[ANN] xampl 0.1.0

ruby-talk
1

Hi,

I've just uploaded the first release (0.1.0) of xampl for Ruby. I'm expecting a few teething pains but I hope they'll be over with soon.

This is a ruby version of a project I've been working on in Java since 1998 or so. The Java version has been used to help develop some relatively large commercial software applications over the years. The Ruby version is a much smaller body of code than the Java version, partly due to the fact that it is new, but, really, mostly because of the dynamic nature of Ruby.

It is in three parts. Xampl proper is in xampl-0.1.0.gem. The xampl code generators are in xampl-generator-0.1.0.gem. And there is documentation, examples, and unit tests in a separate download (the documentation needs debugging too). I don't have access to a windows machine, so I'd really appreciate it if someone could let me know what happens there.

You can download it here <http://rubyforge.org/frs/?group_id=1034> (and I obviously don't know how rubyforge works since only one of the three parts is visible from the project's summary page).

Enjoy!

Cheers,
Bob

Xampl is a tool for developing Ruby programs. It facilitates the 'M' part
of an MVC architecture. It is meant to be very easy to use, supportive of
idiomatic Ruby usage, and mostly invisible.

Features:
   - pure Ruby, no libraries required except those shipped with Ruby 1.8.2
   - uses XML to declaratively describe a object structures
     - uses a collection of example XML documents, no schema are required
     - supports arbitrary object graphs, not just XML-like trees
     - Ruby idiomatic facilities to navigate the object structures (e.g. named
       arrays, hash, iterator support, uses blocks, etc.)
     - support empty, simple (text content only), data (no or limited text
       content, but with arbitrary element content), and mixed content (where
       text and element content can be intermingled)
     - maps XML namespaces to Ruby modules (with handy defaults) and you can
       suggest preferred namespace prefixes for XML output
     - includes an XML pull parser (very fast)
     - code generation is template driven, so the adventurous can change what
       is generated
     - includes a simple but powerful and fast templating engine
     - includes a simple-minded but effective hash-like class that maintains
       insertion order (fast insertion, lookup, and iteration, but at the
       expense of delete)
     - naming conventions are used when generating code (but these conventions
       can be changed)
     - additions to the XML will very rarely break existing code, and so
       incremental development of functionality is supported
     - generated code is readable and useful while debugging
     - a command line tool to generate the code, or you can generate at runtime
   - XML binding to the classes (i.e. parsing an XML file will produce an
     object graph)
   - can augment existing classes
   - programmer adds functionality by opening the class or module, no worries
     about the code generator overwriting your changes
   - object structures can generate XML output (and there is an XML pretty
     printer used for emphasising human readable XML output)
   - easy to use persistence mechanism
     - persistence is in terms of clusters of objects, the cluster is updated
       all at once
     - lazy loading of persisted clusters
     - LRU cache (of clusters)
     - the changed clusters are available for inspection
     - XML, Ruby, and YAML persistence mechanism (purposely no Marshal support)
     - persist to memory, or filesystem (optional persistence to an FSDB)
     - sync and rollback (even with memory persistence); this is a weak form
       of transaction support in this release
     - 'automatic' and 'manual' modes of persistence ('automatic' means that
       any xampl cluster created while a persister is active will be
       automatically managed by that persister, manual means that you have
       to introduce the xampl cluster to the persister)
     - fast alternative to persistence that does not support rollback
     - xampl objects can hold arbitrary attribute values through the
       persistence 'cycle' if using Ruby or YAML persistence (even xampl
       object); with XML you won't loose anything but all attributes will
       be strings after round tripping.
     - multiple persisters, possibly with differing persistence mechanisms,
       are supported
     - dead easy single user applications (e.g. desktop apps, CGI), almost as
       easy for multiple user applications and webapps
     - you can add your own persister types (and formats for that matter)
   - general purpose Visitor pattern facility, with pre and post visit methods,
     cycle and revisit detection and handling
   - lots of hooks
   - many unit tests, all execute without warning when run with the -w Ruby flag
   - there are some examples, and the beginnings of a tutorial in the form of
     a series of examples that lead you through the core parts of xampl

Features that are coming soon:
   - many more hooks
   - more sophisticated augmentation of existing classes
   - indexing and querying of the persisted object structures
   - more persisters (e.g. sqlite)
   - real transactions
   - a better comparison function (that deals with cyclic structures at all, and
     better with non-tree acyclic structures)

Known Bugs or Potential Problems or Suspected Problems
   - generated attribute names may conflict with Ruby keywords and this is not
     a nice thing to witness (this is easy to fix, but I don't want to do this
     until the next release at the earliest)
   - I don't know if this will work on Windows -- I tried, but I don't have a
     windows machine to test this with -- there might be some pathname stuff
     assuming unix (but I hope not)
   - some of the code is unnecessarily ugly (e.g. some of the visitor internals)
   - there are no Ruby docs (but I promise... really)
   - comparison of cyclic structures will crash

License: GPL. An alternative license may be negotiated, contact me.

While the Ruby version of xampl is brand new it is based on a Java
tool that I've been developing since 1998 and in its fifth generation.
There are many features in the Java version that are not available in
this library, but that is either just a matter of time, or they will
never be needed because Ruby programs don't need the help.

The Java version of the tool has been used to write a number of large
webapps, and a few smaller desktop applications, and even an applet.

There is a Common Lisp/CLOS version coming.

···

----
Bob Hutchison -- blogs at <http://www.recursive.ca/hutch/>
Recursive Design Inc. -- <http://www.recursive.ca/>
Raconteur -- <http://www.raconteur.info/>

2

Some questions just out of curiosity. No offense intended.

Bob Hutchison wrote:

<snip/>

Xampl is a tool for developing Ruby programs. It facilitates the 'M'
part
of an MVC architecture. It is meant to be very easy to use,
supportive of
idiomatic Ruby usage, and mostly invisible.

Features:
   - pure Ruby, no libraries required except those shipped with Ruby
1.8.2
   - uses XML to declaratively describe a object structures
     - uses a collection of example XML documents, no schema are
required

Interestingly some days ago I thought about how J2EE is really two
languages (Java for implementation, XML for configuration) and how Ruby
can do both very neatly because of its clean syntax. From your
experience, does it really pay off to use XML here? Or is ist just
because you want to be able to read in arbitrary files and use the content
as Ruby objects?

<snip/>

     - XML, Ruby, and YAML persistence mechanism (purposely no
Marshal support)

Why is that? What's the reasoning behind this?

Kind regards

    robert

3

I'd love to take a look at xampl. Could you, though, upload an archive of it
that doesn't depend on gems?

Thanks,

Kirk Haines

···

On Monday 21 November 2005 7:28 am, Bob Hutchison wrote:

You can download it here <http://rubyforge.org/frs/?group_id=1034&gt;
(and I obviously don't know how rubyforge works since only one of the
three parts is visible from the project's summary page).

4

Some questions just out of curiosity. No offense intended.

No problem. You've asked a couple of interesting questions.

Bob Hutchison wrote:

<snip/>

Xampl is a tool for developing Ruby programs. It facilitates the 'M'
part
of an MVC architecture. It is meant to be very easy to use,
supportive of
idiomatic Ruby usage, and mostly invisible.

Features:
   - pure Ruby, no libraries required except those shipped with Ruby
1.8.2
   - uses XML to declaratively describe a object structures
     - uses a collection of example XML documents, no schema are
required

Interestingly some days ago I thought about how J2EE is really two
languages (Java for implementation, XML for configuration) and how Ruby
can do both very neatly because of its clean syntax. From your
experience, does it really pay off to use XML here? Or is ist just
because you want to be able to read in arbitrary files and use the content
as Ruby objects?

Yes it does make sense I think. How do you express succinctly the relationship between a bunch of live objects? Amusingly, the hyper-verbose XML can actually do that :slight_smile: It all depends on how you interpret the XML. XML can reflect a containment/composition/aggregation relationship about as tersely as you can get in text.

Xampl is not about using XML for configuration, but for 1) describing dynamic relationships between objects; and 2) persistence.

I agree with you that much of what XML, or YAML for that matter, is used for can be better done in Ruby (or Python, or any other dynamic language), certainly the way XML is used conventionally. Though xampl changes the picture a bit.

The other thing xampl does is makes it a lot easier to deal with XML based protocols. I've provided an example with the distribution (and discussed in the documentation) of how to use xampl to read an Atom 1.0 or 0.3 feed over the internet, cache the feeds, extract the entries, convert 0.3 entries to 1.0, aggregate in a new 1.0 feed paying attention to ordering, and serve it up via WEBrick. Xampl really helps in this kind of thing.

This is actually a really good question and I should prepare a better answer. The background for what I'll say is documented in the download file, but there is no direct answer to this question there.

<snip/>

     - XML, Ruby, and YAML persistence mechanism (purposely no
Marshal support)

Why is that? What's the reasoning behind this?

1) Upgrades of marshalled objects can be really nasty, using a text form that xampl has control over while parsing, you have a chance of intervening at an opportune time, making your life a lot easier.
2) You can read XML, Ruby and YAML.
3) You can use the data easily independently of any xampl program (e.g. in a text editor :slight_smile:
4) You cannot control how much of the network of reachable objects is written to one file (this is very important in xampl because of its clustering capabilities).

There are more reasons that I've forgotten, these are enough for me.

Cheers,
Bob

···

On Nov 21, 2005, at 9:47 AM, Robert Klemme wrote:

Kind regards

    robert

----
Bob Hutchison -- blogs at <http://www.recursive.ca/hutch/&gt;
Recursive Design Inc. -- <http://www.recursive.ca/&gt;
Raconteur -- <http://www.raconteur.info/&gt;

5

Absolutely. Good idea. Can you point me to how you deal with require statements that work with either. I think I saw something like that but I can't find it now. How would you like it done, since you've asked first?

Cheers,
Bob

···

On Nov 21, 2005, at 10:46 AM, Kirk Haines wrote:

On Monday 21 November 2005 7:28 am, Bob Hutchison wrote:

You can download it here <http://rubyforge.org/frs/?group_id=1034&gt;
(and I obviously don't know how rubyforge works since only one of the
three parts is visible from the project's summary page).

I'd love to take a look at xampl. Could you, though, upload an archive of it
that doesn't depend on gems?

Thanks,

Kirk Haines

----
Bob Hutchison -- blogs at <http://www.recursive.ca/hutch/&gt;
Recursive Design Inc. -- <http://www.recursive.ca/&gt;
Raconteur -- <http://www.raconteur.info/&gt;

6

Bob Hutchison wrote:

Some questions just out of curiosity. No offense intended.

No problem. You've asked a couple of interesting questions.

Bob Hutchison wrote:

<snip/>

Xampl is a tool for developing Ruby programs. It facilitates the 'M'
part
of an MVC architecture. It is meant to be very easy to use,
supportive of
idiomatic Ruby usage, and mostly invisible.

Features:
   - pure Ruby, no libraries required except those shipped with Ruby
1.8.2
   - uses XML to declaratively describe a object structures
     - uses a collection of example XML documents, no schema are
required

Interestingly some days ago I thought about how J2EE is really two
languages (Java for implementation, XML for configuration) and how
Ruby
can do both very neatly because of its clean syntax. From your
experience, does it really pay off to use XML here? Or is ist just
because you want to be able to read in arbitrary files and use the
content
as Ruby objects?

Yes it does make sense I think. How do you express succinctly the
relationship between a bunch of live objects? Amusingly, the hyper-
verbose XML can actually do that :slight_smile: It all depends on how you
interpret the XML. XML can reflect a containment/composition/
aggregation relationship about as tersely as you can get in text.

Well, you can describe those relationships in Ruby, too. In fact, nearly
every Ruby program does it by creating / assigning member variables. :slight_smile:

Xampl is not about using XML for configuration, but for 1) describing
dynamic relationships between objects; and 2) persistence.

"describe" persistence or "implement" persistence? It seems rather the
latter.

I agree with you that much of what XML, or YAML for that matter, is
used for can be better done in Ruby (or Python, or any other dynamic
language), certainly the way XML is used conventionally. Though xampl
changes the picture a bit.

The other thing xampl does is makes it a lot easier to deal with XML
based protocols. I've provided an example with the distribution (and
discussed in the documentation) of how to use xampl to read an Atom
1.0 or 0.3 feed over the internet, cache the feeds, extract the
entries, convert 0.3 entries to 1.0, aggregate in a new 1.0 feed
paying attention to ordering, and serve it up via WEBrick. Xampl
really helps in this kind of thing.

This is actually a really good question and I should prepare a better
answer. The background for what I'll say is documented in the
download file, but there is no direct answer to this question there.

So one of the strengths of xampl is to deal with existing XML data.

<snip/>

     - XML, Ruby, and YAML persistence mechanism (purposely no
Marshal support)

Why is that? What's the reasoning behind this?

1) Upgrades of marshalled objects can be really nasty, using a text
form that xampl has control over while parsing, you have a chance of
intervening at an opportune time, making your life a lot easier.
2) You can read XML, Ruby and YAML.
3) You can use the data easily independently of any xampl program
(e.g. in a text editor :slight_smile:
4) You cannot control how much of the network of reachable objects is
written to one file (this is very important in xampl because of its
clustering capabilities).

There are more reasons that I've forgotten, these are enough for me.

Well, that's quite comprehensive! Thanks for the quick and exhaustive
answer!

Kind regards

    robert

···

On Nov 21, 2005, at 9:47 AM, Robert Klemme wrote:

7

I recommend looking at the PDF::Writer Rakefile (in the CVS
repository) as I automatically create a gem, a .tar.gz, and a demo
.tar.gz from the rakefile and even upload it to RubyForge.

I hope to be submitting a new version of the Rakefile that has a minor
fix for the .tar.gz creation (the .tar.gz is built properly, but gzip
reports that the compression wasn't completed; there is no damage to
the file, it's mostly a spurious warning) in the next couple of days.

-austin

···

On 11/21/05, Bob Hutchison <hutch@recursive.ca> wrote:

Absolutely. Good idea. Can you point me to how you deal with require
statements that work with either. I think I saw something like that
but I can't find it now. How would you like it done, since you've
asked first?

--
Austin Ziegler * halostatue@gmail.com
               * Alternate: austin@halostatue.ca

8

I've made a couple gems, but I'm not really a gems user now, so I can't really
tell you, except to say that I would like to be able to download a tar
archive of xampl so that I can try it out without having anything that I do
with it forced to depend on gems.

I'd look at what Austin Ziegler has done with his PDF::Writer package. It's a
good practical example of how to target both gems and non-gems systems about
as cleanly as it currently possible.

Thanks,

Kirk Haines

···

On Monday 21 November 2005 9:28 am, Bob Hutchison wrote:

Absolutely. Good idea. Can you point me to how you deal with require
statements that work with either. I think I saw something like that
but I can't find it now. How would you like it done, since you've
asked first?

9

Bob Hutchison wrote:

Some questions just out of curiosity. No offense intended.

No problem. You've asked a couple of interesting questions.

Bob Hutchison wrote:

<snip/>

Xampl is a tool for developing Ruby programs. It facilitates the 'M'
part
of an MVC architecture. It is meant to be very easy to use,
supportive of
idiomatic Ruby usage, and mostly invisible.

Features:
   - pure Ruby, no libraries required except those shipped with Ruby
1.8.2
   - uses XML to declaratively describe a object structures
     - uses a collection of example XML documents, no schema are
required

Interestingly some days ago I thought about how J2EE is really two
languages (Java for implementation, XML for configuration) and how
Ruby
can do both very neatly because of its clean syntax. From your
experience, does it really pay off to use XML here? Or is ist just
because you want to be able to read in arbitrary files and use the
content
as Ruby objects?

Yes it does make sense I think. How do you express succinctly the
relationship between a bunch of live objects? Amusingly, the hyper-
verbose XML can actually do that :slight_smile: It all depends on how you
interpret the XML. XML can reflect a containment/composition/
aggregation relationship about as tersely as you can get in text.

Well, you can describe those relationships in Ruby, too. In fact, nearly
every Ruby program does it by creating / assigning member variables. :slight_smile:

Sure, but not so tersely and not so easily understood by non-programmer. Most people are capable of recognising a document in a slightly unfamiliar form and how to read one, and XML is something they can recognise. You can design a xampl system by modelling paper pushing.

That's not to say xampl won't be able to work directly on Ruby classes at some point :slight_smile: Though that is a ways off I think.

Xampl is not about using XML for configuration, but for 1) describing
dynamic relationships between objects; and 2) persistence.

"describe" persistence or "implement" persistence? It seems rather the
latter.

Implement persistence as an option.

I agree with you that much of what XML, or YAML for that matter, is
used for can be better done in Ruby (or Python, or any other dynamic
language), certainly the way XML is used conventionally. Though xampl
changes the picture a bit.

The other thing xampl does is makes it a lot easier to deal with XML
based protocols. I've provided an example with the distribution (and
discussed in the documentation) of how to use xampl to read an Atom
1.0 or 0.3 feed over the internet, cache the feeds, extract the
entries, convert 0.3 entries to 1.0, aggregate in a new 1.0 feed
paying attention to ordering, and serve it up via WEBrick. Xampl
really helps in this kind of thing.

This is actually a really good question and I should prepare a better
answer. The background for what I'll say is documented in the
download file, but there is no direct answer to this question there.

So one of the strengths of xampl is to deal with existing XML data.

Yes, and producing XML. Though, and I really can't stress this enough, it even helps *a lot* if XML is only used as a description and never in practice.

<snip/>

     - XML, Ruby, and YAML persistence mechanism (purposely no
Marshal support)

Why is that? What's the reasoning behind this?

1) Upgrades of marshalled objects can be really nasty, using a text
form that xampl has control over while parsing, you have a chance of
intervening at an opportune time, making your life a lot easier.
2) You can read XML, Ruby and YAML.
3) You can use the data easily independently of any xampl program
(e.g. in a text editor :slight_smile:
4) You cannot control how much of the network of reachable objects is
written to one file (this is very important in xampl because of its
clustering capabilities).

There are more reasons that I've forgotten, these are enough for me.

Well, that's quite comprehensive! Thanks for the quick and exhaustive
answer!

:slight_smile:

···

On Nov 21, 2005, at 10:32 AM, Robert Klemme wrote:

On Nov 21, 2005, at 9:47 AM, Robert Klemme wrote:

Kind regards

    robert

----
Bob Hutchison -- blogs at <http://www.recursive.ca/hutch/&gt;
Recursive Design Inc. -- <http://www.recursive.ca/&gt;
Raconteur -- <http://www.raconteur.info/&gt;