Resolving Conflicts in your Data Sync app
Introduction
Typically, mobile apps allow users to modify data while offline, which results in conflicts. A conflict occurs when two or more users try to modify the same data.
For example, a user modifies a record while offline, and another user deletes that record at the same time. The system needs to resolve the conflicting data.
Conflict resolution can be handled in two phases:
-
Conflict detection is the ability of an application to detect the possibility of incorrect data being stored.
-
Conflict resolution is the process of ensuring that the correct data is stored.
With AeroGear Data Sync:
-
You implement conflict detection exclusively in the code associated with mutations.
-
The Voyager Server module provides conflict detection on the server side.
-
The Voyager Client module provides conflict resolution on the client side.
Detecting conflicts on the server
A typical flow for detecting conflicts includes the following steps:
-
A Mutation Occurs - A client tries to modify or delete an object on the server using a GraphQL mutation
-
Read the Object - The server reads the current object that the client is trying to modify from the data source
-
Conflict Detection - The server compares the current object with the data sent by the client to see if there is a conflict. The developer chooses how the comparison is performed.
The aerogear/voyager-conflicts
module helps developers with the Conflict Detection steps regardless of the storage technology, while the fetching and storing of data is the responsibility of the developer.
This release supports the following implementations:
-
VersionedObjectState
- depends on the version field supplied in objects (the version field is used by default when importing conflictHandler). For details, please see: Implementing version based conflict detection -
HashObjectState
- depends on a hash calculated from the entire object. For details, please see: Implementing hash based conflict detection
These implementations are based on the ObjectState
interface and that interface can be extended to provide custom implementations for conflict detection.
-
GraphQL server with resolvers.
-
Database or any other form of data storage that can cause data conflicts. AeroGear recommends that you store data in a secure location. If you use a database, it is your responsibility to administer, maintain and backup that database. If you use any other form of data storage, you are responsible for backing up the data.
Implementing version based conflict detection
Version based conflict resolution is the recommended and simplest approach for conflict detection and resolution. The core idea is that every object has a version
property with an integer value. A conflict occurs when the version number sent by the client does not match the version stored in the server. This means a different client has already updated the object.
-
Import the @aerogear/voyager-conflicts package.
const { conflictHandler } = require('@aerogear/voyager-conflicts')
-
Add a version field to the GraphQL type that should support conflict resolution. The version should also be stored in the data storage.
type Task { title: String version: Int }
-
Add an example mutation.
type Mutation { updateTask(title: String!, version: Int!): Task }
-
Implement the resolver. Every conflict can be handled using a set of predefined steps, for example:
// 1. Read data from data source const serverData = db.find(clientData.id) // 2. Check for conflicts const conflict = conflictHandler.checkForConflicts(serverData, clientData) // 3. If there is a conflict, return the details to the client if(conflict) { throw conflict; } // 4. Save object to data source db.save(clientData.id, clientData)
In the example above, the throw
statement ensures that the client receives all necessary data to resolve the conflict client-side. For more information about this data, please see Structure of the Conflict Error.
Since the conflict will be resolved on the client, it is not required to persist the data. However, if there is no conflict, the data sent by the client should be persisted. For more information on resolving the conflict client-side, please see: Resolving Conflicts on the Client.
Implementing hash based conflict detection
Hash based conflict detection is a mechanism to detect conflicts based on the total object being updated by the client. It does this by hashing each object and comparing the hashes. This tells the server whether or not the objects are equivalent and can be considered conflict free.
-
Import the @aerogear/voyager-conflicts package.
const { HashObjectState } = require('@aerogear/voyager-conflicts')
-
When using the
HashObjectState
implementation, a hashing function must be provided. The function signature should be as follows:const hashFunction = (object) { // Using the Hash library of your choice const hashedObject = Hash(object) // return the hashedObject in string form return hashedObject; }
-
Provide this function when instantiating the
HashObjectState
:const conflictHandler = new HashObjectState(hashFunction)
-
Implement the resolver. Every conflict can be handled using a set of predefined steps, for example:
// 1. Read data from data source const serverData = db.find(clientData.id) // 2. Check for conflicts const conflict = conflictHandler.checkForConflicts(serverData, clientData) // 3. If there is a conflict, return the details to the client if(conflict) { throw conflict; } // 4. Save object to data source db.save(clientData.id, clientData)
In the example above, the throw
statement ensures the client receives all necessary data to resolve the conflict client-side. For more information about this data please see Structure of the Conflict Error.
Since the conflict will be resolved on the client, it is not required to persist the data. However, if there is no conflict, the data sent by the client should be persisted. For more information on resolving the conflict client-side, please see: Resolving Conflicts on the Client.
About the structure of the conflict error
The server needs to return a specific error when a conflict is detected containing both the server and client states. This allows the client to resolve the conflict.
"extensions": {
"code": "INTERNAL_SERVER_ERROR",
"exception": {
"conflictInfo": {
"serverState": {
//..
},
"clientState": {
//..
}
},
}
}
Resolving Conflicts on the client
A typical flow for resolving conflicts includes the following steps:
-
A Mutation Occurs - A client tries to modify or delete an object on the server using a GraphQL mutation.
-
Read the Object - The server reads the current object the client is trying to modify from the data source (usually a database).
-
Conflict Detection - The server compares the current object with the data sent by the client to see if there was a conflict. If there is a conflict, the server returns a response to the client containing information outlined in Structure of the Conflict Error
-
Conflict Resolution - The client attempts to resolve this conflict and makes a new request to the server in the hope that this data is no longer conflicted.
The conflict resolution implementation requires the following additions to your application:
-
A
returnType
added to the context of any mutation. see: Working With Conflict Resolution on the Client. -
Additional metadata inside types (for example version field) depending on the conflict implementation you chose. see: Version Based Conflict Detection.
-
Server-side resolvers to return conflicts back to clients first. For more information, see: Server Side Conflict Detection.
Developers can either use the default conflict resolution implementations, or implement their own conflict resolution implementations using the conflict resolution mechanism.
By default, when no changes are made on the same fields, the implementation attempts to resend the modified payload back to the server. When changes on the server and on the client affect the same fields, one of the specified conflict resolution strategies can be used. The default strategy applies client changes on top of the server side data. Developers can modify strategies to suit their needs.
Implementing conflict resolution on the client
To enable conflict resolution, the server side resolvers must be configured to perform conflict detection. Detection can rely on different implementations and return the conflict error back to the client. See Server Side Conflict Detection for more information.
Provide the mutation context with the returnType
parameter to resolve conflicts.
This parameter defines the Object type being operated on.
You can implement this in two ways:
-
If using Data Sync’s
offlineMutate
you can provide thereturnType
parameter directly as follows:client.offlineMutate({ ... returnType: 'Task' ... })
-
If using Apollo’s
mutate
function, provide thereturnType
parameter as follows:client.mutate({ ... context: { returnType: 'Task' } ... })
The client automatically resolves the conflicts based on the current strategy and notifies listeners as required.
Conflict resolution works with the recommended defaults and does not require any specific handling on the client.
For advanced use cases, the conflict implementation can be customised by supplying a custom conflictProvider in the application config. See Conflict Resolution Strategies below.
|
About the default conflict implementation
By default, conflict resolution is configured to rely on a version
field on each GraphQL type.
You must save a version field to the database in order to detect changes on the server.
For example:
type User {
id: ID!
version: String!
name: String!
}
The version field is controlled on the server and maps the last version that was sent from the server. All operations on the version field happen automatically. Make sure that the version field is always passed to the server for mutations that supports conflict resolution:
type Mutation {
updateUser(id: ID!, version: String!): User
}
Implementing conflict resolution strategies
Data Sync allows developers to define custom conflict resolution strategies. You can provide custom conflict resolution strategies to the client in the config by using the provided ConflictResolutionStrategies
type.
By default developers do not need to pass any strategy as UseClient
is the default.
Custom strategies can also be used to provide different resolution strategies for certain operations:
let customStrategy = {
resolve = (base, server, client, operationName) => {
let resolvedData;
switch (operationName) {
case "updateUser":
delete client.socialKey
resolvedData = Object.assign(base, server, client)
break
case "updateRole":
client.role = "none"
resolvedData = Object.assign(base, server, client)
break
default:
resolvedData = Object.assign(base, server, client)
}
return resolvedData
}
}
This custom strategy object provides two distinct strategies. The strategies are named to match the operation. You pass the name of the object as an argument to conflictStrategy in your config object:
let config = {
...
conflictStrategy: customStrategy
...
}
Listening to conflicts
Data Sync allows developers to receive information about the data conflict.
When a conflict occurs, Data Sync attempts to perform a field level resolution of data - it checks all fields of its type to see if both the client or server has changed the same field. The client can be notified in one of two scenarios.
-
If both client and server have changed any of the same fields, the
conflictOccurred
method of theConflictListener
is triggered. -
If the client and server have not changed any of the same fields, and the data can be easily merged, the
mergeOccurred
method of yourConflictListener
is triggered.
Developers can supply their own conflictListener
implementation, for example:
class ConflictLogger implements ConflictListener {
conflictOccurred(operationName, resolvedData, server, client) {
console.log("Conflict occurred with the following:")
console.log(`data: ${JSON.stringify(resolvedData)}, server: ${JSON.stringify(server)}, client: ${JSON.stringify(client)}, operation: ${JSON.stringify(operationName)}`);
}
mergeOccurred(operationName, resolvedData, server, client) {
console.log("Merge occurred with the following:")
console.log(`data: ${JSON.stringify(resolvedData)}, server: ${JSON.stringify(server)}, client: ${JSON.stringify(client)}, operation: ${JSON.stringify(operationName)}`);
}
}
let config = {
...
conflictListener: new ConflictLogger()
...
}
Handling pre-conflict errors
Data Sync provides a mechanism for developers to check for a 'pre-conflict' before a mutation occurs. It checks whether or not the data being sent conflicts locally. This happens when a mutation (or the act of creating a mutation) is initiated.
For example, consider a user performing the following actions:
-
opens a form
-
begins working on the pre-populated data on this form
-
the client receives new data from the server from subscriptions
-
the client is now conflicted but the user is unaware
-
when the user presses Submit Data Sync notices that their data is conflicted and provides the developer with the information to warn the user
To use this feature, and therefore potentially save unecessary round-trips to the server with data which is definitely conflicted, developers can make use of the error returned by Data Sync.
An example of how developers can use this error:
return client.offlineMutate({
...
}).then(result => {
// handle the result
}).catch(error => {
if (error.networkError && error.networkError.localConflict) {
// handle pre-conflict here by potentially
// providing an alert with a chance to update data before pressing send again
}
})


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text
To be able to observe this case easily, use really short deadline:
this.flushQueue({ timeRemaining: () => 0 });
At first, this page should have 2 clickable elements. After clicking on the Remove button, it should have 1 clickable element. Check the performance section in the options page!
This case is tricky because the link is removed from the paragraph after
the paragraph has already been removed from the DOM, but before we’ve had
a chance to run .querySelectorAll("*")
on it. This is why we
need to observe all removed nodes with a separate MutationObserver until
the queue has been flushed.
Note: The case does only seem to trigger if clicking the button with the mouse.


+++ title = "Willy" slug = "willy" date = 2007-07-02T13:00:00+10:00 tags = ["eccentric-encounters", "kids", "locals"] locations = ["bolivia/salar-de-uyuni"] draft = false summary = """
Great little kid, and the eldest son (out of three kids) of our tourguide for our three days in the Salar de Uyuni, Raul. This was Willy's first time tagging along with his Dad on a salt flats tour, and he loved it. He was brought along mainly to help with the cooking, but also to see how the tourguide thing is done (he'll probably be a guide too, one day), and just to enjoy the ride. I gave him my salty dice at the end of the trip.
""" +++Great little kid, and the eldest son (out of three kids) of our tourguide for our three days in the Salar de Uyuni, Raul. This was Willy's first time tagging along with his Dad on a salt flats tour, and he loved it. He was brought along mainly to help with the cooking, but also to see how the tourguide thing is done (he'll probably be a guide too, one day), and just to enjoy the ride. I gave him my salty dice at the end of the trip.
{{< galleryphoto "2007-07-02-13-00-00--willy-s-the-little-fella-in-front-of-chris.jpg" >}}


i am using the yhdc sct013 current transformer to measure the current flows through the 660 ohm resistor(i used the multimeter to mesaure current about 51mA). i have basically everything set up properly, but when i run the sketch "a single Ct" there is a column of zero shown in the serial monitor. i am in australia, so the three pin power plug is like line(brown),netural(blue) i have tried clipping the CT on either line or netural cable with both directions, but there isstill no result shown.
Re: current sensor
So you mean the c.t's burden resistor is 660 Ω? That is far too large and will restrict the range of current that you can read to about 3 A before distortion and errors start to creep in. What is the rest of the hardware that you are using, an emonTx or what? I think you must have an assembly error somewhere. Carefully check what you have built against the photographs and component lists.
Re: current sensor
i upload the photo of the set up, the load(resistor) is 660ohms, but i changed it to 30 ohms and current through the resistor is 1.5 A when i applied the voltage 50v. still does not work.
Re: current sensor
i am using the emontx shield which i think it is the same as the emontx... what is the minimun current that the CT can detect.
Re: current sensor
The emonTX shield is NOT the same as the emonTx, the inputs are arranged differently. You need to get the emonTx SHIELD example from Github.
Note: I have deleted the other thread you started because you will waste everyone's time by having two threads about the same problem.
Re: current sensor
ok, but the emonTx shield example only has the sketch for CT1234 and i have only one CT. so the "single CT " sketch only works for emonTX not emonTX shield? could you plz tell me the minimum current that the CT can detect because i am testing with 1.5A , is it will be detected by CT or not.
Re: current sensor
I hate to ask the obvious, but just in case, your 50V is AC right? Assuming yes, then you should be able to put an AC voltmeter across the burden resistor and see what sort of response you're getting from the CT.
Re: current sensor
my applied voltage 50 v is AC definitely. if i place the AC voltmeter in parallel with the load , there was the correct reading. i dont quite understand what u mean by response from CT, do u mean put the meter to the output pin that was plugged into the shield?
Re: current sensor
Leave the CT plugged into the shield, and put an AC voltmeter across the burden resistor, then you'll see what sort of swing you're getting out of the CT.
Re: current sensor
i will try what you said appreciate first !
but i think i am using the wrong sketch, i am current running the sketch"single CT" as i have only only CT, but this sketch is not actually for the emontx shield. so the correct sketch for emontx shield that i am guessing should be"emontxshield _CT1234" but this one has the four CTs plugged in. so can i still using this code for one CT testing.
the burden resistor you mean is the load(such as lihgt bulb, in my case i am using the 30ohms resistor instead for testing only), right?
Re: current sensor
[Moved from a new thread]
Submitted by chunyang on Tue, 10/09/2013 - 13:58
i am using emontx shield and i have only one CT to use. i try to measure the current flow through the 30ohm resistor with the applied voltage 50v. the flow current would be about 1.5A . i set up the test and run the sketch "single CT" , however there is "zero" keep poping up on the serial monitor. so for my situation, am i suing the correct sketch for emontx shield just for measuring the current first and later will be voltage,power factor so on....
i have also looked at the code for emontx shield CT1234 but since it is for 4 CTs and as i mentioned that i am only using on CT so far.
chunyang: you are making it difficult by starting a new thread each time. Please use THIS thread then all of us can see the whole picture.
I think chunyang is using a wirewound mains dropper resistor as his test load, and running it at reduced voltage (50 V). He's not using the voltage yet so there should be no problem with this test rig.
The burden is the special name for the load for the current transformer, in this case it is a 33 Ω resistor on the Shield p.c.b. The c.t. is a current source - the current out of the secondary winding is proportional to the primary current. The burden converts that secondary current to a voltage suitable for the analogue to digital converter.
You will not get the standard emonTx sketches to work with the shield, because the inputs are different. The shield uses AI 0 for the voltage, AI 1 - 4 for ct inputs 1 - 4. The emonTx uses AI 2 for the voltage, AI 3 for CT1, AI 0 for CT2 & AI 1 for CT3.
Use the sketch emonTxShield_CT1234 if you are not measuring voltage, or emonTxShield_CT1234_Voltage if you are measuring voltage with an AC-AC adapter. If you are not using CT 2, CT3 & CT4, near the top of the sketch you should change
CT2 = 1; to CT2 = 0;
CT3 = 1; to CT3 = 0;
CT4 = 1; to CT4 = 0;
If you have the standard emonTx Shield (you have not changed anything) then you should be able to read 1.5 A reasonably accurately.
Re: current sensor
i did what u told me. but without clipping anything on the CT why there is still reading. and i guess that the reading printed out on the serial monitor is the power instead of the current because in the sketch i didnot see code such as"serial.print(current)"
Re: current sensor
In line 55 you have:
EnergyMonitor ct1,ct2,ct3, ct4;
If you look at emonLib.h (and we know to look there because of "#include EmonLib.h" in the line before) you see EnergyMonitor is defined as a class. In there "Public" means all the quantities listed can be used outside the class, the ones listed as "Private" can only be used inside. The one you are interested in is:
double calcIrms(int NUMBER_OF_SAMPLES, long refCal=1126400L);
calcIrms is "method" - the same as a function in "C" - that does a calculation for us and returns a value.
In the sketch, line 55 makes 4 separate "instances" of EnergyMonitor called ct1, ct2, ct3 & ct4. You are only using ct1.
In line 95 you have:
if (CT1) {
emontx.power1 = ct1.calcIrms(1480) * 240.0; //ct.calcIrms(number of wavelengths sample)
// * AC RMS voltage
Serial.print(emontx.power1);
}
calcIrms( ... ) does the calculation and returns a value - the rms current in this case. To get the one associated with ct1, you write "ct1." in front of the name. Therefore, if you change that to:
if (CT1) {
Serial.print(ct1.calcIrms(1480));
}
you will print the current.
If you want both current and power, you must invent a new variable to store the current, otherwise if you do calcIrms( ... ) again, you will read 1480 samples again.
if (CT1) {
double Irms = ct1.calcIrms(1480);
Serial.print("Irms = "); Serial.print(Irms);
Serial.print(" Power = "); Serial.println(Irms * 240.0); // If your voltage is 240 V
}
There will always be a small reading because electronic noise from the processor is picked up by the analogue input. It will get smaller when you add the voltage sensor and calculate real power.
Re: current sensor
chunyang: have you tried running the sketches that I mentioned a few days ago? This will demonstrate whether your current and voltage sensors are working correctly or not.
If you were to run MinMaxAndRangeChecker.ino and RawSamplesTool_4ss_2.ino from my Summary Page, and post the results here, I would hope to be able to guide you in the right direction. Many constructors have found these tools to be helpful. I regularly use them myself to check the operation of any new hardware.
Re: current sensor
thank you i will try
Re: current sensor
ok i will definitely try both of them so firstly i have to upload them to my arduino just like the normal sketch ?
Re: current sensor
Blimey, you are keen - it must be 4 am where you are now!
Yep, just upload those sketches and run. If using the emonTx Shield, you will need to amend the pin allocations in the RawSamplesTool sketch. The MinAndMax sketch is a generic tool for analog inputs 0 to 3, so should work fine as posted.


Bradlee Speice, Sat 22 October 2016, Blog
I listen to a lot of Drum and Bass music, because it's beautiful music. And there's a particular site, Bassdrive.com that hosts a lot of great content. Specifically, the archives section of the site has a list of the past shows that you can download and listen to. The issue is, it's just a giant list of links to download. I'd really like this in a podcast format to take with me on the road, etc.
So I wrote the elektricity web application to actually accomplish all that. Whenever you request a feed, it goes out to Bassdrive, processes all the links on a page, and serves up some fresh, tasty RSS to satisfy your ears. I hosted it on Heroku using the free tier because it's really not resource-intensive at all.
The issue so far is that I keep running out of free tier hours during a month because my podcasting application likes to have a server scan for new episodes constantly. Not sure why it's doing that, but I don't have a whole lot of control over it. It's a phenomenal application otherwise.
My (over-engineered) solution: Re-write the application using the Rust programming language. I'd like to run this on a small hacker board I own, and doing this in Rust would allow me to easily cross-compile it. Plus, I've been very interested in the Rust language for a while and this would be a great opportunity to really learn it well. The code is available here as development progresses.
We'll be using the iron library to handle the server, and hyper to fetch the data we need from elsewhere on the interwebs. HTML5Ever allows us to ingest the content that will be coming from Bassdrive, and finally, output is done with handlebars-rust.
It will ultimately be interesting to see how much more work must be done to actually get this working over another language like Python. Coming from a dynamic state of mind it's super easy to just chain stuff together, ship it out, and call it a day. I think I'm going to end up getting much dirtier trying to write all of this out.
Strings in Rust are hard. I acknowledge Python can get away with some things
that make strings super easy (and Python 3 has gotten better at cracking down
on some bad cases, str <-> bytes
specifically), but Rust is hard.
Let's take for example the 404
error handler I'm trying to write. The result
should be incredibly simple: All I want is to echo back
Didn't find URL: <url>
. Shouldn't be that hard right? In Python I'd just do
something like:
def echo_handler(request):
return "You're visiting: {}".format(request.uri)
And we'd call it a day. Rust isn't so simple. Let's start with the trivial examples people post online:
fn hello_world(req: &mut Request) -> IronResult<Response> {
Ok(Response::with((status::Ok, "You found the server!")))
}
Doesn't look too bad right? In fact, it's essentially the same as the Python
version! All we need to do is just send back a string of some form. So, we
look up the documentation for Request
and see a url
field that will contain
what we want. Let's try the first iteration:
fn hello_world(req: &mut Request) -> IronResult<Response> {
Ok(Response::with((status::Ok, "You found the URL: " + req.url)))
}
Which yields the error:
error[E0369]: binary operation `+` cannot be applied to type `&'static str`
OK, what's going on here? Time to start Googling for "concatenate strings in Rust". That's what we want to do right? Concatenate a static string and the URL.
After Googling, we come across a helpful concat!
macro that looks really nice! Let's try that one:
fn hello_world(req: &mut Request) -> IronResult<Response> {
Ok(Response::with((status::Ok, concat!("You found the URL: ", req.url))))
}
And the error:
error: expected a literal
Turns out Rust actually blows up because the concat!
macro expects us to know
at compile time what req.url
is. Which, in my outsider opinion, is a bit
strange. println!
and format!
, etc., all handle values they don't know at
compile time. Why can't concat!
? By any means, we need a new plan of attack.
How about we try formatting strings?
fn hello_world(req: &mut Request) -> IronResult<Response> {
Ok(Response::with((status::Ok, format!("You found the URL: {}", req.url))))
}
And at long last, it works. Onwards!
Rust's single coolest feature is how the compiler can guarantee safety in your
program. As long as you don't use unsafe
pointers in Rust, you're guaranteed
safety. And not having truly manual memory management is really cool; I'm
totally OK with never having to write malloc()
again.
That said, even the Rust documentation makes a specific note:
Many new users to Rust experience something we like to call ‘fighting with the borrow checker’, where the Rust compiler refuses to compile a program that the author thinks is valid.
If you have to put it in the documentation, it's not a helpful note: it's hazing.
So now that we have a handler which works with information from the request, we
want to start making something that looks like an actual web application.
The router provided by iron
isn't terribly difficult so I won't cover it.
Instead, the thing that had me stumped for a couple hours was trying to
dynamically create routes.
The unfortunate thing with Rust (in my limited experience at the moment) is that there is a severe lack of non-trivial examples. Using the router is easy when you want to give an example of a static function. But how do you you start working on things that are a bit more complex?
We're going to cover that here. Our first try: creating a function which returns other functions. This is a principle called currying. We set up a function that allows us to keep some data in scope for another function to come later.
fn build_handler(message: String) -> Fn(&mut Request) -> IronResult<Response> {
move |_: &mut Request| {
Ok(Response::with((status::Ok, message)))
}
}
We've simply set up a function that returns another anonymous function with the
message
parameter scoped in. If you compile this, you get not 1, not 2, but 5
new errors. 4 of them are the same though:
error[E0277]: the trait bound `for<'r, 'r, 'r> std::ops::Fn(&'r mut iron::Request<'r, 'r>) -> std::result::Result<iron::Response, iron::IronError> + 'static: std::marker::Sized` is not satisfied
...oookay. I for one, am not going to spend time trying to figure out what's going on there.
And it is here that I will save the audience many hours of frustrated effort.
At this point, I decided to switch from iron
to pure hyper
since using
hyper
would give me a much simpler API. All I would have to do is build a
function that took two parameters as input, and we're done. That said, it
ultimately posed many more issues because I started getting into a weird fight
with the 'static
lifetime
and being a Rust newbie I just gave up on trying to understand it.
Instead, we will abandon (mostly) the curried function attempt, and instead
take advantage of something Rust actually intends us to use: struct
and
trait
.
Remember when I talked about a lack of non-trivial examples on the Internet? This is what I was talking about. I could only find one example of this available online, and it was incredibly complex and contained code we honestly don't need or care about. There was no documentation of how to build routes that didn't use static functions, etc. But, I'm assuming you don't really care about my whining, so let's get to it.
The iron
documentation mentions the Handler
trait as being something we can implement.
Does the function signature for that handle()
method look familiar? It's what
we've been working with so far.
The principle is that we need to define a new struct
to hold our data, then
implement that handle()
method to return the result. Something that looks
like this might do:
struct EchoHandler {
message: String
}
impl Handler for EchoHandler {
fn handle(&self, _: &mut Request) -> IronResult<Response> {
Ok(Response::with((status::Ok, self.message)))
}
}
// Later in the code when we set up the router...
let echo = EchoHandler {
message: "Is it working yet?"
}
router.get("/", echo.handle, "index");
We attempt to build a struct, and give its handle
method off to the router
so the router knows what to do.
You guessed it, more errors:
error: attempted to take value of method `handle` on type `EchoHandler`
Now, the Rust compiler is actually a really nice fellow, and offers us help:
help: maybe a `()` to call it is missing? If not, try an anonymous function
We definitely don't want to call that function, so maybe try an anonymous function as it recommends?
router.get("/", |req: &mut Request| echo.handle(req), "index");
Another error:
error[E0373]: closure may outlive the current function, but it borrows `echo`, which is owned by the current function
Another helpful message:
help: to force the closure to take ownership of `echo` (and any other referenced variables), use the `move` keyword
We're getting closer though! Let's implement this change:
router.get("/", move |req: &mut Request| echo.handle(req), "index");
And here's where things get strange:
error[E0507]: cannot move out of borrowed content
--> src/main.rs:18:40
|
18 | Ok(Response::with((status::Ok, self.message)))
| ^^^^ cannot move out of borrowed content
Now, this took me another couple hours to figure out. I'm going to explain it, but keep this in mind: Rust only allows one reference at a time (exceptions apply of course).
When we attempt to use self.message
as it has been created in the earlier
struct
, we essentially are trying to give it away to another piece of code.
Rust's semantics then state that we may no longer access it unless it is
returned to us (which iron
's code does not do). There are two ways to fix
this:
&self.message
instead of self.message
)
instead of transferring ownershipI didn't know these were the two options originally, so I hope this helps the
audience out. Because iron
won't accept a reference, we are forced into the
second option: making a copy. To do so, we just need to change the function
to look like this:
Ok(Response::with((status::Ok, self.message.clone())))
Not so bad, huh? My only complaint is that it took so long to figure out exactly what was going on.
And now we have a small server that we can configure dynamically. At long last.
Final sidenote: You can actually do this without anonymous functions. Just change the router line to:
router.get("/", echo, "index");
Rust's type system seems to figure out that we want to use the
handle()
method.
After a good long days' work, we now have the routing functionality set up on our application. We should be able to scale this pretty well in the future: the RSS content we need to deliver in the future can be treated as a string, so the building blocks are in place.
There are two important things I learned starting with Rust today:
Number 1 is pretty obvious and not surprising to anyone. Number two caught me
off guard.  You don't
have to worry about object lifetime there. With Rust, it's forcing me to fully
understand and use well the memory in my applications. In the final mistake I
fixed (using .clone()
) I would have been fine in C++ to just give away that
reference and never use it again. I wouldn't have run into a "use-after-free"
error, but I would have potentially been leaking memory. Rust forced me to be
incredibly precise about how I use it.
All said I'm excited for using Rust more. I think it's super cool, it's just going to take me a lot longer to do this than I originally thought.


Greetings, I’m Manuel. I’m a Maker with an engineering background (mechanical and software) living in Lisboa, Portugal. I love technology, innovation and DIY. Solving problems and fixing things is something that really gets me going.
In recent years people have called me an entrepreneur. Still trying to find out why and what that really means but I think that it has something to do with my response to "that's impossible, you can't do it".
Broken things aren't to be disposed of and working things can always be improved upon. DIY can be an awesome endeavor!
Being involved in several projects and having a software engineering background, I ended up building and maintaining various websites.
I like to help make things grow and enable people to thrive using my skillset to do so. I do this in events and other similar spaces.
From 3D printing to electronics. From prototypes to products. I've created things, both alone and in a team, in the hardware space.
This school though me a lot. Really a lot! Started out as a Mechanical Engineer MSc Student, ended up switching to Software Engineering in 2012. Didn't graduate but I attended and acquired most of the skills tought there.
HackerSchool is awesome! Great people, the right atitude and the perfect mindset, all together there. My time there seamed to fly. Tons of projects, workshops, events,... For me it was an honour to help this association grow and to be part of the organization of LX Reactor 2015.
Innovating electronics for the airsoft battlefield. Ongoing product development and a couple of products translates into a small business which best seller product as sold 120+ units in Portugal and has a 0% failure rate (average failure rate of the competition is around 70%).
Productized was a great working experience. Joined to help the association with the talks and with the Productized Conference 2015. Did a bit of everything from sales to event planing and website and social media management.
At the begging of 2016 the No Bullshit Lab idea was presented to me and I just had to join in. It was an opportunity to create a fullsize LX Reactor with facilities out of a dream. The goal is to create a one of kind startup accelerator, focused on hardware startups allowing them to have better chances of overcoming the challenges of hardware.
FUSE.Works is No Bullshit Lab on steroids. At the end of 2016 we closed an investment deal on No Bullshit Lab that will allow us to grow faster and provide even better conditions to hardware startups, from prototiping facilities capable of producing their first batches to seed investiment.
During this time I worked as a Front End freelancer in a few projects including Pavnext's first website or as an Operations Manager in MINI NewCo Festival 2017.
Landing Jobs is Europe's best tech jobs marketplace. Worked with the product team to give a boost to the www.landingfestival.com platform creating new pages, features and fixing bugs mostly using SCSS and Slim.
Being a part of the awesome imatch team enabled me to grow professionaly and personaly on a daily basis at a uge rate. imatch is a creative collaboration consulting company that works innovation, culture and other areas with major companies.
Currently working at Deloitte Portugal as the Webmaster of the Marketing department.
Since I really like to help others, I've volunteered at several events and helped organizations put toghether events. Doesn't matter the area of the assignment, if there's something to be done, it gets done. Like they say in the portuguese military: "Missão dada é missão cumprida"
C
C++
PHP
HTML 5
AngularJS
Matlab
Basic Java knowlage
Basic Python knowlage
SolidWorks
Solid Edge
OnShape
Arduino
Basic Circuit Electronics
Electronic Soldering
3D Printing
Regular & Heavy Tools
Portuguese (Native)
English (Advanced Level)
Basic French
Basic Spanish
GitHub
MS Office Tools
LaTex
AGILE
SCRUM
Business Strategy
Leadership Skils
Team Work & Management
Adobe Photoshop
Final Cut Pro


Obstacle Avoidance algorithm is used with a simple method runAhead(),
which applies the agent with a vector of the length of the maxspeed.
That vector keeps the agent in motion even when the Obstacle Avoidance method doesn't return any vectors.
In the simulation, the vehicle tries to move as fast as he can and avoid objects ahead of him.
The algorithm calculates the normal point of every object on the line parallel to the vehicle's velocity.
Then it considers only those objects that are between the vehicle's position and the predicted position of the vehicle.
If any of the selected objects have a radius that overlaps with a space ahead of
the agent and there is no other object between it and the agent,
a vector from its position to the normal point is added to that normal point.
That way the mirrored point of the object's position is calculated to avoid a collision.
The braking force will be also added to the calculated point and scaled-down or up accordingly to
the distance between the vehicle's position and the object's position.
After that, the point can be returned and passed to Seek.
The orange vector sticking out of the center of the vehicle is a visualization of the desired velocity and the violet one shows the current velocity of the agent. The blue vector represents a braking force, and the green one represents an avoidance.
If you want to change the direction of the vehicle choose a point on the canvas by moving your cursor and keeping the left click mouse button pressed until the modified direction satisfies you.
The average of occurring collisions per step 0
The orange vector sticking out of the center of the vehicle is a visualization of the desired velocity and the violet one shows the current velocity of the agent. The blue vector represents a braking force, and the green one represents an avoidance.
If you want to change the direction of the vehicle choose a point on the canvas by moving your cursor and keeping the left click mouse button pressed until the modified direction satisfies you.
The average of occurring collisions per step 0
Vehicle position x:
y:
velocity:


FileInterface
Defines FileInterface.
Methods
Get file instance.
Free the file instance.
Check if file exits.
Return file modification time.
Lock file for writing. Lock gets automatically released during the save().
Returns true if file has been locked for writing.
Unlock file.
Check if file can be written.
(Re)Load a file and return its contents.
Get/set raw file contents.
Get/set parsed file contents.
Save file.
Delete file from filesystem.
Details
at line 19
static
mixed
instance(
string $filename)
Get file instance.
at line 24
free()
Free the file instance.
at line 31
bool
exists()
Check if file exits.
at line 38
int
modified()
Return file modification time.
at line 46
bool
lock(
bool $block = true)
Lock file for writing. Lock gets automatically released during the save().
at line 53
bool|null
locked()
Returns true if file has been locked for writing.
at line 60
bool
unlock()
Unlock file.
at line 67
bool
writable()
Check if file can be written.
at line 74
string
load()
(Re)Load a file and return its contents.
at line 82
string
raw(
string $var = null)
Get/set raw file contents.
at line 90
string
content(
string $var = null)
Get/set parsed file contents.
at line 98
save(
string $data = null)
Save file.
at line 105
bool
delete()
Delete file from filesystem.


cwmi package¶
Module contents¶
-
cwmi.
call_method
(namespace, obj_path, method_name, input_params=None, user=None, password=None, flags=0)¶ Calls object method
- Args:
- namespace (str): Namespace to connect to obj_path (str): Path to object instance/class method_name (str): Name of the method to call input_params (dict): Method input parameters user (str): Username to use when connecting to remote system password (str): Password to use for remote connection flags (int): Flags to pass into WMI API(s)
- Returns:
- Dictionary containing data returned from the called method
-
cwmi.
create_variant
(val, v_type=None)¶ Creates a VARIANT instance from a given value
- Args:
- val (any): The value to use when creating the VARIANT instance v_type (int): Variant type
- Returns:
- Initialized VARIANT instance
-
cwmi.
destroy_variant
(var)¶ Destroys an instance of a VARIANT
- Args:
- var (VARIANT): Instance to destroy
- Returns:
- Nothing
-
cwmi.
does_object_exist
(namespace, obj_name, user=None, password=None, flags=0)¶ Tests if a given object exists
- Args:
- namespace (str): Namespace to connect to obj_name (str): Path to object instance/class user (str): Username to use when connecting to remote system password (str): Password to use for remote connection flags (int): Flags to pass into WMI API(s)
- Returns:
- True if object exists, or False if not
-
cwmi.
get_all_object_info
(namespace, obj_name, user=None, password=None, include_var_type=False, flags=0)¶ Gets all data from an object
- Args:
- namespace (str): Namespace to connect to obj_name (str): Path to object instance/class user (str): Username to use when connecting to remote system password (str): Password to use for remote connection include_var_type (bool): Include variant type flags (int): Flags to pass into WMI API(s)
- Returns:
- Dictionary containing object data
-
cwmi.
get_method_info
(namespace, obj_name, user=None, password=None, flags=0)¶ Gets method information for a given object/method
- Args:
- namespace (str): Namespace to connect to obj_name (str): Path to object instance/class user (str): Username to use when connecting to remote system password (str): Password to use for remote connection flags (int): Flags to pass into WMI API(s)
- Returns:
- Dictionary containing method parameter info
-
cwmi.
get_method_names
(namespace, obj_name, user=None, password=None, flags=0)¶ Gets all method names from a given object
- Args:
- namespace (str): Namespace to connect to obj_name (str): Path to object instance/class user (str): Username to use when connecting to remote system password (str): Password to use for remote connection flags (int): Flags to pass into WMI API(s)
- Returns:
- List of method names
-
cwmi.
get_object_info
(namespace, obj_name, values, user=None, password=None, include_var_type=False, flags=0)¶ Gets desired values from an object.
- Args:
- namespace (str): Namespace to connect to obj_name (str): Path to object instance/class values (list): List of values to pull from object user (str): Username to use when connecting to remote system password (str): Password to use for remote connection include_var_type (bool): Include variant type flags (int): Flags to pass into WMI API(s)
- Returns:
- Dictionary containing object data
-
cwmi.
get_object_names
(namespace, obj_name, user=None, password=None, flags=0)¶ Gets all names from a given object
- Args:
- namespace (str): Namespace to connect to obj_name (str): Path to object instance/class user (str): Username to use when connecting to remote system password (str): Password to use for remote connection flags (int): Flags to pass into WMI API(s)
- Returns:
- List containing object names
-
cwmi.
obj_to_dict
(obj, include_var_type=False, flags=0)¶ Converts WMI object to python dictionary
- Args:
- obj (any): The object to convert include_var_type (bool): Include variant type flags (int): Flags to pass into WMI API(s)
- Returns:
- Dictionary containing object information
-
cwmi.
query
(namespace, query_str, query_type='WQL', user=None, password=None, include_var_type=False, flags=0)¶ Performs a WMI query
- Args:
- namespace (str): Namespace to connect to query_str (str): String to use for the query query_type (str): Path to object instance/class user (str): Username to use when connecting to remote system password (str): Password to use for remote connection include_var_type (bool): Include variant type flags (int): Flags to pass into WMI API(s)
- Returns:
- Dictionary containing all objects returned by query
-
cwmi.
safe_array_to_list
(safe_array, element_type)¶ Converts SAFEARRAY structure to python list
- Args:
- safe_array (SAFEARRAY): Array structure to convert element_type (any): Type of the elements contained in the structure
- Returns:
- List containing the converted array elements


Apr 25, 2013 9:25 AM
mytuitiontutor (MyTT) was piloted in 2012 with an aim to provide qualitative education in an affordable, flexible and convenient format to school and university students in India. The platform provides an interactive learning environment and equips private tutors, mostly volunteers and young working professionals, to utilize various communication modes to make learning enjoyable for students for under $2 an hour. Even though the product sparked great interest in India, the market was found to be under-ready given the low speed of internet connection available in the country, leading to constant technical glitches. Therefore, it was decided to adapt the existing model, with slight modifications, in New York, with an aim to provide low-cost, qualitative, flexible and interactive education to the masses, while concurrently supporting the marginalized children in India by partnering with Tagore Foundation, an NGO in India that works towards empowerment of youth. A percentage of the students' sign up fees with MyTT will be utilized to provide education and work opportunities to the marginalized children in India. Bio Ashish Mehta began his professional career in India as the marketing lead of the startup TolMol.com. Having served Google as a client, Ashish believes in integrating technology with education to maximize the impact of development work. After spending three years in the digital media space, Ashish founded 'Tagore Foundation' in 2009 to empower youth. Besides conducting training and skill development workshops for youth (16-25yrs), Ashish produced several educational documentary films and hosted interactive talk shows on contemporary issues on national television. At Columbia, in addition to pursuing a Master's of Public Administration degree, Ashish is working with Professor Gary Natriello to launch his social venture mytuitiontutor.com in the United States to make education accessible, affordable and fun! In his free time, Ashish likes to play sports, travel, organize events and cook, an interest that he has recently developed. Open to all members of the university community. If you are coming from outside the Edlab, please RSVP by May 13th by sending a message to Edlab at http://ednode.com/profiles/edlabtc/about (You must have/create an Ednode account and click on ). EdLab Seminars take place on the 5th floor of Russell Hall at Teachers College Columbia University (525 W. 120th Street, NY, NY). For detailed directions within the College visit TC Route Finder: http://maps.tc-library.org


Assignments Assignments Assignments Assignments Assignments Assignments Assignments Assignments Assignments Assignments Assignments


Class GameObject
Base class for any object that has a grid position and can be added to a Map. Implements basic attributes generally common to all objects on a map, as well as properties/methods that the Map class needs to function. It also implements IHasComponents, which means you can attach components to it (see ComponentContainer documentation for details on those functions). In cases where this class cannot be inherited from, have your class implement IGameObject via a private GameObject field.
Inherited Members
Namespace: GoRogue.GameFramework
Assembly: GoRogue.dll
Syntax
public class GameObject : ComponentContainer, IGameObject, IHasID, IHasLayer, IHasComponents
Remarks
This class is designed to serve as a base class for your own game objects in your game. It implements basic common functionality such as walkability and transparency, and provides some infrastructure that allows it to be added to instances of Map, as well as implementing the framework for GoRogue's component system. It also implements the necessary functionality that allows GameObjects to be added to an ISpatialMap implementation.
Generally, you would create one or more classes (say, MyGameObject or MyTerrain), that derives from this one (GameObject), or implement IGameObject by composition using a private field of this class, and use that as the base class for your game's objects. If you utilize the component system, a subclass isn't even strictly necessary, as you could just construct basic GameObject instances and add components to them. In either case, a Map instance can be used to store these objects efficiently. As well, Map provides functionality that will allow you to retrieve your objects as references of their derived type (MyGameObject or MyTerrain, in the example above), meaning that you can implement any common, game-specific functionality you need and have easy access to that information when objects are retrieved from the map (without being forced to make that functionality a component.
Although the component system will accept items of any type as components, there is an optional IGameObjectComponent interface that GoRogue provides, that has a field for the parent, eg. the IGameObject that it is attached to. This field is automatically kept up to date as you add/remove components if you implement this interface for your components.
Constructors
| Improve this Doc View SourceGameObject(Coord, Int32, IGameObject, Boolean, Boolean, Boolean)
Constructor.
Declaration
public GameObject(Coord position, int layer, IGameObject parentObject, bool isStatic = false, bool isWalkable = true, bool isTransparent = true)
Parameters
| Type | Name | Description |
|---|---|---|
| Coord | position | Position to start the object at. |
| System.Int32 | layer | The layer of of a Map the object is assigned to. |
| IGameObject | parentObject | Object holding this GameObject instance. If you are inheriting from GameObject, or using a backing field of type GameObject to implement IGameObject, for example, you would pass "this" at construction. Otherwise, if you are simply instantiating base GameObject instances and adding them to a Map, you would pass null. |
| System.Boolean | isStatic | Whether or not the object can be moved (true if the object CANNOT be moved, false otherwise). |
| System.Boolean | isWalkable | Whether or not the object is considered "transparent", eg. whether or not light passes through it for the sake of a Map's FOV. |
| System.Boolean | isTransparent | Whether or not the object is considered "transparent", eg. whether or not light passes through it for the sake of a Map's FOV. |
Properties
| Improve this Doc View SourceCurrentMap
The current Map which this object resides on. Null if the object has not been assigned an object. A GameObject is allowed to reside on only one map.
Declaration
public Map CurrentMap { get; }
Property Value
| Type | Description |
|---|---|
| Map |
ID
ID of the object. Used for the sake of putting instances of this class in ISpatialMap implementations, and is NOT guaranteed to be entirely unique, though this can be modified by overriding the GenerateID function.
Declaration
public uint ID { get; }
Property Value
| Type | Description |
|---|---|
| System.UInt32 |
IsStatic
Whether or not the object is "static". Static objects CANNOT be moved, and only static objects may be placed on a Map's layer 0.
Declaration
public bool IsStatic { get; }
Property Value
| Type | Description |
|---|---|
| System.Boolean |
IsTransparent
Whether or not the object is considered "transparent", eg. whether or not light passes through it for the sake of a Map's FOV.
Declaration
public virtual bool IsTransparent { get; set; }
Property Value
| Type | Description |
|---|---|
| System.Boolean |
IsWalkable
Whether or not the object is to be considered "walkable", eg. whether or not the square it resides on can be traversed by other, non-walkable objects on the same map. Effectively, whether or not this object collides according to the collision layer.
Declaration
public virtual bool IsWalkable { get; set; }
Property Value
| Type | Description |
|---|---|
| System.Boolean |
Layer
Layer of a Map that this object can reside on.
Declaration
public int Layer { get; }
Property Value
| Type | Description |
|---|---|
| System.Int32 |
Position
The position of this object on the grid. Any time this value is changed, the Moved event is fired.
Declaration
public virtual Coord Position { get; set; }
Property Value
| Type | Description |
|---|---|
| Coord |
Remarks
This property may be overriden to implement custom functionality, however it is highly recommended that you call the base set in the overridden setter, as it performs collision detection.
Methods
| Improve this Doc View SourceAddComponent(Object)
Adds the given object as a component. Throws an exception if that specific instance is already attached to this GameObject.
Declaration
public override void AddComponent(object component)
Parameters
| Type | Name | Description |
|---|---|---|
| System.Object | component | Component to add. |
Overrides
| Improve this Doc View SourceGenerateID()
Function used at construction to assign an ID to the object.
Declaration
protected virtual uint GenerateID()
Returns
| Type | Description |
|---|---|
| System.UInt32 | An ID to assign to the current object. |
Remarks
The default implementation simply assigns a random number in range of valid uints. This is sufficiently distinct for the purposes of placing the objects in an ISpatialMap, however obviously does NOT guarantee true uniqueness. If uniqueness or some other implementation is required, override this function to return an appropriate ID. Bear in mind a relatively high degree of uniqueness is necessary for efficient placement in an ISpatialMap implementation.
MoveIn(Direction)
Attempts to move the object in the given direction, and returns true if the objec was successfully moved, false otherwise.
Declaration
public bool MoveIn(Direction direction)
Parameters
| Type | Name | Description |
|---|---|---|
| Direction | direction | The direction in which to try to move the object. |
Returns
| Type | Description |
|---|---|
| System.Boolean | True if the object was successfully moved, false otherwise. |
OnMapChanged(Map)
Internal use only, do not call manually! This function is (and should only be) called by Map to update the CurrentMap value when this GameObject switches maps.
Declaration
public void OnMapChanged(Map newMap)
Parameters
| Type | Name | Description |
|---|---|---|
| Map | newMap | New map. |
RemoveComponents(Object[])
Removes the given component(s) from the GameObject. Throws an exception if a component given is not attached to the GameObject.
Declaration
public override void RemoveComponents(params object[] components)
Parameters
| Type | Name | Description |
|---|---|---|
| System.Object[] | components | One or more component instances to remove. |
Overrides
Events
| Improve this Doc View SourceMoved
Event fired whenever this object's grid position is successfully changed. Fired regardless of whether the object is part of a Map.
Declaration
public event EventHandler<ItemMovedEventArgs<IGameObject>> Moved
Event Type
| Type | Description |
|---|---|
| System.EventHandler<ItemMovedEventArgs<IGameObject>> |


Shower Presentation Engine
ghcjs
clay
!
| Event |
|---|
| Behavior |
|---|
| Dynamic |
|---|
thanks to rxmarbles.com!
Event
is a Functor
-> fmap (const 5) clickEvt
… ⇒ [Event t a] → Event t a
… ⇒ (a → a → a) → [Event t a] → Event t a
FunctorMaybe f => (a → Bool) → f a → f a
… ⇒ (a → b → b) → b → Event t a → m (Dynamic t b)
(a → b → b) → b → [a] → b
… ⇒ Dynamic t a → Dynamic t a
EventsView.hs
RecursiveDo
const :: a -> b -> a
const x _ = x
fmap (const 6) [1,2,3,4] -> [6,6,6,6]
fmap (\_ -> 6) [1,2,3,4] -> [6,6,6,6]
… ⇒ (a → b) → Dynamic t a → m (Dynamic t b)
… ⇒ Dynamic t a → (a → b) → m (Dynamic t b)
Config.hs
Note we bypassed the input API, and it's self-contained.
… ⇒ (a → b → c) → Dynamic t a → Dynamic t b → m (Dynamic t c)
… ⇒ m (Event t ())
… ⇒ String → Event t b → m (Dynamic t (RemoteData a))
Config.hs
combineDyn
-- we don't need $q.all
and things like that.
… ⇒ a → Dynamic t a
… ⇒ a → Event t a → m (Dynamic t a)
Dynamic t (m (Event t Day))
and things like that are pretty commonrecursive do
: the error could be anywhere in the rec
block...ghcjs
: shims -- builds then crashes at runtime! Had to patch the RTS.ghcjs
: Running on 0.1, ~0.3 is dev..ghcjsi
will help)My SPA GHCJS/Reflex app is 18MB (all in). That's a pretty hefty page load. (I wasn't successful with first run of closure-compiler either)
— Tim Dysinger (@dysinger) February 27, 2016
... and inline CSS...


BathySnippet1 (Class)
Namespace: stdlibXtf.SubPackets
Represent the beam part of the bathy data attached to a PingHeader packet.
Constructors
| BathySnippet1() | Initializes a new instance of the BathySnippet1 class that has default zero values. |
| BathySnippet1(Byte[]) | Initializes a new instance of the BathySnippet1 class that contain the values extracted from the given byte array. The size of array need to be at least of 24 bytes. |
Properties
| HeaderSize | Gets the size, in bytes, of this header packet. |
| DataSize | Gets the size, in bytes, of the following data packets. |
| PingNumber | Gets the sequential number of the ping. |
| Beam | Gets the beam number, from 0 to total number minus 1. |
| SnipSamples | Gets the snippet size, samples. |
| GainStart | Gets the gain at start of snippet, 0.01 dB steps. |
| GainEnd | Gets the gain at end of snippet, 0.01 dB steps. |
| FragOffset | Gets the fragment offset, samples from ping. |
| FragSamples | Gets the fragment size, samples. |
Examples
example ...
Remarks
remarks ...


{% extends 'base.html' %} {% load static %} {% block title %}Home{% endblock title %} {% block style %} {% endblock style %} {% block body %} {% comment %} {% endcomment %} {% comment %} {% endcomment %}
Helps you perform simple to complex calculations in just fractions of seconds. This is an advanced calculator that will allow you to perform all kind of operations.
OPENFind code snippets of almost all the important algorithms at one place. This snippet is written for C++ language and needs to be converted for use in other languages.
OPENSave the snippets you feel important on your own webpage. You can even add new snippets over there as per your convenience and requirement.
OPENFeel free to contact me. Suggestions or improvements are always welcome. You can also share your snippet which you want me to add over here.
OPEN


You are viewing an historical archive of past issues. Please report new issues to the appropriate project issue tracker on GitHub.
Comments
-
Daniel Heron
Created an attachment (id=139) Second Crash report
Second crash report on the 27th of October
-
Daniel Heron
Created an attachment (id=140) First Crash
First Crash on 26th of October
-
Greg Hurrell
Thanks for attaching the crash reports, Daniel. Good to see that they both match up fairly closely, so this is one issue, not two. Will investigate.
-
Daniel Heron
Created an attachment (id=142) Third crash
Third crash Once I updated to leopard I forgot to uninstall synergy and reinstall. Going to do that right now. Attached is the third crash report
-
sjmills
I've seen this one a couple times too. AdjustCarbonMenuItem is near the top of the stack. Let me know if you need the .crash file.
Add a comment
Comments are now closed for this issue.


| Interface | Description |
|---|---|
| EmbeddedPacketExtension |
This interface defines
ExtensionElement implementations that contain other
extensions. |
| Class | Description |
|---|---|
| Affiliation |
Represents a affiliation between a user and a node, where the
Affiliation.type defines
the type of affiliation. |
| AffiliationsExtension |
Represents the affiliations element of the reply to a request for affiliations.
|
| CollectionNode | |
| ConfigurationEvent |
Represents the configuration element of a pubsub message event which
associates a configuration form to the node which was configured.
|
| ConfigureForm |
A decorator for a
Form to easily enable reading and updating
of node configuration. |
| EventElement |
Represents the top level element of a pubsub event extension.
|
| FormNode |
Generic stanza(/packet) extension which represents any pubsub form that is
parsed from the incoming stream or being sent out to the server.
|
| GetItemsRequest |
Represents a request to subscribe to a node.
|
| Item |
This class represents an item that has been, or will be published to a
pubsub node.
|
| ItemDeleteEvent |
Represents an event in which items have been deleted from the node.
|
| ItemPublishEvent<T extends Item> |
Represents an event generated by an item(s) being published to a node.
|
| ItemsExtension |
This class is used to for multiple purposes.
|
| LeafNode |
The main class for the majority of pubsub functionality.
|
| Node | |
| NodeEvent | |
| NodeExtension |
A class which represents a common element within the pubsub defined
schemas.
|
| OptionsExtension |
A stanza(/packet) extension representing the options element.
|
| PayloadItem<E extends org.jivesoftware.smack.packet.ExtensionElement> |
This class represents an item that has been, or will be published to a
pubsub node.
|
| PublishItem<T extends Item> |
Represents a request to publish an item(s) to a specific node.
|
| PubSubManager |
This is the starting point for access to the pubsub service.
|
| RetractItem |
Represents and item that has been deleted from a node.
|
| SimplePayload |
The default payload representation for
PayloadItem.getPayload() . |
| SubscribeExtension |
Represents a request to subscribe to a node.
|
| SubscribeForm |
A decorator for a
Form to easily enable reading and updating
of subscription options. |
| Subscription |
Represents a subscription to node for both requests and replies.
|
| SubscriptionEvent |
Base class to represents events that are associated to subscriptions.
|
| SubscriptionsExtension |
Represents the element holding the list of subscription elements.
|
| UnsubscribeExtension |
Represents an unsubscribe element.
|
| Enum | Description |
|---|---|
| AccessModel |
This enumeration represents the access models for the pubsub node
as defined in the pubsub specification section 16.4.3
|
| Affiliation.Type | |
| ChildrenAssociationPolicy |
This enumeration represents the children association policy for associating leaf nodes
with collection nodes as defined in the pubsub specification section 16.4.3
|
| ConfigureNodeFields |
This enumeration represents all the fields of a node configuration form.
|
| EventElementType |
This enumeration defines the possible event types that are supported within pubsub
event messages.
|
| FormNodeType |
The types of forms supported by the pubsub specification.
|
| ItemReply |
These are the options for the node configuration setting
ConfigureForm.setItemReply(ItemReply) ,
which defines who should receive replies to items. |
| ItemsExtension.ItemsElementType | |
| NodeType |
Defines the available types of nodes
|
| PresenceState |
Defines the possible valid presence states for node subscription via
SubscribeForm.getShowValues() . |
| PublishModel |
Determines who may publish to a node.
|
| PubSubElementType |
Defines all the possible element types as defined for all the pubsub
schemas in all 3 namespaces.
|
| SubscribeOptionFields |
Defines the possible field options for a subscribe options form as defined
by Section 16.4.2.
|
| Subscription.State |


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This is a simple Markdown editor. This example makes it possible to get acquainted with the the markup Markdown format.


| Analysis Situs ./features/active script |
| Download | Features | Source code | Terminology | References |
Most functionality of Analysis Situs is available through scripting. We use Tcl language which we appreciate for its clearness and pure functional paradigm. Each command in Analysis Situs is formulated in the following fashion: verb minus noun, e.g.: offset-shell, start-contour, print-summary, etc.
For scripting, we have a dedicated panel where you write your commands and execute them. This panel is a bit special because it is not a usual one-line prompt, but rather the script editor where each line can be executed individually (one could have met a similar concept in the Maple sheets). Using this editor is advantageous for prototyping: you are free to insert commands to your sheet, erase unsuccessful trials, execute and re-execute lines in arbitrary order, and edit the script the way you like. We have named this concept as "Active Script" which, we think, is a more powerful paradigm than a classical command-line prompt.
Pressing the <Enter> key executes the current command at the position of a cursor. To insert a new command between the two existing ones, use <Ctrl+Enter> key combination. You may save the scripts prepared in the Active Script editor to file and execute them later with the Tcl native source command, e.g.:
Some example scripts can be found in the "scripts" subdirectory of Analysis Situs. This directory is accessible via ASI_TEST_SCRIPTS environment variable in the Active Script console.
When specifying the path for the source command you can use both forward and back slashes.
You can also execute Tcl scripts in the batch mode without GUI.


FORCES OF NATURE A film review by Steve Rhodes Copyright 1999 Steve Rhodes RATING (0 TO ****): ***
In FORCES OF NATURE, Sandra Bullock's fans, who have had to watch her talents wasted in mediocre films (PRACTICAL MAGIC and HOPE FLOATS) and downright stinkers (TWO IF BY SEA), finally have a film of hers again to cheer about. Bullock, tapping her vast reservoir of charm and confidence, gives her best performance since SPEED. And with great chemistry, Ben Affleck, from GOOD WILL HUNTING and CHASING AMY, plays opposite her in an absolutely delightful romantic comedy.
In what is clearly a romantic takeoff on PLANES, TRAINS & AUTOMOBILES, the movie's script by Marc Lawrence is as intelligently funny as it is good-spirited, and it has just enough of a serious underbelly to move your head as well your heart. Second-time director Bronwen Hughes (HARRIET THE SPY) has a perfect sense of comedic timing as well as the ability to make the mundane seem magical.
The story opens in New York with Ben Holmes (Affleck) being suitably embarrassed at his bachelor party. Shortly afterward, he leaves to catch a plane to marry his fiancée, Bridget (Maura Tierney), in Savannah. Before he leaves, his grandfather gives him a shocking piece of advice in one of the first instances of the movie's recurring anti-marriage joke. "Even if you love a woman, don't tie yourself down," his long-married grandfather advises him sternly. "Marriage is a prison."
In a plane accident on the runway, Ben aids his free-spirited fellow passenger Sarah (Bullock), who is extremely grateful. With him scared of flying and with no cars available for rent, they hitch a ride with a harmless looking middle-aged guy named Vic (Jack Kehler). This will be the first of many mistakes they make on their ill-fated journey to Savannah. (Meanwhile, down on the plantation, Bridget, surrounded by more Southern Belles than Scarlet O'Hara at Tara, becomes increasing bored and frustrated. Her story makes a nice companion piece to the larger one of Ben and Sarah.)
Ben, who has no trouble making silly baby-talk phone calls to his future wife, loathes taking risks of any kind. A "jacket copywriter," his work product includes calling a book "a scintillating tale of erotic mummification."
Sarah, who represents everything that Ben isn't but deep down wishes he were, is a born rebel.  She's also been an airline stewardess and a stripper, the latter skill will prove useful later in the story.
A "seize the moment" kind of gal, she takes it as her role in life to break Ben out of his rigid mold. "Do you want to be on your deathbed saying 'I played by the rules' or 'I lived'?" she asks him bluntly.
Bullock, who has never been more likeable than in FORCES OF NATURE, charms Ben as well as the audience, but, being a loyal kind of guy, Ben resists the temptation as long as possible. Affleck, with his boyish grin, is a perfect match for Bullock, and their chemistry is simply adorable.
Among the movie's sight gags is a chintzy honeymoon suite they end up in. Ben, infatuated with Sarah but loyal to his fiancée, plunks down on the bed only to hear the water slosh and the radio play "Love the one you're with." Although he tries to look away, he can see the outline of Sarah's naked body torturing him through the semi-translucent glass separating the bathroom from the bedroom. Even the bathroom door, which should provide a safe barrier, will not close.
The viewers become as conflicted as poor Ben. The reasons for Ben not to choose Sarah mount as fast as her desirability increases.
The picture is gorgeous, thanks to Elliot Davis's stunning cinematography and Lester Cohen's brightly colored sets, full of dramatic shades of green accentuated by lavish, contrasting colors. Among the many memorable scenes are those featuring the forces of nature. Never have hurricanes or hailstorms looked so mystical and inviting. The leading edge of the hurricane, for example, causes colorful strips of paper to swirl around the cast like a multicolored snowstorm.
In a story that revels in chaos and ambiguity, the final resolution wraps things up way too neatly and quickly. The story's freshness goes out the window as the writer seems in a hurry to close off all the loose ends and take a more typical Hollywood approach.
FORCES OF NATURE runs a fast 1:40. It is rated PG-13 for sensuality, some profanity and a brief dope smoking scene and would be fine for kids around 11 and up.
Email<EMAIL_ADDRESS>Web: www.InternetReviews.com
The review above was posted to the
rec.arts.movies.reviews newsgroup (de.rec.film.kritiken for German reviews).
The Internet Movie Database accepts no responsibility for the contents of the
review and has no editorial control. Unless stated otherwise, the copyright
belongs to the author.
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Related links: index of all rec.arts.movies.reviews reviews


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PhD Phys & Math, Kharkov Institute for Physics and Technology (KIPT)
of NASU,1964.
DSc Phys & Math, ILTPE, 1981.
Research area:
Properties of strongly correlated low-dimensional electron systems;
high temperature superconductivity; electron properties of metals;
quantum localization in disordered and incommensurate conductive
systems; non-linear phenomena and synergetics.
Recently has been predicted and studied:
-
Coulomb ordering in electron systems with strong Anderson
localization
-
an effective lowering of dimension in 2D lattice systems with
long-range interactions
-
a quasi-nonergodic behaviour in weakly disordered 1D electron
lattice systems
Main achievements
Of the 80th: formulation of the theory of the coherent magnetic
breakdown in metals (see Phys. Rep., 98(4), pp.189-271 (1983) and
the monograph “Conduction electrons”, Moscow, Nauka (1985)).
Group of Alexander Slutskin
The members of the group:
- Elena Kovtun
-
Victor Slavin
Current research activities:
Many-electron phenomena in non-Fermi conductors.
Nowadays non-Fermi conductors wherein an interaction between the
electrons is strong, and as a consequence of this the conventional
charged-Fermi-liquid theory fails, are in the focus of attention.
Investigations of these systems carried out during the last two
decades revealed fundamentally novel phenomena and structures, which
provide magnificent opportunity to create electronic devices with
remarkable previously unknown features, including quantum computing.
In our theoretical investigations the primary emphasis is placed
upon low-dimensional lattice electron systems wherein the
inter-electron repulsion suppresses electron hopping and results in
formation of a self-localized “frozen” electron phase (FEP). We have
studied various important manifestations of this macroscopic state:
-
The ground state (GS) and superconducting properties of a layered
sd-electron system consisted of wide-band s-electron layers and
narrow-band d-electron ones being in the FEP state were
investigated. This system was found to possess superconductivity
of pure Coulomb origin, the superconducting transition temperature
attaining values of the order of d-band width. (A.A.Slutskin and
L.Yu.Gorelik, Low Temp. Phys., 19(11), p.852, 1993)
-
The low-temperature thermodynamics of 1D FEP (generalized Wigner
crystal) was considered. It was studied how heating modifies
inherent to 1D FEP a devil-stair case GS dependence of the
electron density on the chemical potential. (V.V.Slavin,
A.A.Slutskin, Phys. Rev. B, 54(11), p. 8095 (1996)).
-
A novel macroscopic phenomenon, charge carrier stripe formation
and effective lowering of dimension, was found to be inherent in
2D lattice systems with a long-range inter-particle repulsion.
Basing on this fact, a general analytical procedure has been
formulated to describe fully the GS of these systems. The
conclusion was made that charge ordering into stripes revealed in
copper-oxide superconductors can be caused solely by long-range
Coulomb hole-hole repulsion. (A.A.Slutskin, V.V.Slavin,
H.A.Kovtun, Phys. Rev. B, 61(20), p.14184 (2000))
-
It was shown that under strong-Anderson-localization conditions
and at sufficiently low electron densities a Coulomb
inter-electron repulsion orders localized electrons into a
slightly distorted crystal lattice (for the system dimension > 1).
A phase transition between this state and the conventional Coulomb
glass was found to occur with increasing of the electron density.
(A.A.Slutskin, M. Pepper, H.A.Kovtun, Europhys. Lett., 62(5), p.
705 (2003))
-
The low-temperature thermodynamics of 2D FEP has been recently
studied, taking into account the above-mentioned effective
lowering of dimension. We succeeded in resolving this problem in
terms of the so-called exactly solvable full six-vertex model. A
second-order phase transition between 2D generalized Wigner
crystal and a liquid of strongly correlated electron stripes with
thermally produced fractures (kinks) was found to take place. The
phase equilibrium curve on the plane ‘temperature–chemical
potential’ has a sophisticated structure, abutting on the
chemical-potential axis at the endpoints of the devil-stair
intervals. The charge carriers in the liquid phase turn out to be
kinks with a fractional charge. (A.A.Slutskin, H.A.Kovtun, prep.
for submission to Phys. Rev. B)
-
Recently it has been found that an arbitrarily weak random
distortion of a host lattice causes the formation of point defects
(frustrations) in the 1D generalized Wigner crystal and breaks
down the long-range electron-electron correlation in the GS. This
results in a novel “quasi-nonergodic” macroscopic behavior of the
system. (A.A.Slutskin, H.A.Kovtun, V.V.Slavin, prepared for
submittion to Phys. Rev. Lett.).
Selected publications of the 90es and of the years 2000 -2003
-
A.A.Slutskin, M.Pepper, H.A.Kovtun, Coulomb ordering in
Anderson-localized electron systems, Europhys. Lett., v.62, no.5,
p. 705-711 (2003).
-
A.A. Slutskin, V.V. Slavin, and H.A. Kovtun, The ground state of a
two-dimensional lattice system with a long-range interparticle
repulsion. Stripe formation and effective lowering of dimension,
Phys. Rev. B, v.61, no.20, May 15, p.14184-14193 (2000).
-
N.Fogel, E. Kovtun, R.Shekhter, and A. Slutskin, Size-quantization
controlled tunnelling in metal/semiconductor superlattices, Sov.
J. Low Temp.Phys, v.25, no.2, 122-125 (1999) [Fiz.Nizk.Temp. v.25,
no.2, 168-171 (1999)].
-
V.V. Slavin, A.A. Slutskin, Thermodynamics of a one-dimensional
lattice system with long-ranged interelectron repulsion, Phys.
Rev., September B15-I issue, v. 54(11), p. 8095-8100 (1996).
-
A.A. Slutskin, V.I. Makarov, New approach to description of
posistors and varistors conductive properties, in: Proc. of
Electroceramics 5, September 1996, Aveiro (Portugal).
-
A.A. Slutskin, Frozen" electron phase and high-temperature
superconductivity, Uspekhi Fizicheskikh Nauk, v.165, no.6, 1995
[Physics, uspekhi, June 01 1995, v. 38, No 6, page 669].
-
A.A.Slutskin and L.Yu.Gorelik, Frozen electron phase in layered
conductors and HTS, Sov. J. Low Temp.Phys. v.19 (11), 852-864
(1993) [Fiz.Nizk.Temp. v.19, no.11, p. 1199-1216 (1993)].
Selected publications of the 60es - 80es
-
A.A.Slutskin, M.Yu.Gorelik, Quantum localization in
one-dimensional quasi-random systems and magnetic breakdown,
Sol.State.Comm. v.46, no.8, p.601-604 (1983).
-
A.A.Slutskin and A.M.Kadigrobov, Electric domains in metals at low
temperatures, Sov.Phys.-JETP Lett.(USA), v.28, no.4, p.201-204
(1978).
-
M.I.Kaganov and A.A.Slutskin, Coherent magnetic breakdown, Phys.
Rep., v.98, no.4, p.189-271 (1983).
-
A.A.Slutskin, Motion of a one-dimensional non-linear oscillator
under adiabatic conditions. Sov.Phys. JETP, v.18, no.3, pp.676-682
(1964) [J. Expt. Theoret. Phys. (USSR) vol. 45, p.978-988 (1963)].


Often when you have two things with similar use cases, it's important to pick a side and have heated arguments over which is better.
You know the ones. Those age old battles dividing even the most sanguine of individuals:
And now: Merge vs Rebase
But not really
Git is a swiss army knife with an eye-watering array of little fold out tools. Select the right little fold out tool that's right for you.
This may involve merge or rebase, or even both -- yikes
Let's do a quick recap of merge and rebase
Brings changes from named commits into the current branch. The changes brought in are based on when the histories of the two diverged.
Replays a number commits ontop of a base commit
Both merge and rebase work by replaying commits. Merge is often not discussed in these terms, but that's how it do.
What follows and procedes this slide reflects my opinion (except where it's cold hard facts. The difference is left as an exercise to the viewer)
'All these facts and opinions look the same. I can't tell them apart.'' - Joy (of Inside Out)
Merge and rebase are underpinned by the same tech, they don't do anything radically different.
The above said, a really important difference to note is that rebase rewrites commits by chaning their parent, while merge does not.
Rebase is sometimes described as destructive because of this.
Managing your workflow and history is important. Merge and rebase give you different tools to manage these things.
People and teams use many different workflows and stratergies for managing history. I don't really believe in telling you to use one in particular, and would encourage you to try and find one that suits you and/or your team.
Absolutely. Groovy things can take time, and often do. Let me give you some examples of workflows that work well for me, in the context of discussing merge and rebase.
Caveat: when getting started with git I'd recommend keeping your workflow simple and gradually expanding your knowledge out. I'd say start out with just merge, and then throw some rebases in there once you're comfortable.
There's a number of workflows I've encountered in my travels, let me talk about some of them and how merge and rebase can fit into them.
It can be that you have branches that are merged into master, and then those branches are left to exist (the following commands are executed on master):
git merge my_branch
Maybe you want to merge the branch but then delete it:
git branch -d my_branch
Maybe you want to clean that branch by squashing some commits, or rewriting their commit messages, before merging said branch? In this case interactive rebase may be your friend (executed while on your branch):
git rebase -i
Instead of merging changes into master, you can rebase your changes onto master (the following commands are executed on master):
git rebase my_branch
Or do so interactively, so you can mess with the commits while you rebase:
git rebase -i my_branch
Those examples are simple, but exemplify the importance of bearning in mind different workflows people want:
There are certainly places where merge and rebase can overlap. Decide which is best for you/your team/whatever based on the outcomes you want.
Use both merge and rebase -- we're living in the future!
Once you've considered that there are many different workflows, and that one size doesn't fit all, and thought through the pros and cons of your preferred workflow: well then I guess you can start flaming people on the internet.


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Byte Frequency Distribution Correlation
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Correlation strength
Min-max Correlation strengths


Hi, I'm Andrii Dzhoha (aka Andrew Djoga), Software Engineer in Berlin.
You can find me on GitHub, Twitter and LinkedIn.
E-mail is the best way to get in touch with me<EMAIL_ADDRESS>My site: https://djo.github.io.
Hi, I'm Andrii Dzhoha (aka Andrew Djoga), Software Engineer in Berlin.
You can find me on GitHub, Twitter and LinkedIn.
E-mail is the best way to get in touch with me<EMAIL_ADDRESS>My site: https://djo.github.io.


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|
ArduDAQmx
A simple Arduino-esque wrapper for the National Instruments NI-DAQmx C/C++ API
|
Public Attributes | |
| char | DevName [256] |
| unsigned int | DevNum |
| int | DevSerial |
| int | isDevSim |
| cLinkedList * | pinList |
| char DAQmxDevice::DevName[256] |
DAQmx Device name - max 255 characters.
| unsigned int DAQmxDevice::DevNum |
NI-DAQ device/slot number
| int DAQmxDevice::DevSerial |
Serial number of the NI-DAQ device
| int DAQmxDevice::isDevSim |
This flag is set when device is simulated.
| cLinkedList* DAQmxDevice::pinList |
List of pins of the device used by ArduDAQmx.


Effective Java Exceptions
This article describes how the exception handling in the CRUD framework is done.
One additional complexity in a client server system is that you have to be carful
with the exceptions you serialize so that they also exist on the client.
As a consequence there are two fault barriers. One at the client side and one at the server side.
The server side fault barrier catch all faults and log them to the server log. After that it throws
a new exception WITHOUT wrapping the old one. The reason is:
1. Avoid serialization problems with wrapped exceptions that do not exist at client side.
2. It's no good to display server side stack traces on the client. They should be kept at server side.
Below is one of the good postings about this article:
Re: Effective Java Exceptions
People who defend checked exceptions claim that they should represent
recoverable errors. Fine. Except for one thing: whether the particular
error in a particular application is recoverable or not is defined by
the business requirements of that application! The same type of error
may require an alternative action in one application, while treated as a
generic fault by another. Expecting the compiler to tell you what to do
with an error is wrong – and, well, incompetent! Not to mention: over
90% of all errors in most applications are (or should be) treated as
non-recoverable. Gosling’s unbelievable suggestion that checked
exceptions were designed to create a “creepy” feeling that something may
go wrong is mind-boggling! Every junior software engineer should
understand that “something” might ALWAYS go wrong in a piece of
software! Checked exceptions are creating just the opposite effect:
developers now feel completely “safe” and do NOTHING if the compiler
does not remind them of an exception! Handling a checked exception is
never enough because any such exception generally represents only a
subset of all possible errors. People have forgotten – and many never
have learnt – that error handling must be designed for, that it is an
essential part of the application’s architecture and design. Instead, it
has become an afterthought for most Java developers.
People often ask: "Without checked exceptions, how do I know which error
to expect/handle?" This question reflects the most common misconception
about error handling. You do not need to know anything other than what
is stated in the business requirements for your application. Everything
else should be treated as "something bad that really wasn't meant to
happen per design." This makes the general error handling strategy very
simple! (Yes, there has to be a STRATEGY.) Here are the simple tasks
that the developer/application designer must face when designing the
high-level layout for the application:
1. Determine the location for the top-level handler that will catch all
errors that bubble up to it from within the application/module. This is
usually a "try/catch (Throwable t)/finally" construct around the process
that implements the main task of your application or component/module.
Call it a “fault barrier”, or whatever you want…
2. Get familiar with the business requirements (funny that I should
mention that! :)) and single out the legitimate use cases where an error
should be caught and handled before it reaches the above-mentioned
top-level handler. Such handling will mean implementing an alternative
action in response to the error. Such cases will represent your business
errors.  ;) It doesn’t matter if your business analyst did not supply you
with well-stated requirements. You should have a set of well-defined
design concepts (provided by someone else or gathered by yourself before
you start coding.) You must design for all those alternative actions. In
most cases, you won’t even need to distinguish between the types of
errors occurred, just catch all possible exceptions in that API and
redirect your process accordingly. In rare cases, yes, you might have to
investigate the API a bit deeper to look for a more specific exception
type. For example, you may want to distinguish the Spring's
DataRetrievalFailureException from a NullPointerException. The former
indicates that your data was not retrieved from the database; the latter
indicates something totally unacceptable that has nothing to do with the
business case. But such details are easy to uncover - if you look for
them when following nothing but your business requirements. What
developers must remember is that they absolutely must design for error
handling. Instead, most Java programmers today thoughtlessly catch just
about anything that the compiler points at, put wrappers around
wrappers, re-throw useless exceptions but chop-off valuable stack
traces, log the same error dozens of times at each step in the call
stack, etc.
Fortunately, in practice, most applications have very few cases of the
distinct legitimate "business" cases mentioned in step 2.
3. Ensure that each error propagates freely from the source of the error
to the only dedicated handler that is designed to handle it, the handler
that has the sufficient application context to handle the error
properly. Under no circumstances, the error should be caught and
tinkered with before it reaches that handler.
4. When some (3rd party/JDK) code throws a checked exception, catch it
in your API, and since, most likely, you don’t want to handle it
immediately at the source of the error, wrap it inside your custom RT
exception and re-throw so it can freely propagate to the dedicated (by
design) handler w/o polluting the rest of your code on its way.
5. When re-throwing exceptions, always nest the cause exception within
the new exceptions. Never discard the original error.
6. Always log the exception – with the full stack trace - when the
dedicated handler ultimately catches it. And log it once.
Run-time exceptions were designed to ensure all of that. Most
importantly, they were designed to allow developers not to deal with
errors at their immediate source but rather at the central point where
the application was designed to handle them, while providing the
developer with the complete stack trace information between the error
source and the handler. The fact that the original JDK implementations –
all the way up to 1.4 - provided no nesting functionality in the
Exception class while forcing developers to deal with exceptions at the
very source if each error - demonstrates how ill-conceived the whole
idea was in its core from the beginning.
Mixing checked and unchecked exceptions, as most people suggest, is a
bad idea. As I have said, handling the specific checked exception in
response to the compiler's complaint is never enough.
Therefore, you still have to do everything described above in 1 - 6,
except your code is now polluted with tons of specific (most certainly,
unnecessary) handlers that may interrupt an essential exception on its
way to the one and only correct handler, which inevitably results in the
loss of error information. If we can't reliably mix RT and checked
exceptions, and we don't like RT exceptions, can we indeed make all
exceptions checked? The answer is, most certainly, NO. There is a reason
why the authors of Java didn't do that in the first place. They just
couldn't. That would have made the language totally unusable. Every
method would have to declare countless exceptions in its signature, and
every method would have to deal with the countless checked exceptions
thrown by the code inside. What for? Just to create that “creepy”
feeling Gosling is so proud about?
Finally, look at Sun's EJB3!!! Wow! No checked exceptions there! A
silent admission of the mistake? But how many "average" programmers have
noticed? There’s nothing wrong with making mistakes, and no one has ever
claimed that Java was perfect. Many things have been improved and
corrected in the language since its first release. It is time for Sun to
come out and start helping the industry to recover from this terrible
experiment that has resulted in nothing less than millions of
programmers who are clueless about error-handling! That, in turn, costs
companies hundreds of millions of wasted dollars. Sadly, no matter how
many of the brightest people in the industry have spoken against checked
exceptions (Rod Johnson, Bruce Eckel, Anders Hejlsberg, to name a few),
it has had almost no impact on the programming “masses.” This forum just
proves that.


Iceland
"A journey of a thousand miles begins with a single step"
"A nomad I will remain for life, in love with distant and uncharted places"


§431:10D-313 Limitation of liability. The insurer may in any such policy limit its liability for the same causes and to the same extent as is provided in section 431:10D-312 for other life insurance contracts. [L 1987, c 347, pt of §2]


Did you know that Akan Names that originate from the Ghanian Culture?
Well the Ghanian Culture has a variety of names based on both genders.This names are assigned on the basis of two conditions:


class Config
Properties
| $ignore404 | ||
| $generateStartingRequests | ||
| $host | ||
| $root | ||
| $coverage | ||
| $urls | ||
| $exclusions | ||
| $inclusions |
Methods
|
init($crawler, $browser)
|
||
|
each($browser)
|
Details
at line 14
public
init($crawler, $browser)
at line 17
public
each($browser)


Get default values of parse options
Get types of parse options
Create new Book from context
intermediate result
return Book
Destory fake worker.
intermediate result
return Context containing permissions
load pdf document and get number of pages
intermediate result
return Context containing document and page count
return after tasks
return before tasks
Metadata parsing in Document
intermediate result
return Context containing metadata
Outline parsing in Document
intermediate result
return Context containing outline
Permission parsing in Document
intermediate result
return Context containing permissions
return tasks
Validate parse options and get entries from input
return Context containing parse options, entries
Validate read options and get entries from input
targets
returns Context containing target items, read options, entries
Contents is read using loader suitable for context
properties required for reading
reading results
return after tasks
return before tasks
return tasks
Unzipping if zip source and unzipPath option specified
intermediate result
return Context (no change at this step)
Parse the input
return Book
Returns PDF file as Buffer
Reading contents of Item
target
reading result
Reading contents of Items
targets
reading results
Unzip
success
Generated using TypeDoc
Create new PdfParser
{Errors.ENOENT} no such file
{Errors.EINVAL} invalid input
new PdfParser('./foo/bar.pdf');


| Here
is a list of some of the projects that L.U. Electric, Inc. completed in 2009: |
Irvine Company: Brittany Apartments |
| Dharma Construction: Atria Las Posas Apartments |
| Steadfast: Foxview Apartment |
| PRO-AM: Atria Golden Creek Apartments |
| DeGroodt Construction: Yatai Sushi, She-N-Nails and Pomona Catholic High Schol |
| |
| Below is a list of some of the completed and ongoing projects for 2010: |
| Western National |
| Atria Senior Living |
| Essex: Pathways Apartments |
| RBCI: The Bays Apartments |
| Valley Commercial: Atria Golden Creek Apartments |
| AIMCO: The Lakes Apartments |
| Irvine Company: The Village Apartments |
|
| |
| |


BrightstarDB Download
Full Installer Packages
A full Windows Installer packages can be found on our CodePlex project page. This package includes the binaries for the .NET 4.0 and Windows Phone SDKs as well as the BrightstarDB service and Polaris data management tool.
SDK via NuGet
You can also include BrightstarDB as an embedded database in your project via NuGet - just search for BrightstarDB. There are two versions of the BrightstarDB NuGet package. BrightstarDB provides the .NET 4.0 and Windows Phone libraries as well as the text template file required to generate a BrightstarDB Entity Framework context class. BrightstarDBLibs provides the libraries only, without the text templates.
Source code
The full source code for BrightstarDB can be downloaded or forked on GitHub.


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