I have been going through the book "High performance mysql", its really a nice book. But the only concern for myself is the MySQL sharding part. Even though there are a lot of theories but the practical implementation is lacking and some of the aspects are also like blackbox (arranging shrds on node). It would be great if somebody can point me to some case study article or paper so that i can under it properly.
Thanks in advance!!
I found one [link] (http://tumblr.github.com/assets/2011-11-massively_sharded_mysql.pdf). please share more if somebody has. Thanks.
Yes, "sharding" is rather a design/development pattern... It's not a database feature of any kind, I would call it "it's like the database had outsourced the scale-out capability to the application".
I work for ScaleBase (http://www.scalebase.com), which is a maker of a complete scale-out solution an "automatic sharding machine" if you like, analyzes the data and SQL stream, splits the data across DB nodes, load-balances reads, and aggregates results in runtime – so you won’t have to!
No code changes, everything continues to work with “1 database”. Your application or any other client tool (mysql, mysqldump, PHPMyAdmin...) connects to ScaleBase controller (looks and feels like a MySQL), which is a proxy to a grid of "shards", automating command routing and parallelizing cross-db queries, and merge results – exactly as if the result came from 1 database. ORDER, GROUP, LIMIT, agg functions supported!
Also, please visit my blog, http://database-scalability.blogspot.com/, all about scalability...
ScaleBase my company had a webinar not so long ago, specifically about sharding and data distribution. Amazingly it's not (yet?) in the http://www.scalebase.com/resources/webinars/. I'll see if they can upload it, or I'll have the slides attached here, or similar. Stay tuned!
Hope I helped...
Doron
I'm just getting started with interfacing to MySQL from a C++ app. The app is pretty simple: it's a Linux web server, and the C++ code retrieves JavaScript from a local database to return to the client via Apache and Ajax. The database will contain no more than a few thousand short JavaScript programs.
Question: any advice on which API I should use? I'm just reading through the docs on dev.mysql.com, and there doesn't seem to be any good reason to choose one or other of libmysql, Connector/C, Connector/C++, MySQL++, or Connector/ODBC. Thanks.
With no more than a few thousand rows, chances are, you should pick your API after your language preferences, not the other way round - so go aheead and chose whatever fits your mood.
If your app's performance stands and falls with the performance differences of the MySQL connectors you should be quite busy fixing your design elsewhere.
I personally prefer portability, so I tend to use a lot of ODBC, accepting the small performance hit, but others might think different. If you never ever want to use a different RDBMS stay away from ODBC - without the portability benefit it's quite ugly.
I would just use the raw C API. Seems to be the simplest way with the least overhead.
I'm inheriting a project that has, until now, had all its artifacts maintained in CVS and FogBugz. There's a ton of old and new documentation in MS Office format that needs to be reconciled.
I've seen some presentations on IBM Rational DOORS and think it would solve the lack of traceability across all these different documents and systems. My (possibly incorrect) understanding is that I could, for example, highlight a phrase in a Word document and mark that as a requirement, then create bi-directional links between that phrase and other artifacts, such as tasks in a bug-tracking system or entries in the changelog and user guide, to show that the requirement has been satisfied.
Unfortunately, if I want to use DOORS, I would probably have to install and maintain it myself. I found an open-source product for requirements management called rmtoo, but it looks like it would require me to rewrite all the documents document into a bunch of specially-formatted text files--which, for me, defeats the whole purpose. If DOORs is overkill, are there any low-overhead alternatives to DOORS?
DOORS has bidirectional links, but they are only from "DOORS objects" in a "DOORS module" to another "DOORS object" in the same or another "DOORS module".
A DOORS object is a little like a row in a spreadsheet file, and a DOORS module is a little like a spreadsheet file.
You have to import all of your material into DOORS to work with it -- DOORS can't work with documents or generally communicate with the outside world very well. Importing and exporting Word documents into DOORS is incredibly breaky.
DOORS is really dated and limited.
Update 2022: As a commenter rightly pointed out, the answer is dated due to changes in the tool ecosystem.
One of my frustrations is that there are many expensive tools (the main players are DOORS Next, Jama Connect, Codebeamer and Polarion).
For developers with a low budget, I often recommend R4J, which is a Jira Plugin. I find the installation and configuration process a little cumbersome, but other than that, it provides basic functions, especially traceability. As of this writing, it was $100/year for up to 10 people.
Original Answer
Do I understand correctly that you're trying to trace elements in DOORS, Word, Tracker-entry, etc.? I don't think what you saw is possible with DOORS out of the box. I think you need a tool like agosense for that, and tons of customization for adapters to the tools you need. If you really want to know, I'd talk to an IBM Sales Rep. But a DOORS-based solution will be really expensive.
It's unclear from your description how much control you have over the tool chain. If you have full control and are looking for a cheap solution, you may want to check out something like Trac. It's free and integrates bug tracking and Wiki (so essentially, for this to work you'd have to migrate your documentation from Office to the Wiki, and bugs from FogBugz to Trac - not sure whether your users will accept this, and it creates the same problem that rmtoo does).
Last, you could look into Requisite Pro, an IBM product that is cheaper than DOORS. It has the advantage that your requirements are managed directly in Word.
Hope this helps!
If DOORs is overkill, are there any low-overhead alternatives to
DOORS?
From experience, there are easily over 20 software tools (often ALM) that support the means of 'Requirements Engineering'.
Here is a short list:
Siemens Polarion
Cradle by 3SL
Perforce ALM
Jama
Intland
...and further IBM DOORS NG "Next Gen", SAP, MKS/PTC Integrity with RE Addon, etc.
As for architecture, I'd recommend EA, Rhapsody, NoMagic, Visual Paradigm.
We have also projects that manage requirements with Confluence. Apparently Gitlab is planning a RE feature.
DOORS is still in actively in use depending on your industry. And there is good reason why.
I am developing an application on google map and checking out various options to store and retrieve spatial information within a bounding box.
Initially I thought MySql was not a good option, but after checking http://dev.mysql.com/doc/refman/5.6/en/spatial-analysis-functions.html and http://code.google.com/apis/maps/articles/phpsqlsearch.html, looks like I can use MySql and it does support my use cases.
I was also evaluating node.js and couchdb with geocouch.. With modules like socket.io, geo etc looks like this is also a good choice. check out the book "Getting Started with GEO, CouchDB, and Node.js". My application would be 1 page application and I do not foresee if I would require rdbms anytime in future.
i have also seen this - http://nodeguide.com/convincing_the_boss.html and this makes me little apprehensive about whether to go with node.js-geocouch....
If the architecture for your next apps reads like the cookbook of
NoSQL ingredients, please pause for a second and read this.
Yes, Redis, CouchDB, MongoDB, Riak, Casandra, etc. all look really
tempting, but so did that red apple Eve couldn't resist. If you're
already taking a technological risk with using node.js, you shouldn't
multiply it with more technology you probably don't fully understand
yet.
Sure, there are legitimate use cases for choosing a document oriented
database. But if you are trying to build a business on top of your
software, sticking to conservative database technology (like postgres
or mysql) might just outweigh the benefits of satisfying your inner
nerd and impressing your friends.
What is your opinion ?
GeoCouch sounds like a good solution in your case. If you want to have an easy installation, you can have a look at Couchbase Single Server, which is basically a CouchDB with GeoCouch included (check out the Developer Preview for 2.0.
I have been doing a little reading on Flow Based Programming over the last few days. There is a wiki which provides further detail. And wikipedia has a good overview on it too. My first thought was, "Great another proponent of lego-land pretend programming" - a concept harking back to the late 80's. But, as I read more, I must admit I have become intrigued.
Have you used FBP for a real project?
What is your opinion of FBP?
Does FBP have a future?
In some senses, it seems like the holy grail of reuse that our industry has pursued since the advent of procedural languages.
1. Have you used FBP for a real project?
We've designed and implemented a DF server for our automation project (dispatcher, component iterface, a bunch of components, DF language, DF compiler, UI). It is written in bare C++, and runs on several Unix-like systems (Linux x86, MIPS, avr32 etc., Mac OSX). It lacks several features, e.g. sophisticated flow control, complex thread control (there is only a not too advanced component for it), so it is just a prototype, even it works. We're now working on a full-featured server. We've learnt lot during implementing and using the prototype.
Also, we'll make a visual editor some day.
2. What is your opinion of FBP?
2.1. First of all, dataflow programming is ultimate fun
When I met dataflow programming, I was feel like 20 years ago, when I met programming first. Altough, DF programming differs from procedural/OOP programming, it's just a kind of programming. There are lot of things to discover, even sooo simple ones! It's very funny, when, as an experienced programmer, you met a DF problem, which is a very-very basic thing, but it was completely unknown for you before. So, if you jump into DF programming, you will feel like a rookie programmer, who first met the "cycle" or "condition".
2.2. It can be used only for specific architectures
It's just a hammer, which are for hammering nails. DF is not suitable for UIs, web server and so on.
2.3. Dataflow architecture is optimal for some problems
A dataflow framework can make magic things. It can paralellize procedures, which are not originally designed for paralellization. Components are single-threaded, but when they're organized into a DF graph, they became multi-threaded.
Example: did you know, that make is a DF system? Try make -j (see man, what -j is used for). If you have multi-core machine, compile your project with and without -j, and compare times.
2.4. Optimal split of the problem
If you're writing a program, you often split up the problem for smaller sub-problems. There are usual split points for well-known sub-problems, which you don't need to implement, just use the existing solutions, like SQL for DB, or OpenGL for graphics/animation, etc.
DF architecture splits your problem a very interesting way:
the dataflow framework, which provides the architecture (just use an existing one),
the components: the programmer creates components; the components are simple, well-separated units - it's easy to make components;
the configuration: a.k.a. dataflow programming: the configurator puts the dataflow graph (program) together using components provided by the programmer.
If your component set is well-designed, the configurator can build such system, which the programmer has never even dreamed about. Configurator can implement new features without disturbing the programmer. Customers are happy, because they have personalised solution. Software manufacturer is also happy, because he/she don't need to maintain several customer-specific branches of the software, just customer-specific configurations.
2.5. Speed
If the system is built on native components, the DF program is fast. The only time loss is the message dispatching between components compared to a simple OOP program, it's also minimal.
3. Does FBP have a future?
Yes, sure.
The main reason is that it can solve massive multiprocessing issues without introducing brand new strange software architectures, weird languages. Dataflow programming is easy, and I mean both: component programming and dataflow configuration building. (Even dataflow framework writing is not a rocket science.)
Also, it's very economic. If you have a good set of components, you need only put the lego bricks together. A DF program is easy to maintain. The DF config building requires no experienced programmer, just a system integrator.
I would be happy, if native systems spread, with doors open for custom component creating. Also there should be a standard DF language, which means that it can be used with platform-independent visual editors and several DF servers.
Interesting discussion! It occurred to me yesterday that part of the confusion may be due to the fact that many different notations use directed arcs, but use them to mean different things. In FBP, the lines represent bounded buffers, across which travel streams of data packets. Since the components are typically long-running processes, streams may comprise huge numbers of packets, and FBP applications can run for very long periods - perhaps even "perpetually" (see a 2007 paper on a project called Eon, mostly by folks at UMass Amherst). Since a send to a bounded buffer suspends when the buffer is (temporarily) full (or temporarily empty), indefinite amounts of data can be processed using finite resources.
By comparison, the E in Grafcet comes from Etapes, meaning "steps", which is a rather different concept. In this kind of model (and there are a number of these out there), the data flowing between steps is either limited to what can be held in high-speed memory at one time, or has to be held on disk. FBP also supports loops in the network, which is hard to do in step-based systems - see for example http://www.jpaulmorrison.com/cgi-bin/wiki.pl?BrokerageApplication - notice that this application used both MQSeries and CORBA in a natural way. Furthermore, FBP is natively parallel, so it lends itself to programming of grid networks, multicore machines, and a number of the directions of modern computing. One last comment: in the literature I have found many related projects, but few of them have all the characteristics of FBP. A list that I have amassed over the years (a number of them closer than Grafcet) can be found in http://www.jpaulmorrison.com/cgi-bin/wiki.pl?FlowLikeProjects .
I do have to disagree with the comment about FBP being just a means of implementing FSMs: I think FSMs are neat, and I believe they have a definite role in building applications, but the core concept of FBP is of multiple component processes running asynchronously, communicating by means of streams of data chunks which run across what are now called bounded buffers. Yes, definitely FSMs are one way of building component processes, and in fact there is a whole chapter in my book on FBP devoted to this idea, and the related one of PDAs (1) - http://www.jpaulmorrison.com/fbp/compil.htm - but in my opinion an FSM implementing a non-trivial FBP network would be impossibly complex. As an example the diagram shown in
is about 1/3 of a single batch job running on a mainframe. Every one of those blocks is running asynchronously with all the others. By the way, I would be very interested to hearing more answers to the questions in the first post!
1: http://en.wikipedia.org/wiki/Pushdown_automaton Push-down automata
Whenever I hear the term flow based programming I think of LabView, conceptually. Ie component processes who's scheduling is driven primarily by a change to its input data. This really IS lego programming in the sense that the labview platform was used for the latest crop of mindstorm products. However I disagree that this makes it a less useful programming model.
For industrial systems which typically involve data collection, control, and automation, it fits very well. What is any control system if not data in transformed to data out? Ie what component in your control scheme would you not prefer to represent as a black box in a bigger picture, if you could do so. To achieve that level of architectural clarity using other methodologies you might have to draw a data domain class diagram, then a problem domain run time class relationship, then on top of that a use case diagram, and flip back and forth between them. With flow driven systems you have the luxury of being able to collapse a lot of this information together accurately enough that you can realistically design a system visually once the components are build and defined.
One question I never had to ask when looking at an application written in labview is "What piece of code set this value?", as it was inherent and easy to trace backwards from the data, and also mistakes like multiple untintended writers were impossible to create by mistake.
If only that was true of code written in a more typically procedural fashion!
1) I build a small FBP framework for an anomaly detection project, and it turns out to have been a great idea.
You can also have a look at some of the KNIME videos, that give a good idea of what a flow based framework feels like when the framework is put together by a great team. Admittedly, it is batch based and not created for continuous operation.
By far the best example of flow based programming, however, is UNIX pipes which is one of the oldest, most overlooked FBP framework. I don't think I have to elaborate on the power of nix pipes...
2) FBP is a very powerful tool for a large set of problems. The intrinsic parallelism is a great advantage, and any FBP framework can be made completely network transparent by using adapter modules. Smart frameworks are also absurdly fault tolerant, and able to dynamically reload crashed modules when necessary. The conceptual simplicity also allows cleaner communication with everybody involved in a project, and much cleaner code.
3) Absolutely! Pipes are here to stay, and are one of the most powerful feature of unix. The power inherent in a FBP framework compared to a static program are many, and trivialise change, to the point where some frameworks can be reconfigured while running with no special measures.
FBP FTW! ;-)
In automotive development, they have a language agnostic messaging protocol which is part of the MOST specification (Media Oriented Systems Transport), this was designed to communicate between components over a network or within the same device. Systems usually have both a real and visualized message bus - therefore you effectively have a form of flow based programming.
That was what made the light bulb go on for me several years ago and brought me here. It really is a fantastic way to work and so much more fun than conventional programming. The message catalog form the central specification and point of reference. It works well for both developers and management. i.e. Management are able to browse the message catalog instead of looking at source.
With integrated logging also referencing the catalog to produce intelligible analysis things can get really productive. I have real world experience of developing commercial products in this way. I am interested in taking things further, particularly with regards to tools and IDEs. Unfortunately I think many people within the automotive sector have missed the point about how great this is and have failed to build on it. They are now distracted by other fads and failed to realize that there was far more to most development than the physical bus.
I've used Spring Web Flow extensively in Java Web applications to model (typically) application processes, which tend to be complex wizard-like affairs with lots of conditional logic as to which pages to display. Its incredibly powerful. A new product was added and I managed to recut the existing pieces into a completely new application process in an hour or two (with adding a couple of new views/states).
I also looked into using OS Workflow to model business processes but that project got canned for various reasons.
In the Microsoft world you have Windows Workflow Foundation ("WWF"), which is becoming more popular, particularly in conjunction with Sharepoint.
FBP is just a means of implementing a finite state machine. It's nothing new.
I realize that it is not exactly the same thing, but this model has been used for years in PLC programming. ISO calls it Sequential Flow Chart, but many people call it Grafcet after a popular implementation. It offers parallel processing and defines transitions between states.
It's being used in the Business Intelligence world these days to mashup and process data. Data processing steps like ETL, querying, joining , and producing reports can be done by the end-user. I'm a developer on an open system - ComposableAnalytics.com In CA, the flow-based apps can be shared and executed via the browser.
This is what MQ Series, MSMQ and JMS are for.
This is cornerstone of Web Services and Enterprise Service Bus implementations.
Products like TIBCO and Sun's JCAPS are basically flow-based without using this particular buzz-word.
Most of the work of the application is done with small modules that pass messages through a processing network.