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1 | The Mercurial wire protocol is a request-response based protocol |
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1 | The Mercurial wire protocol is a request-response based protocol | |
2 | with multiple wire representations. |
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2 | with multiple wire representations. | |
3 |
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3 | |||
4 | Each request is modeled as a command name, a dictionary of arguments, and |
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4 | Each request is modeled as a command name, a dictionary of arguments, and | |
5 | optional raw input. Command arguments and their types are intrinsic |
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5 | optional raw input. Command arguments and their types are intrinsic | |
6 | properties of commands. So is the response type of the command. This means |
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6 | properties of commands. So is the response type of the command. This means | |
7 | clients can't always send arbitrary arguments to servers and servers can't |
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7 | clients can't always send arbitrary arguments to servers and servers can't | |
8 | return multiple response types. |
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8 | return multiple response types. | |
9 |
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9 | |||
10 | The protocol is synchronous and does not support multiplexing (concurrent |
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10 | The protocol is synchronous and does not support multiplexing (concurrent | |
11 | commands). |
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11 | commands). | |
12 |
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12 | |||
13 | Transport Protocols |
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13 | Transport Protocols | |
14 | =================== |
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14 | =================== | |
15 |
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15 | |||
16 | HTTP Transport |
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16 | HTTP Transport | |
17 | -------------- |
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17 | -------------- | |
18 |
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18 | |||
19 | Commands are issued as HTTP/1.0 or HTTP/1.1 requests. Commands are |
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19 | Commands are issued as HTTP/1.0 or HTTP/1.1 requests. Commands are | |
20 | sent to the base URL of the repository with the command name sent in |
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20 | sent to the base URL of the repository with the command name sent in | |
21 | the ``cmd`` query string parameter. e.g. |
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21 | the ``cmd`` query string parameter. e.g. | |
22 | ``https://example.com/repo?cmd=capabilities``. The HTTP method is ``GET`` |
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22 | ``https://example.com/repo?cmd=capabilities``. The HTTP method is ``GET`` | |
23 | or ``POST`` depending on the command and whether there is a request |
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23 | or ``POST`` depending on the command and whether there is a request | |
24 | body. |
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24 | body. | |
25 |
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25 | |||
26 | Command arguments can be sent multiple ways. |
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26 | Command arguments can be sent multiple ways. | |
27 |
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27 | |||
28 | The simplest is part of the URL query string using ``x-www-form-urlencoded`` |
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28 | The simplest is part of the URL query string using ``x-www-form-urlencoded`` | |
29 | encoding (see Python's ``urllib.urlencode()``. However, many servers impose |
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29 | encoding (see Python's ``urllib.urlencode()``. However, many servers impose | |
30 | length limitations on the URL. So this mechanism is typically only used if |
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30 | length limitations on the URL. So this mechanism is typically only used if | |
31 | the server doesn't support other mechanisms. |
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31 | the server doesn't support other mechanisms. | |
32 |
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32 | |||
33 | If the server supports the ``httpheader`` capability, command arguments can |
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33 | If the server supports the ``httpheader`` capability, command arguments can | |
34 | be sent in HTTP request headers named ``X-HgArg-<N>`` where ``<N>`` is an |
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34 | be sent in HTTP request headers named ``X-HgArg-<N>`` where ``<N>`` is an | |
35 | integer starting at 1. A ``x-www-form-urlencoded`` representation of the |
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35 | integer starting at 1. A ``x-www-form-urlencoded`` representation of the | |
36 | arguments is obtained. This full string is then split into chunks and sent |
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36 | arguments is obtained. This full string is then split into chunks and sent | |
37 | in numbered ``X-HgArg-<N>`` headers. The maximum length of each HTTP header |
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37 | in numbered ``X-HgArg-<N>`` headers. The maximum length of each HTTP header | |
38 | is defined by the server in the ``httpheader`` capability value, which defaults |
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38 | is defined by the server in the ``httpheader`` capability value, which defaults | |
39 | to ``1024``. The server reassembles the encoded arguments string by |
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39 | to ``1024``. The server reassembles the encoded arguments string by | |
40 | concatenating the ``X-HgArg-<N>`` headers then URL decodes them into a |
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40 | concatenating the ``X-HgArg-<N>`` headers then URL decodes them into a | |
41 | dictionary. |
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41 | dictionary. | |
42 |
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42 | |||
43 | The list of ``X-HgArg-<N>`` headers should be added to the ``Vary`` request |
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43 | The list of ``X-HgArg-<N>`` headers should be added to the ``Vary`` request | |
44 | header to instruct caches to take these headers into consideration when caching |
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44 | header to instruct caches to take these headers into consideration when caching | |
45 | requests. |
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45 | requests. | |
46 |
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46 | |||
47 | If the server supports the ``httppostargs`` capability, the client |
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47 | If the server supports the ``httppostargs`` capability, the client | |
48 | may send command arguments in the HTTP request body as part of an |
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48 | may send command arguments in the HTTP request body as part of an | |
49 | HTTP POST request. The command arguments will be URL encoded just like |
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49 | HTTP POST request. The command arguments will be URL encoded just like | |
50 | they would for sending them via HTTP headers. However, no splitting is |
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50 | they would for sending them via HTTP headers. However, no splitting is | |
51 | performed: the raw arguments are included in the HTTP request body. |
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51 | performed: the raw arguments are included in the HTTP request body. | |
52 |
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52 | |||
53 | The client sends a ``X-HgArgs-Post`` header with the string length of the |
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53 | The client sends a ``X-HgArgs-Post`` header with the string length of the | |
54 | encoded arguments data. Additional data may be included in the HTTP |
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54 | encoded arguments data. Additional data may be included in the HTTP | |
55 | request body immediately following the argument data. The offset of the |
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55 | request body immediately following the argument data. The offset of the | |
56 | non-argument data is defined by the ``X-HgArgs-Post`` header. The |
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56 | non-argument data is defined by the ``X-HgArgs-Post`` header. The | |
57 | ``X-HgArgs-Post`` header is not required if there is no argument data. |
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57 | ``X-HgArgs-Post`` header is not required if there is no argument data. | |
58 |
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58 | |||
59 | Additional command data can be sent as part of the HTTP request body. The |
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59 | Additional command data can be sent as part of the HTTP request body. The | |
60 | default ``Content-Type`` when sending data is ``application/mercurial-0.1``. |
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60 | default ``Content-Type`` when sending data is ``application/mercurial-0.1``. | |
61 | A ``Content-Length`` header is currently always sent. |
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61 | A ``Content-Length`` header is currently always sent. | |
62 |
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62 | |||
63 | Example HTTP requests:: |
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63 | Example HTTP requests:: | |
64 |
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64 | |||
65 | GET /repo?cmd=capabilities |
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65 | GET /repo?cmd=capabilities | |
66 | X-HgArg-1: foo=bar&baz=hello%20world |
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66 | X-HgArg-1: foo=bar&baz=hello%20world | |
67 |
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67 | |||
68 | The ``Content-Type`` HTTP response header identifies the response as coming |
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68 | The ``Content-Type`` HTTP response header identifies the response as coming | |
69 | from Mercurial and can also be used to signal an error has occurred. |
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69 | from Mercurial and can also be used to signal an error has occurred. | |
70 |
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70 | |||
71 | The ``application/mercurial-0.1`` media type indicates a generic Mercurial |
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71 | The ``application/mercurial-0.1`` media type indicates a generic Mercurial | |
72 | response. It matches the media type sent by the client. |
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72 | response. It matches the media type sent by the client. | |
73 |
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73 | |||
74 | The ``application/hg-error`` media type indicates a generic error occurred. |
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74 | The ``application/hg-error`` media type indicates a generic error occurred. | |
75 | The content of the HTTP response body typically holds text describing the |
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75 | The content of the HTTP response body typically holds text describing the | |
76 | error. |
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76 | error. | |
77 |
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77 | |||
78 | The ``application/hg-changegroup`` media type indicates a changegroup response |
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78 | The ``application/hg-changegroup`` media type indicates a changegroup response | |
79 | type. |
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79 | type. | |
80 |
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80 | |||
81 | Clients also accept the ``text/plain`` media type. All other media |
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81 | Clients also accept the ``text/plain`` media type. All other media | |
82 | types should cause the client to error. |
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82 | types should cause the client to error. | |
83 |
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83 | |||
84 | Clients should issue a ``User-Agent`` request header that identifies the client. |
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84 | Clients should issue a ``User-Agent`` request header that identifies the client. | |
85 | The server should not use the ``User-Agent`` for feature detection. |
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85 | The server should not use the ``User-Agent`` for feature detection. | |
86 |
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86 | |||
87 | A command returning a ``string`` response issues the |
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87 | A command returning a ``string`` response issues the | |
88 | ``application/mercurial-0.1`` media type and the HTTP response body contains |
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88 | ``application/mercurial-0.1`` media type and the HTTP response body contains | |
89 | the raw string value. A ``Content-Length`` header is typically issued. |
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89 | the raw string value. A ``Content-Length`` header is typically issued. | |
90 |
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90 | |||
91 | A command returning a ``stream`` response issues the |
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91 | A command returning a ``stream`` response issues the | |
92 | ``application/mercurial-0.1`` media type and the HTTP response is typically |
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92 | ``application/mercurial-0.1`` media type and the HTTP response is typically | |
93 | using *chunked transfer* (``Transfer-Encoding: chunked``). |
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93 | using *chunked transfer* (``Transfer-Encoding: chunked``). | |
94 |
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94 | |||
95 | SSH Transport |
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95 | SSH Transport | |
96 | ============= |
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96 | ============= | |
97 |
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97 | |||
98 | The SSH transport is a custom text-based protocol suitable for use over any |
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98 | The SSH transport is a custom text-based protocol suitable for use over any | |
99 | bi-directional stream transport. It is most commonly used with SSH. |
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99 | bi-directional stream transport. It is most commonly used with SSH. | |
100 |
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100 | |||
101 | A SSH transport server can be started with ``hg serve --stdio``. The stdin, |
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101 | A SSH transport server can be started with ``hg serve --stdio``. The stdin, | |
102 | stderr, and stdout file descriptors of the started process are used to exchange |
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102 | stderr, and stdout file descriptors of the started process are used to exchange | |
103 | data. When Mercurial connects to a remote server over SSH, it actually starts |
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103 | data. When Mercurial connects to a remote server over SSH, it actually starts | |
104 | a ``hg serve --stdio`` process on the remote server. |
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104 | a ``hg serve --stdio`` process on the remote server. | |
105 |
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105 | |||
106 | Commands are issued by sending the command name followed by a trailing newline |
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106 | Commands are issued by sending the command name followed by a trailing newline | |
107 | ``\n`` to the server. e.g. ``capabilities\n``. |
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107 | ``\n`` to the server. e.g. ``capabilities\n``. | |
108 |
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108 | |||
109 | Command arguments are sent in the following format:: |
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109 | Command arguments are sent in the following format:: | |
110 |
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110 | |||
111 | <argument> <length>\n<value> |
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111 | <argument> <length>\n<value> | |
112 |
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112 | |||
113 | That is, the argument string name followed by a space followed by the |
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113 | That is, the argument string name followed by a space followed by the | |
114 | integer length of the value (expressed as a string) followed by a newline |
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114 | integer length of the value (expressed as a string) followed by a newline | |
115 | (``\n``) followed by the raw argument value. |
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115 | (``\n``) followed by the raw argument value. | |
116 |
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116 | |||
117 | Dictionary arguments are encoded differently:: |
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117 | Dictionary arguments are encoded differently:: | |
118 |
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118 | |||
119 | <argument> <# elements>\n |
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119 | <argument> <# elements>\n | |
120 | <key1> <length1>\n<value1> |
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120 | <key1> <length1>\n<value1> | |
121 | <key2> <length2>\n<value2> |
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121 | <key2> <length2>\n<value2> | |
122 | ... |
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122 | ... | |
123 |
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123 | |||
124 | Non-argument data is sent immediately after the final argument value. It is |
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124 | Non-argument data is sent immediately after the final argument value. It is | |
125 | encoded in chunks:: |
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125 | encoded in chunks:: | |
126 |
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126 | |||
127 | <length>\n<data> |
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127 | <length>\n<data> | |
128 |
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128 | |||
129 | Each command declares a list of supported arguments and their types. If a |
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129 | Each command declares a list of supported arguments and their types. If a | |
130 | client sends an unknown argument to the server, the server should abort |
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130 | client sends an unknown argument to the server, the server should abort | |
131 | immediately. The special argument ``*`` in a command's definition indicates |
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131 | immediately. The special argument ``*`` in a command's definition indicates | |
132 | that all argument names are allowed. |
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132 | that all argument names are allowed. | |
133 |
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133 | |||
134 | The definition of supported arguments and types is initially made when a |
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134 | The definition of supported arguments and types is initially made when a | |
135 | new command is implemented. The client and server must initially independently |
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135 | new command is implemented. The client and server must initially independently | |
136 | agree on the arguments and their types. This initial set of arguments can be |
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136 | agree on the arguments and their types. This initial set of arguments can be | |
137 | supplemented through the presence of *capabilities* advertised by the server. |
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137 | supplemented through the presence of *capabilities* advertised by the server. | |
138 |
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138 | |||
139 | Each command has a defined expected response type. |
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139 | Each command has a defined expected response type. | |
140 |
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140 | |||
141 | A ``string`` response type is a length framed value. The response consists of |
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141 | A ``string`` response type is a length framed value. The response consists of | |
142 | the string encoded integer length of a value followed by a newline (``\n``) |
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142 | the string encoded integer length of a value followed by a newline (``\n``) | |
143 | followed by the value. Empty values are allowed (and are represented as |
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143 | followed by the value. Empty values are allowed (and are represented as | |
144 | ``0\n``). |
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144 | ``0\n``). | |
145 |
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145 | |||
146 | A ``stream`` response type consists of raw bytes of data. There is no framing. |
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146 | A ``stream`` response type consists of raw bytes of data. There is no framing. | |
147 |
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147 | |||
148 | A generic error response type is also supported. It consists of a an error |
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148 | A generic error response type is also supported. It consists of a an error | |
149 | message written to ``stderr`` followed by ``\n-\n``. In addition, ``\n`` is |
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149 | message written to ``stderr`` followed by ``\n-\n``. In addition, ``\n`` is | |
150 | written to ``stdout``. |
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150 | written to ``stdout``. | |
151 |
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151 | |||
152 | If the server receives an unknown command, it will send an empty ``string`` |
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152 | If the server receives an unknown command, it will send an empty ``string`` | |
153 | response. |
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153 | response. | |
154 |
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154 | |||
155 | The server terminates if it receives an empty command (a ``\n`` character). |
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155 | The server terminates if it receives an empty command (a ``\n`` character). | |
156 |
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156 | |||
157 | Capabilities |
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157 | Capabilities | |
158 | ============ |
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158 | ============ | |
159 |
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159 | |||
160 | Servers advertise supported wire protocol features. This allows clients to |
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160 | Servers advertise supported wire protocol features. This allows clients to | |
161 | probe for server features before blindly calling a command or passing a |
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161 | probe for server features before blindly calling a command or passing a | |
162 | specific argument. |
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162 | specific argument. | |
163 |
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163 | |||
164 | The server's features are exposed via a *capabilities* string. This is a |
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164 | The server's features are exposed via a *capabilities* string. This is a | |
165 | space-delimited string of tokens/features. Some features are single words |
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165 | space-delimited string of tokens/features. Some features are single words | |
166 | like ``lookup`` or ``batch``. Others are complicated key-value pairs |
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166 | like ``lookup`` or ``batch``. Others are complicated key-value pairs | |
167 | advertising sub-features. e.g. ``httpheader=2048``. When complex, non-word |
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167 | advertising sub-features. e.g. ``httpheader=2048``. When complex, non-word | |
168 | values are used, each feature name can define its own encoding of sub-values. |
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168 | values are used, each feature name can define its own encoding of sub-values. | |
169 | Comma-delimited and ``x-www-form-urlencoded`` values are common. |
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169 | Comma-delimited and ``x-www-form-urlencoded`` values are common. | |
170 |
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170 | |||
171 | The following document capabilities defined by the canonical Mercurial server |
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171 | The following document capabilities defined by the canonical Mercurial server | |
172 | implementation. |
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172 | implementation. | |
173 |
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173 | |||
174 | batch |
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174 | batch | |
175 | ----- |
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175 | ----- | |
176 |
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176 | |||
177 | Whether the server supports the ``batch`` command. |
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177 | Whether the server supports the ``batch`` command. | |
178 |
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178 | |||
179 | This capability/command was introduced in Mercurial 1.9 (released July 2011). |
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179 | This capability/command was introduced in Mercurial 1.9 (released July 2011). | |
180 |
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180 | |||
181 | branchmap |
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181 | branchmap | |
182 | --------- |
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182 | --------- | |
183 |
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183 | |||
184 | Whether the server supports the ``branchmap`` command. |
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184 | Whether the server supports the ``branchmap`` command. | |
185 |
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185 | |||
186 | This capability/command was introduced in Mercurial 1.3 (released July 2009). |
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186 | This capability/command was introduced in Mercurial 1.3 (released July 2009). | |
187 |
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187 | |||
188 | bundle2-exp |
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188 | bundle2-exp | |
189 | ----------- |
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189 | ----------- | |
190 |
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190 | |||
191 | Precursor to ``bundle2`` capability that was used before bundle2 was a |
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191 | Precursor to ``bundle2`` capability that was used before bundle2 was a | |
192 | stable feature. |
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192 | stable feature. | |
193 |
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193 | |||
194 | This capability was introduced in Mercurial 3.0 behind an experimental |
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194 | This capability was introduced in Mercurial 3.0 behind an experimental | |
195 | flag. This capability should not be observed in the wild. |
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195 | flag. This capability should not be observed in the wild. | |
196 |
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196 | |||
197 | bundle2 |
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197 | bundle2 | |
198 | ------- |
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198 | ------- | |
199 |
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199 | |||
200 | Indicates whether the server supports the ``bundle2`` data exchange format. |
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200 | Indicates whether the server supports the ``bundle2`` data exchange format. | |
201 |
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201 | |||
202 | The value of the capability is a URL quoted, newline (``\n``) delimited |
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202 | The value of the capability is a URL quoted, newline (``\n``) delimited | |
203 | list of keys or key-value pairs. |
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203 | list of keys or key-value pairs. | |
204 |
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204 | |||
205 | A key is simply a URL encoded string. |
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205 | A key is simply a URL encoded string. | |
206 |
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206 | |||
207 | A key-value pair is a URL encoded key separated from a URL encoded value by |
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207 | A key-value pair is a URL encoded key separated from a URL encoded value by | |
208 | an ``=``. If the value is a list, elements are delimited by a ``,`` after |
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208 | an ``=``. If the value is a list, elements are delimited by a ``,`` after | |
209 | URL encoding. |
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209 | URL encoding. | |
210 |
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210 | |||
211 | For example, say we have the values:: |
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211 | For example, say we have the values:: | |
212 |
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212 | |||
213 | {'HG20': [], 'changegroup': ['01', '02'], 'digests': ['sha1', 'sha512']} |
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213 | {'HG20': [], 'changegroup': ['01', '02'], 'digests': ['sha1', 'sha512']} | |
214 |
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214 | |||
215 | We would first construct a string:: |
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215 | We would first construct a string:: | |
216 |
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216 | |||
217 | HG20\nchangegroup=01,02\ndigests=sha1,sha512 |
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217 | HG20\nchangegroup=01,02\ndigests=sha1,sha512 | |
218 |
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218 | |||
219 | We would then URL quote this string:: |
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219 | We would then URL quote this string:: | |
220 |
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220 | |||
221 | HG20%0Achangegroup%3D01%2C02%0Adigests%3Dsha1%2Csha512 |
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221 | HG20%0Achangegroup%3D01%2C02%0Adigests%3Dsha1%2Csha512 | |
222 |
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222 | |||
223 | This capability was introduced in Mercurial 3.4 (released May 2015). |
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223 | This capability was introduced in Mercurial 3.4 (released May 2015). | |
224 |
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224 | |||
225 | changegroupsubset |
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225 | changegroupsubset | |
226 | ----------------- |
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226 | ----------------- | |
227 |
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227 | |||
228 | Whether the server supports the ``changegroupsubset`` command. |
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228 | Whether the server supports the ``changegroupsubset`` command. | |
229 |
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229 | |||
230 | This capability was introduced in Mercurial 0.9.2 (released December |
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230 | This capability was introduced in Mercurial 0.9.2 (released December | |
231 | 2006). |
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231 | 2006). | |
232 |
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232 | |||
233 | This capability was introduced at the same time as the ``lookup`` |
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233 | This capability was introduced at the same time as the ``lookup`` | |
234 | capability/command. |
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234 | capability/command. | |
235 |
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235 | |||
236 | getbundle |
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236 | getbundle | |
237 | --------- |
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237 | --------- | |
238 |
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238 | |||
239 | Whether the server supports the ``getbundle`` command. |
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239 | Whether the server supports the ``getbundle`` command. | |
240 |
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240 | |||
241 | This capability was introduced in Mercurial 1.9 (released July 2011). |
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241 | This capability was introduced in Mercurial 1.9 (released July 2011). | |
242 |
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242 | |||
243 | httpheader |
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243 | httpheader | |
244 | ---------- |
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244 | ---------- | |
245 |
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245 | |||
246 | Whether the server supports receiving command arguments via HTTP request |
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246 | Whether the server supports receiving command arguments via HTTP request | |
247 | headers. |
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247 | headers. | |
248 |
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248 | |||
249 | The value of the capability is an integer describing the max header |
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249 | The value of the capability is an integer describing the max header | |
250 | length that clients should send. Clients should ignore any content after a |
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250 | length that clients should send. Clients should ignore any content after a | |
251 | comma in the value, as this is reserved for future use. |
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251 | comma in the value, as this is reserved for future use. | |
252 |
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252 | |||
253 | This capability was introduced in Mercurial 1.9 (released July 2011). |
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253 | This capability was introduced in Mercurial 1.9 (released July 2011). | |
254 |
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254 | |||
255 | httppostargs |
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255 | httppostargs | |
256 | ------------ |
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256 | ------------ | |
257 |
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257 | |||
258 | **Experimental** |
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258 | **Experimental** | |
259 |
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259 | |||
260 | Indicates that the server supports and prefers clients send command arguments |
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260 | Indicates that the server supports and prefers clients send command arguments | |
261 | via a HTTP POST request as part of the request body. |
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261 | via a HTTP POST request as part of the request body. | |
262 |
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262 | |||
263 | This capability was introduced in Mercurial 3.8 (released May 2016). |
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263 | This capability was introduced in Mercurial 3.8 (released May 2016). | |
264 |
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264 | |||
265 | known |
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265 | known | |
266 | ----- |
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266 | ----- | |
267 |
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267 | |||
268 | Whether the server supports the ``known`` command. |
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268 | Whether the server supports the ``known`` command. | |
269 |
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269 | |||
270 | This capability/command was introduced in Mercurial 1.9 (released July 2011). |
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270 | This capability/command was introduced in Mercurial 1.9 (released July 2011). | |
271 |
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271 | |||
272 | lookup |
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272 | lookup | |
273 | ------ |
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273 | ------ | |
274 |
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274 | |||
275 | Whether the server supports the ``lookup`` command. |
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275 | Whether the server supports the ``lookup`` command. | |
276 |
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276 | |||
277 | This capability was introduced in Mercurial 0.9.2 (released December |
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277 | This capability was introduced in Mercurial 0.9.2 (released December | |
278 | 2006). |
|
278 | 2006). | |
279 |
|
279 | |||
280 | This capability was introduced at the same time as the ``changegroupsubset`` |
|
280 | This capability was introduced at the same time as the ``changegroupsubset`` | |
281 | capability/command. |
|
281 | capability/command. | |
282 |
|
282 | |||
283 | pushkey |
|
283 | pushkey | |
284 | ------- |
|
284 | ------- | |
285 |
|
285 | |||
286 | Whether the server supports the ``pushkey`` and ``listkeys`` commands. |
|
286 | Whether the server supports the ``pushkey`` and ``listkeys`` commands. | |
287 |
|
287 | |||
288 | This capability was introduced in Mercurial 1.6 (released July 2010). |
|
288 | This capability was introduced in Mercurial 1.6 (released July 2010). | |
289 |
|
289 | |||
290 | standardbundle |
|
290 | standardbundle | |
291 | -------------- |
|
291 | -------------- | |
292 |
|
292 | |||
293 | **Unsupported** |
|
293 | **Unsupported** | |
294 |
|
294 | |||
295 | This capability was introduced during the Mercurial 0.9.2 development cycle in |
|
295 | This capability was introduced during the Mercurial 0.9.2 development cycle in | |
296 | 2006. It was never present in a release, as it was replaced by the ``unbundle`` |
|
296 | 2006. It was never present in a release, as it was replaced by the ``unbundle`` | |
297 | capability. This capability should not be encountered in the wild. |
|
297 | capability. This capability should not be encountered in the wild. | |
298 |
|
298 | |||
299 | stream-preferred |
|
299 | stream-preferred | |
300 | ---------------- |
|
300 | ---------------- | |
301 |
|
301 | |||
302 | If present the server prefers that clients clone using the streaming clone |
|
302 | If present the server prefers that clients clone using the streaming clone | |
303 | protocol (``hg clone --uncompressed``) rather than the standard |
|
303 | protocol (``hg clone --uncompressed``) rather than the standard | |
304 | changegroup/bundle based protocol. |
|
304 | changegroup/bundle based protocol. | |
305 |
|
305 | |||
306 | This capability was introduced in Mercurial 2.2 (released May 2012). |
|
306 | This capability was introduced in Mercurial 2.2 (released May 2012). | |
307 |
|
307 | |||
308 | streamreqs |
|
308 | streamreqs | |
309 | ---------- |
|
309 | ---------- | |
310 |
|
310 | |||
311 | Indicates whether the server supports *streaming clones* and the *requirements* |
|
311 | Indicates whether the server supports *streaming clones* and the *requirements* | |
312 | that clients must support to receive it. |
|
312 | that clients must support to receive it. | |
313 |
|
313 | |||
314 | If present, the server supports the ``stream_out`` command, which transmits |
|
314 | If present, the server supports the ``stream_out`` command, which transmits | |
315 | raw revlogs from the repository instead of changegroups. This provides a faster |
|
315 | raw revlogs from the repository instead of changegroups. This provides a faster | |
316 | cloning mechanism at the expense of more bandwidth used. |
|
316 | cloning mechanism at the expense of more bandwidth used. | |
317 |
|
317 | |||
318 | The value of this capability is a comma-delimited list of repo format |
|
318 | The value of this capability is a comma-delimited list of repo format | |
319 | *requirements*. These are requirements that impact the reading of data in |
|
319 | *requirements*. These are requirements that impact the reading of data in | |
320 | the ``.hg/store`` directory. An example value is |
|
320 | the ``.hg/store`` directory. An example value is | |
321 | ``streamreqs=generaldelta,revlogv1`` indicating the server repo requires |
|
321 | ``streamreqs=generaldelta,revlogv1`` indicating the server repo requires | |
322 | the ``revlogv1`` and ``generaldelta`` requirements. |
|
322 | the ``revlogv1`` and ``generaldelta`` requirements. | |
323 |
|
323 | |||
324 | If the only format requirement is ``revlogv1``, the server may expose the |
|
324 | If the only format requirement is ``revlogv1``, the server may expose the | |
325 | ``stream`` capability instead of the ``streamreqs`` capability. |
|
325 | ``stream`` capability instead of the ``streamreqs`` capability. | |
326 |
|
326 | |||
327 | This capability was introduced in Mercurial 1.7 (released November 2010). |
|
327 | This capability was introduced in Mercurial 1.7 (released November 2010). | |
328 |
|
328 | |||
329 | stream |
|
329 | stream | |
330 | ------ |
|
330 | ------ | |
331 |
|
331 | |||
332 | Whether the server supports *streaming clones* from ``revlogv1`` repos. |
|
332 | Whether the server supports *streaming clones* from ``revlogv1`` repos. | |
333 |
|
333 | |||
334 | If present, the server supports the ``stream_out`` command, which transmits |
|
334 | If present, the server supports the ``stream_out`` command, which transmits | |
335 | raw revlogs from the repository instead of changegroups. This provides a faster |
|
335 | raw revlogs from the repository instead of changegroups. This provides a faster | |
336 | cloning mechanism at the expense of more bandwidth used. |
|
336 | cloning mechanism at the expense of more bandwidth used. | |
337 |
|
337 | |||
338 | This capability was introduced in Mercurial 0.9.1 (released July 2006). |
|
338 | This capability was introduced in Mercurial 0.9.1 (released July 2006). | |
339 |
|
339 | |||
340 | When initially introduced, the value of the capability was the numeric |
|
340 | When initially introduced, the value of the capability was the numeric | |
341 | revlog revision. e.g. ``stream=1``. This indicates the changegroup is using |
|
341 | revlog revision. e.g. ``stream=1``. This indicates the changegroup is using | |
342 | ``revlogv1``. This simple integer value wasn't powerful enough, so the |
|
342 | ``revlogv1``. This simple integer value wasn't powerful enough, so the | |
343 | ``streamreqs`` capability was invented to handle cases where the repo |
|
343 | ``streamreqs`` capability was invented to handle cases where the repo | |
344 | requirements have more than just ``revlogv1``. Newer servers omit the |
|
344 | requirements have more than just ``revlogv1``. Newer servers omit the | |
345 | ``=1`` since it was the only value supported and the value of ``1`` can |
|
345 | ``=1`` since it was the only value supported and the value of ``1`` can | |
346 | be implied by clients. |
|
346 | be implied by clients. | |
347 |
|
347 | |||
348 | unbundlehash |
|
348 | unbundlehash | |
349 | ------------ |
|
349 | ------------ | |
350 |
|
350 | |||
351 | Whether the ``unbundle`` commands supports receiving a hash of all the |
|
351 | Whether the ``unbundle`` commands supports receiving a hash of all the | |
352 | heads instead of a list. |
|
352 | heads instead of a list. | |
353 |
|
353 | |||
354 | For more, see the documentation for the ``unbundle`` command. |
|
354 | For more, see the documentation for the ``unbundle`` command. | |
355 |
|
355 | |||
356 | This capability was introduced in Mercurial 1.9 (released July 2011). |
|
356 | This capability was introduced in Mercurial 1.9 (released July 2011). | |
357 |
|
357 | |||
358 | unbundle |
|
358 | unbundle | |
359 | -------- |
|
359 | -------- | |
360 |
|
360 | |||
361 | Whether the server supports pushing via the ``unbundle`` command. |
|
361 | Whether the server supports pushing via the ``unbundle`` command. | |
362 |
|
362 | |||
363 | This capability/command has been present since Mercurial 0.9.1 (released |
|
363 | This capability/command has been present since Mercurial 0.9.1 (released | |
364 | July 2006). |
|
364 | July 2006). | |
365 |
|
365 | |||
366 | Mercurial 0.9.2 (released December 2006) added values to the capability |
|
366 | Mercurial 0.9.2 (released December 2006) added values to the capability | |
367 | indicating which bundle types the server supports receiving. This value is a |
|
367 | indicating which bundle types the server supports receiving. This value is a | |
368 | comma-delimited list. e.g. ``HG10GZ,HG10BZ,HG10UN``. The order of values |
|
368 | comma-delimited list. e.g. ``HG10GZ,HG10BZ,HG10UN``. The order of values | |
369 | reflects the priority/preference of that type, where the first value is the |
|
369 | reflects the priority/preference of that type, where the first value is the | |
370 | most preferred type. |
|
370 | most preferred type. | |
|
371 | ||||
|
372 | Handshake Protocol | |||
|
373 | ================== | |||
|
374 | ||||
|
375 | While not explicitly required, it is common for clients to perform a | |||
|
376 | *handshake* when connecting to a server. The handshake accomplishes 2 things: | |||
|
377 | ||||
|
378 | * Obtaining capabilities and other server features | |||
|
379 | * Flushing extra server output (e.g. SSH servers may print extra text | |||
|
380 | when connecting that may confuse the wire protocol) | |||
|
381 | ||||
|
382 | This isn't a traditional *handshake* as far as network protocols go because | |||
|
383 | there is no persistent state as a result of the handshake: the handshake is | |||
|
384 | simply the issuing of commands and commands are stateless. | |||
|
385 | ||||
|
386 | The canonical clients perform a capabilities lookup at connection establishment | |||
|
387 | time. This is because clients must assume a server only supports the features | |||
|
388 | of the original Mercurial server implementation until proven otherwise (from | |||
|
389 | advertised capabilities). Nearly every server running today supports features | |||
|
390 | that weren't present in the original Mercurial server implementation. Rather | |||
|
391 | than wait for a client to perform functionality that needs to consult | |||
|
392 | capabilities, it issues the lookup at connection start to avoid any delay later. | |||
|
393 | ||||
|
394 | For HTTP servers, the client sends a ``capabilities`` command request as | |||
|
395 | soon as the connection is established. The server responds with a capabilities | |||
|
396 | string, which the client parses. | |||
|
397 | ||||
|
398 | For SSH servers, the client sends the ``hello`` command (no arguments) | |||
|
399 | and a ``between`` command with the ``pairs`` argument having the value | |||
|
400 | ``0000000000000000000000000000000000000000-0000000000000000000000000000000000000000``. | |||
|
401 | ||||
|
402 | The ``between`` command has been supported since the original Mercurial | |||
|
403 | server. Requesting the empty range will return a ``\n`` string response, | |||
|
404 | which will be encoded as ``1\n\n`` (value length of ``1`` followed by a newline | |||
|
405 | followed by the value, which happens to be a newline). | |||
|
406 | ||||
|
407 | The ``hello`` command was later introduced. Servers supporting it will issue | |||
|
408 | a response to that command before sending the ``1\n\n`` response to the | |||
|
409 | ``between`` command. Servers not supporting ``hello`` will send an empty | |||
|
410 | response (``0\n``). | |||
|
411 | ||||
|
412 | In addition to the expected output from the ``hello`` and ``between`` commands, | |||
|
413 | servers may also send other output, such as *message of the day (MOTD)* | |||
|
414 | announcements. Clients assume servers will send this output before the | |||
|
415 | Mercurial server replies to the client-issued commands. So any server output | |||
|
416 | not conforming to the expected command responses is assumed to be not related | |||
|
417 | to Mercurial and can be ignored. |
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