A Node.js module that adds a native interface to Bitcoin Core for querying information about the Bitcoin blockchain. Bindings are linked to Bitcoin Core compiled as a static library.
Note: For convenience, we distribute binaries for x86_64 Linux and x86_64 Mac OS X. Upon npm install, the binaries for your platform will be downloaded. This greatly speeds up the process of using this project. If you don't want to compile the project for yourself, then please skip down to "Example Usage" section for next steps. Please see detailed instructions below for complete build details and dependencies needed for installation if you choose to build the project from source.
If git is not already installed, it can be installed by running:
```bash
sudo apt-get install git
git config --global user.email "you@example.com"
git config --global user.name "Your Name"
```
If Node.js v0.12 isn't installed, it can be installed using "nvm", it can be done by following the installation script at https://github.com/creationix/nvm#install-script and then install version v0.12
```bash
nvm install v0.12
```
To build Bitcoin Core and bindings development packages are needed:
And finally run the build which will take several minutes. A script in the "bin" directory will download Bitcoin Core v0.11, apply a patch (see more info below), and compile the static library and Node.js bindings. You can start this by running:
Later versions of Fedora (>= 22) should also work with this project. The directions for Ubuntu should generally work except the installation of system utilities and libraries is a bit different. Git is already installed and ready for use without installation.
If Xcode is not already installed, it can be installed via the Mac App Store (will take several minutes). XCode includes "Clang", "git" and other build tools. Once Xcode is installed, you'll then need to install "xcode-select" via running in a terminal and following the prompts:
```bash
xcode-select --install
```
If "Homebrew" is not yet installed, it's needed to install "autoconf" and others. You can install it using the script at http://brew.sh and following the directions at https://github.com/Homebrew/homebrew/blob/master/share/doc/homebrew/Installation.md And then run in a terminal:
If Node.js v0.12 and associated commands "node", "npm" and "nvm" are not already installed, you can use "nvm" by running the script at https://github.com/creationix/nvm#install-script And then run this command to install Node.js v0.12
And finally run the build which will take several minutes. A script in the "bin" directory will download Bitcoin Core v0.11, apply a patch (see more info below), and compile the static library and Node.js bindings. You can start this by running:
To run tests against the bindings, as defined in `bindings.gyp` the regtest feature of Bitcoin Core is used, and to enable this feature we currently need to build with the wallet enabled *(not a part of the regular build)*. To do this, export an environment variable and recompile:
If any changes have been made to the bindings in the "src" directory, manually compile the Node.js bindings, as defined in `bindings.gyp`, you can run (-d for debug):
To be able to debug you'll need to have `gdb` and `node` compiled for debugging with gdb using `--gdb` (sometimes called node_g), and you can then run:
```bash
$ gdb --args node examples/node.js
```
To run mocha from within gdb (notice `_mocha` and not `mocha` so that the tests run in the same process):
To provide native bindings to JavaScript *(or any other language for that matter)*, Bitcoin code, itself, must be linkable. Currently, Bitcoin Core provides a JSON RPC interface to bitcoind as well as a shared library for script validation *(and hopefully more)* called libbitcoinconsensus. There is a node module, [node-libbitcoinconsensus](https://github.com/bitpay/node-libbitcoinconsensus), that exposes these methods. While these interfaces are useful for several use cases, there are additional use cases that are not fulfilled, and being able to implement customized interfaces is necessary. To be able to do this a few simple changes need to be made to Bitcoin Core to compile as a static library.
The patch is located at `etc/bitcoin.patch` and adds a configure option `--enable-daemonlib` to compile all object files with `-fPIC` (Position Independent Code - needed to create a shared object), exposes leveldb variables and objects, exposes the threadpool to the bindings, and conditionally includes the main function.
Every effort will be made to ensure that this patch stays up-to-date with the latest release of Bitcoin. At the very least, this project began supporting Bitcoin Core v0.11.
A new module can be created by inheriting from `Node.Module`, implementing the methods `blockHandler()`, `getAPIMethods()`, `getPublishEvents()` and any additional methods for querying the data. Here is an example:
Note that if you already have a bitcore-node database, and you want to query data from previous blocks in the blockchain, you will need to reindex. Reindexing right now means deleting your bitcore-node database and resyncing.
-`daemon.isSpent(txid, outputIndex)` - Returns a boolean if a txid and outputIndex is already spent.
-`daemon.getBlockIndex(blockHash)` - Will return the block chain work and previous hash.
-`daemon.estimateFee(blocks)` - Estimates the fees required to have a transaction included in the number of blocks specified as the first argument.
-`daemon.sendTransaction(transaction, allowAbsurdFees)` - Will attempt to add a transaction to the mempool and broadcast to peers.
-`daemon.getTransaction(txid, queryMempool, callback)` - Get any tx asynchronously by reading it from disk, with an argument to optionally not include the mempool.
-`daemon.getTransactionWithBlockInfo(txid, queryMempool, callback)` - Similar to getTransaction but will also include the block timestamp and height.
-`daemon.getMempoolOutputs(address)` - Will return an array of outputs that match an address from the mempool.
-`daemon.getInfo()` - Basic information about the chain including total number of blocks.
-`daemon.stop([callback])` - Stop the JavaScript bitcoin node safely, the callback will be called when bitcoind is closed. This will also be done automatically on `process.exit`. It also takes the bitcoind node off the libuv event loop. If the daemon object is the only thing on the event loop. Node will simply close.