++++++++ 1 file changed, 47 insertions(+) (limited to 'user') diff --git a/user/jkoenig/gsoc2011_proposal.mdwn b/user/jkoenig/gsoc2011_proposal.mdwn index 7179ff87..5e5d2735 100644 --- a/user/jkoenig/gsoc2011_proposal.mdwn +++ b/user/jkoenig/gsoc2011_proposal.mdwn @@ -547,3 +547,50 @@ The dates listed are deadlines for the associated tasks. ## Conclusion +This project is arguably ambitious. +However, I have been thinking about it for some time now +and I'm confident I would be able to accomplish most of it. + +In the event multiple language bindings projects +would be accepted, +some work could probably be done in common. +In particular, +[ArneBab](http://www.bddebian.com/~hurd-web/community/weblogs/ArneBab/2011-04-06-application-pyhurd/) +seems to favor a low-level approach for his Python bindings as I do for Java, +and I would be happy to discuss API design and coordinate MIG changes with him. +I would also have an extra month after the end of the GSoC period +before I go back to school, +which I would be able to use to finish the project +if there is some remaining work. +(Last year's rewrite of procfs was done during this period.) + +As for the project's benefits, +I believe that good support for Java +is a must-have for the Hurd. +Java bindings would also further the Hurd's agenda +of user freedom by extending this freedom to more people: +I expect the set of developers +who would be able to write Java code against a well-written libfoofs +is much larger than +those who master the intricacies of low-level systems C programming. +From a more strategic point of view, +this would also help recruit new contributors +by providing an easier path to learning the inner workings of the Hurd. + +Further developments +which would build on the results of this project +include my planned [[experiment with Joe-E|objcap]] +(which I would possibly take on as a university project next year). +Another possibility would be to reimplement some parts +of the Java standard library +directly in terms of the Hurd interfaces +instead of using the POSIX ones through glibc. +This would possibly improve the performance +of some Java applications (though probably not by much), +and would otherwise be a good project +for someone trying to get acquainted with Hurd. + +Overall, I beleive this project would be fun, interesting and useful. +I hope that you will share this sentiment +and give me the opportunity to spend another summer working on Hurd. + -- cgit v1.2.3 From 67c45ea1f4eef284234d69ffad5fd7548f289a84 Mon Sep 17 00:00:00 2001 From: Jeremie Koenig Date: Fri, 8 Apr 2011 18:02:47 +0200 Subject: gsoc2011 (java): add answers to the remaining question from the template --- user/jkoenig/gsoc2011_proposal.mdwn | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) (limited to 'user') diff --git a/user/jkoenig/gsoc2011_proposal.mdwn b/user/jkoenig/gsoc2011_proposal.mdwn index 5e5d2735..fe05e2c0 100644 --- a/user/jkoenig/gsoc2011_proposal.mdwn +++ b/user/jkoenig/gsoc2011_proposal.mdwn @@ -81,6 +81,28 @@ in a Hurd context. I also believe that improving Java support on Hurd would be an important milestone. +### Organisational matters + +I am subscribed to bug-hurd@g.o and +I do have a permanent internet connexion. + +I would be able to attend the regular IRC meetings, +and otherwise communicate with my mentor +through any means they would prefer +(though I expect email and IRC would be the most practical). +Since I'm already familiar with the Hurd, +I don't expect I would require too much time from them. + +My exams end on May 20 so I would be able to start coding +right at the beginning of the GSoC period. +Next year's term would probably begin around september 15, +so that would not be an issue either. +I expect I would work around 40 hours per week, +and my waking hours would be flexible. + +I don't have any other plans for the summer +and would not make any if my project were to be accepted. + ## Improve Java support -- cgit v1.2.3 From cd0c5d6044001a248c522b55c637a8610567644d Mon Sep 17 00:00:00 2001 From: Jeremie Koenig Date: Fri, 8 Apr 2011 18:06:30 +0200 Subject: gsoc2011 (java): fix --- user/jkoenig/gsoc2011_proposal.mdwn | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'user') diff --git a/user/jkoenig/gsoc2011_proposal.mdwn b/user/jkoenig/gsoc2011_proposal.mdwn index fe05e2c0..d746aa4e 100644 --- a/user/jkoenig/gsoc2011_proposal.mdwn +++ b/user/jkoenig/gsoc2011_proposal.mdwn @@ -309,7 +309,8 @@ examples: operations should be provided by the `Syscall` class instead. Finally, access should be provided to the initial ports and file descriptors -in `_hurd_ports` and `FIXME`, for instance through static methods such as +in `_hurd_ports` and provided by the `getdport()` function, +for instance through static methods such as `getCRDir()`, `getCWDir()`, `getProc()`, ... in a dedicated class such as `org.gnu.hurd.InitPorts`. -- cgit v1.2.3 From ffc40b2f72fa1a44f492122d50678af0cfbf9b7f Mon Sep 17 00:00:00 2001 From: Jeremie Koenig Date: Fri, 8 Apr 2011 18:39:21 +0200 Subject: gsoc2011 (java): mention alternative JVM languages --- user/jkoenig/gsoc2011_proposal.mdwn | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) (limited to 'user') diff --git a/user/jkoenig/gsoc2011_proposal.mdwn b/user/jkoenig/gsoc2011_proposal.mdwn index d746aa4e..b5932006 100644 --- a/user/jkoenig/gsoc2011_proposal.mdwn +++ b/user/jkoenig/gsoc2011_proposal.mdwn @@ -181,21 +181,26 @@ which makes some packages fail to build on Hurd ### Justification -Java is a popular language, used for many applications and often taught to +Java is used for many applications and often taught to introduce object-oriented programming. The fact that Java is a garbage-collected language makes it easier to use, especially for the less -experienced programmers. Besides, the object-oriented nature of Java is a +experienced programmers. Besides, its object-oriented nature is a natural fit for the capability-based design of Hurd. +The JVM is also used as a target for many other languages, +all of which would benefit from the access provided by these bindings. Advantages over other garbage-collected, object-oriented languages include performance, type safety and the possibility to compile a Java translator to native code and [link it statically](http://gcc.gnu.org/wiki/Statically_linking_libgcj) using GCJ, should anyone want to use a -translator written in Java for booting. Note that Java is +translator written in Java for booting. +Note that Java is [being](http://www.linuxjournal.com/article/8757) [used](http://oss.readytalk.com/avian/) in this manner for embedded development. +Since GCJ can take bytecode as its input, +this expect this possibility would apply to any JVM-based language. Java bindings would lower the bar for newcomers to begin experimenting with what makes Hurd unique -- cgit v1.2.3 From 7d86797cb4decbcbf612651e0ad98d1088e9b91d Mon Sep 17 00:00:00 2001 From: Jeremie Koenig Date: Fri, 8 Apr 2011 18:48:50 +0200 Subject: gsoc2011 (java): spell-checking --- user/jkoenig/gsoc2011_proposal.mdwn | 38 ++++++++++++++++++------------------- 1 file changed, 19 insertions(+), 19 deletions(-) (limited to 'user') diff --git a/user/jkoenig/gsoc2011_proposal.mdwn b/user/jkoenig/gsoc2011_proposal.mdwn index b5932006..46ebf945 100644 --- a/user/jkoenig/gsoc2011_proposal.mdwn +++ b/user/jkoenig/gsoc2011_proposal.mdwn @@ -1,5 +1,5 @@ -# Java for Hurd (and vice vera) +# Java for Hurd (and vice versa) *[Draft] I'll finish this later today and send an email to bug-hurd when I'm done* @@ -43,7 +43,7 @@ Shortly afterwards, I rewrote the procfs translator to fix some issues with memory leaks, make it more reliable, -and improve comptibility with Linux-based tools +and improve compatibility with Linux-based tools such as `procps` or `htop`. Although I have not had as much time @@ -55,7 +55,7 @@ on implementing POSIX threads signal semantics in glibc. ### Project-related skills and interests -I have used Java mostly for university assignements. +I have used Java mostly for university assignments. This includes non-trivial projects using threads and distributed programming frameworks such as Java RMI or CORBA. @@ -95,7 +95,7 @@ I don't expect I would require too much time from them. My exams end on May 20 so I would be able to start coding right at the beginning of the GSoC period. -Next year's term would probably begin around september 15, +Next year's term would probably begin around September 15, so that would not be an issue either. I expect I would work around 40 hours per week, and my waking hours would be flexible. @@ -242,7 +242,7 @@ Mach primitives and extending MIG to generate Java code from the interface description files. This approach would be initially more involved, and would introduces several -issues related to overcoming the "impedence mismatch" between Java and Mach. +issues related to overcoming the "impedance mismatch" between Java and Mach. However, once an initial implementation is done it would be easier to maintain in the long run and we would be able to provide Java bindings for a large percentage of the Hurd’s interfaces. @@ -271,9 +271,9 @@ package, which would contain at least the following classes: * `MachPort` would encapsulate a `mach_port_t`. (Some of) its constructors would act as an interface for the `mach_port_allocate()` system call. - `MachPort` objects would also be instanciated from other parts of the JNI + `MachPort` objects would also be instantiated from other parts of the JNI C code to represent port rights received through IPC. The `deallocate()` - mehod would call `mach_port_deallocate()` and replace the encapsulated + method would call `mach_port_deallocate()` and replace the encapsulated port name with `MACH_PORT_DEAD`. We would recommend that users call it when a port is no longer used, but the finalizer would also deallocate the port when the `MachPort` object is garbage collected. @@ -286,11 +286,11 @@ package, which would contain at least the following classes: constructor would allocate a `byte[]` member array of a given size. Additional methods would be provided to fill in or query the information in the message header and additional data items, including `MachPort` and - `Buffer` objects which would be translated to the correponding port names + `Buffer` objects which would be translated to the corresponding port names and out-of-line pointers. A global map from port names to the corresponding `MachPort` object would probably be needed to ensure that there is a one-to-one - correspondance. + correspondence. * `Syscall` would provide static JNI methods for performing system calls not covered by the above classes, such as `mach_msg()` or `mach_thread_self()`. These methods would accept or return `MachPort`, @@ -308,7 +308,7 @@ examples: `Message` object, and to read it back as a `MachPort` or `Buffer` object, since this would allow unsafe access to arbitrary memory addresses and mach port names. - * Providing the `mach_task_self()` system call would also provide acces to + * Providing the `mach_task_self()` system call would also provide access to arbitrary addresses and ports by using the `vm_*` family of RPC operations with the returned `MachPort` object. This means that the relevant task operations should be provided by the `Syscall` class instead. @@ -394,7 +394,7 @@ but basically: would implement this interface by doing RPC over a given MachPort object. * A server class, corresponding to `*Server.c`, would be able to handle incoming messages using a user-provided implementation of the interface. - (Possibly, a skelton class providing methods which would raise + (Possibly, a skeleton class providing methods which would raise `NotImplementedException`s would be provided as well. Users would derive from this class and override the relevant methods. This would allow them not to implement some operations, @@ -409,7 +409,7 @@ primitives described in the previous section. When possible, operations involving the transmission of send rights of some kind would be expressed in terms of the MIG-generated interfaces -intead of `MachPort` objects. +instead of `MachPort` objects. Upon reception of a send right, a `FooUser` object would be created and associated with the corresponding `MachPort` object. @@ -424,10 +424,10 @@ instead of going through RPC mechanisms. Some issues will still need to be solved regarding how MIG will convert interface description files to Java interfaces. For instance: - * `.defs` files are not explicitely associated with a type. For instance in + * `.defs` files are not explicitly associated with a type. For instance in the example above, MIG would have to somehow infer that io_t corresponds to `this` in the `Io` interface. - * More generally, a correspondance between MIG and Java types would have + * More generally, a correspondence between MIG and Java types would have to be determined. Ideally this would be automated and not hardcoded too much. * Initially, reply port parameters would be ignored. However they may be @@ -484,7 +484,7 @@ library. Once MIG can target Java code, and a libports equivalent is available, creating new translators in Java would be greatly facilitated. However, -we would probably want to introduce basic implementations of filesystem +we would probably want to introduce basic implementations of file system translators in the spirit of libtrivfs or libnetfs. They could take the form of base classes implementing the relevant MIG-generated interfaces which would then be derived by users, @@ -497,7 +497,7 @@ to design and implement similar solutions for Java. ### Deliverables - * A hurd-java package would contain the Java code developped + * A hurd-java package would contain the Java code developed in the context of this project. * The Java code would be documented using javadoc and a tutorial for writing translators would be written as well. @@ -513,7 +513,7 @@ Debian GNU/Hurd. This package would be separate from both Hurd and Mach, so as not to impose unreasonable build dependencies on them. -I expect I would be able to act as its maintainer in the forseeable future, +I expect I would be able to act as its maintainer in the foreseeable future, either as an individual or as a part of the Hurd team. Hopefully, my code would be claimed by the Hurd project as their own, @@ -524,7 +524,7 @@ could be integrated upstream. Since by design, the Java code would use only a small number of stable interfaces, it would not be subject to excessive amounts of bitrot. -Consequenty, +Consequently, maintenance would primarily consist in fixing bugs as they are reported, and adding new features as they are requested. @@ -618,7 +618,7 @@ of some Java applications (though probably not by much), and would otherwise be a good project for someone trying to get acquainted with Hurd. -Overall, I beleive this project would be fun, interesting and useful. +Overall, I believe this project would be fun, interesting and useful. I hope that you will share this sentiment and give me the opportunity to spend another summer working on Hurd. -- cgit v1.2.3 From 6712fac46834ed661d34b3df37e1f6b18b226b8c Mon Sep 17 00:00:00 2001 From: Jeremie Koenig Date: Fri, 8 Apr 2011 20:16:46 +0200 Subject: gsoc2011 (java): last touch --- user/jkoenig/gsoc2011_proposal.mdwn | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) (limited to 'user') diff --git a/user/jkoenig/gsoc2011_proposal.mdwn b/user/jkoenig/gsoc2011_proposal.mdwn index 46ebf945..eeaa5aaa 100644 --- a/user/jkoenig/gsoc2011_proposal.mdwn +++ b/user/jkoenig/gsoc2011_proposal.mdwn @@ -1,8 +1,6 @@ # Java for Hurd (and vice versa) -*[Draft] I'll finish this later today and send an email to bug-hurd when I'm done* - Contact information: * Full name: Jérémie Koenig @@ -103,6 +101,11 @@ and my waking hours would be flexible. I don't have any other plans for the summer and would not make any if my project were to be accepted. +Full disclosure: +I also submitted a proposal to the Jikes RVM project +(which is a research-oriented Java Virtual Machine, +itself written in Java) +for implementing a new garbage collector into the MMTk subsystem. ## Improve Java support -- cgit v1.2.3