CDX Server API

Ilya Kreymer edited this page Oct 12, 2015 · 8 revisions

In addition to replay capabilities, pywb also provides an extensive api for querying the capture index (CDX).

The api can be used to get information about a range of archive captures/mementos, including filtering, sorting, and pagination for bulk query. The actual archive files (WARC/ARC) files are not loaded during this query, only the generated CDX index. pywb actually uses this same api internally to perform all index lookups in a consistent way.

For example, the following query might return the first 10 results from host http://example.com/* where the mime type is text/html:

http://localhost:8080/coll-cdx?url=http://example.com/*&page=1&filter=mime:text/html&limit=10

Usage and Configuration

The cdx-server command line application starts pywb in cdx server only mode (web archive replay functionality is not loaded, only the index). It can be used the same way as the wayback command line application, including the auto-configuration init.

The cdx server functionality can also be enabled when running full-replay with wayback by setting:

enable_cdx_api: true

API Endpoint

When enable_cdx_api is set to true, a cdx server endpoint is created for each collection and accessible by adding -cdx to the regular collection path, ex:

  • http://localhost:8080/pywb/<timestamp>/<url> - web archive replay

  • http://localhost:8080/pywb-cdx - cdx server endpoint

  • http://localhost:8080/other_collection/<timestamp>/<url> - web archive replay

  • http://localhost:8080/other_collection-cdx - cdx server endpoint

The suffix can additionally be customized through the enable_cdx_api setting

enable_cdx_api: -index

This will make the endpoint be http://localhost:8080/pywb-index instead

API Reference

Unless otherwise specified, all API params are available from pywb 0.9.1.

url

The only required parameter to the cdx server api is the url, ex: http://localhost:8080/coll-cdx?url=example.com

will return a list of captures for 'example.com'

from / to

Setting from=<ts> or to=<ts> will restrict the results to the given date/time range (inclusive).

Timestamps may be <=14 digits and will be padded to either lower or upper bound.

For example, ...coll-cdx?url=example.com&from=2014&to=2014 will return results of example.com that have a timestamp between 20140101000000 and 20141231235959

Available from pywb 0.10.9

matchType

The cdx server supports the following matchType

  • exact -- default setting, will return captures that match the url exactly

  • prefix -- return captures that begin with a specified path, eg: http://example.com/path/*

  • host -- return captures which for a begin host (the path segment is ignored if specified)

  • domain -- return captures for the current host and all subdomains, eg. *.example.com

As a shortcut, instead of specifying a separate matchType parameter, wildcards may be used in the url:

  • ...coll-cdx?url=http://example.com/path/* is equivalent to ...coll-cdx?url=http://example.com/path/&matchType=prefix

  • ...coll-cdx?url=*.example.com is equivalent to ...coll-cdx?url=example.com&matchType=domain

Note: if you are using legacy cdx index files which are not SURT-ordered, the domain option will not be available. if this is the case, you can use the wb-manager convert-cdx option to easily convert any cdx to latest format`

limit

Setting limit= will limit the number of index lines returned. Limit must be set to a positive integer. If no limit is provided, all the matching lines are returned, which may be slow. (If using a ZipNum compressed cluster, the page size limit is enforced and no captures are read beyond the single page. See Pagination API for more info).

sort

The sort param can be set as follows:

  • reverse -- will sort the matching captures in reverse order. It is only recommended for exact query as reverse a large match may be very slow. (An optimized version is planned)

  • closest -- setting this option also requires setting closest=<ts> where <ts> is a specific timestamp to sort by. This option will only work correctly for exact query and is useful for sorting captures based no time distance from a certain timestamp. (pywb uses this option internally for replay in order to fallback to 'next closest' capture if one fails)

Both options may be combined with limit to return the top N closest, or the last N results.

output (JSON output)

Setting output=json will return each line as a proper JSON dictionary. (Default format is text which will return the native format of the underlying CDX index, and may not be consistent). Using output=json is recommended for extensive analysis and it may become the default option in a future release.

filter

The filter param can be specified multiple times to filter by specific fields in the cdx index. Field names correspond to the fields returned in the JSON output. Filters can be specified as follows:

...coll-cdx?url=example.com/*&filter=mime:text/html&!status:200

Return captures from example.com/* where mime is text/html and http status is not 200.

The ! modified before status indicates negation. The ~ modifier can also be used to specify a regex instead of exact filter match. For example: filter=~mime:text/.* will match any CDX line where mime field matches the regex text/.*. Negation and regex modifier may be combined, eg. filter=!~text/.*

fl

The fl param can be used to specify which fields to include in the output. The standard available fields are usually: urlkey, timestamp, url, mime, status, digest, length, offset, filename

If a minimal cdx index is used, the mime and status fields may not be available. Additional fields may be introduced in the future, especially in the CDX JSON format.

Fields can be comma delimited, for example fl=urlkey,timestamp will only include the urlkey, timestamp and filename in the output.

Pagination API

The cdx server supports an optional pagination api, but it is currently only available when using ZipNum Compressed Index instead of a plain text cdx files. (Additional pagination support may be added for CDXJ files as well).

The pagination api supports the following params:

page

page is the current page number, and defaults to 0 if omitted. If the page exceeds the number of available pages from the page count query, a 400 error will be returned.

pageSize

pageSize is an optional parameter which can increase or decrease the amount of data returned in each page. The default setting can be configuration dependent.

showPageCount=true

This is a special query which, if successful, always returns a json result of the form. The query should be very quick regardless of the size of the query.

{"blocks": 423, "pages": 85, "pageSize": 5}

In this result:

  • pages is the total number of pages available for this query. The page parameter may be between 0 and pages - 1

  • pageSize is the total number of ZipNum compressed blocks that are read for each page. The default value can be set in the pywb config.yaml via the max_blocks: 5 option.

  • blocks is the actual number of compressed blocks that match the query. This can be used to quickly estimate the total number of captures, within a margin of error. In general, blocks / pageSize + 1 = pages (since there is always at least 1 page even if blocks < pageSize)

If changing pageSize, the same value should be used for both the showNumPages query and the regular paged query. ex:

  • Use ...pageSize=2&showPageCount=true and read pages to get total number of pages

  • Use ...pageSize=2&page=N to read the N-th pages from 0 to pages-1

showPagedIndex=true

When this param is set, the returned data is the secondary index instead of the actual CDX. Each line represents a compressed cdx block, and the number of lines returned should correspond to the blocks value in showNumPages query. This query is used internally before reading the actual compressed blocks and should be significantly faster. At this time, this option can not be combined with other query params listed in the api, except for output=json. Using output=json is recommended with this query as the default text format may change in the future.