Categorygithub.com/aaronland/go-marc

modulepackage

0.9.2

Repository: https://github.com/aaronland/go-marc.git

Documentation: pkg.go.dev

# README

go-marc

Go package for working with MARC records.

Important

Not all of MARC. Probably not ever. Just the 034 field so far. If you are looking for a general-purpose library for working with MARC records I'd recommend looking at miku/marc21.

Tools

$> make cli
go build -mod vendor -o bin/marc-034 cmd/marc-034/main.go
go build -mod vendor -o bin/marc-034d cmd/marc-034d/main.go

marc-034

Convert a MARC 034 string in to a (S, W, N, E) bounding box.

$> ./bin/marc-034 -h
Usage of ./bin/marc-034:
  -f string
    	A valid MARC 034 string (default "1#$aa$b22000000$dW1800000$eE1800000$fN0840000$gS0700000")

Currently this only supports hdddmmss (hemisphere-degrees-minutes-seconds) and dddmmss (degrees-minutes-seconds) notation. For example:

$> ./bin/marc-034
2017/02/13 22:23:38 1#$aa$b22000000$dW1800000$eE1800000$fN0840000$gS0700000 <-- input (MARC 034)
2017/02/13 22:23:38 -70.000000, -180.000000 84.000000, 180.000000 <-- output (decimal WSG84)

marc-034d

A web server for converting MARC 034 strings in to bounding boxes (formatted as GeoJSON)

$> ./bin/marc-034d -h
Usage of ./bin/marc-034d:
  -nextzen-api-key string
    	A valid Nextzen API key (default "mapzen-xxxxxx")
  -nextzen-style-url string
    	A valid Nextzen style URL (default "/tangram/refill-style.zip")
  -server-uri string
    	A valid aaronland/go-http-server URI (default "http://localhost:8080")

For example:

$> ./bin/marc-034d -nextzen-api-key {APIKEY}

2018/01/12 09:12:44 listening on localhost:8080

The marc-034d server exposes the following endpoints:

/ (or "root")

The / (or default) endpoint will display a handy web interface for converting MARC 034 records in to bounding boxes. For example, here's what it looks like querying for 1#$aa$b80000$dW0825500$eW0822000$fN0273000$gN0265000:

/bbox

The /bbox endpoint will return a bounding box for a MARC 034 field as GeoJSON.

$> curl -s 'http://localhost:8080/bbox?034=1%23%24aa$b22000000%24dW1800000%24eE1800000%24fN0840000%24gS0700000' | python -mjson.tool

{
    "bbox": [
        -180,
        -70,
        180,
        84
    ],
    "geometry": {
        "coordinates": [
            [
                [
                    -180,
                    -70
                ],
                [
                    -180,
                    84
                ],
                [
                    180,
                    84
                ],
                [
                    180,
                    -70
                ],
                [
                    -180,
                    -70
                ]
            ]
        ],
        "type": "Polygon"
    },
    "properties": {
        "marc:034": "1#$aa$b22000000$dW1800000$eE1800000$fN0840000$gS0700000"
    },
    "type": "Feature"
}

Note the way the 034 parameter is URL-encoded.

Command-line flags and environment variables

Command line flags can be set also be set from environment variables. Environment variables for any given command line flag should be formatted as follows:

Replace all - characters with _
Upper case the flag name
Prepend the string with MARC_

For example the equivalent environment variable for the nextzen-api-key flag would be MARC_NEXTZEN_API_KEY.

Nextzen, Nextzen API keys and Nextzen "tilepacks"

The default behaviour for the marc-034d application is to use the TangramJS rendering engine in combination with the freely available Nextzen vector tiles. Use of the Nextzen vector tiles require a valid API key which can be created at:

https://developers.nextzen.org/.

It is also possible to configure the marc-034d application to use Nextzen vector tile "tilepacks" to serve tile data locally. The tilepacks are just MBTiles databases containing vector tile data compiled using the tilezen/go-tilepacks package.

To use a local tilepack with the marc-034d application pass in the path to your database with the -nextzen-tilepack-database flag. For example:

$> ./bin/marc-034d -nextzen-tilepack-database tiles/nextzen-world-2019-1-10.db 
2021/10/23 14:27:33 listening on http://localhost:8080

The application won't perform any differently but if you look "under the hood" you'll see that the vector tile data is being served from the marc-034d application itself.

Notes

It is currently only possible to serve tiles from a single "tilepack" database.

It is not possible to dynamically limit the map to the zoom range and tile extent of a given "tilepack" database. Yet. I'm working on it.

There are precompile databases with global tile coverage for zoom levels 1-10, 11 and 12 available on the Internet Archive:

Global tiles, zoom levels 1 through 10 (1.8GB)
Global tiles, zoom level 11 (3.5GB)
Global tiles, zoom level 12 (7.9GB)

Docker

Yes, for marc-034d at least.

$> docker build -t marc-034d .

$> docker run -it -p 8080:8080 marc-034d \
	/usr/local/bin/marc-034d \
	-server-uri http://0.0.0.0:8080 \
	-nextzen-api-key {APIKEY}

The Dockerfile will copy any "tilepacks" (ending in .db) in this package's tiles folder in to the container's /usr/local/data/tiles folder. This allows you to bundle and load local vector tile data with your container application. For example:

$> docker run -it -p 8080:8080 marc-034d \
	/usr/local/bin/marc-034d \
	-server-uri http://0.0.0.0:8080 \
	-nextzen-tilepack-database /usr/local/data/tiles/nextzen-world-2019-1-10.db

Note that any files ending in .db in the tiles folder are explicitly excluded from any Git commits.