<PAGE>   1
                                                                   EXHIBIT 10.28


                              EMPLOYMENT AGREEMENT


         This Employment Agreement ("Agreement") made as of this 9th day of
April, 1999, by and between The viaLink Company, an Oklahoma corporation with
its principal place of business at 13800 Benson Road, Edmond, Oklahoma, 71034
("viaLink"), and David M. Lloyd ("Lloyd"), 3106 Drexel Drive, Dallas, Texas
75205.

         WHEREAS, viaLink desires to hire Lloyd as its Vice President of Human
Resources, and

         WHEREAS Lloyd desires to become an employee of viaLink, and

         WHEREAS, the parties hereto wish to set forth the terms and conditions
of Lloyd's employment with viaLink.

         NOW, THEREFORE, in consideration of the above premises and the mutual
covenants hereinafter set forth, the parties hereto do agree as follows:

1.       Employment. viaLink hereby employs Lloyd, and Lloyd hereby accepts such
         employment, as Vice President of Human Resources for viaLink upon the
         terms and subject to the conditions contained herein.

2.       Duties. Lloyd shall perform all duties which are commensurate with his
         position and any other duties which may be reasonably assigned to him
         by viaLink's Chief Executive Officer ("CEO") from time to time during
         the Term of this Agreement.

3.       Covenants. In order to induce viaLink to enter into this Agreement,
         Lloyd hereby represents, covenants and agrees as follows:

    3.1.       Throughout his employment hereunder, Lloyd shall devote his full
               business time, attention, knowledge and skills during normal
               business hours in furtherance of the business of viaLink and will
               faithfully, diligently, and to the best of his ability, perform
               such duties.

    3.2.       During the Term of this Agreement, Lloyd shall not knowingly
               engage in, and shall not knowingly solicit any employees of
               viaLink or its subsidiaries or other affiliates to engage in any
               commercial activities which are in any way in competition with
               the activities of viaLink, or which in any way materially
               interfere with the performance of such employee's duties or
               responsibilities to viaLink.

    3.3.       Throughout his employment hereunder, Lloyd shall at all times be
               subject to, observe and carry out such rules, regulations,
               policies, directions and restrictions as viaLink may from time to
               time establish



                                       1
<PAGE>   2

               and those imposed by law, provided that the same are generally
               applicable to all employees similarly situated to Lloyd.

    3.4.       Confidential Information. "Confidential Information" means
               proprietary business information, Trade Secrets and/or other
               confidential information regarding viaLink or any of its
               subsidiaries and/or clients which (i) has not otherwise become
               public knowledge, (ii) was not already learned by Lloyd from
               independent and unrestricted sources prior to the Effective Date
               of this Agreement (as hereinafter defined), and (iii) has not
               been disclosed by viaLink to others without substantial
               restriction on further disclosure. "Trade Secrets" means any
               proprietary information not generally known in the industry in
               which viaLink is engaged or may become engaged, including,
               without limitation, information relating to viaLink's business
               affairs, finances, properties, methods of operation, software
               developed by viaLink, sources of and arrangements for hardware
               supplied to clients of viaLink, submission and proposal
               procedures of viaLink, viaLink's client or contact lists,
               commercial information supplied to viaLink by viaLink's clients,
               and other confidential information respecting or otherwise
               relating to the business or affairs of viaLink. Lloyd agrees and
               acknowledges that any such Confidential Information or Trade
               Secrets disclosed to Lloyd at any time before, during or after
               the Term of this Agreement shall be subject to the terms and
               conditions of this Agreement.

    3.5.       Non-Disclosure. Lloyd acknowledges and agrees that the business
               and good will of viaLink depend upon its protection of such
               Confidential Information. Except when directed to do otherwise by
               viaLink's Chief Executive Officer, and except as may be required
               by law, court order or subpoena, Lloyd shall keep confidential
               and shall not divulge to any other person or entity, during the
               term of this Agreement or at any time thereafter, any of
               viaLink's Confidential Information. In any case where Lloyd is
               compelled by law, court order or subpoena to disclose any
               Confidential Information to any third person, Lloyd shall advise
               viaLink in advance of such required disclosure and shall permit
               viaLink to object, contest, intervene or obtain appropriate
               protection of such information prior to its disclosure to any
               person.

    3.6.       Return of Property. Upon termination of this Agreement, Lloyd
               shall turn over to viaLink all documents, papers and other matter
               in the possession of or under the control of Lloyd that are or
               relate to such Confidential Information or to viaLink's Work
               Product.

    3.7.       Work Product. Lloyd agrees that any and all inventions,
               improvements, developments, discoveries, copyrightable works, or
               contributions thereto, including, without limitation, any written
               works, software products or code, images, designs, and/or
               instructions, whether or not



                                        2


<PAGE>   3




               they are the subject of patent or copyright or other proprietary
               rights protection under any federal, state, local or foreign
               law(s), which are created in whole or part by Lloyd during the
               term of this Agreement or relating in any way to the business of
               viaLink (hereinafter "Work Product") shall be the sole and
               exclusive property of viaLink and shall belong to viaLink free
               and clear from all right, title and interest of any other person,
               including, without limiting the generality of the foregoing,
               Lloyd. It is specifically agreed and understood that Lloyd shall
               not retain any right, title, interest or any right to use any of
               such Work Product. Lloyd shall promptly and fully disclose to
               viaLink all such Work Product. Lloyd acknowledges that all Work
               Product shall be a work for hire. Moreover, Lloyd conveys,
               transfers and assigns all rights, title and interest in and to
               any Work Product to viaLink, and further agrees to execute any
               written assignment or other agreement viaLink deems necessary at
               any time to effect the foregoing and to obtain or uphold, for
               viaLink's benefit, all copyright, patent, and/or other rights of
               viaLink in such Work Product.

    3.8.       Misappropriation. Lloyd shall not knowingly acquire, use, copy,
               or misappropriate any trade secret or proprietary information
               belonging to any other company or person and shall not cause,
               encourage or induce viaLink to acquire, use, copy, or
               misappropriate any trade secret or proprietary information
               belonging to any other company or person.

    3.9.       Compliance. Lloyd agrees:

        3.9.1.         Throughout the Term of this Agreement, that he is and
                       shall at all times remain in compliance with any and all
                       applicable federal and/or state laws, rules or
                       regulations regarding Lloyd's eligibility for employment
                       and/or continued employment with viaLink; and

        3.9.2.         That by executing this Agreement he will not be in
                       violation of any agreement, term or condition of any
                       other agreement that he has with any third party; and

        3.9.3.         That the execution of this Agreement will not constitute
                       or nor otherwise cause a breach of any other agreement to
                       which Lloyd is a party

    3.10.      Injunction. Lloyd acknowledges that disclosure of any
               Confidential Information or Work Product by Lloyd will give rise
               to irreparable injury, which is inadequately compensable in
               damages, to viaLink and/or the owner of such Confidential
               Information. Accordingly, viaLink or such other party, in
               addition to any other remedies which are elsewhere granted in
               this Agreement, may seek and obtain injunctive relief against the
               breach or threatened breach of (i) the foregoing Sections 3.5,
               3.6,


                                       3

<PAGE>   4






               3.7 and/or 3.8 (ii) any infringement upon any intellectual
               property rights of viaLink and/or (iii) any other breach of any
               term, covenant, condition, warranty or representation of this
               Agreement relating thereto.

    3.11.      Survival. Lloyd's obligations in this Section 3 shall survive the
               termination of this Agreement.

4.       Compensation. As full compensation for Lloyd's services hereunder and
         in exchange for his promises contained herein, during the Term of this
         Agreement, viaLink shall compensate Lloyd in the manner set forth
         below. The amounts set forth below shall be subject to any withholding
         or other deductions required by law.

    4.1.       Lloyd shall receive an annualized salary of one hundred and
               ninety thousand dollars ($190,000) which shall be earned and
               payable biweekly. viaLink may increase Lloyd's salary during the
               Term of this Agreement in viaLink's sole discretion. Lloyd's
               salary may not be decreased during the Term of this Agreement
               without the prior consent of Lloyd.

    4.2.       During the Term of this Agreement, commencing with the second
               quarter of 1999, Lloyd shall also be eligible to receive
               quarterly bonuses, which if completely earned for each quarter of
               a given calendar year, would equal thirty-three percent (33%) of
               his annualized salary as of the beginning of such calendar year
               ("Applicable Annualized Salary"); except that such bonuses for
               1999, if fully earned, would equal forty-seven thousand
               twenty-five dollars ($47,025.00). The bonuses shall accrue and be
               calculated quarterly. The criteria which Lloyd must meet to earn
               a bonus for a given quarter shall be established by viaLink's CEO
               and communicated to Lloyd prior to the beginning of such quarter;
               except that the criteria for the second quarter of 1999 shall be
               established by viaLink's CEO and communicated to Lloyd within ten
               days of the commencement of Lloyd's employment with viaLink
               pursuant to this Agreement. The amount of each such quarterly
               bonus, if the criteria to earn such bonus for a given quarter is
               met, shall be an amount equal to eight and one-quarter percent
               (8.25%) of Lloyd's Applicable Annualized Salary. If such criteria
               is not met for a given quarter, no bonus shall be earned for that
               quarter. Notwithstanding anything to the contrary in this Section
               4.2, in order to receive a bonus hereunder, Lloyd must be an
               employee of viaLink under this Agreement at the end of the
               quarter for which such bonus is earned pursuant to this Section
               4.2. Any payment due for a quarterly bonus under this Section 4.2
               shall be paid not later than the next regular payroll after the
               sixtieth (60th) day following the end of each quarter for which
               any Bonus amount is earned.


                                       4

<PAGE>   5






    4.3.       Lloyd shall be vested with two (2) weeks vacation as of the
               commencement of this Employment Agreement and shall also receive
               two weeks vacation during each subsequent calendar year of the
               Term of this Agreement.

    4.4.       Lloyd shall be eligible for viaLink's group benefits programs
               which are in place from time to time to the extent that the same
               are offered to all employees of viaLink ("Programs"); provided,
               however, that such Programs may be amended by viaLink from time
               to time in its sole and absolute discretion. Eligibility for each
               of such Programs shall be subject to and administered according
               to any applicable documents relating to such Programs.

    4.5.       Subject to the conditions and restrictions ("Conditions and
               Restrictions") hereinafter set forth and subject to the terms,
               covenants and conditions of viaLink's 1995 Stock Option Plan
               ("Plan"), viaLink shall grant to Lloyd an option to purchase one
               hundred thousand (100,000) shares of viaLink common stock at the
               grant price equal to eighty-five percent (85%) of the closing
               price of the viaLink common stock on the date of the actual grant
               of the options to Lloyd by viaLink. For purposes of this Section,
               the date of the grant shall be the date upon which the
               shareholders approve the increase in the number of options
               available under the Plan. Such Conditions and Restrictions are as
               follows:

        4.5.1.         That Lloyd is an employee of viaLink on the date of said
                       grant.

        4.5.2.         The approval by viaLink's shareholders of an increase in
                       the number of options available under viaLink's 1995
                       Stock Option Plan. viaLink agrees to use its best efforts
                       to obtain such approval. Lloyd agrees and understands
                       that in the event that viaLink's shareholders fail at
                       their 1999 annual meeting to increase the number of
                       shares available under the Plan in an amount sufficient
                       to satisfy both the grant of options set forth herein
                       hereof as well as all other grants of options granted to
                       other persons which are subject to similar Conditions and
                       Restrictions, the grant of options hereunder is null and
                       void and of no further force and effect. Provided,
                       however, that in the event viaLink's shareholders fail at
                       their 1999 annual meeting to increase the number of
                       shares available under the Plan as above set forth,
                       Lloyd, within forty-five (45) days after such annual
                       meeting, and notwithstanding anything to the contrary in
                       this Agreement, may give viaLink notice of termination of
                       this Agreement. Such termination shall be effective as of
                       the latter of the following: (i) two (2) weeks from the
                       day such notice of termination is received by viaLink or
                       (ii) the end of such forty-five (45) day period. In the
                       event that Lloyd elects to exercise such


                                       5

<PAGE>   6






                       right to terminate under this Section 4.5.2, viaLink,
                       within five (5) business days following the effective
                       date of such termination, shall pay Lloyd a sum equal to
                       90/365ths of his then current annualized salary (i.e.
                       annual salary divided by 365, times 90).

        4.5.3.         The execution by Lloyd of a Stock Option Agreement
                       generally used by viaLink for the granting of stock
                       options under said Plan. Such Stock Option Agreement
                       shall include, but not limited to, the following terms
                       and conditions:

                  4.5.3.1.    The option rights shall vest in equal amounts over
                              a three year period during the Term of this
                              Agreement; and

                  4.5.3.2.    If Lloyd is terminated or this Agreement is not
                              renewed, whether with or without cause, or if this
                              Agreement otherwise expires, except as may
                              otherwise be provided in the change of control
                              provisions in the Plan under which any options
                              granted, Lloyd shall not be entitled to exercise
                              any of such options which have not vested as of
                              the date of such termination, non-renewal or
                              earlier expiration of this Agreement.

                  4.5.3.3.    The approval by viaLink's shareholders of an
                              increase in the number of options available under
                              viaLink's 1995 Stock Option Plan. viaLink agrees
                              to use its best efforts to obtain such approval.

    4.6.       During the term of this Agreement, Lloyd shall have the use of a
               company car of his choice while an employee of viaLink on such
               terms and conditions and subject to such policy(s) as may be
               reasonably adopted by viaLink from time to time. The car shall be
               of Lloyd's choosing but shall not have a final sales price,
               exclusive of tags, title and tax expenses, in excess of thirty
               thousand dollars ($30,000.00). Alternatively, Lloyd, in his sole
               discretion, may, subject to the appropriate withholdings for
               federal and/or state taxes, elect to receive a seven hundred
               dollar ($700) per month car allowance in lieu of use of a company
               car. Also, if Lloyd elects to receive such allowance, viaLink,
               subject to the appropriate withholdings for federal and/or state
               taxes, will reimburse Lloyd for expenses incurred in the
               maintenance of his vehicle, but not for gas, and for the cost of
               such insurance thereon as may be required by viaLink.

5.       Non-competition.

    5.1.       If viaLink terminates this Agreement for cause (as defined in
               Section 6 of this Agreement) or if Lloyd terminates this
               Agreement for other than


                                        6


<PAGE>   7






               cause, for a period of two (2) years after the termination of
               this Agreement, Lloyd shall not, directly or indirectly, alone,
               or as a partner, officer, director, employee, stockholder,
               consultant or agent of any other corporation, partnership or
               other business organization, knowingly solicit the employment of,
               or hire, any employee of viaLink, or any viaLink subsidiary, or
               cause any such employee to terminate such employee's relationship
               with viaLink or any viaLink subsidiary, without the prior written
               approval of viaLink. If viaLink terminates Lloyd's employment
               without Cause, the provisions of this section 5.1 of this
               Agreement shall be enforceable against Lloyd only as long as
               Lloyd is receiving the compensation set forth in Section 4.1 of
               this Agreement.

    5.2.       If viaLink terminates this Agreement for cause (as defined in
               Section 6 of this Agreement) or if Lloyd terminates this
               Agreement for other than cause, for a period of two (2) years
               after the termination of this Agreement, Lloyd shall not,
               directly or indirectly, alone, or as a partner, officer,
               director, employee, stockholder, consultant or agent of any other
               corporation, partnership or other business organization,
               knowingly solicit any of the accounts of viaLink which were
               customers of viaLink unless such solicitation is undertaken on
               behalf of a business venture or entity which does not compete
               directly with the products or services owned, sold, manufactured,
               marketed, provided or developed by viaLink during Lloyd's
               employment by viaLink. For the purposes of this subparagraph, a
               business shall be deemed to be in competition with viaLink if the
               products or services of such business are substantially similar
               in purpose, function or capability to the products or services
               then being developed, manufactured, marketed, provided or sold by
               viaLink. If viaLink terminates Lloyd's employment without Cause,
               the provisions of this section 5.2 of this Agreement shall be
               enforceable against Lloyd only as long as Lloyd is receiving the
               compensation set forth in Section 4.1 of this Agreement.

6.       Duration and Termination.

    6.1.       Except as hereinafter set forth, the term ("Term") of this
               Agreement shall commence on the Ninth day of April, 1999
               ("Effective Date") and shall continue through the Ninth day of
               April, 2000 and shall be automatically renewed on a year to year
               basis thereafter unless one party hereto notifies the other party
               hereto in writing at least thirty (30) days prior to the end of
               the then current Term that it will not renew this Agreement at
               the end of such then current Term. Provided, however, and
               notwithstanding anything to the contrary herein, this Agreement
               may also be terminated by viaLink (i) at any time during its then
               current Term pursuant to Sections 6.2, 6.3, or 6.4, or (ii)
               without cause at any time during a then current Term upon thirty
               (30) days written notice to the other party. In the event that
               viaLink terminates this Agreement


                                        7


<PAGE>   8






               without cause either as of the end of a then current term or at
               any time during a then current term, Lloyd shall be entitled to
               receive all compensation earned by Lloyd hereunder to the date of
               termination but then unpaid, plus an additional amount equal to
               the entirety of his then full current annual salary (i.e., in the
               original term of this Agreement, $190,000), all of which will be
               paid to Lloyd on the effective date of such termination. Upon
               such payment, Lloyd shall not be entitled to any further
               compensation. For purposes of this Agreement, unless otherwise
               specifically indicated, the word "Term" shall include both the
               original one year period of this Agreement and any renewal period
               thereof.

    6.2.       Notwithstanding anything to the contrary herein, this Agreement
               shall immediately terminate, and all rights, benefits and
               obligations hereunder shall cease, in the event of Lloyd's death,
               except such rights of Lloyd which have accrued as of the date of
               death.

    6.3.       Notwithstanding anything to the contrary herein, upon the
               occurrence of the earlier of the following events, this
               Agreement shall immediately terminate and all rights, benefits
               and obligations hereunder shall cease, except such rights of
               Lloyd which have accrued as of the date of disability:

        6.3.1.         if a mutually acceptable physician determines that Lloyd
                       is unable to substantially perform his usual and
                       customary duties under this Agreement for more than three
                       (3) months in any calendar year, or

        6.3.2.         if Lloyd is eligible to begin receiving monthly benefits
                       under any current long-term disability insurance plan.

    6.4.       In addition to the other rights granted to viaLink under this
               Agreement, viaLink shall have the right to terminate this
               Agreement in any of the following events, each of which shall
               constitute "Cause". Cause is defined as:

        6.4.1.         Any breach by Lloyd's of his obligations under Sections
                       3.5, 3.6, 3.7 and/or 3.8 of this Agreement;

        6.4.2.         Lloyd's breach of any of his other duties under this
                       Agreement if such breach continues unremedied for thirty
                       (30) days after written notice thereof to Lloyd
                       specifying the acts constituting the breach and
                       requesting that they be remedied; or

        6.4.3.         a conviction, plea of nolo contendere, plea to a lesser
                       charge in lieu of a felony, of a felony, a crime
                       involving fraud or


                                        8


<PAGE>   9

                       misrepresentation, or any other crime, the effect of
                       which is likely to materially adversely affect viaLink;
                       or

        6.4.4.         violation of any law which results in material liability
                       to viaLink.

        6.4.5.         abuse of alcohol or other drugs, or the illegal use of
                       drugs, which materially interferes with the performance
                       by Lloyd of his duties hereunder.

7.       Successors and Assigns. The rights and obligations of viaLink hereunder
         shall run in favor of and shall be binding upon viaLink, its
         successors, assigns, nominees or other legal representatives. Lloyd may
         not assign his rights and obligations hereunder.

8.       Notices. All notices, requests, demands and other communications
         hereunder must be in writing and shall be deemed to have been duly
         given upon receipt if delivered by hand, sent by telecopier or courier,
         or three (3) days after such communication is mailed within the
         continental United States by first class certified mail, return receipt
         requested, postage prepaid, to the other party, in each case addressed
         as follows:

        8.1.           if to viaLink, The viaLink Company, 13800 Benson Road,
                       Edmond, Oklahoma 73034, Attention Chief Executive
                       Officer; and

        8.2.           if to Lloyd, 3106 Drexel Drive, Dallas, Texas 75205

         Addresses may be changed by written notice sent to the other party at
         the last recorded address of that party.

9.       Severability. If any provision of this Agreement shall be adjudged by
         any court of competent jurisdiction to be invalid or unenforceable for
         any reason, such judgment shall not affect, impair or invalidate the
         remainder of this Agreement.

10.      Entire Understanding. This Agreement embodies the entire understanding
         of the parties hereto, and supersedes all other oral or written
         agreements or understandings between them regarding the subject matter.
         No change, alteration or modification hereof may be made except in a
         writing, signed by both parties hereto. Without limiting the generality
         of the foregoing, but except as may be otherwise stated in this
         Agreement, any prior oral or written offer(s) of employment to Lloyd by
         viaLink shall be null and void and of no further force and effect.

11.      Headings. The headings in this Agreement are for convenience and
         reference only and shall not be construed as part of this Agreement or
         to limit or otherwise affect the meaning hereof.



                                        9


<PAGE>   10






12.      Execution in Counterparts. This Agreement may be executed by the
         parties hereto in counterparts, each of which shall be deemed to be
         original, but all such counterparts shall constitute one and the same
         instrument, and all signatures need not appear on any one counterpart.

13.      Choice of Laws. Jurisdiction over disputes with regard to this
         Agreement shall be exclusively in the courts of the State of Oklahoma,
         and this Agreement shall be construed in accordance with and governed
         by the laws of the state of Oklahoma without giving effect to
         principles of conflicts of law hereunder.

14.      Attorney Fees. In the event of any litigation between the parties
         hereto, the prevailing shall be entitled to all of its costs incurred
         in such litigation, including reasonable attorneys' fees.

15.      Nonwaiver. The waiver of any violation or breach of this Agreement by
         either party hereto shall not be deemed to be a waiver of any
         continuing violation or breach or a waiver of any other violation or
         breach of this Agreement.

16.      Arbitration. Any controversy or claim arising out of or relating to
         this Agreement, or its breach, or its validity or interpretation,
         except claims for injunctive relief and/or claims involving necessary
         third parties who refuse to participate, shall be settled by binding
         arbitration in accordance with the then current rules for arbitration
         of the American Arbitration Association subject to the following:

    16.1.      The location for the arbitration shall be at such location as
               agreed by the parties in Oklahoma County, Oklahoma or if the
               parties cannot agree at such location in Oklahoma County,
               Oklahoma as designated by the American Arbitration Association.

    16.2.      Such arbitration shall be heard and determined by a panel of
               three (3) arbitrators in accordance with the then current rules
               or regulations of the AAA relating to commercial disputes
               ("Rules").

    16.3.      All arbitrators shall be selected pursuant to the then current
               Rules thereof within thirty (30) days after the filing of a
               demand for arbitration. Each arbitrator shall be a person with
               experience in handling disputes relating to the employment
               contracts of corporate executives.

    16.4.      The hearing on the arbitration shall be heard not later than six
               (6) months after the demand for arbitration has been made by a
               party.

    16.5.      The arbitration award shall be binding on the parties and may be
               enforced in any court of competent jurisdiction.



                                       10

<PAGE>   11






    16.6.      The prevailing party in the arbitration and/or in any court
               action authorized by this Agreement shall be entitled to recover
               its reasonable costs and attorney fees incurred by such
               prevailing party, provided however, the parties will split the
               cost of the arbitrators' fees regardless of who prevails in the
               arbitration.

    16.7.      The arbitrators will not have the authority to nor shall they
               award punitive or exemplary damages. Each party hereby waives the
               right to such damages.

    16.8.      In resolving all disputes between the parties, the arbitrators
               will apply the laws of the State of Oklahoma and/or the
               applicable federal law, as the case may be

17.      Survival. In addition to any others Sections of this Agreement which
         survive pursuant to their terms, Sections 3.4, 3.5, 3.6, 3.7, 3.8, 3.9,
         3.10, 5.1, 5.2, 7-16 (inclusive) and this Section 17 shall survive the
         termination or expiration of this Agreement.

IN WITNESS HEREOF, the parties hereto have executed and delivered this Agreement
as of the day and year first above written.

THE viaLink Company                          David M. Lloyd



By: /s/ LEWIS B. KILBOURNE                   /s/ DAVID M. LLOYD
   ------------------------------------      -----------------------------------
     Lewis B. Kilbourne                      David M. Lloyd

Its: Chief Executive Officer


Date:  4/8/99                                Date:  4/9/99
     ----------------------------------           ------------------------------


                                       11