README.dev

   1 ====================================
   2 Setup PVE Development Environment
   3 ====================================
   4
   5 1.  Install Debian 'jessie'
   6 2.  Install prerequisites for development environment:
   7
   8 # new jessie depends
   9 apt-get -y install build-essential git-core debhelper autotools-dev \
  10 doxygen check pkg-config groff quilt dpatch automake autoconf libtool  \
  11 lintian libdevel-cycle-perl libjson-perl libcommon-sense-perl     \
  12 liblinux-inotify2-perl libio-stringy-perl libstring-shellquote-perl  \
  13 dh-systemd rpm2cpio libsqlite3-dev sqlite3 libglib2.0-dev librrd-dev \
  14 librrds-perl rrdcached libdigest-hmac-perl libxml-parser-perl \
  15 gdb
  16
  17 # old wheezy depends
  18 apt-get -y install build-essential git-core debhelper autotools-dev \
  19 doxygen check pkg-config libnss3-dev groff quilt dpatch libxml2-dev \
  20 libncurses5-dev libslang2-dev libldap2-dev xsltproc python-pexpect \
  21 python-pycurl libdbus-1-dev openipmi sg3-utils libnet-snmp-perl \
  22 libnet-telnet-perl snmp python-openssl libxml2-utils automake autoconf \
  23 libsqlite3-dev sqlite3 libfuse-dev libglib2.0-dev librrd-dev \
  24 librrds-perl rrdcached lintian libdevel-cycle-perl libjson-perl \
  25 liblinux-inotify2-perl libio-stringy-perl unzip fuse-utils \
  26 libcrypt-openssl-random-perl libcrypt-openssl-rsa-perl \
  27 libauthen-pam-perl libterm-readline-gnu-perl libssl-dev open-iscsi \
  28 libapache2-mod-perl2 libfilesys-df-perl libfile-readbackwards-perl \
  29 libpci-dev texi2html libgnutls-dev libsdl1.2-dev bridge-utils \
  30 libvncserver0 rpm2cpio  apache2-mpm-prefork libintl-perl \
  31 libapache2-request-perl libnet-dns-perl vlan libio-socket-ssl-perl \
  32 libfile-sync-perl ifenslave-2.6 libnet-ldap-perl console-data \
  33 libtool dietlibc-dev liblocale-po-perl libstring-shellquote-perl \
  34 libio-multiplex-perl liblockfile-simple-perl
  35
  36 3.  Download and install the following git modules in order from top to bottom:
  37
  38 # git clone git://git.proxmox.com/git/<PACKAGE.git>
  39
  40 You currently need the following packages:
  41
  42 libqb.git
  43 corosync-pve.git
  44 openais-pve.git
  45 pve-common.git
  46 pve-cluster.git
  47 redhat-cluster-pve.git
  48 lvm.git
  49 pve-access-control.git
  50 pve-storage.git
  51 pve-qemu-kvm.git
  52 qemu-server.git
  53 vncterm.git
  54 vzquota.git
  55 vzctl.git
  56 fence-agents-pve.git
  57 resource-agents-pve.git
  58 pve-manager.git
  59 pve-kernel-2.6.32.git
  60 libiscsi.git
  61 gfs2-utils.git
  62 ksm-control-daemon.git
  63
  64 Most packages can be installed with 'make dinstall' command.
  65
  66 4.  Reboot the system.
  67 5.  Learn to use the quilt patch scripts.
  68 6.  Happy coding.
  69
  70 There is an experimental package containing the API documentation
  71 as ExtJS application:
  72
  73 pve2-api-doc.git
  74
  75 You can view the source code at:
  76
  77 https://git.proxmox.com
  78
  79
  80 REST vs. SOAP
  81 =============
  82
  83 We decided to change our SOAP API (1.X) and use a REST like API. The
  84 concept is described in [1] (Resource Oriented Architecture
  85 (ROA)). The main advantage is that we are able to remove a lot of code
  86 (the whole SOAP stack) to reduce software complexity.
  87
  88 We also moved away from server side content generation. Instead we use
  89 the ExtJS Rich Internet Application Framework
  90 (http://www.sencha.com).
  91
  92 That framework, like any other AJAX toolkit, can talk directly to the
  93 REST API using JSON. So we were able to remove the server side
  94 template toolkit completely.
  95
  96 JSON and JSON Schema
  97 ====================
  98
  99 We use JSON as data format, because it is simple and parse-able by any
 100 web browser.
 101
 102 Additionally, we use JSON Schema [2] to formally describe our API. So
 103 we can automatically generate the whole API Documentation, and we can
 104 verify all parameters and return values.
 105
 106 A great side effect was that we are able to use JSON Schema to
 107 produce command line argument parsers automatically. In fact, the REST
 108 API and the command line tools use the same code.
 109
 110 Object linkage is done using the JSON Hyper Schema (links property).
 111
 112 A small utility called 'pvesh' exposes the whole REST API on the command
 113 line.
 114
 115 So here is a summary of the advantage:
 116
 117    - easy, human readable data format (native web browser format)
 118    - automatic parameter verification (we can also verify return values)
 119    - automatic generation of API documentation
 120    - easy way to create command line tools (using same API).
 121
 122 API Implementation (PVE::RESTHandler)
 123 =====================================
 124
 125 All classes exposing methods on the API use PVE::RESTHandler as base class.
 126
 127   use base qw(PVE::RESTHandler);
 128
 129 To expose methods, one needs to call register_method():
 130
 131   __PACKAGE__->register_method ($schema);
 132
 133 Where $schema is a PVE method schema as described in
 134 PVE::JSONSchema. It includes a description of parameters and return
 135 values, and a reference to the actual code
 136
 137 __PACKAGE__->register_method ({
 138     name => 'echo',
 139     path => 'echo',
 140     method => 'GET',
 141     description => "simple return value of parameter 'text'",
 142     parameters => {
 143         additionalProperties => 0,
 144         properties => {
 145             text => {
 146                  type => 'string',
 147             }
 148         },
 149     },
 150     returns => {
 151         type => 'string',
 152     },
 153     code => sub {
 154         my ($conn, $resp, $param) = @_;
 155
 156         return $param->{text};
 157     }
 158 });
 159
 160 The 'name' property is only used if you want to call the method
 161 directly from Perl. You can do that using:
 162
 163   print __PACKAGE__->echo({ text => "a test" });
 164
 165 We use Perl's AUTOLOAD feature to implement this. Note: You need to
 166 pass parameters a HASH reference.
 167
 168 There is a special helper method called cli_handler(). This is used by
 169 the CLIHandler Class for command line tools, where you want to pass
 170 arguments as array of strings. This uses Getopt::Long to parse parameters.
 171
 172 There is a second way to map names to methods - using the 'path'
 173 property.  And you can register subclasses. That way you can set up a
 174 filesystem like hierarchy to access methods.
 175
 176 Here is an example:
 177 ----------------------------
 178 package C1;
 179
 180 __PACKAGE__->register_method ({
 181     subclass => "C2",
 182     path => 'sub2',
 183 });
 184
 185
 186 __PACKAGE__->register_method ({
 187     name => 'list1',
 188     path => 'index',
 189     method => 'GET',
 190     ...
 191 });
 192
 193 package C2;
 194
 195 __PACKAGE__->register_method ({
 196     name => 'list2',
 197     path => 'index',
 198     method => 'GET',
 199     ...
 200 });
 201 -------------------------------
 202
 203 The utily method find_handler (in PVE::RESTHandler) can be use to do
 204 'path' related method lookups.
 205
 206 C1->find_handler('GET', "/index")      => C1::list1
 207 C1->find_handler('GET', "/sub2/index") => C2::list2
 208
 209 The HTTP server use the URL (a path) to find the corresponding method.
 210
 211
 212 References
 213 ==========
 214 [1] RESTful Web Services
 215 Web services for the real world
 216
 217 By
 218     Leonard Richardson, Sam Ruby
 219 Publisher:
 220     O'Reilly Media
 221 Released:
 222     May 2007
 223
 224 [2] JSON Schema links: http://json-schema.org/