@hapi-server/server v1.0.12
HAPI Server Front-End
A generic HAPI front-end server.
Contents
1. About
The intended use for this server-side software is a data provider wants to serve data through a HAPI API. With this software, the data provider only needs
- HAPI metadata, in one of a variety of forms, for a collection of datasets and
- a command-line program that returns at least headerless HAPI CSV for all parameters in the dataset over the full time range of available data. Optionally, the command line program can take inputs of a start and stop time, a list of one or more parameters to output, and an output format
to be able to serve data from a HAPI API from their server. This software handles
- HAPI metadata validation,
- request validation and error responses,
- logging and alerts,
- time and parameter subsetting (as needed), and
- generation of HAPI JSON or HAPI binary (as needed).
A list of catalogs that are served using this software is given at http://hapi-server.org/servers.
2. Installation
npm install -g "@hapi-server/server"
Binary packages are available for OS-X x64 and Linux x64. A Docker image is also available. Installation and startup commands are given below the binary packages and docker image. See the Development section for instructions on installing from source.
OS-X x64:
curl -L https://github.com/hapi-server/server-nodejs/releases/download/v1.0.12/hapi-server-v1.0.12-darwin-x64.tgz | tar zxf -
cd hapi-server-v1.0.12
./hapi-server --open
Linux x64:
curl -L https://github.com/hapi-server/server-nodejs/releases/download/v1.0.12/hapi-server-v1.0.12-linux-x64.tgz | tar zxf -
cd hapi-server-v1.0.12
./hapi-server --open
Docker:
docker pull rweigel/hapi-server:v1.0.12
docker run -dit --name hapi-server-v1.0.12 --expose 8999 -p 8999:8999 rweigel/hapi-server:v1.0.12
docker exec -it hapi-server-v1.0.12 ./hapi-server
# Open http://localhost:8999/TestData/hapi in a web browser
2. Examples
List of Included Examples
The following examples are included in the metadata directory. The examples can be run using
./hapi-server -f metadata/FILENAME.json
where FILENAME.json
is one of the file names listed below (e.g., Example0.json
).
- Example0.json - A Python program dumps a full dataset in the headerless HAPI CSV format; the server handles time and parameter subsetting and creation of HAPI Binary and JSON. See section 2.1.
- Example1.json - Same as Example0 except the Python program handles time subsetting.
- Example2.json - Same as Example0 except the Python program handles time and parameter subsetting and creation of HAPI CSV and Binary. See section 2.2.
- Example3.json - Same as Example2 except for HAPI info metadata for each dataset is stored in an external file.
- Example4.json - Same as Example2 except for HAPI info metadata for each dataset is generated by a command-line command.
- Example5.json - Same as Example2 except catalog metadata is stored in an external file.
- Example6.json - Same as Example2 except catalog metadata is generated by a command-line command.
- Example7.json - Pass-through example; Same as Example2 except that data is generated by remote request and catalog metadata is returned from a URL.
- Example8.json - A dataset in headerless HAPI CSV format is stored in a single file; the server handles parameter and time subsetting and creation of HAPI JSON and Binary.
- Example9.json - A dataset in headerless HAPI CSV format is returned by a URL; the server handles parameter and time subsetting and creation of HAPI JSON and Binary.
- AutoplotExample1.json - A dataset is stored in multiple files and AutoplotDataServer is used to subset in time. See section 2.6.
- AutoplotExample2.json - A dataset is stored in a CDF file and AutoplotDataserver is used to generate HAPI CSV. See section 2.6.
- TestData.json - A test dataset used to test HAPI clients.
- SSCWeb.json - Data from a non-HAPI web service is made available from a HAPI server. See section 2.3.
- INTERMAGNET.json - Data in ASCII files on an FTP site is made available from a HAPI server. See section 2.4.
- QinDenton.json - Data in a single ASCII file is converted to headerless HAPI CSV by a Python program. See section 2.5.
2.1 Serve data from a minimal Python program
In this example, we assume that the command line program that returns a dataset has the minimal capabilities required - when executed, it generates a headerless HAPI CSV file with all parameters in the dataset over the full time range of available data. The server handles time and parameter subsetting and the generation of HAPI Binary and JSON.
The Python script Example.py returns HAPI-formatted CSV data (with no header) with two parameters. To serve this data, only a configuration file, Example0.json, is needed. The configuration file has information that is used to call the command line program and it also has HAPI metadata that describes the output of Example.py. Details about the configuration file format are described in the Metadata section.
The Python calling syntax of Example.py is
python Example.py
To run this example locally after installation, execute
./hapi-server --file metdata/Example0.json
and then open http://localhost:8999/Example0/hapi
. You should see the same landing page as that at http://hapi-server.org/servers/Example0/hapi. Note that the --open
command-line switch can be used to automatically open the landing page, e.g.,
./hapi-server --file metdata/Example0.json --open
2.2 Serve data from an enhanced Python program
The Python script Example.py actually can subset parameters and time and provide binary output. To force the server to use these capabilities, we need to modify the server configuration metadata in Example1.json. The changes are replacing
"command": "python bin/Example.py"
with
"command": "python bin/Example.py --params ${parameters} --start ${start} --stop ${stop} --fmt ${format}"
and adding
"formats": ["csv","binary"]
The modified file is Example2.json. To run this example locally after installation, execute
./hapi-server --file metadata/Example2.json
and then open http://localhost:8999/Example2/hapi
. The command-line program now produces binary output and performs parameter subsetting as needed and the response time for data should decrease.
The server responses will be identical to that in the previous example. You should see the same landing page as that at http://hapi-server.org/servers/Example2/hapi.
2.3 Serve data from a non-HAPI web service
A non-HAPI server can be quickly made HAPI compliant by using this server as a pass-through. Data from SSCWeb, which is available from a REST API, has been made available through a HAPI API at http://hapi-server.org/servers/SSCWeb/hapi. The configuration file is SSCWeb.json and the command line program is SSCWeb.js. Note that the metadata file SSCWeb.json was created using code in metadata/SSCWeb.
To run this example locally after installation, execute
./hapi-server --file metadata/SSCWeb.json --open
You should see the same landing page as that at http://hapi-server.org/servers/SSCWeb/hapi.
2.4 Serve data stored in a single file
The Qin-Denton dataset contains multiple parameters stored in a single large file.
The command-line program that produces HAPI CSV from this file is QinDenton.py and the metadata is in QinDenton.json.
To run this example, use
./hapi-server --file metadata/QinDenton.json
2.5 Serve data stored in multiple files
INTERMAGNET has ground magnetometer data stored in daily files from over 150 magnetometer stations at 1-minute and 1-second cadence made available from a FTP site.
The command-line program that produces HAPI CSV is INTERMAGNET.py and the metadata is in INTERMAGNET.json. The code that produces the metadata is in metadata/INTERMAGNET. To run this example, execute
./hapi-server --file metadata/INTERMAGNET.json --open
2.6 Serve data read by Autoplot
Nearly any data file that can be read by Autoplot can be served using this server.
Serving data requires at most two steps:
- Generating an Autoplot URI for each parameter; and (in some cases)
- Writing (by hand) metadata for each parameter.
Example 1
The first example serves data stored in a single CDF file. The configuration file is AutoplotExample1.json.
In this example, step 2. above (writing metadata by hand) is not required because the data file has metadata that is in a format that Autoplot can translate to HAPI metadata.
To run this example locally, execute
./hapi-server --file metadata/AutoplotExample1.json
Example 2
The second example serves data stored in multiple ASCII files. The configuration file is AutoplotExample2.json.
To run this example locally, execute
./hapi-server --file metadata/AutoplotExample2.json
3. Usage
List command-line options:
./hapi-server -h
Options:
--help, -h Show help [boolean]
--https Start https server [boolean] [default: false]
--cert https certificate file path
--key https key file path
--file, -f Catalog configuration file or file pattern
--port, -p Server port [default: 8999]
--conf, -c Server configuration file
--ignore, -i Start server even if metadata error
[boolean] [default: false]
--logdir, -l Log directory
--open, -o Open web page on start [boolean] [default: false]
--test, -t Run URL tests and exit [boolean] [default: false]
--verify, -v Run verification tests on command line and exit
[boolean] [default: false]
--loglevel info or debug [default: "info"]
--verifier Verifier server URL on landing page
[default: "http://hapi-server.org/verify"]
--plotserver Plot server URL on landing page
[default: "http://hapi-server.org/plot"]
--server-ui-include Also include these servers in server-ui server drop-down.
[default: ""]
--proxy-whitelist Allow proxying of these servers (so one can use
server=http://... in addressbar of server-ui). [default: ""]
Basic usage:
./hapi-server --file metdata/TestData.json
Starts HAPI server at http://localhost:8999/TestData/hapi and serves datasets specified in the catalog ./metadata/TestData.json.
Multiple catalogs can be served by providing multiple catalog files on the command line:
./hapi-server --file CATALOG1.json --file CATALOG2.json
For example
./hapi-server --file metadata/TestData.json --file metadata/Example1.json
will serve the two datasets at
http://localhost:8999/TestData/hapi
http://localhost:8999/Example1/hapi
And the page at http://localhost:8999/
will point to these two URLs.
4. Server Configuration
4.1 conf/config.json
The variables HAPISERVERPATH
, HAPISERVERHOME
, NODEEXE
, and PYTHONEXE
can be set in conf/config.json
or as environment variables. These variables can be used in commands, files, and URLs in the server metadata (the file passed using the command-line --file
switch).
The default configuration file is conf/config.json
and this location can be set using a command-line argument, e.g.,
./hapiserver -c /tmp/config.json
To set variables using environment variables, use, e.g.,
PYTHONEXE=/opt/python/bin/python ./hapi-server
Variables set as environment variables take precedence over those set in conf/config.json
.
HAPISERVERPATH
and HAPISERVERHOME
These two variables can be used in metadata to reference a directory. For example,
"catalog": "$HAPISERVERHOME/mymetadata/Data.json"
By default, $HAPISERVERPATH
is the installation directory (the directory containing the shell launch script hapi-server
) and should not be changed as it is referenced in the demonstration metadata files. Modify HAPISERVERHOME
in conf/config.json
to use a custom path.
All relative paths in commands in metadata files are relative to the directory where hapi-server
was executed.
For example, if
/tmp/hapi-server
is executed from /home/username
, the file
/home/username/metadata/TestData.json
is read and relative paths in TestData.json
have /home/username/
prepended.
PYTHONEXE
This is the command used to call Python. By default, it is python
. If python
is not in the path, this can be set using a relative or absolute path. Python is used by several of the demonstration catalogs.
Example:
"command": "$PYTHONEXE $HAPISERVERHOME/mybin/Data.py"
NODEEXE
This is the command used to call NodeJS. By default, it is the command used to start the server. The start-up script looks for a NodeJS executable in $HAPISERVERPATH/bin
and then tries node
and then nodejs
.
4.2 Apache
To expose a URL through Apache, (1) enable mod_proxy
and mod_proxy_http
, (2) add the following in a <VirtualHost>
node in a Apache Virtual Hosts file
<VirtualHost *:80>
ProxyPass /TestData http://localhost:8999/TestData retry=1
ProxyPassReverse /TestData http://localhost:8999/TestData
</VirtualHost>
and (3) Include
this file in the Apache start-up configuration file.
If serving multiple catalogs, use
<VirtualHost *:80>
ProxyPass /servers http://localhost:8999/servers retry=1
ProxyPassReverse /servers http://localhost:8999/servers
</VirtualHost>
4.3 Nginx
For Nginx, add the following to nginx.conf
location /TestData { proxy_pass http://localhost:8999/TestData;}
If serving multiple catalogs, use
location /servers {proxy_pass http://localhost:8999/servers;}
5. Metadata
The metadata required for this server is similar to the /catalog
and /info
response of a HAPI server.
The server requires that the /catalog
response is combined with the /info
response for all datasets in the catalog in a single JSON catalog configuration file. Additional information about how to generate data must also be included in this JSON file.
The top-level structure of the configuration file is
{
"server": // See section 5.1
{
"id": "",
"prefix": "",
"contact": "",
"landingFile": "",
"landingPath": "",
"verify": "",
"catalog-update": null
},
"catalog": "array or string" // See section 5.2
"data": // See section 5.3
{
"command": "Command line template",
or
"file": "HAPI CSV file"
"fileformat": "one of 'csv', 'binary', 'json'"
or
"url": "URL that returns HAPI data"
"urlformat": "one of 'csv', 'binary', 'json'"
"contact": "Email address if error in command line program",
"testcommands": [
{
"command": string,
"Nlines": integer,
"Nbytes": integer,
"Ncommas", integer
},
...
],
"testurls": [
{
"url": string,
"Nlines": integer,
"Nbytes": integer,
"Ncommas": integer
},
...
]
},
}
A variety of examples are given in ./metadata
and described below along with options for the catalog property.
The string command
in the data node is a command that produces a headerless HAPI data response and can have placeholders for time range of data to return (using start (${start}
) and stop (${stop}
)), a dataset id (${id}
), a comma-separated list of parameters (${parameters}
) and an output format (${format}
). For example,
python ./bin/Example.py --dataset ${id} --parameters \
${parameters} --start ${start} --stop ${stop} --format ${format}"`
5.1 server
The server node has the form
"server": {
"id": "",
"prefix": "",
"contact": "",
"landingFile": "",
"landingPath": "",
"verify": "",
"catalog-update": null
"id": "", // Default is file name without extension.
"prefix": "", // Default is id.
"contact": "", // Required. Server will not start without this set.
"landingFile": "",
"landingPath": "",
"verify": "",
"catalog-update": null // How often in seconds to re-read content
// in the catalog node (5.2).
}
5.1.1 id
and prefix
The id
is by default the name of the server configuration file, e.g.,
./hapi-server --file metadata/TestData.json
then id=TestData
and prefix=TestData
.
By default, this catalog would be served from
http://localhost:8999/TestData/hapi
TestData
in the URL can be changed to TestData2
by using prefix=TestData2
.
5.1.2 contact
This element must not be empty or the server will not start. It should be at minimum the email address of a system administrator.
5.1.3 landingFile
and landingPath
landingFile
is the file to serve in response to requests for
http://localhost:8999/TestData/hapi
By default, the landing page served is single.htm from the HAPI server UI codebase. The double underscore variables in this file are replaced using the information in the metadata file (e.g., __CONTACT__
is replaced with the server.contact
value. A different landing page can be served by setting the landingFile
configuration variable, e.g. "landingFile": "$HAPISERVERPATH/public/index.htm"
, where $HAPISERVERPATH
is described in Server Configuration.
If landingFile
has local CSS and JS dependencies, set landingPath
to be the local directory of the referenced files. Several possible settings are
"landingFile": "$HAPISERVERPATH/index.htm",
// $HAPISERVERPATH will be replaced with location of hapi-server binary
"landingPath": "/var/www/public/" // Location of CSS and JS files
// If index.htm has <script src="index.js">, index.js should be in /var/www/public/
To serve a directory listing, use
"landingFile": "",
"landingPath": "/var/www/public/"
// Server will look for index.htm and index.html in /var/www/public/. If not
// found, directory listing of /var/www/public/ will be served.
5.1.4 catalog-update
This is an integer number of seconds corresponding to how often the catalog
node should be updated. Use this if the catalog
node is not static.
5.2 catalog
The catalog
node can be either a string or an array.
In the case that it is an array, it should contain either the combined HAPI /catalog
and /info
response (5.2.1) or a /catalog
response with references to the \info
response (5.2.1).
In the case that it is a string (5.2.3), the string is either a file containing a catalog array or a command-line template that returns a catalog array.
5.2.1 Combined HAPI /catalog
and /info
object
If catalog
is an array, it should have the same format as a HAPI /catalog
response (each object in the array has an id
property and optional title
property) with the addition of an info
property that is the HAPI response for that id
, e.g., /info?id=dataset1
.
"catalog":
[
{
"id": "dataset1",
"title": "a dataset",
"info": {
"startDate": "2000-01-01Z",
"stopDate": "2000-01-02Z",
"parameters": [...]
}
},
{
"id": "dataset2",
"title": "another dataset",
"info": {
"startDate": "2000-01-01Z",
"stopDate": "2000-01-02Z",
"parameters": [...]
}
}
]
In the following subsections, this type of JSON structure is referred to as a fully resolved catalog.
Examples of this type of catalog include
5.2.2 /catalog
response with file or command template for info
object
The info
value can be a path to an info
JSON file
"catalog":
[
{
"id": "dataset1",
"title": "a dataset",
"info": "relativepath/to/dataset2/info_file.json"
},
{
"id": "dataset2",
"title": "another dataset",
"info": "/absolutepath/to/dataset2/info_file.json"
}
]
See also Example3.json.
Alternatively, the metadata for each dataset may be produced by the execution of a command-line program for each dataset. For example, in the following, program1
should result in a HAPI JSON response from /info?id=dataset1
to stdout
. Before execution, the string ${id}
, if found, is replaced with the requested dataset ID. Execution of program2
should produce the HAPI JSON corresponding to the query /info?id=dataset2
.
"catalog":
[
{
"id": "dataset1",
"title": "a dataset",
"info": "bin/program --id ${id}"
},
{
"id": "dataset2",
"title": "another dataset",
"info": "program2"
}
]
See also Example4.json.
5.2.3 References to a command-line template or file
The catalog
value can be a command-line program that generates a fully resolved catalog, e.g.,
"catalog": "program --arg1 val1 ..."
The command-line command should return the response of an /info
query (with no id
argument).
The path to a fully resolved catalog can also be given. See also Example5.json.
5.3 data
6. Development
6.1 Installation
Install nodejs (tested with v8) using either the standard installer or NVM.
# Install Node Version Manager
curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/v0.35.3/install.sh | bash
# Open a new shell (see displayed instructions from above command)
# Install and use node.js version 8
nvm install 8
# Clone the server repository
git clone https://github.com/hapi-server/server-nodejs
# Install dependencies
cd server-nodejs; npm install
# Start server
node server.js
# Run tests; Python 2.7+ required for certain tests.
npm test
7. Contact
Please submit questions, bug reports, and feature requests to the issue tracker.