Ledgeracio: CLI for Use with The Ledger Staking App

WARNING: This is alpha quality software and not suitable for production. It is incomplete and will have bugs.

Ledgeracio CLI

Ledgeracio is a command-line tool and a Ledger app designed for staking operations on Substrate-based networks.

Running ledgeracio --help will provide top-level usage instructions.

Ledgeracio CLI is intended to work with a special Ledgeracio Ledger app, but most of its commands will work with stock Kusama or Polkadot Ledger apps as well. This is less secure, however, as these apps do not enforce the same restrictions that the Ledgeracio app does. Using a stock app in production is not recommended.

The Polkadot app can be found here and the Kusama app can be found here. Other Substrate-based chains are currently not supported, but local devnets should work as long as their RPC API matches Kusama/Polkadot's.

Ledgeracio only supports Unix-like systems, and has mostly been tested on Linux. That said, it works on macOS and other Unix-like systems that provide the necessary support for userspace USB drivers.

What is Ledgeracio?

Ledgeracio is a CLI app to perform various tasks common to staking on Kusama and Polkadot, aka staking-ops. Ledgeracio is designed to reduce the risk of user error by way of an allowlist of validators that is set up and signed once and stored on the Ledger device. Furthermore, Ledgeracio can speed up the workflow considerably when compared to alternatives using Parity Signer + Polkadot{.js}.

This repository only contains the CLI. To submit transactions with Ledgeracio, you will also need the companion Ledger app that you can install from the Ledger app store for Polkadot and Kusama. Development versions of the apps are available at Zondax/ledger-polkadot and Zondax/ledger-kusama. Please do not use the unaudited versions in production. For instruction on how to setup and use your Ledger device with Polkadot/Kusama, see the Polkadot wiki.

The Ledgeracio CLI contains two binaries. The first, simply called ledgeracio, is used to submit transactions. The second, called ledgeracio-allowlist, is used to manage the Ledgeracio Ledger app’s list of allowed stash accounts. Generally, one will use ledgeracio for normal operations, and only use ledgeracio-allowlist when the list of allowed stash accounts must be changed. ledgeracio does not handle sensitive data, so it can safely be used on virtually any machine on which it will run. Some subcommands of ledgeracio-allowlist, however, generate and use secret keys, which are stored unencrypted on disk. Therefore, they MUST NOT be used except on trusted and secured machines. Ideally, these subcommands should be run on a machine that is reserved for provisioning of Ledger devices with the Ledgeracio app, and which has no network connectivity.

The allowlist serves to prevent one from accidentally nominating the wrong validator, which could result in a slash. It does NOT protect against malicious use of the device. Anyone with both the device and its PIN can uninstall the Ledgeracio app and install the standard Polkadot or Kusama app, which uses the same derivation path and thus can perform the same transactions.


  • An index is an integer, at least 1, specified in decimal. Indexes are used to determine which BIP44 derivation path to use.
  • Subcommands that take a single argument take it directly. Subcommands that take multiple arguments use keyword arguments, which are passed as --key value or --key=value. This avoids needing to memorize the order of arguments.
  • All commands require that a network name be passed as the first argument. You might want to make a shell alias for this, such as
alias 'ledgeracio-polkadot=ledgeracio --network polkadot'
alias 'ledgeracio-kusama=ledgeracio --network kusama'

Getting Started

Allowlist signing

Provisioning the Ledgeracio Ledger app requires a trusted computer. This computer will store the secret key used to sign allowlists. This computer does not need network access, and generally should not have it. ledgeracio-allowlist does not encrypt the secret key, so operations that involve secret keys should only be done on machines that use encrypted storage.

Only devices used for nomination need to be provisioned. However, if you only intend to use the app for validator management, you should set an empty allowlist, which blocks all nominator operations.

First, ledgeracio-allowlist gen-key <file> is used to generate a secret key. The public part will be placed in <file>.pub and the secret part in <file>.sec. Both will be created with 0400 permissions, so that they are not accidentally overwritten or exposed. This operation requires a trusted computer. The public key file can be freely redistributed, while the secret key file should never leave the machine it was generated on.

You can now sign a textual allowlist file with ledgeracio-allowlist sign. A textual allowlist file has one SS58 address per line. Leading and trailing whitespace is stripped. If the first non-whitespace character on a line is # or ;, or if the line is empty or consists entirely of whitespace, it is considered to be a comment and ignored.

ledgeracio-allowlist sign is invoked as follows:

ledgeracio-allowlist --network <network> sign --file <file> --nonce <nonce> --output <output> --secret <secret>

<file> is the allowlist file. <nonce> is the nonce, which is incorporated into the signed allowlist file named <output>. Ledgeracio apps keep track of the nonce of the most recent allowlist uploaded, and reject new uploads unless the new allowlist has a nonce higher than the old one. Nonces do not need to be contiguous, so skipping a nonce is okay. Signed allowlists are stored in a binary format.

Device provisioning

ledgeracio-allowlist is also used for device provisioning. To set the allowlist, use ledgeracio-allowlist set-key. This command will only succeed once. If an allowlist has already been uploaded, it will fail. The only way to change the allowlist signing key is to reinstall the Ledgeracio app, which does not result in any funds being lost.

ledgeracio-allowlist upload is used to upload an allowlist. The uploaded allowlist must have a nonce that is greater than the nonce of the previous allowlist. If there was no previous allowlist, any nonce is allowed.

To verify the signature of a binary allowlist file, use ledgeracio-allowlist inspect. This also displays the allowlist on stdout.

Ledgeracio Use

ledgeracio is used for staking operations. Before accounts on a Ledger device can be used for staking, they must be chosen as a controller account. You can obtain the address by running ledgeracio <validator|nominator> address. The address can be directly pasted into a GUI tool, such as Polkadot{.js}.

ledgeracio nominator nominate is used to nominate an approved validator, and ledgeracio validator announce is used to announce intention to validate. ledgeracio [nominator|validator] set-payee is used to set the payment target. ledgeracio [nominator|validator] chill is used to stop staking, while ledgeracio [nominator|validator] show and ledgeracio [nominator|validator] show-address are used to display staking status. The first takes an index, while the second takes an address. show-address does not require a Ledger device. ledgeracio validator replace-key is used to set a validator’s session key.

Subcommand Reference

Allowlist handling: ledgeracio-allowlist

The Ledgeracio app enforces a list of allowed stash accounts. This is managed using the ledgeracio-allowlist command.

Some subcommands involve the generation or use of secret keys, which are stored on disk without encryption. These subcommands MUST NOT be used on untrusted machines. Ideally, they should be run on a machine that is reserved for provisioning of Ledgeracio apps, and which has no access to the Internet.

Key generation: ledgeracio-allowlist gen-key

This command takes one argument: the basename (filename without extension) of the keys to generate. The public key will be given the extension .pub and the secret key the extension .sec. The files will be generated with 0400 permissions, which means that they can only be read by the current user and the system administrator, and they cannot be written to except by the administrator. This is to prevent accidental overwrites.

The public key is not sensitive, and is required by anyone who wishes to verify signed allowlists and operate on the allowed accounts. It will be uploaded to the Ledger device by ledgeracio-allowlist set-key. The secret key allows generating signatures, and therefore must be kept secret. It should never leave the (preferably air gapped) machine it is generated on.

Uploading an allowlist signing key to a device: ledgeracio-allowlist set-key

This command takes one argument, the name of the public key file (including extension). The key will be parsed and uploaded to the Ledgeracio app running on the attached Ledger device. If it is not able to do so, Ledgeracio will print an error message and exit with a non-zero status.

If a key has already been uploaded, uploading a new key will fail. The only workaround is to reinstall the Ledgeracio app. This does not forfeit any funds stored on the device. We strongly recommend users to use separate Ledger devices for ledgeracio and cold storage.

The user will be required to confirm the upload via the Ledger UI. This allows the user to check that the correct key has been uploaded, instead of a key chosen by an attacker who has compromised the user’s machine.

Retrieving the uploaded key: ledgeracio-allowlist get-key

This command takes no arguments. The public key that has been uploaded will be retrieved and printed to stdout. If no public key has been uploaded, or if the app is not the Ledgeracio app, an error will be returned.

Signing an allowlist: ledgeracio-allowlist sign

This command takes the following arguments. All of them are mandatory.

  • --file <file>: the textual allowlist file to sign. See FORMATS.md for its format.
  • --nonce <nonce>: The nonce to sign the file with. The nonce must be greater than the previous nonce, or the Ledgeracio app will reject the allowlist.
  • --output <output>: The name of the output file to write.
  • --secret <secret>: The name of the secret key file.

Inspecting a signed allowlist: ledgeracio-allowlist inspect

This command takes two arguments. Both of them are mandatory.

  • --file <file>: The name of the signed allowlist to inspect.
  • --public <public>: The name of the public key file that signed the allowlist. This command will fail if the signature cannot be verified.

Uploading an allowlist: ledgeracio-allowlist upload

This command takes one argument: the filename of the signed binary allowlist to upload. The command will fail if any of the following occurs:

  • There is no Ledger device connected.
  • The attached device is not running the Ledgeracio app.
  • The Ledgeracio app refuses the operation.

The Ledgeracio app will refuse the operation if:

  • No signing key has been uploaded.
  • The allowlist has not been signed by the public key stored in the app.
  • The nonce is not greater than that of the previously uploaded allowlist. If no allowlist has been previously uploaded, any nonce is allowed.
  • The user refuses the operation.

Metadata inspection: ledgeracio metadata

This command takes no arguments. It pretty-prints the chain metadata to stdout. It is primarily intended for debugging. Requires a network connection.

Properties inspection: ledgeracio properties

This command takes no arguments. It pretty-prints the chain properties to stdout. It is primarily intended for debugging. Requires a network connection.

Nominator operations: ledgeracio nominator

This command performs operations using nominator keys ― that is, keys on a nominator derivation path. Requires a network connection. The following subcommands are available:

Displaying the address at an index: ledgeracio nominator address

This command takes an index as a parameter. The address on the device corresponding to that index is displayed on stdout.

Showing a nominator controller: ledgeracio nominator show

This command takes an index as parameter, and displays information about the corresponding nominator controller account.

Showing a nominator controller address: ledgeracio nominator show-address

This command takes an SS58-formatted address as parameter, and displays information about the corresponding nominator controller account. It does not require a Ledger device.

Nominating a new validator set: ledgeracio nominator nominate

This command takes a index followed by a list of SS58-formatted addresses. It uses the account at the provided index to nominate the provided validator stash accounts.

The user must confirm this action on the Ledger device. For security reasons, users MUST confirm that the addresses displayed on the device are the intended ones. A compromised host machine can send a set of accounts that is not the ones the user intended. If any of the addresses sent to the device are not on the allowlist, the transaction will not be signed.

Stopping nomination: ledgeracio nominator chill

This command stops the account at the provided index from nominating.

The user must confirm this action on the Ledger device.

Setting a payment target: ledgeracio nominator set-payee

This command takes an index as argument, and sets the payment target. The target must be one of Stash, Staked, or Controller (case-insensitive).

Validator operations: ledgeracio validator

This command handles validator operations. It requires a network connection, and has the following subcommands:

Displaying a validator address: ledgeracio validator address <index>

This command displays the address of the validator controller account at the given index.

Announcing an intention to validate: ledgeracio validator announce <index> [commission]

This command announces that the controller account at <index> intends to validate. An optional commission (as a decimal between 0 and 1 inclusive) may also be provided. If none is supplied, it defaults to 1, or 100%.

Cease validation: ledgeracio validator chill

This command stops validation.

The user must confirm this action on the Ledger device.

Setting the payment target: ledgeracio validator set-payee

This command is the validator version of ledgeracio nominator set-payee. See its documentation for details.

Displaying information on a given validator: ledgeracio validator show

This command is the validator version of ledgeracio nominator show. See its documentation for details.

Displaying information on a given validator address: ledgeracio validator show-address

This command is the validator version of ledgeracio nominator show-address. See its documentation for details.

Rotating a session key: ledgeracio validator replace-key <index> <keys>

This command sets the session keys of the validator controlled by the account at <index>. The keys must be in hexidecimal, as returned by the key rotation RPC call.

Download Details:
Author: paritytech
Source Code: https://github.com/paritytech/ledgeracio
License: GPL-3.0 License

#blockchain  #polkadot  #smartcontract  #substrate 

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Ledgeracio: CLI for Use with The Ledger Staking App
Carmen  Grimes

Carmen Grimes


Best Electric Bikes and Scooters for Rental Business or Campus Facility

The electric scooter revolution has caught on super-fast taking many cities across the globe by storm. eScooters, a renovated version of old-school scooters now turned into electric vehicles are an environmentally friendly solution to current on-demand commute problems. They work on engines, like cars, enabling short traveling distances without hassle. The result is that these groundbreaking electric machines can now provide faster transport for less — cheaper than Uber and faster than Metro.

Since they are durable, fast, easy to operate and maintain, and are more convenient to park compared to four-wheelers, the eScooters trend has and continues to spike interest as a promising growth area. Several companies and universities are increasingly setting up shop to provide eScooter services realizing a would-be profitable business model and a ready customer base that is university students or residents in need of faster and cheap travel going about their business in school, town, and other surrounding areas.

Electric Scooters Trends and Statistics

In many countries including the U.S., Canada, Mexico, U.K., Germany, France, China, Japan, India, Brazil and Mexico and more, a growing number of eScooter users both locals and tourists can now be seen effortlessly passing lines of drivers stuck in the endless and unmoving traffic.

A recent report by McKinsey revealed that the E-Scooter industry will be worth― $200 billion to $300 billion in the United States, $100 billion to $150 billion in Europe, and $30 billion to $50 billion in China in 2030. The e-Scooter revenue model will also spike and is projected to rise by more than 20% amounting to approximately $5 billion.

And, with a necessity to move people away from high carbon prints, traffic and congestion issues brought about by car-centric transport systems in cities, more and more city planners are developing more bike/scooter lanes and adopting zero-emission plans. This is the force behind the booming electric scooter market and the numbers will only go higher and higher.

Companies that have taken advantage of the growing eScooter trend develop an appthat allows them to provide efficient eScooter services. Such an app enables them to be able to locate bike pick-up and drop points through fully integrated google maps.

List of Best Electric Bikes for Rental Business or Campus Facility 2020:

It’s clear that e scooters will increasingly become more common and the e-scooter business model will continue to grab the attention of manufacturers, investors, entrepreneurs. All this should go ahead with a quest to know what are some of the best electric bikes in the market especially for anyone who would want to get started in the electric bikes/scooters rental business.

We have done a comprehensive list of the best electric bikes! Each bike has been reviewed in depth and includes a full list of specs and a photo.

Billy eBike

mobile-best-electric-bikes-scooters https://www.kickstarter.com/projects/enkicycles/billy-were-redefining-joyrides

To start us off is the Billy eBike, a powerful go-anywhere urban electric bike that’s specially designed to offer an exciting ride like no other whether you want to ride to the grocery store, cafe, work or school. The Billy eBike comes in 4 color options – Billy Blue, Polished aluminium, Artic white, and Stealth black.

Price: $2490

Available countries

Available in the USA, Europe, Asia, South Africa and Australia.This item ships from the USA. Buyers are therefore responsible for any taxes and/or customs duties incurred once it arrives in your country.


  • Control – Ride with confidence with our ultra-wide BMX bars and a hyper-responsive twist throttle.
  • Stealth- Ride like a ninja with our Gates carbon drive that’s as smooth as butter and maintenance-free.
  • Drive – Ride further with our high torque fat bike motor, giving a better climbing performance.
  • Accelerate – Ride quicker with our 20-inch lightweight cutout rims for improved acceleration.
  • Customize – Ride your own way with 5 levels of power control. Each level determines power and speed.
  • Flickable – Ride harder with our BMX /MotoX inspired geometry and lightweight aluminum package


  • Maximum speed: 20 mph (32 km/h)
  • Range per charge: 41 miles (66 km)
  • Maximum Power: 500W
  • Motor type: Fat Bike Motor: Bafang RM G060.500.DC
  • Load capacity: 300lbs (136kg)
  • Battery type: 13.6Ah Samsung lithium-ion,
  • Battery capacity: On/off-bike charging available
  • Weight: w/o batt. 48.5lbs (22kg), w/ batt. 54lbs (24.5kg)
  • Front Suspension: Fully adjustable air shock, preload/compression damping /lockout
  • Rear Suspension: spring, preload adjustment
  • Built-in GPS

Why Should You Buy This?

  • Riding fun and excitement
  • Better climbing ability and faster acceleration.
  • Ride with confidence
  • Billy folds for convenient storage and transportation.
  • Shorty levers connect to disc brakes ensuring you stop on a dime
  • belt drives are maintenance-free and clean (no oil or lubrication needed)

**Who Should Ride Billy? **

Both new and experienced riders

**Where to Buy? **Local distributors or ships from the USA.

Genze 200 series e-Bike

genze-best-electric-bikes-scooters https://www.genze.com/fleet/

Featuring a sleek and lightweight aluminum frame design, the 200-Series ebike takes your riding experience to greater heights. Available in both black and white this ebike comes with a connected app, which allows you to plan activities, map distances and routes while also allowing connections with fellow riders.

Price: $2099.00

Available countries

The Genze 200 series e-Bike is available at GenZe retail locations across the U.S or online via GenZe.com website. Customers from outside the US can ship the product while incurring the relevant charges.


  • 2 Frame Options
  • 2 Sizes
  • Integrated/Removable Battery
  • Throttle and Pedal Assist Ride Modes
  • Integrated LCD Display
  • Connected App
  • 24 month warranty
  • GPS navigation
  • Bluetooth connectivity


  • Maximum speed: 20 mph with throttle
  • Range per charge: 15-18 miles w/ throttle and 30-50 miles w/ pedal assist
  • Charging time: 3.5 hours
  • Motor type: Brushless Rear Hub Motor
  • Gears: Microshift Thumb Shifter
  • Battery type: Removable Samsung 36V, 9.6AH Li-Ion battery pack
  • Battery capacity: 36V and 350 Wh
  • Weight: 46 pounds
  • Derailleur: 8-speed Shimano
  • Brakes: Dual classic
  • Wheels: 26 x 20 inches
  • Frame: 16, and 18 inches
  • Operating Mode: Analog mode 5 levels of Pedal Assist Thrott­le Mode

Norco from eBikestore

norco-best-electric-bikes-scooters https://ebikestore.com/shop/norco-vlt-s2/

The Norco VLT S2 is a front suspension e-Bike with solid components alongside the reliable Bosch Performance Line Power systems that offer precise pedal assistance during any riding situation.

Price: $2,699.00

Available countries

This item is available via the various Norco bikes international distributors.


  • VLT aluminum frame- for stiffness and wheel security.
  • Bosch e-bike system – for their reliability and performance.
  • E-bike components – for added durability.
  • Hydraulic disc brakes – offer riders more stopping power for safety and control at higher speeds.
  • Practical design features – to add convenience and versatility.


  • Maximum speed: KMC X9 9spd
  • Motor type: Bosch Active Line
  • Gears: Shimano Altus RD-M2000, SGS, 9 Speed
  • Battery type: Power Pack 400
  • Battery capacity: 396Wh
  • Suspension: SR Suntour suspension fork
  • Frame: Norco VLT, Aluminum, 12x142mm TA Dropouts

Bodo EV


Manufactured by Bodo Vehicle Group Limited, the Bodo EV is specially designed for strong power and extraordinary long service to facilitate super amazing rides. The Bodo Vehicle Company is a striking top in electric vehicles brand field in China and across the globe. Their Bodo EV will no doubt provide your riders with high-level riding satisfaction owing to its high-quality design, strength, breaking stability and speed.

Price: $799

Available countries

This item ships from China with buyers bearing the shipping costs and other variables prior to delivery.


  • Reliable
  • Environment friendly
  • Comfortable riding
  • Fashionable
  • Economical
  • Durable – long service life
  • Braking stability
  • LED lighting technology


  • Maximum speed: 45km/h
  • Range per charge: 50km per person
  • Charging time: 8 hours
  • Maximum Power: 3000W
  • Motor type: Brushless DC Motor
  • Load capacity: 100kg
  • Battery type: Lead-acid battery
  • Battery capacity: 60V 20AH
  • Weight: w/o battery 47kg

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Carmen  Grimes

Carmen Grimes


How to start an electric scooter facility/fleet in a university campus/IT park

Are you leading an organization that has a large campus, e.g., a large university? You are probably thinking of introducing an electric scooter/bicycle fleet on the campus, and why wouldn’t you?

Introducing micro-mobility in your campus with the help of such a fleet would help the people on the campus significantly. People would save money since they don’t need to use a car for a short distance. Your campus will see a drastic reduction in congestion, moreover, its carbon footprint will reduce.

Micro-mobility is relatively new though and you would need help. You would need to select an appropriate fleet of vehicles. The people on your campus would need to find electric scooters or electric bikes for commuting, and you need to provide a solution for this.

To be more specific, you need a short-term electric bike rental app. With such an app, you will be able to easily offer micro-mobility to the people on the campus. We at Devathon have built Autorent exactly for this.

What does Autorent do and how can it help you? How does it enable you to introduce micro-mobility on your campus? We explain these in this article, however, we will touch upon a few basics first.

Micro-mobility: What it is


You are probably thinking about micro-mobility relatively recently, aren’t you? A few relevant insights about it could help you to better appreciate its importance.

Micro-mobility is a new trend in transportation, and it uses vehicles that are considerably smaller than cars. Electric scooters (e-scooters) and electric bikes (e-bikes) are the most popular forms of micro-mobility, however, there are also e-unicycles and e-skateboards.

You might have already seen e-scooters, which are kick scooters that come with a motor. Thanks to its motor, an e-scooter can achieve a speed of up to 20 km/h. On the other hand, e-bikes are popular in China and Japan, and they come with a motor, and you can reach a speed of 40 km/h.

You obviously can’t use these vehicles for very long commutes, however, what if you need to travel a short distance? Even if you have a reasonable public transport facility in the city, it might not cover the route you need to take. Take the example of a large university campus. Such a campus is often at a considerable distance from the central business district of the city where it’s located. While public transport facilities may serve the central business district, they wouldn’t serve this large campus. Currently, many people drive their cars even for short distances.

As you know, that brings its own set of challenges. Vehicular traffic adds significantly to pollution, moreover, finding a parking spot can be hard in crowded urban districts.

Well, you can reduce your carbon footprint if you use an electric car. However, electric cars are still new, and many countries are still building the necessary infrastructure for them. Your large campus might not have the necessary infrastructure for them either. Presently, electric cars don’t represent a viable option in most geographies.

As a result, you need to buy and maintain a car even if your commute is short. In addition to dealing with parking problems, you need to spend significantly on your car.

All of these factors have combined to make people sit up and think seriously about cars. Many people are now seriously considering whether a car is really the best option even if they have to commute only a short distance.

This is where micro-mobility enters the picture. When you commute a short distance regularly, e-scooters or e-bikes are viable options. You limit your carbon footprints and you cut costs!

Businesses have seen this shift in thinking, and e-scooter companies like Lime and Bird have entered this field in a big way. They let you rent e-scooters by the minute. On the other hand, start-ups like Jump and Lyft have entered the e-bike market.

Think of your campus now! The people there might need to travel short distances within the campus, and e-scooters can really help them.

How micro-mobility can benefit you


What advantages can you get from micro-mobility? Let’s take a deeper look into this question.

Micro-mobility can offer several advantages to the people on your campus, e.g.:

  • Affordability: Shared e-scooters are cheaper than other mass transportation options. Remember that the people on your campus will use them on a shared basis, and they will pay for their short commutes only. Well, depending on your operating model, you might even let them use shared e-scooters or e-bikes for free!
  • Convenience: Users don’t need to worry about finding parking spots for shared e-scooters since these are small. They can easily travel from point A to point B on your campus with the help of these e-scooters.
  • Environmentally sustainable: Shared e-scooters reduce the carbon footprint, moreover, they decongest the roads. Statistics from the pilot programs in cities like Portland and Denver showimpressive gains around this key aspect.
  • Safety: This one’s obvious, isn’t it? When people on your campus use small e-scooters or e-bikes instead of cars, the problem of overspeeding will disappear. you will see fewer accidents.

#android app #autorent #ios app #mobile app development #app like bird #app like bounce #app like lime #autorent #bird scooter business model #bird scooter rental #bird scooter rental cost #bird scooter rental price #clone app like bird #clone app like bounce #clone app like lime #electric rental scooters #electric scooter company #electric scooter rental business #how do you start a moped #how to start a moped #how to start a scooter rental business #how to start an electric company #how to start electric scooterrental business #lime scooter business model #scooter franchise #scooter rental business #scooter rental business for sale #scooter rental business insurance #scooters franchise cost #white label app like bird #white label app like bounce #white label app like lime

Fredy  Larson

Fredy Larson


How long does it take to develop/build an app?

With more of us using smartphones, the popularity of mobile applications has exploded. In the digital era, the number of people looking for products and services online is growing rapidly. Smartphone owners look for mobile applications that give them quick access to companies’ products and services. As a result, mobile apps provide customers with a lot of benefits in just one device.

Likewise, companies use mobile apps to increase customer loyalty and improve their services. Mobile Developers are in high demand as companies use apps not only to create brand awareness but also to gather information. For that reason, mobile apps are used as tools to collect valuable data from customers to help companies improve their offer.

There are many types of mobile applications, each with its own advantages. For example, native apps perform better, while web apps don’t need to be customized for the platform or operating system (OS). Likewise, hybrid apps provide users with comfortable user experience. However, you may be wondering how long it takes to develop an app.

To give you an idea of how long the app development process takes, here’s a short guide.

App Idea & Research


_Average time spent: two to five weeks _

This is the initial stage and a crucial step in setting the project in the right direction. In this stage, you brainstorm ideas and select the best one. Apart from that, you’ll need to do some research to see if your idea is viable. Remember that coming up with an idea is easy; the hard part is to make it a reality.

All your ideas may seem viable, but you still have to run some tests to keep it as real as possible. For that reason, when Web Developers are building a web app, they analyze the available ideas to see which one is the best match for the targeted audience.

Targeting the right audience is crucial when you are developing an app. It saves time when shaping the app in the right direction as you have a clear set of objectives. Likewise, analyzing how the app affects the market is essential. During the research process, App Developers must gather information about potential competitors and threats. This helps the app owners develop strategies to tackle difficulties that come up after the launch.

The research process can take several weeks, but it determines how successful your app can be. For that reason, you must take your time to know all the weaknesses and strengths of the competitors, possible app strategies, and targeted audience.

The outcomes of this stage are app prototypes and the minimum feasible product.

#android app #frontend #ios app #minimum viable product (mvp) #mobile app development #web development #android app development #app development #app development for ios and android #app development process #ios and android app development #ios app development #stages in app development

YuccaPrerenderBundle: Symfony2 Bundle to Use Prerender.io


Backbone, EmberJS, Angular and so more are your daily basis ? In case of an admin area, that's fine, but on your front office, you might encounter some SEO problems

Thanks to Prerender.io, you now can dynamically render your JavaScript pages in your server using PhantomJS.

This bundle is largely inspired by bakura10 work on zfr-prerender


Install the module by typing (or add it to your composer.json file):

$ php composer.phar require "yucca/prerender-bundle" "0.1.*@dev"

Register the bundle in app/AppKernel.php:

// app/AppKernel.php
public function registerBundles()
    return array(
        // ...
        new Yucca\PrerenderBundle\YuccaPrerenderBundle(),

Enable the bundle's configuration in app/config/config.yml:

# app/config/config.yml
yucca_prerender: ~


How it works

  1. Check to make sure we should show a prerendered page
    1. Check if the request is from a crawler (agent string)
    2. Check to make sure we aren't requesting a resource (js, css, etc...)
    3. (optional) Check to make sure the url is in the whitelist
    4. (optional) Check to make sure the url isn't in the blacklist
  2. Make a GET request to the prerender service (PhantomJS server) for the page's prerendered HTML
  3. Return that HTML to the crawler


This bundle comes with a sane default, extracted from prerender-node middleware, but you can easily customize it:


Prerender URL

By default, YuccaPrerenderBundle uses the Prerender.io service deployed at http://prerender.herokuapp.com. However, you may want to deploy it on your own server. To that extent, you can customize YuccaPrerenderBundle to use your server using the following configuration:

    backend_url: http://localhost:3000

With this config, here is how YuccaPrerender will proxy the "https://google.com" request:

GET http://localhost:3000/https://google.com

Crawler user-agents

YuccaPrerender decides to pre-render based on the User-Agent string to check if a request comes from a bot or not. By default, those user agents are registered: 'baiduspider', 'facebookexternalhit', 'twitterbot'. Googlebot, Yahoo, and Bingbot should not be in this list because we support escaped_fragment instead of checking user agent for those crawlers. Your site must have to understand the '#!' ajax url notation.

You can add other User-Agent string to evaluate using this sample configuration:

    crawler_user_agents: ['yandex', 'msnbot']

Ignored extensions

YuccaPrerender is configured by default to ignore all the requests for resources with those extensions: .js, .css, .less, .png, .jpg, .jpeg, .gif, .pdf, .doc, .txt, .zip, .mp3, .rar, .exe, .wmv, .doc, .avi, .ppt, .mpg, .mpeg, .tif, .wav, .mov, .psd, .ai, .xls, .mp4, .m4a, .swf, .dat, .dmg, .iso, .flv, .m4v, .torrent . Those are never pre-rendered.

You can add your own extensions using this sample configuration:

    ignored_extensions: ['.less', '.pdf']


Whitelist a single url path or multiple url paths. Compares using regex, so be specific when possible. If a whitelist is supplied, only url's containing a whitelist path will be prerendered.

Here is a sample configuration that only pre-render URLs that contains "/users/":

    whitelist_urls: ['/users/*']

Note: remember to specify URL here and not Symfony2 route names.


Blacklist a single url path or multiple url paths. Compares using regex, so be specific when possible. If a blacklist is supplied, all url's will be pre-rendered except ones containing a blacklist part. Please note that if the referer is part of the blacklist, it won't be pre-rendered too.

Here is a sample configuration that prerender all URLs excepting the ones that contains "/users/":

    blacklist_urls: ['/users/*']

Note: remember to specify URL here and not Symfony22 route names.


If you want to make sure your pages are rendering correctly:

  1. Open the Developer Tools in Chrome (Cmd + Atl + J)
  2. Click the Settings gear in the bottom right corner.
  3. Click "Overrides" on the left side of the settings panel.
  4. Check the "User Agent" checkbox.
  5. Choose "Other..." from the User Agent dropdown.
  6. Type googlebot into the input box.
  7. Refresh the page (make sure to keep the developer tools open).


  • Thanks to bakura10 for the Zend Framework version.
  • Thanks to Romain Boyer to make me discover prerender.io
  • Thanks to the prerender team and all JS MVC developpers

Author: rjanot
Source Code: https://github.com/rjanot/YuccaPrerenderBundle 
License: MIT License

#php #symfony 

ThruwayBundle: Bundle for Building Real-time Apps in Symfony


This a Symfony Bundle for Thruway, which is a php implementation of WAMP (Web Application Messaging Protocol).

Note: This project is still undergoing a lot of changes, so the API will change.

Quick Start with Composer

Install the Thruway Bundle

  $ composer require "voryx/thruway-bundle"

Update AppKernel.php (when using Symfony < 4)

$bundles = array(
    // ...
    new Voryx\ThruwayBundle\VoryxThruwayBundle(),
    // ...



    realm: 'realm1'
    url: 'ws://' #The url that the clients will use to connect to the router
        ip: ''  # the ip that the router should start on
        port: '8080'  # public facing port.  If authentication is enabled, this port will be protected
        trusted_port: '8081' # Bypasses all authentication.  Use this for trusted clients.
#        authentication: false # true will load the AuthenticationManager
        bundles: ["AppBundle"]
#        files:
#            - "Acme\\DemoBundle\\Controller\\DemoController"
# For symfony 4, this bundle will automatically scan for annotated worker files in the src/Controller folder

With Symfony 4 use a filename like: config/packages/voryx.yaml

If you are using the in-memory user provider, you'll need to add a thruway to the security firewall and set the in_memory_user_provider.


            security: false	     

You can also tag services with thruway.resource and any annotation will get picked up

<service id="some.service" class="Acme\Bundle\SomeService">
    <tag name="thruway.resource"/>

Note: tagging a service as thruway.resource will make it public.

        resource: '../src/Worker'
        tags: ['thruway.resource']

Authentication with FOSUserBundle via WampCRA

Change the Password Encoder (tricky on existing sites) to master wamp challenge


            algorithm:            pbkdf2
            hash_algorithm:       sha256
            encode_as_base64:     true
            iterations:           1000
            key_length:           32

set voryx_thruway.user_provider to "fos_user.user_provider"


    user_provider: 'fos_user.user_provider.username' #fos_user.user_provider.username_email login with email

The WAMP-CRA service is already configured, we just need to add a tag to it to have the bundle install it:

        class: Thruway\Authentication\WampCraAuthProvider
        parent: voryx.thruway.wamp.cra.auth.client
            - { name: thruway.internal_client }

Custom Authorization Manager

You can set your own Authorization Manager in order to check if a user (identified by its authid) is allowed to publish | subscribe | call | register

Create your Authorization Manager service, extending RouterModuleClient and implementing RealmModuleInterface (see the Thruway doc for details)

// src/ACME/AppBundle/Security/MyAuthorizationManager.php

use Thruway\Event\MessageEvent;
use Thruway\Event\NewRealmEvent;
use Thruway\Module\RealmModuleInterface;
use Thruway\Module\RouterModuleClient;

class MyAuthorizationManager extends RouterModuleClient implements RealmModuleInterface
     * Listen for Router events.
     * Required to add the authorization module to the realm
     * @return array
    public static function getSubscribedEvents()
        return [
            'new_realm' => ['handleNewRealm', 10]

     * @param NewRealmEvent $newRealmEvent
    public function handleNewRealm(NewRealmEvent $newRealmEvent)
        $realm = $newRealmEvent->realm;

        if ($realm->getRealmName() === $this->getRealm()) {

     * @return array
    public function getSubscribedRealmEvents()
        return [
            'PublishMessageEvent'   => ['authorize', 100],
            'SubscribeMessageEvent' => ['authorize', 100],
            'RegisterMessageEvent'  => ['authorize', 100],
            'CallMessageEvent'      => ['authorize', 100],

     * @param MessageEvent $msg
     * @return bool
    public function authorize(MessageEvent $msg)
        if ($msg->session->getAuthenticationDetails()->getAuthId() === 'username') {
            return true;
        return false;

Register your authorization manager service

        class: ACME\AppBundle\Security\MyAuthorizationManager

Insert your service name in the voryx_thruway config


        authorization: my_authorization_manager # insert the name of your custom authorizationManager

Restart the Thruway server; it will now check authorization upon publish | subscribe | call | register. Remember to catch error when you try to subscribe to a topic (or any other action) as it may now be denied and this will be returned as an error.


Register RPC

    use Voryx\ThruwayBundle\Annotation\Register;
     * @Register("com.example.add")
    public function addAction($num1, $num2)
        return $num1 + $num2;

Call RPC

    public function call($value)
        $client = $this->container->get('thruway.client');
        $client->call("com.myapp.add", [2, 3])->then(
            function ($res) {
                echo $res[0];


     use Voryx\ThruwayBundle\Annotation\Subscribe;

     * @Subscribe("com.example.subscribe")
    public function subscribe($value)
        echo $value;


    public function publish($value)
        $client = $this->container->get('thruway.client');
        $client->publish("com.myapp.hello_pubsub", [$value]);

It uses Symfony Serializer, so it can serialize and deserialize Entities

         use Voryx\ThruwayBundle\Annotation\Register;

     * @Register("com.example.addrpc", serializerEnableMaxDepthChecks=true)
    public function addAction(Post $post)
        //Do something to $post

        return $post;

Start the Thruway Process

You can start the default Thruway workers (router and client workers), without any additional configuration.

$ nohup php app/console thruway:process start &

By default, the router starts on ws://


The Thruway bundle will start up a separate process for the router and each defined worker. If you haven't defined any workers, all of the annotated calls and subscriptions will be started within the default worker.

There are two main ways to break your application apart into multiple workers.

Use the worker property on the Register and Subscribe annotations. The following RPC will be added to the posts worker.

  use Voryx\ThruwayBundle\Annotation\Register;

  * @Register("com.example.addrpc", serializerEnableMaxDepthChecks=true, worker="posts")
  public function addAction(Post $post)

Use the @Worker annotation on the class. The following annotation will create a worker called chat that can have a max of 5 instances.

  use Voryx\ThruwayBundle\Annotation\Worker;

  * @Worker("chat", maxProcesses="5")
  class ChatController

If a worker is shut down with anything other than SIGTERM, it will automatically be restarted.

More Commands

To see a list of running processes (workers)

$ php app/console thruway:process status

Stop a process, i.e. default

$ php app/console thruway:process stop default

Start a process, i.e. default

$ php app/console thruway:process start default

Javascript Client

For the client, you can use AutobahnJS or any other WAMPv2 compatible client.

Here are some examples

Symfony 4 Quick Start

composer create-project symfony/skeleton my_project
cd my_project
composer require symfony/expression-language
composer require symfony/annotations-pack
composer require voryx/thruway-bundle:dev-master

Create config/packages/my_project.yml with the following config:

    realm: 'realm1'
    url: 'ws://' #The url that the clients will use to connect to the router
        ip: ''  # the ip that the router should start on
        port: '8080'  # public facing port.  If authentication is enabled, this port will be protected
        trusted_port: '8081' # Bypasses all authentication.  Use this for trusted clients.

Create the controller src/Controller/TestController.php

namespace App\Controller;

use Voryx\ThruwayBundle\Annotation\Register;

class TestController
     * @Register("com.example.add")
    public function addAction($num1, $num2)
        return $num1 + $num2;

Test to see if the RPC has been configured correctly bin/console thruway:debug

 URI             Type Worker  File                                                  Method    
 com.example.add RPC  default /my_project/src/Controller/TestController.php         addAction 

For more debug info for the RPC we created: bin/console thruway:debug com.example.add

Start everything: bin/console thruway:process start

The RPC com.example.add is now available to any WAMP client connected to ws:// on realm1.

Author: Voryx
Source Code: https://github.com/voryx/ThruwayBundle 

#php #symfony